1641196915
在加密中备份私钥的初学者指南 | 4 种最佳方式
在这篇文章中,我们将仔细研究什么是私钥,并就如何改进其保护提供一些建议,即备份加密货币钱包密钥的 4 种最佳方法。
尽管加密货币让他们的用户可以自由地在点对点的基础上转移资金,但这并非没有潜在的问题。在大多数情况下,无法访问您的资金意味着资金本身的损失。为了避免这种情况,您必须注意的关键方面是您的加密钱包的私钥。
私钥是一种复杂的密码学形式,使用户能够访问他们的加密货币。这是一个关键的aspe...?
私钥是对称和非对称加密类型的核心元素。不过,不要让“钥匙”这个词让您感到困惑。密钥本身只是一个用于对编码信息进行加扰和解密的代码,这对于提供您数据的安全性非常重要。当应用于加密货币时,它的作用更为重要。
这两种数据加密方式的区别如下:
现在,这一切与加密货币有什么关系?加密货币钱包的安全性建立在公钥和私钥的原则之上,它们结合起来提供了一种不会危及交易机密性和安全性的加密方法。
公钥代表用户的地址。任何想要将资金发送给钱包所有者的人都知道,他需要私钥才能访问它们。这就是确保私钥受到可靠保护如此重要的原因。它的保护方式在很大程度上取决于钱包类型。
在以安全的方式存储您的数字资金时,有两种基本类型的钱包可供选择:热(在线)和冷(离线)钱包。热钱包需要互联网连接,这可能使它们容易受到黑客攻击。热钱包的主要安全问题是私钥由第三方存储并可通过互联网访问。这就是为什么尽管实施了严格的安全措施,但在使用热钱包时总是存在资产被黑客入侵的风险。
相反,冷钱包是不需要互联网连接的物理设备。您的资金将始终处于离线状态,与热门替代品相比,这使它们更加安全。它们对黑客或计算机病毒免疫,并且私钥通过生成并保存在离线环境中而得到有效保护,远离互联网。从私钥安全的角度来看,冷钱包是一个更好的解决方案。
为什么要备份私钥?
当应用于仅由其所有者控制(而不是由第三方在热钱包上控制)的加密货币时,私钥在确保您的资产安全方面起着至关重要的作用。另一方面,一旦丢失,私钥将无法恢复,无法从钱包中提取资金。
重要的是不要低估备份私钥的重要性,因为人们永远无法知道安装钱包的设备何时出现问题。您的台式机、笔记本电脑、智能手机甚至硬钱包设备都可能丢失、损坏、毁坏或被盗。这就是为什么您应该确保提前备份您的私钥。不过好消息是,只要采取了正确的措施,您仍然可以在任何设备上恢复您的钱包,而且您的资金不会永远被锁定。让我们回顾一下如何做到这一点的一些基本方法。
2. 如何备份您的私钥
请注意,有许多不同类型的钱包,具有各种类型的接口,这可能会使问题复杂化。您可以尝试自己在钱包设置中找到备份选项,或在他们的在线帮助部分搜索说明。总的来说,备份有三种基本形式:
钱包生成的备份类型取决于您使用的钱包类型。例如,最受欢迎的硬件钱包 Trezor 和 Ledger 通过 24 个单词的 BIP39 助记词短语作为种子生成私钥和公钥。
创建备份后,下一步是决定如何存储它。有几种方法可以做到这一点:
管理加密货币并不容易,但您可以从一开始就采取一些措施来保护私钥免受许多危险:
种子短语的工作方式与传统密码类似,但要长得多。它由一组单词(通常长度在 12 到 24 个单词之间)组成,并且对每个用户都是唯一的。它不是一个句子,而是不同单词(例如,toe、box、connect、cricket 等)的随机组合,因此几乎无法预测或猜测。您的种子短语将确保您可以访问与之相关的任何内容,包括您的私钥。
但在这里要非常小心。不能像您的社交媒体或电子邮件密码那样更改种子短语。它旨在作为您的加密帐户的不变默认备份密码保持非常安全。因此,一旦给您这个短语,请确保您将其保持超级安全。将您的种子短语分成两个或多个部分也是一个好主意,这样它就永远不会被整个盗取。
将您的私钥导出到外部位置总是一个好主意。但是,请务必注意,导出您的密钥会将它们显示为清晰、可读的文本,如果您的设备或帐户受到攻击,则它们很容易被网络犯罪分子使用,或者您附近的人可以在屏幕上查看您的密钥(因此请确保您单独在私人区域时执行导出过程)。
但是,将您的私钥导出到其他位置确实意味着它们已被备份并且您可以在紧急情况下访问它们。只需确保将它们导出到重要设备或虚拟位置,并在导出后受到保护。
导出密钥的过程因您使用的钱包而异,因此最好访问钱包提供商的网站并查看常见问题解答部分,或者只是通过搜索引擎搜索如何从您选择的钱包中导出密钥. 无论如何,这不是一个非常困难的过程,所以如果您知道为您的密钥准备了一个安全的位置,请试一试。
当您备份您的加密钱包文件时,私钥将随之备份,这使其成为可行的虚拟备份选项。再一次,这应该单独进行,切勿在公共场合进行。
您可以通过将主密钥复制到文本文件并将其备份到单独的设备来备份此加密钱包文件。或者,您可以创建一个唯一的 QR 码来存储您的主密钥,然后将其打印出来,使其成为物理备份的一种形式(我们将在接下来讨论)。
您也可以将此二维码存储在设备上,但请注意,这会使其更容易受到恶意软件和盗窃的影响。如果您想在设备上存储您的钱包文件或二维码,请尝试专为此设计的软件程序,而不仅仅是您的笔记应用程序。
这可能是所有备份方法中最简单的一种,因为您不需要任何技术知识就可以做到。物理备份涉及使用非虚拟的设备或对象(例如一张纸或闪存驱动器)来备份您的私钥。
这样做的好处在于,它完全避免了网络犯罪分子盗窃您的私钥或因服务器崩溃或故障而丢失您的私钥。但是,您应该注意用于物理备份密钥的内容。例如,一张纸如果没有保存在安全的位置(或意外损坏),很容易被找到或访问,而闪存驱动器很容易丢失(或物理上被盗)。
如果您想像这样物理备份您的密钥,请确保您有一个超级安全的位置,例如安全或隐藏的容器,其他人都不知道。这样,您就可以安全地备份您的密钥,而不必担心它们会消失。
照顾好您的加密资金的安全性似乎很复杂。但是,一旦掌握了可以帮助您避免资金损失的所有原则,您将继续充分了解加密货币的好处,以及确保它们安全的好处。
🔺免责声明:帖子中的信息不是财务建议,仅用于一般信息目的。交易加密货币风险很大。确保您了解这些风险,并且您对自己的资金用途负责。
🔥 如果您是初学者。我相信下面的文章对你有用☞ 投资加密货币之前你应该知道的 - 初学者
感谢您的阅读!
1648803600
I founded this project, because I wanted to publish the code I wrote in the last two years, when I tried to write enhanced checking for PostgreSQL upstream. It was not fully successful - integration into upstream requires some larger plpgsql refactoring - probably it will not be done in next years (now is Dec 2013). But written code is fully functional and can be used in production (and it is used in production). So, I created this extension to be available for all plpgsql developers.
If you like it and if you would to join to development of this extension, register yourself to postgresql extension hacking google group.
Features
I invite any ideas, patches, bugreports.
plpgsql_check is next generation of plpgsql_lint. It allows to check source code by explicit call plpgsql_check_function.
PostgreSQL PostgreSQL 10, 11, 12, 13 and 14 are supported.
The SQL statements inside PL/pgSQL functions are checked by validator for semantic errors. These errors can be found by plpgsql_check_function:
Active mode
postgres=# CREATE EXTENSION plpgsql_check;
LOAD
postgres=# CREATE TABLE t1(a int, b int);
CREATE TABLE
postgres=#
CREATE OR REPLACE FUNCTION public.f1()
RETURNS void
LANGUAGE plpgsql
AS $function$
DECLARE r record;
BEGIN
FOR r IN SELECT * FROM t1
LOOP
RAISE NOTICE '%', r.c; -- there is bug - table t1 missing "c" column
END LOOP;
END;
$function$;
CREATE FUNCTION
postgres=# select f1(); -- execution doesn't find a bug due to empty table t1
f1
────
(1 row)
postgres=# \x
Expanded display is on.
postgres=# select * from plpgsql_check_function_tb('f1()');
─[ RECORD 1 ]───────────────────────────
functionid │ f1
lineno │ 6
statement │ RAISE
sqlstate │ 42703
message │ record "r" has no field "c"
detail │ [null]
hint │ [null]
level │ error
position │ 0
query │ [null]
postgres=# \sf+ f1
CREATE OR REPLACE FUNCTION public.f1()
RETURNS void
LANGUAGE plpgsql
1 AS $function$
2 DECLARE r record;
3 BEGIN
4 FOR r IN SELECT * FROM t1
5 LOOP
6 RAISE NOTICE '%', r.c; -- there is bug - table t1 missing "c" column
7 END LOOP;
8 END;
9 $function$
Function plpgsql_check_function() has three possible formats: text, json or xml
select * from plpgsql_check_function('f1()', fatal_errors := false);
plpgsql_check_function
------------------------------------------------------------------------
error:42703:4:SQL statement:column "c" of relation "t1" does not exist
Query: update t1 set c = 30
-- ^
error:42P01:7:RAISE:missing FROM-clause entry for table "r"
Query: SELECT r.c
-- ^
error:42601:7:RAISE:too few parameters specified for RAISE
(7 rows)
postgres=# select * from plpgsql_check_function('fx()', format:='xml');
plpgsql_check_function
────────────────────────────────────────────────────────────────
<Function oid="16400"> ↵
<Issue> ↵
<Level>error</level> ↵
<Sqlstate>42P01</Sqlstate> ↵
<Message>relation "foo111" does not exist</Message> ↵
<Stmt lineno="3">RETURN</Stmt> ↵
<Query position="23">SELECT (select a from foo111)</Query>↵
</Issue> ↵
</Function>
(1 row)
You can set level of warnings via function's parameters:
'fx()'::regprocedure
or 16799::regprocedure
. Possible alternative is using a name only, when function's name is unique - like 'fx'
. When the name is not unique or the function doesn't exists it raises a error.relid DEFAULT 0
- oid of relation assigned with trigger function. It is necessary for check of any trigger function.
fatal_errors boolean DEFAULT true
- stop on first error
other_warnings boolean DEFAULT true
- show warnings like different attributes number in assignmenet on left and right side, variable overlaps function's parameter, unused variables, unwanted casting, ..
extra_warnings boolean DEFAULT true
- show warnings like missing RETURN
, shadowed variables, dead code, never read (unused) function's parameter, unmodified variables, modified auto variables, ..
performance_warnings boolean DEFAULT false
- performance related warnings like declared type with type modificator, casting, implicit casts in where clause (can be reason why index is not used), ..
security_warnings boolean DEFAULT false
- security related checks like SQL injection vulnerability detection
anyelementtype regtype DEFAULT 'int'
- a real type used instead anyelement type
anyenumtype regtype DEFAULT '-'
- a real type used instead anyenum type
anyrangetype regtype DEFAULT 'int4range'
- a real type used instead anyrange type
anycompatibletype DEFAULT 'int'
- a real type used instead anycompatible type
anycompatiblerangetype DEFAULT 'int4range'
- a real type used instead anycompatible range type
without_warnings DEFAULT false
- disable all warnings
all_warnings DEFAULT false
- enable all warnings
newtable DEFAULT NULL
, oldtable DEFAULT NULL
- the names of NEW or OLD transitive tables. These parameters are required when transitive tables are used.
When you want to check any trigger, you have to enter a relation that will be used together with trigger function
CREATE TABLE bar(a int, b int);
postgres=# \sf+ foo_trg
CREATE OR REPLACE FUNCTION public.foo_trg()
RETURNS trigger
LANGUAGE plpgsql
1 AS $function$
2 BEGIN
3 NEW.c := NEW.a + NEW.b;
4 RETURN NEW;
5 END;
6 $function$
Missing relation specification
postgres=# select * from plpgsql_check_function('foo_trg()');
ERROR: missing trigger relation
HINT: Trigger relation oid must be valid
Correct trigger checking (with specified relation)
postgres=# select * from plpgsql_check_function('foo_trg()', 'bar');
plpgsql_check_function
--------------------------------------------------------
error:42703:3:assignment:record "new" has no field "c"
(1 row)
For triggers with transitive tables you can set a oldtable
or newtable
parameters:
create or replace function footab_trig_func()
returns trigger as $$
declare x int;
begin
if false then
-- should be ok;
select count(*) from newtab into x;
-- should fail;
select count(*) from newtab where d = 10 into x;
end if;
return null;
end;
$$ language plpgsql;
select * from plpgsql_check_function('footab_trig_func','footab', newtable := 'newtab');
You can use the plpgsql_check_function for mass check functions and mass check triggers. Please, test following queries:
-- check all nontrigger plpgsql functions
SELECT p.oid, p.proname, plpgsql_check_function(p.oid)
FROM pg_catalog.pg_namespace n
JOIN pg_catalog.pg_proc p ON pronamespace = n.oid
JOIN pg_catalog.pg_language l ON p.prolang = l.oid
WHERE l.lanname = 'plpgsql' AND p.prorettype <> 2279;
or
SELECT p.proname, tgrelid::regclass, cf.*
FROM pg_proc p
JOIN pg_trigger t ON t.tgfoid = p.oid
JOIN pg_language l ON p.prolang = l.oid
JOIN pg_namespace n ON p.pronamespace = n.oid,
LATERAL plpgsql_check_function(p.oid, t.tgrelid) cf
WHERE n.nspname = 'public' and l.lanname = 'plpgsql'
or
-- check all plpgsql functions (functions or trigger functions with defined triggers)
SELECT
(pcf).functionid::regprocedure, (pcf).lineno, (pcf).statement,
(pcf).sqlstate, (pcf).message, (pcf).detail, (pcf).hint, (pcf).level,
(pcf)."position", (pcf).query, (pcf).context
FROM
(
SELECT
plpgsql_check_function_tb(pg_proc.oid, COALESCE(pg_trigger.tgrelid, 0)) AS pcf
FROM pg_proc
LEFT JOIN pg_trigger
ON (pg_trigger.tgfoid = pg_proc.oid)
WHERE
prolang = (SELECT lang.oid FROM pg_language lang WHERE lang.lanname = 'plpgsql') AND
pronamespace <> (SELECT nsp.oid FROM pg_namespace nsp WHERE nsp.nspname = 'pg_catalog') AND
-- ignore unused triggers
(pg_proc.prorettype <> (SELECT typ.oid FROM pg_type typ WHERE typ.typname = 'trigger') OR
pg_trigger.tgfoid IS NOT NULL)
OFFSET 0
) ss
ORDER BY (pcf).functionid::regprocedure::text, (pcf).lineno
Passive mode
Functions should be checked on start - plpgsql_check module must be loaded.
plpgsql_check.mode = [ disabled | by_function | fresh_start | every_start ]
plpgsql_check.fatal_errors = [ yes | no ]
plpgsql_check.show_nonperformance_warnings = false
plpgsql_check.show_performance_warnings = false
Default mode is by_function, that means that the enhanced check is done only in active mode - by plpgsql_check_function. fresh_start
means cold start.
You can enable passive mode by
load 'plpgsql'; -- 1.1 and higher doesn't need it
load 'plpgsql_check';
set plpgsql_check.mode = 'every_start';
SELECT fx(10); -- run functions - function is checked before runtime starts it
Limits
plpgsql_check should find almost all errors on really static code. When developer use some PLpgSQL's dynamic features like dynamic SQL or record data type, then false positives are possible. These should be rare - in well written code - and then the affected function should be redesigned or plpgsql_check should be disabled for this function.
CREATE OR REPLACE FUNCTION f1()
RETURNS void AS $$
DECLARE r record;
BEGIN
FOR r IN EXECUTE 'SELECT * FROM t1'
LOOP
RAISE NOTICE '%', r.c;
END LOOP;
END;
$$ LANGUAGE plpgsql SET plpgsql.enable_check TO false;
A usage of plpgsql_check adds a small overhead (in enabled passive mode) and you should use it only in develop or preprod environments.
