Rupert  Beatty

Rupert Beatty

1638257520

9 Best Most Essential Features of a Scheduler

A scheduler is a tool for managing time and resources efficiently in our day-to-day life. Before choosing a scheduler for your WPF application, check if it has the following essential features:

9 Most Essential Features of a Scheduler

  • Variety of built-in calendar views
  • High performance
  • Recurrence events
  • Resource grouping
  • Easy editing of appointments
  • Appointment rescheduling
  • Appointment reminders
  • Time zone and daylight saving time management
  • Customizable UI

Let’s take a close look at each of these features.

#blazor 

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Buddha Community

9 Best Most Essential Features of a Scheduler
bindu singh

bindu singh

1647351133

Procedure To Become An Air Hostess/Cabin Crew

Minimum educational required – 10+2 passed in any stream from a recognized board.

The age limit is 18 to 25 years. It may differ from one airline to another!

 

Physical and Medical standards –

  • Females must be 157 cm in height and males must be 170 cm in height (for males). This parameter may vary from one airline toward the next.
  • The candidate's body weight should be proportional to his or her height.
  • Candidates with blemish-free skin will have an advantage.
  • Physical fitness is required of the candidate.
  • Eyesight requirements: a minimum of 6/9 vision is required. Many airlines allow applicants to fix their vision to 20/20!
  • There should be no history of mental disease in the candidate's past.
  • The candidate should not have a significant cardiovascular condition.

You can become an air hostess if you meet certain criteria, such as a minimum educational level, an age limit, language ability, and physical characteristics.

As can be seen from the preceding information, a 10+2 pass is the minimal educational need for becoming an air hostess in India. So, if you have a 10+2 certificate from a recognized board, you are qualified to apply for an interview for air hostess positions!

You can still apply for this job if you have a higher qualification (such as a Bachelor's or Master's Degree).

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Email:     info@aerofly.co.in

 

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FAQs On a Udemy clone app That You Should Know Before Buying!

BSETEC's Udemy clone app based on formalized teaching but with the help of electronic resources is known as E-learning.E-learning, also referred to as online learning or electronic learning, is the acquisition of knowledge which takes place through electronic technologies .

Udemy, which was founded more than a decade ago, has established itself as a global leader in the online teaching industry. People in our digital era rely on technology and devices for nearly everything, including education. When it comes to online learning, or eLearning, which is regarded as a lifesaver– capable of sustaining the educational environment even during the Covid-19 pandemic– it has evolved into a platform bursting with potential, not only for students but also for tutors, educators, and instructors. Furthermore, when compared to traditional educational techniques, the flexibility and customization given by online tutoring software like Expertplus LMS are unrivalled. As a result, it is gradually becoming an important component of the learning process, which is why eLearning is here to stay– even after the epidemic has passed, it is a huge increase in the number of eLearning applications and websites, and most businesses are choosing for Udemy Clone App instead of starting from scratch.

BigBlueButton Technology – Make Efficient Interaction with LMS

How can I get started with your own online tutoring company?

To use the Udemy Clone App script to establish an online tutoring marketplace similar to Udemy, bear the following factors in mind:

  • How to define your target audience?– Before you start developing your Learning Management System, you should think about who you're going to serve, what their background is, what kind of job they want to do, and what their career goals are. These are all things to consider before you begin the development process. As a result, you must be clear about who you are developing your app for.
  • Why have a clear set of goals and objectives in mind?– If you're creating an app for eLearning, you should have a solid strategy and set of goals in mind. You can't simply take a leap of faith and draw conclusions. You must have both long and short term objectives, and you must put them into action.
  • Why create a simple and speedy registration process?– No one wants to spend more than a minute or two on a signup screen, especially if the app is intended for educational reasons. As a result, it's critical that the user registration, login, and signup procedure be simple and quick. It should provide one-tap or social login options so that the AI can read the social account and fill in the data on its own.
  • Why have a visually appealing homepage– "The first impression is the final impression" and "The last impression is the enduring impression" are two prominent expressions. When you initially open the app, the first thing that appears on your screen is the homepage, and if it isn't appealing enough, you will most likely not want to use it. As a result, the user interface must be simple to use and appealing to the eye.
  • Why do we alter and revise– Once you've begun creating the app, you can customise and revise it to meet the needs of your users, thanks to the Udemy Clone Script's high level of customization and a large range of templates and motifs to select from.