This module doesn't check queries that are assembled in runtime. It is not possible to identify results of dynamic queries - so plpgsql_check cannot to set correct type to record variables and cannot to check a dependent SQLs and expressions.
When type of record's variable is not know, you can assign it explicitly with pragma type
:
DECLARE r record;
BEGIN
EXECUTE format('SELECT * FROM %I', _tablename) INTO r;
PERFORM plpgsql_check_pragma('type: r (id int, processed bool)');
IF NOT r.processed THEN
...
Attention: The SQL injection check can detect only some SQL injection vulnerabilities. This tool cannot be used for security audit! Some issues should not be detected. This check can raise false alarms too - probably when variable is sanitized by other command or when value is of some compose type.
plpgsql_check should not to detect structure of referenced cursors. A reference on cursor in PLpgSQL is implemented as name of global cursor. In check time, the name is not known (not in all possibilities), and global cursor doesn't exist. It is significant break for any static analyse. PLpgSQL cannot to set correct type for record variables and cannot to check a dependent SQLs and expressions. A solution is same like dynamic SQL. Don't use record variable as target when you use refcursor type or disable plpgsql_check for these functions.
CREATE OR REPLACE FUNCTION foo(refcur_var refcursor)
RETURNS void AS $$
DECLARE
rec_var record;
BEGIN
FETCH refcur_var INTO rec_var; -- this is STOP for plpgsql_check
RAISE NOTICE '%', rec_var; -- record rec_var is not assigned yet error
In this case a record type should not be used (use known rowtype instead):
CREATE OR REPLACE FUNCTION foo(refcur_var refcursor)
RETURNS void AS $$
DECLARE
rec_var some_rowtype;
BEGIN
FETCH refcur_var INTO rec_var;
RAISE NOTICE '%', rec_var;
plpgsql_check cannot verify queries over temporary tables that are created in plpgsql's function runtime. For this use case it is necessary to create a fake temp table or disable plpgsql_check for this function.
In reality temp tables are stored in own (per user) schema with higher priority than persistent tables. So you can do (with following trick safetly):
CREATE OR REPLACE FUNCTION public.disable_dml()
RETURNS trigger
LANGUAGE plpgsql AS $function$
BEGIN
RAISE EXCEPTION SQLSTATE '42P01'
USING message = format('this instance of %I table doesn''t allow any DML operation', TG_TABLE_NAME),
hint = format('you should to run "CREATE TEMP TABLE %1$I(LIKE %1$I INCLUDING ALL);" statement',
TG_TABLE_NAME);
RETURN NULL;
END;
$function$;
CREATE TABLE foo(a int, b int); -- doesn't hold data ever
CREATE TRIGGER foo_disable_dml
BEFORE INSERT OR UPDATE OR DELETE ON foo
EXECUTE PROCEDURE disable_dml();
postgres=# INSERT INTO foo VALUES(10,20);
ERROR: this instance of foo table doesn't allow any DML operation
HINT: you should to run "CREATE TEMP TABLE foo(LIKE foo INCLUDING ALL);" statement
postgres=#
CREATE TABLE
postgres=# INSERT INTO foo VALUES(10,20);
INSERT 0 1
This trick emulates GLOBAL TEMP tables partially and it allows a statical validation. Other possibility is using a [template foreign data wrapper] (https://github.com/okbob/template_fdw)
You can use pragma table
and create ephemeral table:
BEGIN
CREATE TEMP TABLE xxx(a int);
PERFORM plpgsql_check_pragma('table: xxx(a int)');
INSERT INTO xxx VALUES(10);
Dependency list
A function plpgsql_show_dependency_tb can show all functions, operators and relations used inside processed function:
postgres=# select * from plpgsql_show_dependency_tb('testfunc(int,float)');
┌──────────┬───────┬────────┬─────────┬────────────────────────────┐
│ type │ oid │ schema │ name │ params │
╞══════════╪═══════╪════════╪═════════╪════════════════════════════╡
│ FUNCTION │ 36008 │ public │ myfunc1 │ (integer,double precision) │
│ FUNCTION │ 35999 │ public │ myfunc2 │ (integer,double precision) │
│ OPERATOR │ 36007 │ public │ ** │ (integer,integer) │
│ RELATION │ 36005 │ public │ myview │ │
│ RELATION │ 36002 │ public │ mytable │ │
└──────────┴───────┴────────┴─────────┴────────────────────────────┘
(4 rows)
Profiler
The plpgsql_check contains simple profiler of plpgsql functions and procedures. It can work with/without a access to shared memory. It depends on shared_preload_libraries
config. When plpgsql_check was initialized by shared_preload_libraries
, then it can allocate shared memory, and function's profiles are stored there. When plpgsql_check cannot to allocate shared momory, the profile is stored in session memory.
Due dependencies, shared_preload_libraries
should to contains plpgsql
first
postgres=# show shared_preload_libraries ;
┌──────────────────────────┐
│ shared_preload_libraries │
╞══════════════════════════╡
│ plpgsql,plpgsql_check │
└──────────────────────────┘
(1 row)
The profiler is active when GUC plpgsql_check.profiler
is on. The profiler doesn't require shared memory, but if there are not shared memory, then the profile is limmitted just to active session.
When plpgsql_check is initialized by shared_preload_libraries
, another GUC is available to configure the amount of shared memory used by the profiler: plpgsql_check.profiler_max_shared_chunks
. This defines the maximum number of statements chunk that can be stored in shared memory. For each plpgsql function (or procedure), the whole content is split into chunks of 30 statements. If needed, multiple chunks can be used to store the whole content of a single function. A single chunk is 1704 bytes. The default value for this GUC is 15000, which should be enough for big projects containing hundred of thousands of statements in plpgsql, and will consume about 24MB of memory. If your project doesn't require that much number of chunks, you can set this parameter to a smaller number in order to decrease the memory usage. The minimum value is 50 (which should consume about 83kB of memory), and the maximum value is 100000 (which should consume about 163MB of memory). Changing this parameter requires a PostgreSQL restart.
The profiler will also retrieve the query identifier for each instruction that contains an expression or optimizable statement. Note that this requires pg_stat_statements, or another similar third-party extension), to be installed. There are some limitations to the query identifier retrieval:
Attention: A update of shared profiles can decrease performance on servers under higher load.
The profile can be displayed by function plpgsql_profiler_function_tb
:
postgres=# select lineno, avg_time, source from plpgsql_profiler_function_tb('fx(int)');
┌────────┬──────────┬───────────────────────────────────────────────────────────────────┐
│ lineno │ avg_time │ source │
╞════════╪══════════╪═══════════════════════════════════════════════════════════════════╡
│ 1 │ │ │
│ 2 │ │ declare result int = 0; │
│ 3 │ 0.075 │ begin │
│ 4 │ 0.202 │ for i in 1..$1 loop │
│ 5 │ 0.005 │ select result + i into result; select result + i into result; │
│ 6 │ │ end loop; │
│ 7 │ 0 │ return result; │
│ 8 │ │ end; │
└────────┴──────────┴───────────────────────────────────────────────────────────────────┘
(9 rows)
The profile per statements (not per line) can be displayed by function plpgsql_profiler_function_statements_tb:
CREATE OR REPLACE FUNCTION public.fx1(a integer)
RETURNS integer
LANGUAGE plpgsql
1 AS $function$
2 begin
3 if a > 10 then
4 raise notice 'ahoj';
5 return -1;
6 else
7 raise notice 'nazdar';
8 return 1;
9 end if;
10 end;
11 $function$
postgres=# select stmtid, parent_stmtid, parent_note, lineno, exec_stmts, stmtname
from plpgsql_profiler_function_statements_tb('fx1');
┌────────┬───────────────┬─────────────┬────────┬────────────┬─────────────────┐
│ stmtid │ parent_stmtid │ parent_note │ lineno │ exec_stmts │ stmtname │
╞════════╪═══════════════╪═════════════╪════════╪════════════╪═════════════════╡
│ 0 │ ∅ │ ∅ │ 2 │ 0 │ statement block │
│ 1 │ 0 │ body │ 3 │ 0 │ IF │
│ 2 │ 1 │ then body │ 4 │ 0 │ RAISE │
│ 3 │ 1 │ then body │ 5 │ 0 │ RETURN │
│ 4 │ 1 │ else body │ 7 │ 0 │ RAISE │
│ 5 │ 1 │ else body │ 8 │ 0 │ RETURN │
└────────┴───────────────┴─────────────┴────────┴────────────┴─────────────────┘
(6 rows)
All stored profiles can be displayed by calling function plpgsql_profiler_functions_all
:
postgres=# select * from plpgsql_profiler_functions_all();
┌───────────────────────┬────────────┬────────────┬──────────┬─────────────┬──────────┬──────────┐
│ funcoid │ exec_count │ total_time │ avg_time │ stddev_time │ min_time │ max_time │
╞═══════════════════════╪════════════╪════════════╪══════════╪═════════════╪══════════╪══════════╡
│ fxx(double precision) │ 1 │ 0.01 │ 0.01 │ 0.00 │ 0.01 │ 0.01 │
└───────────────────────┴────────────┴────────────┴──────────┴─────────────┴──────────┴──────────┘
(1 row)
There are two functions for cleaning stored profiles: plpgsql_profiler_reset_all()
and plpgsql_profiler_reset(regprocedure)
.
plpgsql_check provides two functions:
plpgsql_coverage_statements(name)
plpgsql_coverage_branches(name)
There is another very good PLpgSQL profiler - https://bitbucket.org/openscg/plprofiler
My extension is designed to be simple for use and practical. Nothing more or less.
plprofiler is more complex. It build call graphs and from this graph it can creates flame graph of execution times.
Both extensions can be used together with buildin PostgreSQL's feature - tracking functions.
set track_functions to 'pl';
...
select * from pg_stat_user_functions;
Tracer
plpgsql_check provides a tracing possibility - in this mode you can see notices on start or end functions (terse and default verbosity) and start or end statements (verbose verbosity). For default and verbose verbosity the content of function arguments is displayed. The content of related variables are displayed when verbosity is verbose.
postgres=# do $$ begin perform fx(10,null, 'now', e'stěhule'); end; $$;
NOTICE: #0 ->> start of inline_code_block (Oid=0)
NOTICE: #2 ->> start of function fx(integer,integer,date,text) (Oid=16405)
NOTICE: #2 call by inline_code_block line 1 at PERFORM
NOTICE: #2 "a" => '10', "b" => null, "c" => '2020-08-03', "d" => 'stěhule'
NOTICE: #4 ->> start of function fx(integer) (Oid=16404)
NOTICE: #4 call by fx(integer,integer,date,text) line 1 at PERFORM
NOTICE: #4 "a" => '10'
NOTICE: #4 <<- end of function fx (elapsed time=0.098 ms)
NOTICE: #2 <<- end of function fx (elapsed time=0.399 ms)
NOTICE: #0 <<- end of block (elapsed time=0.754 ms)
The number after #
is a execution frame counter (this number is related to deep of error context stack). It allows to pair start end and of function.
Tracing is enabled by setting plpgsql_check.tracer
to on
. Attention - enabling this behaviour has significant negative impact on performance (unlike the profiler). You can set a level for output used by tracer plpgsql_check.tracer_errlevel
(default is notice
). The output content is limited by length specified by plpgsql_check.tracer_variable_max_length
configuration variable.
In terse verbose mode the output is reduced:
postgres=# set plpgsql_check.tracer_verbosity TO terse;
SET
postgres=# do $$ begin perform fx(10,null, 'now', e'stěhule'); end; $$;
NOTICE: #0 start of inline code block (oid=0)
NOTICE: #2 start of fx (oid=16405)
NOTICE: #4 start of fx (oid=16404)
NOTICE: #4 end of fx
NOTICE: #2 end of fx
NOTICE: #0 end of inline code block
In verbose mode the output is extended about statement details:
postgres=# do $$ begin perform fx(10,null, 'now', e'stěhule'); end; $$;
NOTICE: #0 ->> start of block inline_code_block (oid=0)
NOTICE: #0.1 1 --> start of PERFORM
NOTICE: #2 ->> start of function fx(integer,integer,date,text) (oid=16405)
NOTICE: #2 call by inline_code_block line 1 at PERFORM
NOTICE: #2 "a" => '10', "b" => null, "c" => '2020-08-04', "d" => 'stěhule'
NOTICE: #2.1 1 --> start of PERFORM
NOTICE: #2.1 "a" => '10'
NOTICE: #4 ->> start of function fx(integer) (oid=16404)
NOTICE: #4 call by fx(integer,integer,date,text) line 1 at PERFORM
NOTICE: #4 "a" => '10'
NOTICE: #4.1 6 --> start of assignment
NOTICE: #4.1 "a" => '10', "b" => '20'
NOTICE: #4.1 <-- end of assignment (elapsed time=0.076 ms)
NOTICE: #4.1 "res" => '130'
NOTICE: #4.2 7 --> start of RETURN
NOTICE: #4.2 "res" => '130'
NOTICE: #4.2 <-- end of RETURN (elapsed time=0.054 ms)
NOTICE: #4 <<- end of function fx (elapsed time=0.373 ms)
NOTICE: #2.1 <-- end of PERFORM (elapsed time=0.589 ms)
NOTICE: #2 <<- end of function fx (elapsed time=0.727 ms)
NOTICE: #0.1 <-- end of PERFORM (elapsed time=1.147 ms)
NOTICE: #0 <<- end of block (elapsed time=1.286 ms)
Special feature of tracer is tracing of ASSERT
statement when plpgsql_check.trace_assert
is on
. When plpgsql_check.trace_assert_verbosity
is DEFAULT
, then all function's or procedure's variables are displayed when assert expression is false. When this configuration is VERBOSE
then all variables from all plpgsql frames are displayed. This behaviour is independent on plpgsql.check_asserts
value. It can be used, although the assertions are disabled in plpgsql runtime.
postgres=# set plpgsql_check.tracer to off;
postgres=# set plpgsql_check.trace_assert_verbosity TO verbose;
postgres=# do $$ begin perform fx(10,null, 'now', e'stěhule'); end; $$;
NOTICE: #4 PLpgSQL assert expression (false) on line 12 of fx(integer) is false
NOTICE: "a" => '10', "res" => null, "b" => '20'
NOTICE: #2 PL/pgSQL function fx(integer,integer,date,text) line 1 at PERFORM
NOTICE: "a" => '10', "b" => null, "c" => '2020-08-05', "d" => 'stěhule'
NOTICE: #0 PL/pgSQL function inline_code_block line 1 at PERFORM
ERROR: assertion failed
CONTEXT: PL/pgSQL function fx(integer) line 12 at ASSERT
SQL statement "SELECT fx(a)"
PL/pgSQL function fx(integer,integer,date,text) line 1 at PERFORM
SQL statement "SELECT fx(10,null, 'now', e'stěhule')"
PL/pgSQL function inline_code_block line 1 at PERFORM
postgres=# set plpgsql.check_asserts to off;
SET
postgres=# do $$ begin perform fx(10,null, 'now', e'stěhule'); end; $$;
NOTICE: #4 PLpgSQL assert expression (false) on line 12 of fx(integer) is false
NOTICE: "a" => '10', "res" => null, "b" => '20'
NOTICE: #2 PL/pgSQL function fx(integer,integer,date,text) line 1 at PERFORM
NOTICE: "a" => '10', "b" => null, "c" => '2020-08-05', "d" => 'stěhule'
NOTICE: #0 PL/pgSQL function inline_code_block line 1 at PERFORM
DO
Tracer prints content of variables or function arguments. For security definer function, this content can hold security sensitive data. This is reason why tracer is disabled by default and should be enabled only with super user rights plpgsql_check.enable_tracer
.
Pragma
You can configure plpgsql_check behave inside checked function with "pragma" function. This is a analogy of PL/SQL or ADA language of PRAGMA feature. PLpgSQL doesn't support PRAGMA, but plpgsql_check detects function named plpgsql_check_pragma
and get options from parameters of this function. These plpgsql_check options are valid to end of group of statements.
CREATE OR REPLACE FUNCTION test()
RETURNS void AS $$
BEGIN
...