If you want to develop a platform with high-quality eLearning features that cater to the needs of a large mass of audience, then opt for ExpertPlus LMS, and contact BSEtec now! Hurry!

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Substrate Parachain Template: A New Cumulus-based Substrate Node

Substrate Cumulus Parachain Template

A new Cumulus-based Substrate node, ready for hacking :cloud:

This project is a fork of the Substrate Node Template modified to include dependencies required for registering this node as a parathread or parachain to an established relay chain.

👉 Learn more about parachains here, and parathreads here.

Build & Run

Follow these steps to prepare a local Substrate development environment :hammer_and_wrench:

Setup of Machine

If necessary, refer to the setup instructions at the Substrate Developer Hub.

Build

Once the development environment is set up, build the Cumulus Parachain Template. This command will build the Wasm Runtime and native code:

cargo build --release

Relay Chain

NOTE: In the following two sections, we document how to manually start a few relay chain nodes, start a parachain node (collator), and register the parachain with the relay chain.

We also have the polkadot-launch CLI tool that automate the following steps and help you easily launch relay chains and parachains. However it is still good to go through the following procedures once to understand the mechanism for running and registering a parachain.

To operate a parathread or parachain, you must connect to a relay chain. Typically you would test on a local Rococo development network, then move to the testnet, and finally launch on the mainnet. Keep in mind you need to configure the specific relay chain you will connect to in your collator chain_spec.rs. In the following examples, we will use rococo-local as the relay network.

Build Relay Chain

Clone and build Polkadot (beware of the version tag we used):

# Get a fresh clone, or `cd` to where you have polkadot already:
git clone -b v0.9.7 --depth 1 https://github.com/paritytech/polkadot.git
cd polkadot
cargo build --release

Generate the Relay Chain Chainspec

First, we create the chain specification file (chainspec). Note the chainspec file must be generated on a single node and then shared among all nodes!

👉 Learn more about chain specification here.

./target/release/polkadot build-spec \
--chain rococo-local \
--raw \
--disable-default-bootnode \
> rococo_local.json

Start Relay Chain

We need n + 1 full validator nodes running on a relay chain to accept n parachain / parathread connections. Here we will start two relay chain nodes so we can have one parachain node connecting in later.

From the Polkadot working directory:

# Start Relay `Alice` node
./target/release/polkadot \
--chain ./rococo_local.json \
-d /tmp/relay/alice \
--validator \
--alice \
--port 50555

Open a new terminal, same directory:

# Start Relay `Bob` node
./target/release/polkadot \
--chain ./rococo_local.json \
-d /tmp/relay/bob \
--validator \
--bob \
--port 50556

Add more nodes as needed, with non-conflicting ports, DB directories, and validator keys (--charlie, --dave, etc.).

Reserve a ParaID

To connect to a relay chain, you must first _reserve a ParaId for your parathread that will become a parachain. To do this, you will need sufficient amount of currency on the network account to reserve the ID.

In this example, we will use Charlie development account where we have funds available. Once you submit this extrinsic successfully, you can start your collators.

The easiest way to reserve your ParaId is via Polkadot Apps UI under the Parachains -> Parathreads tab and use the + ParaID button.

Parachain

Select the Correct Relay Chain

To operate your parachain, you need to specify the correct relay chain you will connect to in your collator chain_spec.rs. Specifically you pass the command for the network you need in the Extensions of your ChainSpec::from_genesis() in the code.

Extensions {
    relay_chain: "rococo-local".into(), // You MUST set this to the correct network!
    para_id: id.into(),
},

You can choose from any pre-set runtime chainspec in the Polkadot repo, by referring to the cli/src/command.rs and node/service/src/chain_spec.rs files or generate your own and use that. See the Cumulus Workshop for how.

In the following examples, we will use the rococo-local relay network we setup in the last section.

Export the Parachain Genesis and Runtime

We first generate the genesis state and genesis wasm needed for the parachain registration.

# Build the parachain node (from it's top level dir)
cd substrate-parachain-template
cargo build --release

# Folder to store resource files needed for parachain registration
mkdir -p resources

# Build the chainspec
./target/release/parachain-collator build-spec \
--disable-default-bootnode > ./resources/template-local-plain.json

# Build the raw chainspec file
./target/release/parachain-collator build-spec \
--chain=./resources/template-local-plain.json \
--raw --disable-default-bootnode > ./resources/template-local-raw.json

# Export genesis state to `./resources`, using 2000 as the ParaId
./target/release/parachain-collator export-genesis-state --parachain-id 2000 > ./resources/para-2000-genesis

# Export the genesis wasm
./target/release/parachain-collator export-genesis-wasm > ./resources/para-2000-wasm

NOTE: we have set the para_ID to be 2000 here. This must be unique for all parathreads/chains on the relay chain you register with. You must reserve this first on the relay chain for the testnet or mainnet.

Start a Parachain Node (Collator)

From the parachain template working directory:

# NOTE: this command assumes the chain spec is in a directory named `polkadot`
# that is at the same level of the template working directory. Change as needed.
#
# It also assumes a ParaId of 2000. Change as needed.
./target/release/parachain-collator \
-d /tmp/parachain/alice \
--collator \
--alice \
--force-authoring \
--ws-port 9945 \
--parachain-id 2000 \
-- \
--execution wasm \
--chain ../polkadot/rococo_local.json

Output:

2021-05-30 16:57:39 Parachain Collator Template
2021-05-30 16:57:39 ✌️  version 3.0.0-acce183-x86_64-linux-gnu
2021-05-30 16:57:39 ❤️  by Anonymous, 2017-2021
2021-05-30 16:57:39 📋 Chain specification: Local Testnet
2021-05-30 16:57:39 🏷 Node name: Alice
2021-05-30 16:57:39 👤 Role: AUTHORITY
2021-05-30 16:57:39 💾 Database: RocksDb at /tmp/parachain/alice/chains/local_testnet/db
2021-05-30 16:57:39 ⛓  Native runtime: template-parachain-1 (template-parachain-0.tx1.au1)
2021-05-30 16:57:41 Parachain id: Id(2000)
2021-05-30 16:57:41 Parachain Account: 5Ec4AhPUwPeyTFyuhGuBbD224mY85LKLMSqSSo33JYWCazU4
2021-05-30 16:57:41 Parachain genesis state: 0x0000000000000000000000000000000000000000000000000000000000000000000a96f42b5cb798190e5f679bb16970905087a9a9fc612fb5ca6b982b85783c0d03170a2e7597b7b7e3d84c05391d139a62b157e78786d8c082f29dcf4c11131400
2021-05-30 16:57:41 Is collating: yes
2021-05-30 16:57:41 [Parachain] 🔨 Initializing Genesis block/state (state: 0x0a96…3c0d, header-hash: 0xd42b…f271)
2021-05-30 16:57:41 [Parachain] ⏱  Loaded block-time = 12s from block 0xd42bb78354bc21770e3f0930ed45c7377558d2d8e81ca4d457e573128aabf271
2021-05-30 16:57:43 [Relaychain] 🔨 Initializing Genesis block/state (state: 0xace1…1b62, header-hash: 0xfa68…cf58)
2021-05-30 16:57:43 [Relaychain] 👴 Loading GRANDPA authority set from genesis on what appears to be first startup.
2021-05-30 16:57:44 [Relaychain] ⏱  Loaded block-time = 6s from block 0xfa68f5abd2a80394b87c9bd07e0f4eee781b8c696d0a22c8e5ba38ae10e1cf58
2021-05-30 16:57:44 [Relaychain] 👶 Creating empty BABE epoch changes on what appears to be first startup.
2021-05-30 16:57:44 [Relaychain] 🏷 Local node identity is: 12D3KooWBjYK2W4dsBfsrFA9tZCStb5ogPb6STQqi2AK9awXfXyG
2021-05-30 16:57:44 [Relaychain] 📦 Highest known block at #0
2021-05-30 16:57:44 [Relaychain] 〽️ Prometheus server started at 127.0.0.1:9616
2021-05-30 16:57:44 [Relaychain] Listening for new connections on 127.0.0.1:9945.
2021-05-30 16:57:44 [Parachain] Using default protocol ID "sup" because none is configured in the chain specs
2021-05-30 16:57:44 [Parachain] 🏷 Local node identity is: 12D3KooWADBSC58of6ng2M29YTDkmWCGehHoUZhsy9LGkHgYscBw
2021-05-30 16:57:44 [Parachain] 📦 Highest known block at #0
2021-05-30 16:57:44 [Parachain] Unable to listen on 127.0.0.1:9945
2021-05-30 16:57:44 [Parachain] Unable to bind RPC server to 127.0.0.1:9945. Trying random port.
2021-05-30 16:57:44 [Parachain] Listening for new connections on 127.0.0.1:45141.
2021-05-30 16:57:45 [Relaychain] 🔍 Discovered new external address for our node: /ip4/192.168.42.204/tcp/30334/ws/p2p/12D3KooWBjYK2W4dsBfsrFA9tZCStb5ogPb6STQqi2AK9awXfXyG
2021-05-30 16:57:45 [Parachain] 🔍 Discovered new external address for our node: /ip4/192.168.42.204/tcp/30333/p2p/12D3KooWADBSC58of6ng2M29YTDkmWCGehHoUZhsy9LGkHgYscBw
2021-05-30 16:57:48 [Relaychain] ✨ Imported #8 (0xe60b…9b0a)
2021-05-30 16:57:49 [Relaychain] 💤 Idle (2 peers), best: #8 (0xe60b…9b0a), finalized #5 (0x1e6f…567c), ⬇ 4.5kiB/s ⬆ 2.2kiB/s
2021-05-30 16:57:49 [Parachain] 💤 Idle (0 peers), best: #0 (0xd42b…f271), finalized #0 (0xd42b…f271), ⬇ 2.0kiB/s ⬆ 1.7kiB/s
2021-05-30 16:57:54 [Relaychain] ✨ Imported #9 (0x1af9…c9be)
2021-05-30 16:57:54 [Relaychain] ✨ Imported #9 (0x6ed8…fdf6)
2021-05-30 16:57:54 [Relaychain] 💤 Idle (2 peers), best: #9 (0x1af9…c9be), finalized #6 (0x3319…69a2), ⬇ 1.8kiB/s ⬆ 0.5kiB/s
2021-05-30 16:57:54 [Parachain] 💤 Idle (0 peers), best: #0 (0xd42b…f271), finalized #0 (0xd42b…f271), ⬇ 0.2kiB/s ⬆ 0.2kiB/s
2021-05-30 16:57:59 [Relaychain] 💤 Idle (2 peers), best: #9 (0x1af9…c9be), finalized #7 (0x5b50…1e5b), ⬇ 0.6kiB/s ⬆ 0.4kiB/s
2021-05-30 16:57:59 [Parachain] 💤 Idle (0 peers), best: #0 (0xd42b…f271), finalized #0 (0xd42b…f271), ⬇ 0 ⬆ 0
2021-05-30 16:58:00 [Relaychain] ✨ Imported #10 (0xc9c9…1ca3)

You see messages are from both a relaychain node and a parachain node. This is because a relay chain light client is also run next to the parachain collator.

Parachain Registration

Now that you have two relay chain nodes, and a parachain node accompanied with a relay chain light client running, the next step is to register the parachain in the relay chain with the following steps (for detail, refer to the Substrate Cumulus Worship):

  • Goto Polkadot Apps UI, connecting to your relay chain.
  • Execute a sudo extrinsic on the relay chain by going to Developer -> sudo page.
  • Pick paraSudoWrapper -> sudoScheduleParaInitialize(id, genesis) as the extrinsic type, shown below.