-- for following statements disable check
PERFORM plpgsql_check_pragma('disable:check');
...
-- enable check again
PERFORM plpgsql_check_pragma('enable:check');
...
END;
$$ LANGUAGE plpgsql;
The function plpgsql_check_pragma
is immutable function that returns one. It is defined by plpgsql_check
extension. You can declare alternative plpgsql_check_pragma
function like:
CREATE OR REPLACE FUNCTION plpgsql_check_pragma(VARIADIC args[])
RETURNS int AS $$
SELECT 1
$$ LANGUAGE sql IMMUTABLE;
Using pragma function in declaration part of top block sets options on function level too.
CREATE OR REPLACE FUNCTION test()
RETURNS void AS $$
DECLARE
aux int := plpgsql_check_pragma('disable:extra_warnings');
...
Shorter syntax for pragma is supported too:
CREATE OR REPLACE FUNCTION test()
RETURNS void AS $$
DECLARE r record;
BEGIN
PERFORM 'PRAGMA:TYPE:r (a int, b int)';
PERFORM 'PRAGMA:TABLE: x (like pg_class)';
...
echo:str
- print string (for testing)
status:check
,status:tracer
, status:other_warnings
, status:performance_warnings
, status:extra_warnings
,status:security_warnings
enable:check
,enable:tracer
, enable:other_warnings
, enable:performance_warnings
, enable:extra_warnings
,enable:security_warnings
disable:check
,disable:tracer
, disable:other_warnings
, disable:performance_warnings
, disable:extra_warnings
,disable:security_warnings
type:varname typename
or type:varname (fieldname type, ...)
- set type to variable of record type
table: name (column_name type, ...)
or table: name (like tablename)
- create ephereal table
Pragmas enable:tracer
and disable:tracer
are active for Postgres 12 and higher
Compilation
You need a development environment for PostgreSQL extensions:
make clean
make install
result:
[pavel@localhost plpgsql_check]$ make USE_PGXS=1 clean
rm -f plpgsql_check.so libplpgsql_check.a libplpgsql_check.pc
rm -f plpgsql_check.o
rm -rf results/ regression.diffs regression.out tmp_check/ log/
[pavel@localhost plpgsql_check]$ make USE_PGXS=1 all
clang -O2 -Wall -Wmissing-prototypes -Wpointer-arith -Wdeclaration-after-statement -Wendif-labels -Wmissing-format-attribute -Wformat-security -fno-strict-aliasing -fwrapv -fpic -I/usr/local/pgsql/lib/pgxs/src/makefiles/../../src/pl/plpgsql/src -I. -I./ -I/usr/local/pgsql/include/server -I/usr/local/pgsql/include/internal -D_GNU_SOURCE -c -o plpgsql_check.o plpgsql_check.c
clang -O2 -Wall -Wmissing-prototypes -Wpointer-arith -Wdeclaration-after-statement -Wendif-labels -Wmissing-format-attribute -Wformat-security -fno-strict-aliasing -fwrapv -fpic -I/usr/local/pgsql/lib/pgxs/src/makefiles/../../src/pl/plpgsql/src -shared -o plpgsql_check.so plpgsql_check.o -L/usr/local/pgsql/lib -Wl,--as-needed -Wl,-rpath,'/usr/local/pgsql/lib',--enable-new-dtags
[pavel@localhost plpgsql_check]$ su root
Password: *******
[root@localhost plpgsql_check]# make USE_PGXS=1 install
/usr/bin/mkdir -p '/usr/local/pgsql/lib'
/usr/bin/mkdir -p '/usr/local/pgsql/share/extension'
/usr/bin/mkdir -p '/usr/local/pgsql/share/extension'
/usr/bin/install -c -m 755 plpgsql_check.so '/usr/local/pgsql/lib/plpgsql_check.so'
/usr/bin/install -c -m 644 plpgsql_check.control '/usr/local/pgsql/share/extension/'
/usr/bin/install -c -m 644 plpgsql_check--0.9.sql '/usr/local/pgsql/share/extension/'
[root@localhost plpgsql_check]# exit
[pavel@localhost plpgsql_check]$ make USE_PGXS=1 installcheck
/usr/local/pgsql/lib/pgxs/src/makefiles/../../src/test/regress/pg_regress --inputdir=./ --psqldir='/usr/local/pgsql/bin' --dbname=pl_regression --load-language=plpgsql --dbname=contrib_regression plpgsql_check_passive plpgsql_check_active plpgsql_check_active-9.5
(using postmaster on Unix socket, default port)
============== dropping database "contrib_regression" ==============
DROP DATABASE
============== creating database "contrib_regression" ==============
CREATE DATABASE
ALTER DATABASE
============== installing plpgsql ==============
CREATE LANGUAGE
============== running regression test queries ==============
test plpgsql_check_passive ... ok
test plpgsql_check_active ... ok
test plpgsql_check_active-9.5 ... ok
=====================
All 3 tests passed.
=====================
Sometimes successful compilation can require libicu-dev package (PostgreSQL 10 and higher - when pg was compiled with ICU support)
sudo apt install libicu-dev
You can check precompiled dll libraries http://okbob.blogspot.cz/2015/02/plpgsqlcheck-is-available-for-microsoft.html
or compile by self:
plpgsql_check.dll
to PostgreSQL\14\lib
plpgsql_check.control
and plpgsql_check--2.1.sql
to PostgreSQL\14\share\extension
Compilation against PostgreSQL 10 requires libICU!
Licence
Copyright (c) Pavel Stehule (pavel.stehule@gmail.com)
Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:
The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.
THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
Note
If you like it, send a postcard to address
Pavel Stehule
Skalice 12
256 01 Benesov u Prahy
Czech Republic
I invite any questions, comments, bug reports, patches on mail address pavel.stehule@gmail.com
Author: okbob
Source Code: https://github.com/okbob/plpgsql_check
License: View license
1648900800
I founded this project, because I wanted to publish the code I wrote in the last two years, when I tried to write enhanced checking for PostgreSQL upstream. It was not fully successful - integration into upstream requires some larger plpgsql refactoring - probably it will not be done in next years (now is Dec 2013). But written code is fully functional and can be used in production (and it is used in production). So, I created this extension to be available for all plpgsql developers.
If you like it and if you would to join to development of this extension, register yourself to postgresql extension hacking google group.
Features
I invite any ideas, patches, bugreports.
plpgsql_check is next generation of plpgsql_lint. It allows to check source code by explicit call plpgsql_check_function.
PostgreSQL PostgreSQL 10, 11, 12, 13 and 14 are supported.
The SQL statements inside PL/pgSQL functions are checked by validator for semantic errors. These errors can be found by plpgsql_check_function:
Active mode
postgres=# CREATE EXTENSION plpgsql_check;
LOAD
postgres=# CREATE TABLE t1(a int, b int);
CREATE TABLE
postgres=#
CREATE OR REPLACE FUNCTION public.f1()
RETURNS void
LANGUAGE plpgsql
AS $function$
DECLARE r record;
BEGIN
FOR r IN SELECT * FROM t1
LOOP
RAISE NOTICE '%', r.c; -- there is bug - table t1 missing "c" column
END LOOP;
END;
$function$;
CREATE FUNCTION
postgres=# select f1(); -- execution doesn't find a bug due to empty table t1
f1
────
(1 row)
postgres=# \x
Expanded display is on.
postgres=# select * from plpgsql_check_function_tb('f1()');
─[ RECORD 1 ]───────────────────────────
functionid │ f1
lineno │ 6
statement │ RAISE
sqlstate │ 42703
message │ record "r" has no field "c"
detail │ [null]
hint │ [null]
level │ error
position │ 0
query │ [null]
postgres=# \sf+ f1
CREATE OR REPLACE FUNCTION public.f1()
RETURNS void
LANGUAGE plpgsql
1 AS $function$
2 DECLARE r record;
3 BEGIN
4 FOR r IN SELECT * FROM t1
5 LOOP
6 RAISE NOTICE '%', r.c; -- there is bug - table t1 missing "c" column
7 END LOOP;
8 END;
9 $function$
Function plpgsql_check_function() has three possible formats: text, json or xml
select * from plpgsql_check_function('f1()', fatal_errors := false);
plpgsql_check_function
------------------------------------------------------------------------
error:42703:4:SQL statement:column "c" of relation "t1" does not exist
Query: update t1 set c = 30
-- ^
error:42P01:7:RAISE:missing FROM-clause entry for table "r"
Query: SELECT r.c
-- ^
error:42601:7:RAISE:too few parameters specified for RAISE
(7 rows)
postgres=# select * from plpgsql_check_function('fx()', format:='xml');
plpgsql_check_function
────────────────────────────────────────────────────────────────
<Function oid="16400"> ↵
<Issue> ↵
<Level>error</level> ↵
<Sqlstate>42P01</Sqlstate> ↵
<Message>relation "foo111" does not exist</Message> ↵
<Stmt lineno="3">RETURN</Stmt> ↵
<Query position="23">SELECT (select a from foo111)</Query>↵
</Issue> ↵
</Function>
(1 row)
You can set level of warnings via function's parameters:
'fx()'::regprocedure
or 16799::regprocedure
. Possible alternative is using a name only, when function's name is unique - like 'fx'
. When the name is not unique or the function doesn't exists it raises a error.relid DEFAULT 0
- oid of relation assigned with trigger function. It is necessary for check of any trigger function.
fatal_errors boolean DEFAULT true
- stop on first error
other_warnings boolean DEFAULT true
- show warnings like different attributes number in assignmenet on left and right side, variable overlaps function's parameter, unused variables, unwanted casting, ..
extra_warnings boolean DEFAULT true
- show warnings like missing RETURN
, shadowed variables, dead code, never read (unused) function's parameter, unmodified variables, modified auto variables, ..
performance_warnings boolean DEFAULT false
- performance related warnings like declared type with type modificator, casting, implicit casts in where clause (can be reason why index is not used), ..
security_warnings boolean DEFAULT false
- security related checks like SQL injection vulnerability detection
anyelementtype regtype DEFAULT 'int'
- a real type used instead anyelement type
anyenumtype regtype DEFAULT '-'
- a real type used instead anyenum type
anyrangetype regtype DEFAULT 'int4range'
- a real type used instead anyrange type
anycompatibletype DEFAULT 'int'
- a real type used instead anycompatible type
anycompatiblerangetype DEFAULT 'int4range'
- a real type used instead anycompatible range type
without_warnings DEFAULT false
- disable all warnings
all_warnings DEFAULT false
- enable all warnings
newtable DEFAULT NULL
, oldtable DEFAULT NULL
- the names of NEW or OLD transitive tables. These parameters are required when transitive tables are used.
When you want to check any trigger, you have to enter a relation that will be used together with trigger function
CREATE TABLE bar(a int, b int);
postgres=# \sf+ foo_trg
CREATE OR REPLACE FUNCTION public.foo_trg()
RETURNS trigger
LANGUAGE plpgsql
1 AS $function$
2 BEGIN
3 NEW.c := NEW.a + NEW.b;
4 RETURN NEW;
5 END;
6 $function$
Missing relation specification
postgres=# select * from plpgsql_check_function('foo_trg()');
ERROR: missing trigger relation
HINT: Trigger relation oid must be valid
Correct trigger checking (with specified relation)
postgres=# select * from plpgsql_check_function('foo_trg()', 'bar');
plpgsql_check_function
--------------------------------------------------------
error:42703:3:assignment:record "new" has no field "c"
(1 row)
For triggers with transitive tables you can set a oldtable
or newtable
parameters:
create or replace function footab_trig_func()
returns trigger as $$
declare x int;
begin
if false then
-- should be ok;
select count(*) from newtab into x;
-- should fail;
select count(*) from newtab where d = 10 into x;
end if;
return null;
end;
$$ language plpgsql;
select * from plpgsql_check_function('footab_trig_func','footab', newtable := 'newtab');
You can use the plpgsql_check_function for mass check functions and mass check triggers. Please, test following queries:
-- check all nontrigger plpgsql functions
SELECT p.oid, p.proname, plpgsql_check_function(p.oid)
FROM pg_catalog.pg_namespace n
JOIN pg_catalog.pg_proc p ON pronamespace = n.oid
JOIN pg_catalog.pg_language l ON p.prolang = l.oid
WHERE l.lanname = 'plpgsql' AND p.prorettype <> 2279;
or
SELECT p.proname, tgrelid::regclass, cf.*
FROM pg_proc p
JOIN pg_trigger t ON t.tgfoid = p.oid
JOIN pg_language l ON p.prolang = l.oid
JOIN pg_namespace n ON p.pronamespace = n.oid,
LATERAL plpgsql_check_function(p.oid, t.tgrelid) cf
WHERE n.nspname = 'public' and l.lanname = 'plpgsql'
or
-- check all plpgsql functions (functions or trigger functions with defined triggers)
SELECT
(pcf).functionid::regprocedure, (pcf).lineno, (pcf).statement,
(pcf).sqlstate, (pcf).message, (pcf).detail, (pcf).hint, (pcf).level,
(pcf)."position", (pcf).query, (pcf).context
FROM
(
SELECT
plpgsql_check_function_tb(pg_proc.oid, COALESCE(pg_trigger.tgrelid, 0)) AS pcf
FROM pg_proc
LEFT JOIN pg_trigger
ON (pg_trigger.tgfoid = pg_proc.oid)
WHERE
prolang = (SELECT lang.oid FROM pg_language lang WHERE lang.lanname = 'plpgsql') AND
pronamespace <> (SELECT nsp.oid FROM pg_namespace nsp WHERE nsp.nspname = 'pg_catalog') AND
-- ignore unused triggers
(pg_proc.prorettype <> (SELECT typ.oid FROM pg_type typ WHERE typ.typname = 'trigger') OR
pg_trigger.tgfoid IS NOT NULL)
OFFSET 0
) ss
ORDER BY (pcf).functionid::regprocedure::text, (pcf).lineno
Passive mode
Functions should be checked on start - plpgsql_check module must be loaded.
plpgsql_check.mode = [ disabled | by_function | fresh_start | every_start ]
plpgsql_check.fatal_errors = [ yes | no ]
plpgsql_check.show_nonperformance_warnings = false
plpgsql_check.show_performance_warnings = false
Default mode is by_function, that means that the enhanced check is done only in active mode - by plpgsql_check_function. fresh_start
means cold start.
You can enable passive mode by
load 'plpgsql'; -- 1.1 and higher doesn't need it
load 'plpgsql_check';
set plpgsql_check.mode = 'every_start';
SELECT fx(10); -- run functions - function is checked before runtime starts it
Limits
plpgsql_check should find almost all errors on really static code. When developer use some PLpgSQL's dynamic features like dynamic SQL or record data type, then false positives are possible. These should be rare - in well written code - and then the affected function should be redesigned or plpgsql_check should be disabled for this function.
CREATE OR REPLACE FUNCTION f1()
RETURNS void AS $$
DECLARE r record;
BEGIN
FOR r IN EXECUTE 'SELECT * FROM t1'
LOOP
RAISE NOTICE '%', r.c;
END LOOP;
END;
$$ LANGUAGE plpgsql SET plpgsql.enable_check TO false;
A usage of plpgsql_check adds a small overhead (in enabled passive mode) and you should use it only in develop or preprod environments.
This module doesn't check queries that are assembled in runtime. It is not possible to identify results of dynamic queries - so plpgsql_check cannot to set correct type to record variables and cannot to check a dependent SQLs and expressions.
When type of record's variable is not know, you can assign it explicitly with pragma type
:
DECLARE r record;
BEGIN
EXECUTE format('SELECT * FROM %I', _tablename) INTO r;
PERFORM plpgsql_check_pragma('type: r (id int, processed bool)');
IF NOT r.processed THEN
...
Attention: The SQL injection check can detect only some SQL injection vulnerabilities. This tool cannot be used for security audit! Some issues should not be detected. This check can raise false alarms too - probably when variable is sanitized by other command or when value is of some compose type.
plpgsql_check should not to detect structure of referenced cursors. A reference on cursor in PLpgSQL is implemented as name of global cursor. In check time, the name is not known (not in all possibilities), and global cursor doesn't exist. It is significant break for any static analyse. PLpgSQL cannot to set correct type for record variables and cannot to check a dependent SQLs and expressions. A solution is same like dynamic SQL. Don't use record variable as target when you use refcursor type or disable plpgsql_check for these functions.