Polkadot Apps UI

  • Set the id: ParaId to 2,000 (or whatever ParaId you used above), and set the parachain: Bool option to Yes.
  • For the genesisHead, drag the genesis state file exported above, para-2000-genesis, in.
  • For the validationCode, drag the genesis wasm file exported above, para-2000-wasm, in.

Note: When registering to the public Rococo testnet, ensure you set a unique paraId larger than 1,000. Values below 1,000 are reserved exclusively for system parachains.

Restart the Parachain (Collator)

The collator node may need to be restarted to get it functioning as expected. After a new epoch starts on the relay chain, your parachain will come online. Once this happens, you should see the collator start reporting parachain blocks:

# Notice the relay epoch change! Only then do we start parachain collating!
#
2021-05-30 17:00:04 [Relaychain] 💤 Idle (2 peers), best: #30 (0xfc02…2a2a), finalized #28 (0x10ff…6539), ⬇ 1.0kiB/s ⬆ 0.3kiB/s
2021-05-30 17:00:04 [Parachain] 💤 Idle (0 peers), best: #0 (0xd42b…f271), finalized #0 (0xd42b…f271), ⬇ 0 ⬆ 0
2021-05-30 17:00:06 [Relaychain] 👶 New epoch 3 launching at block 0x68bc…0605 (block slot 270402601 >= start slot 270402601).
2021-05-30 17:00:06 [Relaychain] 👶 Next epoch starts at slot 270402611
2021-05-30 17:00:06 [Relaychain] ✨ Imported #31 (0x68bc…0605)
2021-05-30 17:00:06 [Parachain] Starting collation. relay_parent=0x68bcc93d24a31a2c89800a56c7a2b275fe9ca7bd63f829b64588ae0d99280605 at=0xd42bb78354bc21770e3f0930ed45c7377558d2d8e81ca4d457e573128aabf271
2021-05-30 17:00:06 [Parachain] 🙌 Starting consensus session on top of parent 0xd42bb78354bc21770e3f0930ed45c7377558d2d8e81ca4d457e573128aabf271
2021-05-30 17:00:06 [Parachain] 🎁 Prepared block for proposing at 1 [hash: 0xf6507812bf60bf53af1311f775aac03869be870df6b0406b2969784d0935cb92; parent_hash: 0xd42b…f271; extrinsics (2): [0x1bf5…1d76, 0x7c9b…4e23]]
2021-05-30 17:00:06 [Parachain] 🔖 Pre-sealed block for proposal at 1. Hash now 0x80fc151d7ccf228b802525022b6de257e42388ec7dc3c1dd7de491313650ccae, previously 0xf6507812bf60bf53af1311f775aac03869be870df6b0406b2969784d0935cb92.
2021-05-30 17:00:06 [Parachain] ✨ Imported #1 (0x80fc…ccae)
2021-05-30 17:00:06 [Parachain] Produced proof-of-validity candidate. block_hash=0x80fc151d7ccf228b802525022b6de257e42388ec7dc3c1dd7de491313650ccae
2021-05-30 17:00:09 [Relaychain] 💤 Idle (2 peers), best: #31 (0x68bc…0605), finalized #29 (0xa6fa…9e16), ⬇ 1.2kiB/s ⬆ 129.9kiB/s
2021-05-30 17:00:09 [Parachain] 💤 Idle (0 peers), best: #0 (0xd42b…f271), finalized #0 (0xd42b…f271), ⬇ 0 ⬆ 0
2021-05-30 17:00:12 [Relaychain] ✨ Imported #32 (0x5e92…ba30)
2021-05-30 17:00:12 [Relaychain] Moving approval window from session 0..=2 to 0..=3
2021-05-30 17:00:12 [Relaychain] ✨ Imported #32 (0x8144…74eb)
2021-05-30 17:00:14 [Relaychain] 💤 Idle (2 peers), best: #32 (0x5e92…ba30), finalized #29 (0xa6fa…9e16), ⬇ 1.4kiB/s ⬆ 0.2kiB/s
2021-05-30 17:00:14 [Parachain] 💤 Idle (0 peers), best: #0 (0xd42b…f271), finalized #0 (0xd42b…f271), ⬇ 0 ⬆ 0
2021-05-30 17:00:18 [Relaychain] ✨ Imported #33 (0x8c30…9ccd)