CREATE OR REPLACE FUNCTION foo(refcur_var refcursor)
RETURNS void AS $$
DECLARE
rec_var record;
BEGIN
FETCH refcur_var INTO rec_var; -- this is STOP for plpgsql_check
RAISE NOTICE '%', rec_var; -- record rec_var is not assigned yet error
In this case a record type should not be used (use known rowtype instead):
CREATE OR REPLACE FUNCTION foo(refcur_var refcursor)
RETURNS void AS $$
DECLARE
rec_var some_rowtype;
BEGIN
FETCH refcur_var INTO rec_var;
RAISE NOTICE '%', rec_var;
plpgsql_check cannot verify queries over temporary tables that are created in plpgsql's function runtime. For this use case it is necessary to create a fake temp table or disable plpgsql_check for this function.
In reality temp tables are stored in own (per user) schema with higher priority than persistent tables. So you can do (with following trick safetly):
CREATE OR REPLACE FUNCTION public.disable_dml()
RETURNS trigger
LANGUAGE plpgsql AS $function$
BEGIN
RAISE EXCEPTION SQLSTATE '42P01'
USING message = format('this instance of %I table doesn''t allow any DML operation', TG_TABLE_NAME),
hint = format('you should to run "CREATE TEMP TABLE %1$I(LIKE %1$I INCLUDING ALL);" statement',
TG_TABLE_NAME);
RETURN NULL;
END;
$function$;
CREATE TABLE foo(a int, b int); -- doesn't hold data ever
CREATE TRIGGER foo_disable_dml
BEFORE INSERT OR UPDATE OR DELETE ON foo
EXECUTE PROCEDURE disable_dml();
postgres=# INSERT INTO foo VALUES(10,20);
ERROR: this instance of foo table doesn't allow any DML operation
HINT: you should to run "CREATE TEMP TABLE foo(LIKE foo INCLUDING ALL);" statement
postgres=#
CREATE TABLE
postgres=# INSERT INTO foo VALUES(10,20);
INSERT 0 1
This trick emulates GLOBAL TEMP tables partially and it allows a statical validation. Other possibility is using a [template foreign data wrapper] (https://github.com/okbob/template_fdw)
You can use pragma table
and create ephemeral table:
BEGIN
CREATE TEMP TABLE xxx(a int);
PERFORM plpgsql_check_pragma('table: xxx(a int)');
INSERT INTO xxx VALUES(10);
Dependency list
A function plpgsql_show_dependency_tb can show all functions, operators and relations used inside processed function:
postgres=# select * from plpgsql_show_dependency_tb('testfunc(int,float)');
┌──────────┬───────┬────────┬─────────┬────────────────────────────┐
│ type │ oid │ schema │ name │ params │
╞══════════╪═══════╪════════╪═════════╪════════════════════════════╡
│ FUNCTION │ 36008 │ public │ myfunc1 │ (integer,double precision) │
│ FUNCTION │ 35999 │ public │ myfunc2 │ (integer,double precision) │
│ OPERATOR │ 36007 │ public │ ** │ (integer,integer) │
│ RELATION │ 36005 │ public │ myview │ │
│ RELATION │ 36002 │ public │ mytable │ │
└──────────┴───────┴────────┴─────────┴────────────────────────────┘
(4 rows)
Profiler
The plpgsql_check contains simple profiler of plpgsql functions and procedures. It can work with/without a access to shared memory. It depends on shared_preload_libraries
config. When plpgsql_check was initialized by shared_preload_libraries
, then it can allocate shared memory, and function's profiles are stored there. When plpgsql_check cannot to allocate shared momory, the profile is stored in session memory.
Due dependencies, shared_preload_libraries
should to contains plpgsql
first
postgres=# show shared_preload_libraries ;
┌──────────────────────────┐
│ shared_preload_libraries │
╞══════════════════════════╡
│ plpgsql,plpgsql_check │
└──────────────────────────┘
(1 row)
The profiler is active when GUC plpgsql_check.profiler
is on. The profiler doesn't require shared memory, but if there are not shared memory, then the profile is limmitted just to active session.
When plpgsql_check is initialized by shared_preload_libraries
, another GUC is available to configure the amount of shared memory used by the profiler: plpgsql_check.profiler_max_shared_chunks
. This defines the maximum number of statements chunk that can be stored in shared memory. For each plpgsql function (or procedure), the whole content is split into chunks of 30 statements. If needed, multiple chunks can be used to store the whole content of a single function. A single chunk is 1704 bytes. The default value for this GUC is 15000, which should be enough for big projects containing hundred of thousands of statements in plpgsql, and will consume about 24MB of memory. If your project doesn't require that much number of chunks, you can set this parameter to a smaller number in order to decrease the memory usage. The minimum value is 50 (which should consume about 83kB of memory), and the maximum value is 100000 (which should consume about 163MB of memory). Changing this parameter requires a PostgreSQL restart.
The profiler will also retrieve the query identifier for each instruction that contains an expression or optimizable statement. Note that this requires pg_stat_statements, or another similar third-party extension), to be installed. There are some limitations to the query identifier retrieval:
Attention: A update of shared profiles can decrease performance on servers under higher load.
The profile can be displayed by function plpgsql_profiler_function_tb
:
postgres=# select lineno, avg_time, source from plpgsql_profiler_function_tb('fx(int)');
┌────────┬──────────┬───────────────────────────────────────────────────────────────────┐
│ lineno │ avg_time │ source │
╞════════╪══════════╪═══════════════════════════════════════════════════════════════════╡
│ 1 │ │ │
│ 2 │ │ declare result int = 0; │
│ 3 │ 0.075 │ begin │
│ 4 │ 0.202 │ for i in 1..$1 loop │
│ 5 │ 0.005 │ select result + i into result; select result + i into result; │
│ 6 │ │ end loop; │
│ 7 │ 0 │ return result; │
│ 8 │ │ end; │
└────────┴──────────┴───────────────────────────────────────────────────────────────────┘
(9 rows)
The profile per statements (not per line) can be displayed by function plpgsql_profiler_function_statements_tb:
CREATE OR REPLACE FUNCTION public.fx1(a integer)
RETURNS integer
LANGUAGE plpgsql
1 AS $function$
2 begin
3 if a > 10 then
4 raise notice 'ahoj';
5 return -1;
6 else
7 raise notice 'nazdar';
8 return 1;
9 end if;
10 end;
11 $function$
postgres=# select stmtid, parent_stmtid, parent_note, lineno, exec_stmts, stmtname
from plpgsql_profiler_function_statements_tb('fx1');
┌────────┬───────────────┬─────────────┬────────┬────────────┬─────────────────┐
│ stmtid │ parent_stmtid │ parent_note │ lineno │ exec_stmts │ stmtname │
╞════════╪═══════════════╪═════════════╪════════╪════════════╪═════════════════╡
│ 0 │ ∅ │ ∅ │ 2 │ 0 │ statement block │
│ 1 │ 0 │ body │ 3 │ 0 │ IF │
│ 2 │ 1 │ then body │ 4 │ 0 │ RAISE │
│ 3 │ 1 │ then body │ 5 │ 0 │ RETURN │
│ 4 │ 1 │ else body │ 7 │ 0 │ RAISE │
│ 5 │ 1 │ else body │ 8 │ 0 │ RETURN │
└────────┴───────────────┴─────────────┴────────┴────────────┴─────────────────┘
(6 rows)
All stored profiles can be displayed by calling function plpgsql_profiler_functions_all
:
postgres=# select * from plpgsql_profiler_functions_all();
┌───────────────────────┬────────────┬────────────┬──────────┬─────────────┬──────────┬──────────┐
│ funcoid │ exec_count │ total_time │ avg_time │ stddev_time │ min_time │ max_time │
╞═══════════════════════╪════════════╪════════════╪══════════╪═════════════╪══════════╪══════════╡
│ fxx(double precision) │ 1 │ 0.01 │ 0.01 │ 0.00 │ 0.01 │ 0.01 │
└───────────────────────┴────────────┴────────────┴──────────┴─────────────┴──────────┴──────────┘
(1 row)
There are two functions for cleaning stored profiles: plpgsql_profiler_reset_all()
and plpgsql_profiler_reset(regprocedure)
.
plpgsql_check provides two functions:
plpgsql_coverage_statements(name)
plpgsql_coverage_branches(name)
There is another very good PLpgSQL profiler - https://bitbucket.org/openscg/plprofiler
My extension is designed to be simple for use and practical. Nothing more or less.
plprofiler is more complex. It build call graphs and from this graph it can creates flame graph of execution times.
Both extensions can be used together with buildin PostgreSQL's feature - tracking functions.
set track_functions to 'pl';
...
select * from pg_stat_user_functions;
Tracer
plpgsql_check provides a tracing possibility - in this mode you can see notices on start or end functions (terse and default verbosity) and start or end statements (verbose verbosity). For default and verbose verbosity the content of function arguments is displayed. The content of related variables are displayed when verbosity is verbose.
postgres=# do $$ begin perform fx(10,null, 'now', e'stěhule'); end; $$;
NOTICE: #0 ->> start of inline_code_block (Oid=0)
NOTICE: #2 ->> start of function fx(integer,integer,date,text) (Oid=16405)
NOTICE: #2 call by inline_code_block line 1 at PERFORM
NOTICE: #2 "a" => '10', "b" => null, "c" => '2020-08-03', "d" => 'stěhule'
NOTICE: #4 ->> start of function fx(integer) (Oid=16404)
NOTICE: #4 call by fx(integer,integer,date,text) line 1 at PERFORM
NOTICE: #4 "a" => '10'
NOTICE: #4 <<- end of function fx (elapsed time=0.098 ms)
NOTICE: #2 <<- end of function fx (elapsed time=0.399 ms)
NOTICE: #0 <<- end of block (elapsed time=0.754 ms)
The number after #
is a execution frame counter (this number is related to deep of error context stack). It allows to pair start end and of function.
Tracing is enabled by setting plpgsql_check.tracer
to on
. Attention - enabling this behaviour has significant negative impact on performance (unlike the profiler). You can set a level for output used by tracer plpgsql_check.tracer_errlevel
(default is notice
). The output content is limited by length specified by plpgsql_check.tracer_variable_max_length
configuration variable.
In terse verbose mode the output is reduced:
postgres=# set plpgsql_check.tracer_verbosity TO terse;
SET
postgres=# do $$ begin perform fx(10,null, 'now', e'stěhule'); end; $$;
NOTICE: #0 start of inline code block (oid=0)
NOTICE: #2 start of fx (oid=16405)
NOTICE: #4 start of fx (oid=16404)
NOTICE: #4 end of fx
NOTICE: #2 end of fx
NOTICE: #0 end of inline code block
In verbose mode the output is extended about statement details:
postgres=# do $$ begin perform fx(10,null, 'now', e'stěhule'); end; $$;
NOTICE: #0 ->> start of block inline_code_block (oid=0)
NOTICE: #0.1 1 --> start of PERFORM
NOTICE: #2 ->> start of function fx(integer,integer,date,text) (oid=16405)
NOTICE: #2 call by inline_code_block line 1 at PERFORM
NOTICE: #2 "a" => '10', "b" => null, "c" => '2020-08-04', "d" => 'stěhule'
NOTICE: #2.1 1 --> start of PERFORM
NOTICE: #2.1 "a" => '10'
NOTICE: #4 ->> start of function fx(integer) (oid=16404)
NOTICE: #4 call by fx(integer,integer,date,text) line 1 at PERFORM
NOTICE: #4 "a" => '10'
NOTICE: #4.1 6 --> start of assignment
NOTICE: #4.1 "a" => '10', "b" => '20'
NOTICE: #4.1 <-- end of assignment (elapsed time=0.076 ms)
NOTICE: #4.1 "res" => '130'
NOTICE: #4.2 7 --> start of RETURN
NOTICE: #4.2 "res" => '130'
NOTICE: #4.2 <-- end of RETURN (elapsed time=0.054 ms)
NOTICE: #4 <<- end of function fx (elapsed time=0.373 ms)
NOTICE: #2.1 <-- end of PERFORM (elapsed time=0.589 ms)
NOTICE: #2 <<- end of function fx (elapsed time=0.727 ms)
NOTICE: #0.1 <-- end of PERFORM (elapsed time=1.147 ms)
NOTICE: #0 <<- end of block (elapsed time=1.286 ms)
Special feature of tracer is tracing of ASSERT
statement when plpgsql_check.trace_assert
is on
. When plpgsql_check.trace_assert_verbosity
is DEFAULT
, then all function's or procedure's variables are displayed when assert expression is false. When this configuration is VERBOSE
then all variables from all plpgsql frames are displayed. This behaviour is independent on plpgsql.check_asserts
value. It can be used, although the assertions are disabled in plpgsql runtime.
postgres=# set plpgsql_check.tracer to off;
postgres=# set plpgsql_check.trace_assert_verbosity TO verbose;
postgres=# do $$ begin perform fx(10,null, 'now', e'stěhule'); end; $$;
NOTICE: #4 PLpgSQL assert expression (false) on line 12 of fx(integer) is false
NOTICE: "a" => '10', "res" => null, "b" => '20'
NOTICE: #2 PL/pgSQL function fx(integer,integer,date,text) line 1 at PERFORM
NOTICE: "a" => '10', "b" => null, "c" => '2020-08-05', "d" => 'stěhule'
NOTICE: #0 PL/pgSQL function inline_code_block line 1 at PERFORM
ERROR: assertion failed
CONTEXT: PL/pgSQL function fx(integer) line 12 at ASSERT
SQL statement "SELECT fx(a)"
PL/pgSQL function fx(integer,integer,date,text) line 1 at PERFORM
SQL statement "SELECT fx(10,null, 'now', e'stěhule')"
PL/pgSQL function inline_code_block line 1 at PERFORM
postgres=# set plpgsql.check_asserts to off;
SET
postgres=# do $$ begin perform fx(10,null, 'now', e'stěhule'); end; $$;
NOTICE: #4 PLpgSQL assert expression (false) on line 12 of fx(integer) is false
NOTICE: "a" => '10', "res" => null, "b" => '20'
NOTICE: #2 PL/pgSQL function fx(integer,integer,date,text) line 1 at PERFORM
NOTICE: "a" => '10', "b" => null, "c" => '2020-08-05', "d" => 'stěhule'
NOTICE: #0 PL/pgSQL function inline_code_block line 1 at PERFORM
DO
Tracer prints content of variables or function arguments. For security definer function, this content can hold security sensitive data. This is reason why tracer is disabled by default and should be enabled only with super user rights plpgsql_check.enable_tracer
.
Pragma
You can configure plpgsql_check behave inside checked function with "pragma" function. This is a analogy of PL/SQL or ADA language of PRAGMA feature. PLpgSQL doesn't support PRAGMA, but plpgsql_check detects function named plpgsql_check_pragma
and get options from parameters of this function. These plpgsql_check options are valid to end of group of statements.
CREATE OR REPLACE FUNCTION test()
RETURNS void AS $$
BEGIN
...
-- for following statements disable check
PERFORM plpgsql_check_pragma('disable:check');
...
-- enable check again
PERFORM plpgsql_check_pragma('enable:check');
...
END;
$$ LANGUAGE plpgsql;
The function plpgsql_check_pragma
is immutable function that returns one. It is defined by plpgsql_check
extension. You can declare alternative plpgsql_check_pragma
function like:
CREATE OR REPLACE FUNCTION plpgsql_check_pragma(VARIADIC args[])
RETURNS int AS $$
SELECT 1
$$ LANGUAGE sql IMMUTABLE;
Using pragma function in declaration part of top block sets options on function level too.
CREATE OR REPLACE FUNCTION test()
RETURNS void AS $$
DECLARE
aux int := plpgsql_check_pragma('disable:extra_warnings');
...
Shorter syntax for pragma is supported too:
CREATE OR REPLACE FUNCTION test()
RETURNS void AS $$
DECLARE r record;
BEGIN
PERFORM 'PRAGMA:TYPE:r (a int, b int)';
PERFORM 'PRAGMA:TABLE: x (like pg_class)';
...
echo:str
- print string (for testing)
status:check
,status:tracer
, status:other_warnings
, status:performance_warnings
, status:extra_warnings
,status:security_warnings
enable:check
,enable:tracer
, enable:other_warnings
, enable:performance_warnings
, enable:extra_warnings
,enable:security_warnings
disable:check
,disable:tracer
, disable:other_warnings
, disable:performance_warnings
, disable:extra_warnings
,disable:security_warnings
type:varname typename
or type:varname (fieldname type, ...)
- set type to variable of record type
table: name (column_name type, ...)
or table: name (like tablename)
- create ephereal table
Pragmas enable:tracer
and disable:tracer
are active for Postgres 12 and higher
Compilation
You need a development environment for PostgreSQL extensions:
make clean
make install
result:
[pavel@localhost plpgsql_check]$ make USE_PGXS=1 clean
rm -f plpgsql_check.so libplpgsql_check.a libplpgsql_check.pc
rm -f plpgsql_check.o
rm -rf results/ regression.diffs regression.out tmp_check/ log/
[pavel@localhost plpgsql_check]$ make USE_PGXS=1 all
clang -O2 -Wall -Wmissing-prototypes -Wpointer-arith -Wdeclaration-after-statement -Wendif-labels -Wmissing-format-attribute -Wformat-security -fno-strict-aliasing -fwrapv -fpic -I/usr/local/pgsql/lib/pgxs/src/makefiles/../../src/pl/plpgsql/src -I. -I./ -I/usr/local/pgsql/include/server -I/usr/local/pgsql/include/internal -D_GNU_SOURCE -c -o plpgsql_check.o plpgsql_check.c
clang -O2 -Wall -Wmissing-prototypes -Wpointer-arith -Wdeclaration-after-statement -Wendif-labels -Wmissing-format-attribute -Wformat-security -fno-strict-aliasing -fwrapv -fpic -I/usr/local/pgsql/lib/pgxs/src/makefiles/../../src/pl/plpgsql/src -shared -o plpgsql_check.so plpgsql_check.o -L/usr/local/pgsql/lib -Wl,--as-needed -Wl,-rpath,'/usr/local/pgsql/lib',--enable-new-dtags
[pavel@localhost plpgsql_check]$ su root
Password: *******
[root@localhost plpgsql_check]# make USE_PGXS=1 install
/usr/bin/mkdir -p '/usr/local/pgsql/lib'
/usr/bin/mkdir -p '/usr/local/pgsql/share/extension'
/usr/bin/mkdir -p '/usr/local/pgsql/share/extension'
/usr/bin/install -c -m 755 plpgsql_check.so '/usr/local/pgsql/lib/plpgsql_check.so'
/usr/bin/install -c -m 644 plpgsql_check.control '/usr/local/pgsql/share/extension/'
/usr/bin/install -c -m 644 plpgsql_check--0.9.sql '/usr/local/pgsql/share/extension/'
[root@localhost plpgsql_check]# exit
[pavel@localhost plpgsql_check]$ make USE_PGXS=1 installcheck
/usr/local/pgsql/lib/pgxs/src/makefiles/../../src/test/regress/pg_regress --inputdir=./ --psqldir='/usr/local/pgsql/bin' --dbname=pl_regression --load-language=plpgsql --dbname=contrib_regression plpgsql_check_passive plpgsql_check_active plpgsql_check_active-9.5
(using postmaster on Unix socket, default port)
============== dropping database "contrib_regression" ==============
DROP DATABASE
============== creating database "contrib_regression" ==============
CREATE DATABASE
ALTER DATABASE
============== installing plpgsql ==============
CREATE LANGUAGE
============== running regression test queries ==============
test plpgsql_check_passive ... ok
test plpgsql_check_active ... ok
test plpgsql_check_active-9.5 ... ok
=====================
All 3 tests passed.
=====================
Sometimes successful compilation can require libicu-dev package (PostgreSQL 10 and higher - when pg was compiled with ICU support)
sudo apt install libicu-dev
You can check precompiled dll libraries http://okbob.blogspot.cz/2015/02/plpgsqlcheck-is-available-for-microsoft.html
or compile by self:
plpgsql_check.dll
to PostgreSQL\14\lib
plpgsql_check.control
and plpgsql_check--2.1.sql
to PostgreSQL\14\share\extension
Compilation against PostgreSQL 10 requires libICU!
Licence
Copyright (c) Pavel Stehule (pavel.stehule@gmail.com)
Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:
The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.
THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
Note
If you like it, send a postcard to address
Pavel Stehule
Skalice 12
256 01 Benesov u Prahy
Czech Republic
I invite any questions, comments, bug reports, patches on mail address pavel.stehule@gmail.com
Author: okbob
Source Code: https://github.com/okbob/plpgsql_check
License: View license
1653475560
msgpack.php
A pure PHP implementation of the MessagePack serialization format.
The recommended way to install the library is through Composer:
composer require rybakit/msgpack
To pack values you can either use an instance of a Packer
:
$packer = new Packer();
$packed = $packer->pack($value);
or call a static method on the MessagePack
class:
$packed = MessagePack::pack($value);
In the examples above, the method pack
automatically packs a value depending on its type. However, not all PHP types can be uniquely translated to MessagePack types. For example, the MessagePack format defines map
and array
types, which are represented by a single array
type in PHP. By default, the packer will pack a PHP array as a MessagePack array if it has sequential numeric keys, starting from 0
and as a MessagePack map otherwise:
$mpArr1 = $packer->pack([1, 2]); // MP array [1, 2]
$mpArr2 = $packer->pack([0 => 1, 1 => 2]); // MP array [1, 2]
$mpMap1 = $packer->pack([0 => 1, 2 => 3]); // MP map {0: 1, 2: 3}
$mpMap2 = $packer->pack([1 => 2, 2 => 3]); // MP map {1: 2, 2: 3}
$mpMap3 = $packer->pack(['a' => 1, 'b' => 2]); // MP map {a: 1, b: 2}
However, sometimes you need to pack a sequential array as a MessagePack map. To do this, use the packMap
method:
$mpMap = $packer->packMap([1, 2]); // {0: 1, 1: 2}
Here is a list of type-specific packing methods:
$packer->packNil(); // MP nil
$packer->packBool(true); // MP bool
$packer->packInt(42); // MP int
$packer->packFloat(M_PI); // MP float (32 or 64)
$packer->packFloat32(M_PI); // MP float 32
$packer->packFloat64(M_PI); // MP float 64
$packer->packStr('foo'); // MP str
$packer->packBin("\x80"); // MP bin
$packer->packArray([1, 2]); // MP array
$packer->packMap(['a' => 1]); // MP map
$packer->packExt(1, "\xaa"); // MP ext
Check the "Custom types" section below on how to pack custom types.
The Packer
object supports a number of bitmask-based options for fine-tuning the packing process (defaults are in bold):
Name | Description |
---|---|
FORCE_STR | Forces PHP strings to be packed as MessagePack UTF-8 strings |
FORCE_BIN | Forces PHP strings to be packed as MessagePack binary data |
DETECT_STR_BIN | Detects MessagePack str/bin type automatically |
FORCE_ARR | Forces PHP arrays to be packed as MessagePack arrays |
FORCE_MAP | Forces PHP arrays to be packed as MessagePack maps |
DETECT_ARR_MAP | Detects MessagePack array/map type automatically |
FORCE_FLOAT32 | Forces PHP floats to be packed as 32-bits MessagePack floats |
FORCE_FLOAT64 | Forces PHP floats to be packed as 64-bits MessagePack floats |
The type detection mode (
DETECT_STR_BIN
/DETECT_ARR_MAP
) adds some overhead which can be noticed when you pack large (16- and 32-bit) arrays or strings. However, if you know the value type in advance (for example, you only work with UTF-8 strings or/and associative arrays), you can eliminate this overhead by forcing the packer to use the appropriate type, which will save it from running the auto-detection routine. Another option is to explicitly specify the value type. The library provides 2 auxiliary classes for this,Map
andBin
. Check the "Custom types" section below for details.
Examples:
// detect str/bin type and pack PHP 64-bit floats (doubles) to MP 32-bit floats
$packer = new Packer(PackOptions::DETECT_STR_BIN | PackOptions::FORCE_FLOAT32);
// these will throw MessagePack\Exception\InvalidOptionException
$packer = new Packer(PackOptions::FORCE_STR | PackOptions::FORCE_BIN);
$packer = new Packer(PackOptions::FORCE_FLOAT32 | PackOptions::FORCE_FLOAT64);
To unpack data you can either use an instance of a BufferUnpacker
:
$unpacker = new BufferUnpacker();
$unpacker->reset($packed);
$value = $unpacker->unpack();
or call a static method on the MessagePack
class:
$value = MessagePack::unpack($packed);
If the packed data is received in chunks (e.g. when reading from a stream), use the tryUnpack
method, which attempts to unpack data and returns an array of unpacked messages (if any) instead of throwing an InsufficientDataException
:
while ($chunk = ...) {
$unpacker->append($chunk);
if ($messages = $unpacker->tryUnpack()) {
return $messages;
}
}
If you want to unpack from a specific position in a buffer, use seek
:
$unpacker->seek(42); // set position equal to 42 bytes
$unpacker->seek(-8); // set position to 8 bytes before the end of the buffer
To skip bytes from the current position, use skip
:
$unpacker->skip(10); // set position to 10 bytes ahead of the current position
To get the number of remaining (unread) bytes in the buffer:
$unreadBytesCount = $unpacker->getRemainingCount();
To check whether the buffer has unread data:
$hasUnreadBytes = $unpacker->hasRemaining();
If needed, you can remove already read data from the buffer by calling:
$releasedBytesCount = $unpacker->release();
With the read
method you can read raw (packed) data:
$packedData = $unpacker->read(2); // read 2 bytes
Besides the above methods BufferUnpacker
provides type-specific unpacking methods, namely:
$unpacker->unpackNil(); // PHP null
$unpacker->unpackBool(); // PHP bool
$unpacker->unpackInt(); // PHP int
$unpacker->unpackFloat(); // PHP float
$unpacker->unpackStr(); // PHP UTF-8 string
$unpacker->unpackBin(); // PHP binary string
$unpacker->unpackArray(); // PHP sequential array
$unpacker->unpackMap(); // PHP associative array
$unpacker->unpackExt(); // PHP MessagePack\Type\Ext object
The BufferUnpacker
object supports a number of bitmask-based options for fine-tuning the unpacking process (defaults are in bold):
Name | Description |
---|---|
BIGINT_AS_STR | Converts overflowed integers to strings [1] |
BIGINT_AS_GMP | Converts overflowed integers to GMP objects [2] |
BIGINT_AS_DEC | Converts overflowed integers to Decimal\Decimal objects [3] |
1. The binary MessagePack format has unsigned 64-bit as its largest integer data type, but PHP does not support such integers, which means that an overflow can occur during unpacking.
2. Make sure the GMP extension is enabled.
3. Make sure the Decimal extension is enabled.
Examples:
$packedUint64 = "\xcf"."\xff\xff\xff\xff"."\xff\xff\xff\xff";
$unpacker = new BufferUnpacker($packedUint64);
var_dump($unpacker->unpack()); // string(20) "18446744073709551615"
$unpacker = new BufferUnpacker($packedUint64, UnpackOptions::BIGINT_AS_GMP);
var_dump($unpacker->unpack()); // object(GMP) {...}
$unpacker = new BufferUnpacker($packedUint64, UnpackOptions::BIGINT_AS_DEC);
var_dump($unpacker->unpack()); // object(Decimal\Decimal) {...}
In addition to the basic types, the library provides functionality to serialize and deserialize arbitrary types. This can be done in several ways, depending on your use case. Let's take a look at them.
If you need to serialize an instance of one of your classes into one of the basic MessagePack types, the best way to do this is to implement the CanBePacked interface in the class. A good example of such a class is the Map
type class that comes with the library. This type is useful when you want to explicitly specify that a given PHP array should be packed as a MessagePack map without triggering an automatic type detection routine:
$packer = new Packer();
$packedMap = $packer->pack(new Map([1, 2, 3]));
$packedArray = $packer->pack([1, 2, 3]);
More type examples can be found in the src/Type directory.
As with type objects, type transformers are only responsible for serializing values. They should be used when you need to serialize a value that does not implement the CanBePacked interface. Examples of such values could be instances of built-in or third-party classes that you don't own, or non-objects such as resources.
A transformer class must implement the CanPack interface. To use a transformer, it must first be registered in the packer. Here is an example of how to serialize PHP streams into the MessagePack bin
format type using one of the supplied transformers, StreamTransformer
:
$packer = new Packer(null, [new StreamTransformer()]);
$packedBin = $packer->pack(fopen('/path/to/file', 'r+'));
More type transformer examples can be found in the src/TypeTransformer directory.
In contrast to the cases described above, extensions are intended to handle extension types and are responsible for both serialization and deserialization of values (types).
An extension class must implement the Extension interface. To use an extension, it must first be registered in the packer and the unpacker.
The MessagePack specification divides extension types into two groups: predefined and application-specific. Currently, there is only one predefined type in the specification, Timestamp.
Timestamp
The Timestamp extension type is a predefined type. Support for this type in the library is done through the TimestampExtension
class. This class is responsible for handling Timestamp
objects, which represent the number of seconds and optional adjustment in nanoseconds:
$timestampExtension = new TimestampExtension();
$packer = new Packer();
$packer = $packer->extendWith($timestampExtension);
$unpacker = new BufferUnpacker();
$unpacker = $unpacker->extendWith($timestampExtension);
$packedTimestamp = $packer->pack(Timestamp::now());
$timestamp = $unpacker->reset($packedTimestamp)->unpack();
$seconds = $timestamp->getSeconds();
$nanoseconds = $timestamp->getNanoseconds();
When using the MessagePack
class, the Timestamp extension is already registered:
$packedTimestamp = MessagePack::pack(Timestamp::now());
$timestamp = MessagePack::unpack($packedTimestamp);
Application-specific extensions
In addition, the format can be extended with your own types. For example, to make the built-in PHP DateTime
objects first-class citizens in your code, you can create a corresponding extension, as shown in the example. Please note, that custom extensions have to be registered with a unique extension ID (an integer from 0
to 127
).
More extension examples can be found in the examples/MessagePack directory.
To learn more about how extension types can be useful, check out this article.
If an error occurs during packing/unpacking, a PackingFailedException
or an UnpackingFailedException
will be thrown, respectively. In addition, an InsufficientDataException
can be thrown during unpacking.
An InvalidOptionException
will be thrown in case an invalid option (or a combination of mutually exclusive options) is used.
Run tests as follows:
vendor/bin/phpunit
Also, if you already have Docker installed, you can run the tests in a docker container. First, create a container:
./dockerfile.sh | docker build -t msgpack -
The command above will create a container named msgpack
with PHP 8.1 runtime. You may change the default runtime by defining the PHP_IMAGE
environment variable:
PHP_IMAGE='php:8.0-cli' ./dockerfile.sh | docker build -t msgpack -
See a list of various images here.