2021-05-30 17:00:18 [Parachain] Starting collation. relay_parent=0x8c30ce9e6e9867824eb2aff40148ac1ed64cf464f51c5f2574013b44b20f9ccd at=0x80fc151d7ccf228b802525022b6de257e42388ec7dc3c1dd7de491313650ccae
2021-05-30 17:00:19 [Relaychain] 💤 Idle (2 peers), best: #33 (0x8c30…9ccd), finalized #30 (0xfc02…2a2a), ⬇ 0.7kiB/s ⬆ 0.4kiB/s
2021-05-30 17:00:19 [Parachain] 💤 Idle (0 peers), best: #1 (0x80fc…ccae), finalized #0 (0xd42b…f271), ⬇ 0 ⬆ 0
2021-05-30 17:00:22 [Relaychain] 👴 Applying authority set change scheduled at block #31
2021-05-30 17:00:22 [Relaychain] 👴 Applying GRANDPA set change to new set [(Public(88dc3417d5058ec4b4503e0c12ea1a0a89be200fe98922423d4334014fa6b0ee (5FA9nQDV...)), 1), (Public(d17c2d7823ebf260fd138f2d7e27d114c0145d968b5ff5006125f2414fadae69 (5GoNkf6W...)), 1)]
2021-05-30 17:00:22 [Relaychain] 👴 Imported justification for block #31 that triggers command Changing authorities, signaling voter.
2021-05-30 17:00:24 [Relaychain] ✨ Imported #34 (0x211b…febf)
2021-05-30 17:00:24 [Parachain] Starting collation. relay_parent=0x211b3c53bebeff8af05e8f283d59fe171b7f91a5bf9c4669d88943f5a42bfebf at=0x80fc151d7ccf228b802525022b6de257e42388ec7dc3c1dd7de491313650ccae
2021-05-30 17:00:24 [Parachain] 🙌 Starting consensus session on top of parent 0x80fc151d7ccf228b802525022b6de257e42388ec7dc3c1dd7de491313650ccae
2021-05-30 17:00:24 [Parachain] 🎁 Prepared block for proposing at 2 [hash: 0x10fcb3180e966729c842d1b0c4d8d2c4028cfa8bef02b909af5ef787e6a6a694; parent_hash: 0x80fc…ccae; extrinsics (2): [0x4a6c…1fc6, 0x6b84…7cea]]
2021-05-30 17:00:24 [Parachain] 🔖 Pre-sealed block for proposal at 2. Hash now 0x5087fd06b1b73d90cfc3ad175df8495b378fffbb02fea212cc9e49a00fd8b5a0, previously 0x10fcb3180e966729c842d1b0c4d8d2c4028cfa8bef02b909af5ef787e6a6a694.
2021-05-30 17:00:24 [Parachain] ✨ Imported #2 (0x5087…b5a0)
2021-05-30 17:00:24 [Parachain] Produced proof-of-validity candidate. block_hash=0x5087fd06b1b73d90cfc3ad175df8495b378fffbb02fea212cc9e49a00fd8b5a0
2021-05-30 17:00:24 [Relaychain] 💤 Idle (2 peers), best: #34 (0x211b…febf), finalized #31 (0x68bc…0605), ⬇ 1.0kiB/s ⬆ 130.1kiB/s
2021-05-30 17:00:24 [Parachain] 💤 Idle (0 peers), best: #1 (0x80fc…ccae), finalized #0 (0xd42b…f271), ⬇ 0 ⬆ 0
2021-05-30 17:00:29 [Relaychain] 💤 Idle (2 peers), best: #34 (0x211b…febf), finalized #32 (0x5e92…ba30), ⬇ 0.2kiB/s ⬆ 0.1kiB/s
2021-05-30 17:00:29 [Parachain] 💤 Idle (0 peers), best: #1 (0x80fc…ccae), finalized #0 (0xd42b…f271), ⬇ 0 ⬆ 0
2021-05-30 17:00:30 [Relaychain] ✨ Imported #35 (0xee07…38a0)
2021-05-30 17:00:34 [Relaychain] 💤 Idle (2 peers), best: #35 (0xee07…38a0), finalized #33 (0x8c30…9ccd), ⬇ 0.9kiB/s ⬆ 0.3kiB/s
2021-05-30 17:00:34 [Parachain] 💤 Idle (0 peers), best: #1 (0x80fc…ccae), finalized #1 (0x80fc…ccae), ⬇ 0 ⬆ 0
2021-05-30 17:00:36 [Relaychain] ✨ Imported #36 (0xe8ce…4af6)
2021-05-30 17:00:36 [Parachain] Starting collation. relay_parent=0xe8cec8015c0c7bf508bf3f2f82b1696e9cca078e814b0f6671f0b0d5dfe84af6 at=0x5087fd06b1b73d90cfc3ad175df8495b378fffbb02fea212cc9e49a00fd8b5a0
2021-05-30 17:00:39 [Relaychain] 💤 Idle (2 peers), best: #36 (0xe8ce…4af6), finalized #33 (0x8c30…9ccd), ⬇ 0.6kiB/s ⬆ 0.1kiB/s
2021-05-30 17:00:39 [Parachain] 💤 Idle (0 peers), best: #2 (0x5087…b5a0), finalized #1 (0x80fc…ccae), ⬇ 0 ⬆ 0

Note the delay here! It may take some time for your relay chain to enter a new epoch.

Rococo & Westend Relay Chain Testnets

Is this Cumulus Parachain Template Rococo & Westend testnets compatible? Yes!

  • Rococo is the testnet of Kusama (join the Rococo Faucet to get testing funds).
  • Westend is the testnet of Polkadot (join the Westend Faucet to get testing funds).

See the Cumulus Workshop for the latest instructions to register a parathread/parachain on a relay chain.

NOTE: When running the relay chain and parachain, you must use the same tagged version of Polkadot and Cumulus so the collator would register successfully to the relay chain. You should test locally registering your parachain successfully before attempting to connect to any running relay chain network!

Find chainspec files to connect to live networks here. You want to be sure to use the correct git release tag in these files, as they change from time to time and must match the live network!

These networks are under constant development - so please follow the progress and update of your parachains in lock step with the testnet changes if you wish to connect to the network. Do join the Parachain Technical matrix chat room to ask questions and connect with the parachain building teams.

Learn More

  • More detailed instructions to use Cumulus parachains are found in the Cumulus Workshop.
  • Refer to the upstream Substrate Node Template to learn more about the structure of this project, the capabilities it encapsulates and the way in which those capabilities are implemented.
  • Learn more about how a parachain block is added to a finalized chain here.

Download Details:
Author: aresprotocols
Source Code: https://github.com/aresprotocols/substrate-parachain-template
License: Unlicense License

#rust  #blockchain #substrate #parachain #polkadot 

Carmen  Grimes

Carmen Grimes

1595491178

Best Electric Bikes and Scooters for Rental Business or Campus Facility

The electric scooter revolution has caught on super-fast taking many cities across the globe by storm. eScooters, a renovated version of old-school scooters now turned into electric vehicles are an environmentally friendly solution to current on-demand commute problems. They work on engines, like cars, enabling short traveling distances without hassle. The result is that these groundbreaking electric machines can now provide faster transport for less — cheaper than Uber and faster than Metro.

Since they are durable, fast, easy to operate and maintain, and are more convenient to park compared to four-wheelers, the eScooters trend has and continues to spike interest as a promising growth area. Several companies and universities are increasingly setting up shop to provide eScooter services realizing a would-be profitable business model and a ready customer base that is university students or residents in need of faster and cheap travel going about their business in school, town, and other surrounding areas.