Then run the unit tests:
docker run --rm -v $PWD:/msgpack -w /msgpack msgpack
To ensure that the unpacking works correctly with malformed/semi-malformed data, you can use a testing technique called Fuzzing. The library ships with a help file (target) for PHP-Fuzzer and can be used as follows:
php-fuzzer fuzz tests/fuzz_buffer_unpacker.php
To check performance, run:
php -n -dzend_extension=opcache.so \
-dpcre.jit=1 -dopcache.enable=1 -dopcache.enable_cli=1 \
tests/bench.php
Example output
Filter: MessagePack\Tests\Perf\Filter\ListFilter
Rounds: 3
Iterations: 100000
=============================================
Test/Target Packer BufferUnpacker
---------------------------------------------
nil .................. 0.0030 ........ 0.0139
false ................ 0.0037 ........ 0.0144
true ................. 0.0040 ........ 0.0137
7-bit uint #1 ........ 0.0052 ........ 0.0120
7-bit uint #2 ........ 0.0059 ........ 0.0114
7-bit uint #3 ........ 0.0061 ........ 0.0119
5-bit sint #1 ........ 0.0067 ........ 0.0126
5-bit sint #2 ........ 0.0064 ........ 0.0132
5-bit sint #3 ........ 0.0066 ........ 0.0135
8-bit uint #1 ........ 0.0078 ........ 0.0200
8-bit uint #2 ........ 0.0077 ........ 0.0212
8-bit uint #3 ........ 0.0086 ........ 0.0203
16-bit uint #1 ....... 0.0111 ........ 0.0271
16-bit uint #2 ....... 0.0115 ........ 0.0260
16-bit uint #3 ....... 0.0103 ........ 0.0273
32-bit uint #1 ....... 0.0116 ........ 0.0326
32-bit uint #2 ....... 0.0118 ........ 0.0332
32-bit uint #3 ....... 0.0127 ........ 0.0325
64-bit uint #1 ....... 0.0140 ........ 0.0277
64-bit uint #2 ....... 0.0134 ........ 0.0294
64-bit uint #3 ....... 0.0134 ........ 0.0281
8-bit int #1 ......... 0.0086 ........ 0.0241
8-bit int #2 ......... 0.0089 ........ 0.0225
8-bit int #3 ......... 0.0085 ........ 0.0229
16-bit int #1 ........ 0.0118 ........ 0.0280
16-bit int #2 ........ 0.0121 ........ 0.0270
16-bit int #3 ........ 0.0109 ........ 0.0274
32-bit int #1 ........ 0.0128 ........ 0.0346
32-bit int #2 ........ 0.0118 ........ 0.0339
32-bit int #3 ........ 0.0135 ........ 0.0368
64-bit int #1 ........ 0.0138 ........ 0.0276
64-bit int #2 ........ 0.0132 ........ 0.0286
64-bit int #3 ........ 0.0137 ........ 0.0274
64-bit int #4 ........ 0.0180 ........ 0.0285
64-bit float #1 ...... 0.0134 ........ 0.0284
64-bit float #2 ...... 0.0125 ........ 0.0275
64-bit float #3 ...... 0.0126 ........ 0.0283
fix string #1 ........ 0.0035 ........ 0.0133
fix string #2 ........ 0.0094 ........ 0.0216
fix string #3 ........ 0.0094 ........ 0.0222
fix string #4 ........ 0.0091 ........ 0.0241
8-bit string #1 ...... 0.0122 ........ 0.0301
8-bit string #2 ...... 0.0118 ........ 0.0304
8-bit string #3 ...... 0.0119 ........ 0.0315
16-bit string #1 ..... 0.0150 ........ 0.0388
16-bit string #2 ..... 0.1545 ........ 0.1665
32-bit string ........ 0.1570 ........ 0.1756
wide char string #1 .. 0.0091 ........ 0.0236
wide char string #2 .. 0.0122 ........ 0.0313
8-bit binary #1 ...... 0.0100 ........ 0.0302
8-bit binary #2 ...... 0.0123 ........ 0.0324
8-bit binary #3 ...... 0.0126 ........ 0.0327
16-bit binary ........ 0.0168 ........ 0.0372
32-bit binary ........ 0.1588 ........ 0.1754
fix array #1 ......... 0.0042 ........ 0.0131
fix array #2 ......... 0.0294 ........ 0.0367
fix array #3 ......... 0.0412 ........ 0.0472
16-bit array #1 ...... 0.1378 ........ 0.1596
16-bit array #2 ........... S ............. S
32-bit array .............. S ............. S
complex array ........ 0.1865 ........ 0.2283
fix map #1 ........... 0.0725 ........ 0.1048
fix map #2 ........... 0.0319 ........ 0.0405
fix map #3 ........... 0.0356 ........ 0.0665
fix map #4 ........... 0.0465 ........ 0.0497
16-bit map #1 ........ 0.2540 ........ 0.3028
16-bit map #2 ............. S ............. S
32-bit map ................ S ............. S
complex map .......... 0.2372 ........ 0.2710
fixext 1 ............. 0.0283 ........ 0.0358
fixext 2 ............. 0.0291 ........ 0.0371
fixext 4 ............. 0.0302 ........ 0.0355
fixext 8 ............. 0.0288 ........ 0.0384
fixext 16 ............ 0.0293 ........ 0.0359
8-bit ext ............ 0.0302 ........ 0.0439
16-bit ext ........... 0.0334 ........ 0.0499
32-bit ext ........... 0.1845 ........ 0.1888
32-bit timestamp #1 .. 0.0337 ........ 0.0547
32-bit timestamp #2 .. 0.0335 ........ 0.0560
64-bit timestamp #1 .. 0.0371 ........ 0.0575
64-bit timestamp #2 .. 0.0374 ........ 0.0542
64-bit timestamp #3 .. 0.0356 ........ 0.0533
96-bit timestamp #1 .. 0.0362 ........ 0.0699
96-bit timestamp #2 .. 0.0381 ........ 0.0701
96-bit timestamp #3 .. 0.0367 ........ 0.0687
=============================================
Total 2.7618 4.0820
Skipped 4 4
Failed 0 0
Ignored 0 0
With JIT:
php -n -dzend_extension=opcache.so \
-dpcre.jit=1 -dopcache.jit_buffer_size=64M -dopcache.jit=tracing -dopcache.enable=1 -dopcache.enable_cli=1 \
tests/bench.php
Example output
Filter: MessagePack\Tests\Perf\Filter\ListFilter
Rounds: 3
Iterations: 100000
=============================================
Test/Target Packer BufferUnpacker
---------------------------------------------
nil .................. 0.0005 ........ 0.0054
false ................ 0.0004 ........ 0.0059
true ................. 0.0004 ........ 0.0059
7-bit uint #1 ........ 0.0010 ........ 0.0047
7-bit uint #2 ........ 0.0010 ........ 0.0046
7-bit uint #3 ........ 0.0010 ........ 0.0046
5-bit sint #1 ........ 0.0025 ........ 0.0046
5-bit sint #2 ........ 0.0023 ........ 0.0046
5-bit sint #3 ........ 0.0024 ........ 0.0045
8-bit uint #1 ........ 0.0043 ........ 0.0081
8-bit uint #2 ........ 0.0043 ........ 0.0079
8-bit uint #3 ........ 0.0041 ........ 0.0080
16-bit uint #1 ....... 0.0064 ........ 0.0095
16-bit uint #2 ....... 0.0064 ........ 0.0091
16-bit uint #3 ....... 0.0064 ........ 0.0094
32-bit uint #1 ....... 0.0085 ........ 0.0114
32-bit uint #2 ....... 0.0077 ........ 0.0122
32-bit uint #3 ....... 0.0077 ........ 0.0120
64-bit uint #1 ....... 0.0085 ........ 0.0159
64-bit uint #2 ....... 0.0086 ........ 0.0157
64-bit uint #3 ....... 0.0086 ........ 0.0158
8-bit int #1 ......... 0.0042 ........ 0.0080
8-bit int #2 ......... 0.0042 ........ 0.0080
8-bit int #3 ......... 0.0042 ........ 0.0081
16-bit int #1 ........ 0.0065 ........ 0.0095
16-bit int #2 ........ 0.0065 ........ 0.0090
16-bit int #3 ........ 0.0056 ........ 0.0085
32-bit int #1 ........ 0.0067 ........ 0.0107
32-bit int #2 ........ 0.0066 ........ 0.0106
32-bit int #3 ........ 0.0063 ........ 0.0104
64-bit int #1 ........ 0.0072 ........ 0.0162
64-bit int #2 ........ 0.0073 ........ 0.0174
64-bit int #3 ........ 0.0072 ........ 0.0164
64-bit int #4 ........ 0.0077 ........ 0.0161
64-bit float #1 ...... 0.0053 ........ 0.0135
64-bit float #2 ...... 0.0053 ........ 0.0135
64-bit float #3 ...... 0.0052 ........ 0.0135
fix string #1 ....... -0.0002 ........ 0.0044
fix string #2 ........ 0.0035 ........ 0.0067
fix string #3 ........ 0.0035 ........ 0.0077
fix string #4 ........ 0.0033 ........ 0.0078
8-bit string #1 ...... 0.0059 ........ 0.0110
8-bit string #2 ...... 0.0063 ........ 0.0121
8-bit string #3 ...... 0.0064 ........ 0.0124
16-bit string #1 ..... 0.0099 ........ 0.0146
16-bit string #2 ..... 0.1522 ........ 0.1474
32-bit string ........ 0.1511 ........ 0.1483
wide char string #1 .. 0.0039 ........ 0.0084
wide char string #2 .. 0.0073 ........ 0.0123
8-bit binary #1 ...... 0.0040 ........ 0.0112
8-bit binary #2 ...... 0.0075 ........ 0.0123
8-bit binary #3 ...... 0.0077 ........ 0.0129
16-bit binary ........ 0.0096 ........ 0.0145
32-bit binary ........ 0.1535 ........ 0.1479
fix array #1 ......... 0.0008 ........ 0.0061
fix array #2 ......... 0.0121 ........ 0.0165
fix array #3 ......... 0.0193 ........ 0.0222
16-bit array #1 ...... 0.0607 ........ 0.0479
16-bit array #2 ........... S ............. S
32-bit array .............. S ............. S
complex array ........ 0.0749 ........ 0.0824
fix map #1 ........... 0.0329 ........ 0.0431
fix map #2 ........... 0.0161 ........ 0.0189
fix map #3 ........... 0.0205 ........ 0.0262
fix map #4 ........... 0.0252 ........ 0.0205
16-bit map #1 ........ 0.1016 ........ 0.0927
16-bit map #2 ............. S ............. S
32-bit map ................ S ............. S
complex map .......... 0.1096 ........ 0.1030
fixext 1 ............. 0.0157 ........ 0.0161
fixext 2 ............. 0.0175 ........ 0.0183
fixext 4 ............. 0.0156 ........ 0.0185
fixext 8 ............. 0.0163 ........ 0.0184
fixext 16 ............ 0.0164 ........ 0.0182
8-bit ext ............ 0.0158 ........ 0.0207
16-bit ext ........... 0.0203 ........ 0.0219
32-bit ext ........... 0.1614 ........ 0.1539
32-bit timestamp #1 .. 0.0195 ........ 0.0249
32-bit timestamp #2 .. 0.0188 ........ 0.0260
64-bit timestamp #1 .. 0.0207 ........ 0.0281
64-bit timestamp #2 .. 0.0212 ........ 0.0291
64-bit timestamp #3 .. 0.0207 ........ 0.0295
96-bit timestamp #1 .. 0.0222 ........ 0.0358
96-bit timestamp #2 .. 0.0228 ........ 0.0353
96-bit timestamp #3 .. 0.0210 ........ 0.0319
=============================================
Total 1.6432 1.9674
Skipped 4 4
Failed 0 0
Ignored 0 0
You may change default benchmark settings by defining the following environment variables:
Name | Default |
---|---|
MP_BENCH_TARGETS | pure_p,pure_u , see a list of available targets |
MP_BENCH_ITERATIONS | 100_000 |
MP_BENCH_DURATION | not set |
MP_BENCH_ROUNDS | 3 |
MP_BENCH_TESTS | -@slow , see a list of available tests |
For example:
export MP_BENCH_TARGETS=pure_p
export MP_BENCH_ITERATIONS=1000000
export MP_BENCH_ROUNDS=5
# a comma separated list of test names
export MP_BENCH_TESTS='complex array, complex map'
# or a group name
# export MP_BENCH_TESTS='-@slow' // @pecl_comp
# or a regexp
# export MP_BENCH_TESTS='/complex (array|map)/'
Another example, benchmarking both the library and the PECL extension:
MP_BENCH_TARGETS=pure_p,pure_u,pecl_p,pecl_u \
php -n -dextension=msgpack.so -dzend_extension=opcache.so \
-dpcre.jit=1 -dopcache.enable=1 -dopcache.enable_cli=1 \
tests/bench.php
Example output
Filter: MessagePack\Tests\Perf\Filter\ListFilter
Rounds: 3
Iterations: 100000
===========================================================================
Test/Target Packer BufferUnpacker msgpack_pack msgpack_unpack
---------------------------------------------------------------------------
nil .................. 0.0031 ........ 0.0141 ...... 0.0055 ........ 0.0064
false ................ 0.0039 ........ 0.0154 ...... 0.0056 ........ 0.0053
true ................. 0.0038 ........ 0.0139 ...... 0.0056 ........ 0.0044
7-bit uint #1 ........ 0.0061 ........ 0.0110 ...... 0.0059 ........ 0.0046
7-bit uint #2 ........ 0.0065 ........ 0.0119 ...... 0.0042 ........ 0.0029
7-bit uint #3 ........ 0.0054 ........ 0.0117 ...... 0.0045 ........ 0.0025
5-bit sint #1 ........ 0.0047 ........ 0.0103 ...... 0.0038 ........ 0.0022
5-bit sint #2 ........ 0.0048 ........ 0.0117 ...... 0.0038 ........ 0.0022
5-bit sint #3 ........ 0.0046 ........ 0.0102 ...... 0.0038 ........ 0.0023
8-bit uint #1 ........ 0.0063 ........ 0.0174 ...... 0.0039 ........ 0.0031
8-bit uint #2 ........ 0.0063 ........ 0.0167 ...... 0.0040 ........ 0.0029
8-bit uint #3 ........ 0.0063 ........ 0.0168 ...... 0.0039 ........ 0.0030
16-bit uint #1 ....... 0.0092 ........ 0.0222 ...... 0.0049 ........ 0.0030
16-bit uint #2 ....... 0.0096 ........ 0.0227 ...... 0.0042 ........ 0.0046
16-bit uint #3 ....... 0.0123 ........ 0.0274 ...... 0.0059 ........ 0.0051
32-bit uint #1 ....... 0.0136 ........ 0.0331 ...... 0.0060 ........ 0.0048
32-bit uint #2 ....... 0.0130 ........ 0.0336 ...... 0.0070 ........ 0.0048
32-bit uint #3 ....... 0.0127 ........ 0.0329 ...... 0.0051 ........ 0.0048
64-bit uint #1 ....... 0.0126 ........ 0.0268 ...... 0.0055 ........ 0.0049
64-bit uint #2 ....... 0.0135 ........ 0.0281 ...... 0.0052 ........ 0.0046
64-bit uint #3 ....... 0.0131 ........ 0.0274 ...... 0.0069 ........ 0.0044
8-bit int #1 ......... 0.0077 ........ 0.0236 ...... 0.0058 ........ 0.0044
8-bit int #2 ......... 0.0087 ........ 0.0244 ...... 0.0058 ........ 0.0048
8-bit int #3 ......... 0.0084 ........ 0.0241 ...... 0.0055 ........ 0.0049
16-bit int #1 ........ 0.0112 ........ 0.0271 ...... 0.0048 ........ 0.0045
16-bit int #2 ........ 0.0124 ........ 0.0292 ...... 0.0057 ........ 0.0049
16-bit int #3 ........ 0.0118 ........ 0.0270 ...... 0.0058 ........ 0.0050
32-bit int #1 ........ 0.0137 ........ 0.0366 ...... 0.0058 ........ 0.0051
32-bit int #2 ........ 0.0133 ........ 0.0366 ...... 0.0056 ........ 0.0049
32-bit int #3 ........ 0.0129 ........ 0.0350 ...... 0.0052 ........ 0.0048
64-bit int #1 ........ 0.0145 ........ 0.0254 ...... 0.0034 ........ 0.0025
64-bit int #2 ........ 0.0097 ........ 0.0214 ...... 0.0034 ........ 0.0025
64-bit int #3 ........ 0.0096 ........ 0.0287 ...... 0.0059 ........ 0.0050
64-bit int #4 ........ 0.0143 ........ 0.0277 ...... 0.0059 ........ 0.0046
64-bit float #1 ...... 0.0134 ........ 0.0281 ...... 0.0057 ........ 0.0052
64-bit float #2 ...... 0.0141 ........ 0.0281 ...... 0.0057 ........ 0.0050
64-bit float #3 ...... 0.0144 ........ 0.0282 ...... 0.0057 ........ 0.0050
fix string #1 ........ 0.0036 ........ 0.0143 ...... 0.0066 ........ 0.0053
fix string #2 ........ 0.0107 ........ 0.0222 ...... 0.0065 ........ 0.0068
fix string #3 ........ 0.0116 ........ 0.0245 ...... 0.0063 ........ 0.0069
fix string #4 ........ 0.0105 ........ 0.0253 ...... 0.0083 ........ 0.0077
8-bit string #1 ...... 0.0126 ........ 0.0318 ...... 0.0075 ........ 0.0088
8-bit string #2 ...... 0.0121 ........ 0.0295 ...... 0.0076 ........ 0.0086
8-bit string #3 ...... 0.0125 ........ 0.0293 ...... 0.0130 ........ 0.0093
16-bit string #1 ..... 0.0159 ........ 0.0368 ...... 0.0117 ........ 0.0086
16-bit string #2 ..... 0.1547 ........ 0.1686 ...... 0.1516 ........ 0.1373
32-bit string ........ 0.1558 ........ 0.1729 ...... 0.1511 ........ 0.1396
wide char string #1 .. 0.0098 ........ 0.0237 ...... 0.0066 ........ 0.0065
wide char string #2 .. 0.0128 ........ 0.0291 ...... 0.0061 ........ 0.0082
8-bit binary #1 ........... I ............. I ........... F ............. I
8-bit binary #2 ........... I ............. I ........... F ............. I
8-bit binary #3 ........... I ............. I ........... F ............. I
16-bit binary ............. I ............. I ........... F ............. I
32-bit binary ............. I ............. I ........... F ............. I
fix array #1 ......... 0.0040 ........ 0.0129 ...... 0.0120 ........ 0.0058
fix array #2 ......... 0.0279 ........ 0.0390 ...... 0.0143 ........ 0.0165
fix array #3 ......... 0.0415 ........ 0.0463 ...... 0.0162 ........ 0.0187
16-bit array #1 ...... 0.1349 ........ 0.1628 ...... 0.0334 ........ 0.0341
16-bit array #2 ........... S ............. S ........... S ............. S
32-bit array .............. S ............. S ........... S ............. S
complex array ............. I ............. I ........... F ............. F
fix map #1 ................ I ............. I ........... F ............. I
fix map #2 ........... 0.0345 ........ 0.0391 ...... 0.0143 ........ 0.0168
fix map #3 ................ I ............. I ........... F ............. I
fix map #4 ........... 0.0459 ........ 0.0473 ...... 0.0151 ........ 0.0163
16-bit map #1 ........ 0.2518 ........ 0.2962 ...... 0.0400 ........ 0.0490
16-bit map #2 ............. S ............. S ........... S ............. S
32-bit map ................ S ............. S ........... S ............. S
complex map .......... 0.2380 ........ 0.2682 ...... 0.0545 ........ 0.0579
fixext 1 .................. I ............. I ........... F ............. F
fixext 2 .................. I ............. I ........... F ............. F
fixext 4 .................. I ............. I ........... F ............. F
fixext 8 .................. I ............. I ........... F ............. F
fixext 16 ................. I ............. I ........... F ............. F
8-bit ext ................. I ............. I ........... F ............. F
16-bit ext ................ I ............. I ........... F ............. F
32-bit ext ................ I ............. I ........... F ............. F
32-bit timestamp #1 ....... I ............. I ........... F ............. F
32-bit timestamp #2 ....... I ............. I ........... F ............. F
64-bit timestamp #1 ....... I ............. I ........... F ............. F
64-bit timestamp #2 ....... I ............. I ........... F ............. F
64-bit timestamp #3 ....... I ............. I ........... F ............. F
96-bit timestamp #1 ....... I ............. I ........... F ............. F
96-bit timestamp #2 ....... I ............. I ........... F ............. F
96-bit timestamp #3 ....... I ............. I ........... F ............. F
===========================================================================
Total 1.5625 2.3866 0.7735 0.7243
Skipped 4 4 4 4
Failed 0 0 24 17
Ignored 24 24 0 7
With JIT:
MP_BENCH_TARGETS=pure_p,pure_u,pecl_p,pecl_u \
php -n -dextension=msgpack.so -dzend_extension=opcache.so \
-dpcre.jit=1 -dopcache.jit_buffer_size=64M -dopcache.jit=tracing -dopcache.enable=1 -dopcache.enable_cli=1 \
tests/bench.php
Example output
Filter: MessagePack\Tests\Perf\Filter\ListFilter
Rounds: 3
Iterations: 100000
===========================================================================
Test/Target Packer BufferUnpacker msgpack_pack msgpack_unpack
---------------------------------------------------------------------------
nil .................. 0.0001 ........ 0.0052 ...... 0.0053 ........ 0.0042
false ................ 0.0007 ........ 0.0060 ...... 0.0057 ........ 0.0043
true ................. 0.0008 ........ 0.0060 ...... 0.0056 ........ 0.0041
7-bit uint #1 ........ 0.0031 ........ 0.0046 ...... 0.0062 ........ 0.0041
7-bit uint #2 ........ 0.0021 ........ 0.0043 ...... 0.0062 ........ 0.0041
7-bit uint #3 ........ 0.0022 ........ 0.0044 ...... 0.0061 ........ 0.0040
5-bit sint #1 ........ 0.0030 ........ 0.0048 ...... 0.0062 ........ 0.0040
5-bit sint #2 ........ 0.0032 ........ 0.0046 ...... 0.0062 ........ 0.0040
5-bit sint #3 ........ 0.0031 ........ 0.0046 ...... 0.0062 ........ 0.0040
8-bit uint #1 ........ 0.0054 ........ 0.0079 ...... 0.0062 ........ 0.0050
8-bit uint #2 ........ 0.0051 ........ 0.0079 ...... 0.0064 ........ 0.0044
8-bit uint #3 ........ 0.0051 ........ 0.0082 ...... 0.0062 ........ 0.0044
16-bit uint #1 ....... 0.0077 ........ 0.0094 ...... 0.0065 ........ 0.0045
16-bit uint #2 ....... 0.0077 ........ 0.0094 ...... 0.0063 ........ 0.0045
16-bit uint #3 ....... 0.0077 ........ 0.0095 ...... 0.0064 ........ 0.0047
32-bit uint #1 ....... 0.0088 ........ 0.0119 ...... 0.0063 ........ 0.0043
32-bit uint #2 ....... 0.0089 ........ 0.0117 ...... 0.0062 ........ 0.0039
32-bit uint #3 ....... 0.0089 ........ 0.0118 ...... 0.0063 ........ 0.0044
64-bit uint #1 ....... 0.0097 ........ 0.0155 ...... 0.0063 ........ 0.0045
64-bit uint #2 ....... 0.0095 ........ 0.0153 ...... 0.0061 ........ 0.0045
64-bit uint #3 ....... 0.0096 ........ 0.0156 ...... 0.0063 ........ 0.0047
8-bit int #1 ......... 0.0053 ........ 0.0083 ...... 0.0062 ........ 0.0044
8-bit int #2 ......... 0.0052 ........ 0.0080 ...... 0.0062 ........ 0.0044
8-bit int #3 ......... 0.0052 ........ 0.0080 ...... 0.0062 ........ 0.0043
16-bit int #1 ........ 0.0089 ........ 0.0097 ...... 0.0069 ........ 0.0046
16-bit int #2 ........ 0.0075 ........ 0.0093 ...... 0.0063 ........ 0.0043
16-bit int #3 ........ 0.0075 ........ 0.0094 ...... 0.0062 ........ 0.0046
32-bit int #1 ........ 0.0086 ........ 0.0122 ...... 0.0063 ........ 0.0044
32-bit int #2 ........ 0.0087 ........ 0.0120 ...... 0.0066 ........ 0.0046
32-bit int #3 ........ 0.0086 ........ 0.0121 ...... 0.0060 ........ 0.0044
64-bit int #1 ........ 0.0096 ........ 0.0149 ...... 0.0060 ........ 0.0045
64-bit int #2 ........ 0.0096 ........ 0.0157 ...... 0.0062 ........ 0.0044
64-bit int #3 ........ 0.0096 ........ 0.0160 ...... 0.0063 ........ 0.0046
64-bit int #4 ........ 0.0097 ........ 0.0157 ...... 0.0061 ........ 0.0044
64-bit float #1 ...... 0.0079 ........ 0.0153 ...... 0.0056 ........ 0.0044
64-bit float #2 ...... 0.0079 ........ 0.0152 ...... 0.0057 ........ 0.0045
64-bit float #3 ...... 0.0079 ........ 0.0155 ...... 0.0057 ........ 0.0044
fix string #1 ........ 0.0010 ........ 0.0045 ...... 0.0071 ........ 0.0044
fix string #2 ........ 0.0048 ........ 0.0075 ...... 0.0070 ........ 0.0060
fix string #3 ........ 0.0048 ........ 0.0086 ...... 0.0068 ........ 0.0060
fix string #4 ........ 0.0050 ........ 0.0088 ...... 0.0070 ........ 0.0059
8-bit string #1 ...... 0.0081 ........ 0.0129 ...... 0.0069 ........ 0.0062
8-bit string #2 ...... 0.0086 ........ 0.0128 ...... 0.0069 ........ 0.0065
8-bit string #3 ...... 0.0086 ........ 0.0126 ...... 0.0115 ........ 0.0065
16-bit string #1 ..... 0.0105 ........ 0.0137 ...... 0.0128 ........ 0.0068
16-bit string #2 ..... 0.1510 ........ 0.1486 ...... 0.1526 ........ 0.1391
32-bit string ........ 0.1517 ........ 0.1475 ...... 0.1504 ........ 0.1370
wide char string #1 .. 0.0044 ........ 0.0085 ...... 0.0067 ........ 0.0057
wide char string #2 .. 0.0081 ........ 0.0125 ...... 0.0069 ........ 0.0063
8-bit binary #1 ........... I ............. I ........... F ............. I
8-bit binary #2 ........... I ............. I ........... F ............. I
8-bit binary #3 ........... I ............. I ........... F ............. I
16-bit binary ............. I ............. I ........... F ............. I
32-bit binary ............. I ............. I ........... F ............. I
fix array #1 ......... 0.0014 ........ 0.0059 ...... 0.0132 ........ 0.0055
fix array #2 ......... 0.0146 ........ 0.0156 ...... 0.0155 ........ 0.0148
fix array #3 ......... 0.0211 ........ 0.0229 ...... 0.0179 ........ 0.0180
16-bit array #1 ...... 0.0673 ........ 0.0498 ...... 0.0343 ........ 0.0388
16-bit array #2 ........... S ............. S ........... S ............. S
32-bit array .............. S ............. S ........... S ............. S
complex array ............. I ............. I ........... F ............. F
fix map #1 ................ I ............. I ........... F ............. I
fix map #2 ........... 0.0148 ........ 0.0180 ...... 0.0156 ........ 0.0179
fix map #3 ................ I ............. I ........... F ............. I
fix map #4 ........... 0.0252 ........ 0.0201 ...... 0.0214 ........ 0.0167
16-bit map #1 ........ 0.1027 ........ 0.0836 ...... 0.0388 ........ 0.0510
16-bit map #2 ............. S ............. S ........... S ............. S
32-bit map ................ S ............. S ........... S ............. S
complex map .......... 0.1104 ........ 0.1010 ...... 0.0556 ........ 0.0602
fixext 1 .................. I ............. I ........... F ............. F
fixext 2 .................. I ............. I ........... F ............. F
fixext 4 .................. I ............. I ........... F ............. F
fixext 8 .................. I ............. I ........... F ............. F
fixext 16 ................. I ............. I ........... F ............. F
8-bit ext ................. I ............. I ........... F ............. F
16-bit ext ................ I ............. I ........... F ............. F
32-bit ext ................ I ............. I ........... F ............. F
32-bit timestamp #1 ....... I ............. I ........... F ............. F
32-bit timestamp #2 ....... I ............. I ........... F ............. F
64-bit timestamp #1 ....... I ............. I ........... F ............. F
64-bit timestamp #2 ....... I ............. I ........... F ............. F
64-bit timestamp #3 ....... I ............. I ........... F ............. F
96-bit timestamp #1 ....... I ............. I ........... F ............. F
96-bit timestamp #2 ....... I ............. I ........... F ............. F
96-bit timestamp #3 ....... I ............. I ........... F ............. F
===========================================================================
Total 0.9642 1.0909 0.8224 0.7213
Skipped 4 4 4 4
Failed 0 0 24 17
Ignored 24 24 0 7
Note that the msgpack extension (v2.1.2) doesn't support ext, bin and UTF-8 str types.
The library is released under the MIT License. See the bundled LICENSE file for details.
Author: rybakit
Source Code: https://github.com/rybakit/msgpack.php
License: MIT License
1677907260
Node.js client for the official ChatGPT API.
This package is a Node.js wrapper around ChatGPT by OpenAI. TS batteries included. ✨
March 1, 2023
The official OpenAI chat completions API has been released, and it is now the default for this package! 🔥
Method | Free? | Robust? | Quality? |
---|---|---|---|
ChatGPTAPI | ❌ No | ✅ Yes | ✅️ Real ChatGPT models |
ChatGPTUnofficialProxyAPI | ✅ Yes | ☑️ Maybe | ✅ Real ChatGPT |
Note: We strongly recommend using ChatGPTAPI
since it uses the officially supported API from OpenAI. We may remove support for ChatGPTUnofficialProxyAPI
in a future release.
ChatGPTAPI
- Uses the gpt-3.5-turbo-0301
model with the official OpenAI chat completions API (official, robust approach, but it's not free)ChatGPTUnofficialProxyAPI
- Uses an unofficial proxy server to access ChatGPT's backend API in a way that circumvents Cloudflare (uses the real ChatGPT and is pretty lightweight, but relies on a third-party server and is rate-limited)To run the CLI, you'll need an OpenAI API key:
export OPENAI_API_KEY="sk-TODO"
npx chatgpt "your prompt here"
By default, the response is streamed to stdout, the results are stored in a local config file, and every invocation starts a new conversation. You can use -c
to continue the previous conversation and --no-stream
to disable streaming.
Under the hood, the CLI uses ChatGPTAPI
with text-davinci-003
to mimic ChatGPT.
Usage:
$ chatgpt <prompt>
Commands:
<prompt> Ask ChatGPT a question
rm-cache Clears the local message cache
ls-cache Prints the local message cache path
For more info, run any command with the `--help` flag:
$ chatgpt --help
$ chatgpt rm-cache --help
$ chatgpt ls-cache --help
Options:
-c, --continue Continue last conversation (default: false)
-d, --debug Enables debug logging (default: false)
-s, --stream Streams the response (default: true)
-s, --store Enables the local message cache (default: true)
-t, --timeout Timeout in milliseconds
-k, --apiKey OpenAI API key
-n, --conversationName Unique name for the conversation
-h, --help Display this message
-v, --version Display version number
npm install chatgpt
Make sure you're using node >= 18
so fetch
is available (or node >= 14
if you install a fetch polyfill).
To use this module from Node.js, you need to pick between two methods:
Method | Free? | Robust? | Quality? |
---|---|---|---|
ChatGPTAPI | ❌ No | ✅ Yes | ✅️ Real ChatGPT models |
ChatGPTUnofficialProxyAPI | ✅ Yes | ☑️ Maybe | ✅ Real ChatGPT |
ChatGPTAPI
- Uses the gpt-3.5-turbo-0301
model with the official OpenAI chat completions API (official, robust approach, but it's not free). You can override the model, completion params, and system message to fully customize your assistant.
ChatGPTUnofficialProxyAPI
- Uses an unofficial proxy server to access ChatGPT's backend API in a way that circumvents Cloudflare (uses the real ChatGPT and is pretty lightweight, but relies on a third-party server and is rate-limited)
Both approaches have very similar APIs, so it should be simple to swap between them.
Note: We strongly recommend using ChatGPTAPI
since it uses the officially supported API from OpenAI. We may remove support for ChatGPTUnofficialProxyAPI
in a future release.
Sign up for an OpenAI API key and store it in your environment.
import { ChatGPTAPI } from 'chatgpt'
async function example() {
const api = new ChatGPTAPI({
apiKey: process.env.OPENAI_API_KEY
})
const res = await api.sendMessage('Hello World!')
console.log(res.text)
}
You can override the default model
(gpt-3.5-turbo-0301
) and any OpenAI chat completion params using completionParams
:
const api = new ChatGPTAPI({
apiKey: process.env.OPENAI_API_KEY,
completionParams: {
temperature: 0.5,
top_p: 0.8
}
})
If you want to track the conversation, you'll need to pass the parentMessageId
like this:
const api = new ChatGPTAPI({ apiKey: process.env.OPENAI_API_KEY })
// send a message and wait for the response
let res = await api.sendMessage('What is OpenAI?')
console.log(res.text)
// send a follow-up
res = await api.sendMessage('Can you expand on that?', {
parentMessageId: res.id
})
console.log(res.text)
// send another follow-up
res = await api.sendMessage('What were we talking about?', {
parentMessageId: res.id
})
console.log(res.text)
You can add streaming via the onProgress
handler:
const res = await api.sendMessage('Write a 500 word essay on frogs.', {
// print the partial response as the AI is "typing"
onProgress: (partialResponse) => console.log(partialResponse.text)
})
// print the full text at the end
console.log(res.text)
You can add a timeout using the timeoutMs
option:
// timeout after 2 minutes (which will also abort the underlying HTTP request)
const response = await api.sendMessage(
'write me a really really long essay on frogs',
{
timeoutMs: 2 * 60 * 1000
}
)
If you want to see more info about what's actually being sent to OpenAI's chat completions API, set the debug: true
option in the ChatGPTAPI
constructor:
const api = new ChatGPTAPI({
apiKey: process.env.OPENAI_API_KEY,
debug: true
})
We default to a basic systemMessage
. You can override this in either the ChatGPTAPI
constructor or sendMessage
:
const res = await api.sendMessage('what is the answer to the universe?', {
systemMessage: `You are ChatGPT, a large language model trained by OpenAI. You answer as concisely as possible for each responseIf you are generating a list, do not have too many items.
Current date: ${new Date().toISOString()}\n\n`
})
Note that we automatically handle appending the previous messages to the prompt and attempt to optimize for the available tokens (which defaults to 4096
).
Usage in CommonJS (Dynamic import)
async function example() {
// To use ESM in CommonJS, you can use a dynamic import
const { ChatGPTAPI } = await import('chatgpt')
const api = new ChatGPTAPI({ apiKey: process.env.OPENAI_API_KEY })
const res = await api.sendMessage('Hello World!')
console.log(res.text)
}
The API for ChatGPTUnofficialProxyAPI
is almost exactly the same. You just need to provide a ChatGPT accessToken
instead of an OpenAI API key.
import { ChatGPTUnofficialProxyAPI } from 'chatgpt'
async function example() {
const api = new ChatGPTUnofficialProxyAPI({
accessToken: process.env.OPENAI_ACCESS_TOKEN
})
const res = await api.sendMessage('Hello World!')
console.log(res.text)
}
See demos/demo-reverse-proxy for a full example:
npx tsx demos/demo-reverse-proxy.ts
ChatGPTUnofficialProxyAPI
messages also contain a conversationid
in addition to parentMessageId
, since the ChatGPT webapp can't reference messages across
You can override the reverse proxy by passing apiReverseProxyUrl
:
const api = new ChatGPTUnofficialProxyAPI({
accessToken: process.env.OPENAI_ACCESS_TOKEN,
apiReverseProxyUrl: 'https://your-example-server.com/api/conversation'
})
Known reverse proxies run by community members include:
Reverse Proxy URL | Author | Rate Limits | Last Checked |
---|---|---|---|
https://chat.duti.tech/api/conversation | @acheong08 | 120 req/min by IP | 2/19/2023 |
https://gpt.pawan.krd/backend-api/conversation | @PawanOsman | ? | 2/19/2023 |
Note: info on how the reverse proxies work is not being published at this time in order to prevent OpenAI from disabling access.
To use ChatGPTUnofficialProxyAPI
, you'll need an OpenAI access token from the ChatGPT webapp. To do this, you can use any of the following methods which take an email
and password
and return an access token:
These libraries work with email + password accounts (e.g., they do not support accounts where you auth via Microsoft / Google).
Alternatively, you can manually get an accessToken
by logging in to the ChatGPT webapp and then opening https://chat.openai.com/api/auth/session
, which will return a JSON object containing your accessToken
string.
Access tokens last for days.
Note: using a reverse proxy will expose your access token to a third-party. There shouldn't be any adverse effects possible from this, but please consider the risks before using this method.
See the auto-generated docs for more info on methods and parameters.
Most of the demos use ChatGPTAPI
. It should be pretty easy to convert them to use ChatGPTUnofficialProxyAPI
if you'd rather use that approach. The only thing that needs to change is how you initialize the api with an accessToken
instead of an apiKey
.
To run the included demos:
OPENAI_API_KEY
in .envA basic demo is included for testing purposes:
npx tsx demos/demo.ts
A demo showing on progress handler:
npx tsx demos/demo-on-progress.ts
The on progress demo uses the optional onProgress
parameter to sendMessage
to receive intermediary results as ChatGPT is "typing".
npx tsx demos/demo-conversation.ts
A persistence demo shows how to store messages in Redis for persistence:
npx tsx demos/demo-persistence.ts
Any keyv adaptor is supported for persistence, and there are overrides if you'd like to use a different way of storing / retrieving messages.
Note that persisting message is required for remembering the context of previous conversations beyond the scope of the current Node.js process, since by default, we only store messages in memory. Here's an external demo of using a completely custom database solution to persist messages.
Note: Persistence is handled automatically when using ChatGPTUnofficialProxyAPI
because it is connecting indirectly to ChatGPT.
All of these awesome projects are built using the chatgpt
package. 🤯
If you create a cool integration, feel free to open a PR and add it to the list.
node >= 14
.fetch
is installed.chatgpt
, we recommend using it only from your backend APIPrevious Updates
Feb 19, 2023
We now provide three ways of accessing the unofficial ChatGPT API, all of which have tradeoffs:
Method | Free? | Robust? | Quality? |
---|---|---|---|
ChatGPTAPI | ❌ No | ✅ Yes | ☑️ Mimics ChatGPT |
ChatGPTUnofficialProxyAPI | ✅ Yes | ☑️ Maybe | ✅ Real ChatGPT |
ChatGPTAPIBrowser (v3) | ✅ Yes | ❌ No | ✅ Real ChatGPT |
Note: I recommend that you use either ChatGPTAPI
or ChatGPTUnofficialProxyAPI
.
ChatGPTAPI
- Uses text-davinci-003
to mimic ChatGPT via the official OpenAI completions API (most robust approach, but it's not free and doesn't use a model fine-tuned for chat)ChatGPTUnofficialProxyAPI
- Uses an unofficial proxy server to access ChatGPT's backend API in a way that circumvents Cloudflare (uses the real ChatGPT and is pretty lightweight, but relies on a third-party server and is rate-limited)ChatGPTAPIBrowser
- (deprecated; v3.5.1 of this package) Uses Puppeteer to access the official ChatGPT webapp (uses the real ChatGPT, but very flaky, heavyweight, and error prone)Feb 5, 2023
OpenAI has disabled the leaked chat model we were previously using, so we're now defaulting to text-davinci-003
, which is not free.
We've found several other hidden, fine-tuned chat models, but OpenAI keeps disabling them, so we're searching for alternative workarounds.
Feb 1, 2023
This package no longer requires any browser hacks – it is now using the official OpenAI completions API with a leaked model that ChatGPT uses under the hood. 🔥
import { ChatGPTAPI } from 'chatgpt'
const api = new ChatGPTAPI({
apiKey: process.env.OPENAI_API_KEY
})
const res = await api.sendMessage('Hello World!')
console.log(res.text)
Please upgrade to chatgpt@latest
(at least v4.0.0). The updated version is significantly more lightweight and robust compared with previous versions. You also don't have to worry about IP issues or rate limiting.
Huge shoutout to @waylaidwanderer for discovering the leaked chat model!
If you run into any issues, we do have a pretty active Discord with a bunch of ChatGPT hackers from the Node.js & Python communities.
Lastly, please consider starring this repo and following me on twitter to help support the project.
Thanks && cheers, Travis
Author: Transitive-bullshit
Source Code: https://github.com/transitive-bullshit/chatgpt-api
License: MIT license
1669952228
In this tutorial, you'll learn: What is Dijkstra's Algorithm and how Dijkstra's algorithm works with the help of visual guides.
You can use algorithms in programming to solve specific problems through a set of precise instructions or procedures.
Dijkstra's algorithm is one of many graph algorithms you'll come across. It is used to find the shortest path from a fixed node to all other nodes in a graph.
There are different representations of Dijkstra's algorithm. You can either find the shortest path between two nodes, or the shortest path from a fixed node to the rest of the nodes in a graph.
In this article, you'll learn how Dijkstra's algorithm works with the help of visual guides.
Before we dive into more detailed visual examples, you need to understand how Dijkstra's algorithm works.
Although the theoretical explanation may seem a bit abstract, it'll help you understand the practical aspect better.
In a given graph containing different nodes, we are required to get the shortest path from a given node to the rest of the nodes.
These nodes can represent any object like the names of cities, letters, and so on.
Between each node is a number denoting the distance between two nodes, as you can see in the image below:
We usually work with two arrays – one for visited nodes, and another for unvisited nodes. You'll learn more about the arrays in the next section.
When a node is visited, the algorithm calculates how long it took to get to the node and stores the distance. If a shorter path to a node is found, the initial value assigned for the distance is updated.
Note that a node cannot be visited twice.
The algorithm runs recursively until all the nodes have been visited.
In this section, we'll take a look at a practical example that shows how Dijkstra's algorithm works.
Here's the graph we'll be working with:
We'll use the table below to put down the visited nodes and their distance from the fixed node:
NODE | SHORTEST DISTANCE FROM FIXED NODE |
---|---|
A | ∞ |
B | ∞ |
C | ∞ |
D | ∞ |
E | ∞ |
Visited nodes = []
Unvisited nodes = [A,B,C,D,E]
Above, we have a table showing each node and the shortest distance from the that node to the fixed node. We are yet to choose the fixed node.
Note that the distance for each node in the table is currently denoted as infinity (∞). This is because we don't know the shortest distance yet.
We also have two arrays – visited and unvisited. Whenever a node is visited, it is added to the visited nodes array.
Let's get started!
To simplify things, I'll break the process down into iterations. You'll see what happens in each step with the aid of diagrams.
The first iteration might seem confusing, but that's totally fine. Once we start repeating the process in each iteration, you'll have a clearer picture of how the algorithm works.
Step #1 - Pick an unvisited node
We'll choose A as the fixed node. So we'll find the shortest distance from A to every other node in the graph.
We're going to give A a distance of 0 because it is the initial node. So the table would look like this:
NODE | SHORTEST DISTANCE FROM FIXED NODE |
---|---|
A | 0 |
B | ∞ |
C | ∞ |
D | ∞ |
E | ∞ |
Step #2 - Find the distance from current node
The next thing to do after choosing a node is to find the distance from it to the unvisited nodes around it.
The two unvisited nodes directly linked to A are B and C.
To get the distance from A to B:
0 + 4 = 4
0 being the value of the current node (A), and 4 being the distance between A and B in the graph.
To get the distance from A to C:
0 + 2 = 2
Step #3 - Update table with known distances
In the last step, we got 4 and 2 as the values of B and C respectively. So we'll update the table with those values:
NODE | SHORTEST DISTANCE FROM FIXED NODE |
---|---|
A | 0 |
B | 4 |
C | 2 |
D | ∞ |
E | ∞ |
Step #4 - Update arrays
At this point, the first iteration is complete. We'll move node A to the visited nodes array:
Visited nodes = [A]
Unvisited nodes = [B,C,D,E]
Before we proceed to the next iteration, you should know the following:
Step #1 - Pick an unvisited node
We have four unvisited nodes — [B,C,D,E]. So how do you know which node to pick for the next iteration?
Well, we pick the node with the smallest known distance recorded in the table. Here's the table:
NODE | SHORTEST DISTANCE FROM FIXED NODE |
---|---|
A | 0 |
B | 4 |
C | 2 |
D | ∞ |
E | ∞ |
So we're going with node C.
Step #2 - Find the distance from current node
To find the distance from the current node to the fixed node, we have to consider the nodes linked to the current node.
The nodes linked to the current node are A and B.
But A has been visited in the previous iteration so it will not be linked to the current node. That is:
From the diagram above,
To find the distance from C to B:
2 + 1 = 3
2 above is recorded distance for node C while 1 is the distance between C and B in the graph.
Step #3 - Update table with known distances
In the last step, we got the value of B to be 3. In the first iteration, it was 4.
We're going to update the distance in the table to 3.
NODE | SHORTEST DISTANCE FROM FIXED NODE |
---|---|
A | 0 |
B | 3 |
C | 2 |
D | ∞ |
E | ∞ |
So, A --> B = 4 (First iteration).
A --> C --> B = 3 (Second iteration).
The algorithm has helped us find the shortest path to B from A.
Step #4 - Update arrays
We're done with the last visited node. Let's add it to the visited nodes array:
Visited nodes = [A,C]
Unvisited nodes = [B,D,E]
Step #1 - Pick an unvisited node
We're down to three unvisited nodes — [B,D,E]. From the array, B has the shortest known distance.
To restate what is going on in the diagram above:
Step #2 - Find the distance from current node
The nodes linked to the current node are D and E.
B (the current node) has a value of 3. Therefore,
For node D, 3 + 3 = 6.
For node E, 3 + 2 = 5.
Step #3 - Update table with known distances
NODE | SHORTEST DISTANCE FROM FIXED NODE |
---|---|
A | 0 |
B | 3 |
C | 2 |
D | 6 |
E | 5 |
Step #4 - Update arrays
Visited nodes = [A,C,B]
Unvisited nodes = [D,E]
Step #1 - Pick an unvisited node
Like other iterations, we'll go with the unvisited node with the shortest known distance. That is E.
Step #2 - Find the distance from current node
According to our table, E has a value of 5.
For D in the current iteration,
5 + 5 = 10.
The value gotten for D here is 10, which is greater than the recorded value of 6 in the previous iteration. For this reason, we'll not update the table.
Step #3 - Update table with known distances
Our table remains the same:
NODE | SHORTEST DISTANCE FROM FIXED NODE |
---|---|
A | 0 |
B | 3 |
C | 2 |
D | 6 |
E | 5 |
Step #4 - Update arrays
Visited nodes = [A,C,B,E]
Unvisited nodes = [D]
Step #1 - Pick an unvisited node
We're currently left with one node in the unvisited array — D.
Step #2 - Find the distance from current node
The algorithm has gotten to the last iteration. This is because all nodes linked to the current node have been visited already so we can't link to them.
Step #3 - Update table with known distances
Our table remains the same:
NODE | SHORTEST DISTANCE FROM FIXED NODE |
---|---|
A | 0 |
B | 3 |
C | 2 |
D | 6 |
E | 5 |
At this point, we have updated the table with the shortest distance from the fixed node to every other node in the graph.
Step #4 - Update arrays
Visited nodes = [A,C,B,E,D]
Unvisited nodes = []
As can be seen above, we have no nodes left to visit. Using Dijkstra's algorithm, we've found the shortest distance from the fixed node to others nodes in the graph.
The pseudocode example in this section was gotten from Wikipedia. Here it is:
1 function Dijkstra(Graph, source):
2
3 for each vertex v in Graph.Vertices:
4 dist[v] ← INFINITY
5 prev[v] ← UNDEFINED
6 add v to Q
7 dist[source] ← 0
8
9 while Q is not empty:
10 u ← vertex in Q with min dist[u]
11 remove u from Q
12
13 for each neighbor v of u still in Q:
14 alt ← dist[u] + Graph.Edges(u, v)
15 if alt < dist[v]:
16 dist[v] ← alt
17 prev[v] ← u
18
19 return dist[], prev[]
Here are some of the common applications of Dijkstra's algorithm:
In this article, we talked about Dijkstra's algorithm. It is used to find the shortest distance from a fixed node to all other nodes in a graph.
We started by giving a brief summary of how the algorithm works.
We then had a look at an example that further explained Dijkstra's algorithm in steps using visual guides.
We concluded with a pseudocode example and some of the applications of Dijkstra's algorithm.
Happy coding!
Original article source at https://www.freecodecamp.org
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