Electric Scooters Trends and Statistics

In many countries including the U.S., Canada, Mexico, U.K., Germany, France, China, Japan, India, Brazil and Mexico and more, a growing number of eScooter users both locals and tourists can now be seen effortlessly passing lines of drivers stuck in the endless and unmoving traffic.

A recent report by McKinsey revealed that the E-Scooter industry will be worth― $200 billion to $300 billion in the United States, $100 billion to $150 billion in Europe, and $30 billion to $50 billion in China in 2030. The e-Scooter revenue model will also spike and is projected to rise by more than 20% amounting to approximately $5 billion.

And, with a necessity to move people away from high carbon prints, traffic and congestion issues brought about by car-centric transport systems in cities, more and more city planners are developing more bike/scooter lanes and adopting zero-emission plans. This is the force behind the booming electric scooter market and the numbers will only go higher and higher.

Companies that have taken advantage of the growing eScooter trend develop an appthat allows them to provide efficient eScooter services. Such an app enables them to be able to locate bike pick-up and drop points through fully integrated google maps.

List of Best Electric Bikes for Rental Business or Campus Facility 2020:

It’s clear that e scooters will increasingly become more common and the e-scooter business model will continue to grab the attention of manufacturers, investors, entrepreneurs. All this should go ahead with a quest to know what are some of the best electric bikes in the market especially for anyone who would want to get started in the electric bikes/scooters rental business.

We have done a comprehensive list of the best electric bikes! Each bike has been reviewed in depth and includes a full list of specs and a photo.

Billy eBike

mobile-best-electric-bikes-scooters https://www.kickstarter.com/projects/enkicycles/billy-were-redefining-joyrides

To start us off is the Billy eBike, a powerful go-anywhere urban electric bike that’s specially designed to offer an exciting ride like no other whether you want to ride to the grocery store, cafe, work or school. The Billy eBike comes in 4 color options – Billy Blue, Polished aluminium, Artic white, and Stealth black.

Price: $2490

Available countries

Available in the USA, Europe, Asia, South Africa and Australia.This item ships from the USA. Buyers are therefore responsible for any taxes and/or customs duties incurred once it arrives in your country.

Features

  • Control – Ride with confidence with our ultra-wide BMX bars and a hyper-responsive twist throttle.
  • Stealth- Ride like a ninja with our Gates carbon drive that’s as smooth as butter and maintenance-free.
  • Drive – Ride further with our high torque fat bike motor, giving a better climbing performance.
  • Accelerate – Ride quicker with our 20-inch lightweight cutout rims for improved acceleration.
  • Customize – Ride your own way with 5 levels of power control. Each level determines power and speed.
  • Flickable – Ride harder with our BMX /MotoX inspired geometry and lightweight aluminum package

Specifications

  • Maximum speed: 20 mph (32 km/h)
  • Range per charge: 41 miles (66 km)
  • Maximum Power: 500W
  • Motor type: Fat Bike Motor: Bafang RM G060.500.DC
  • Load capacity: 300lbs (136kg)
  • Battery type: 13.6Ah Samsung lithium-ion,
  • Battery capacity: On/off-bike charging available
  • Weight: w/o batt. 48.5lbs (22kg), w/ batt. 54lbs (24.5kg)
  • Front Suspension: Fully adjustable air shock, preload/compression damping /lockout
  • Rear Suspension: spring, preload adjustment
  • Built-in GPS

Why Should You Buy This?

  • Riding fun and excitement
  • Better climbing ability and faster acceleration.
  • Ride with confidence
  • Billy folds for convenient storage and transportation.
  • Shorty levers connect to disc brakes ensuring you stop on a dime
  • belt drives are maintenance-free and clean (no oil or lubrication needed)

**Who Should Ride Billy? **

Both new and experienced riders

**Where to Buy? **Local distributors or ships from the USA.

Genze 200 series e-Bike

genze-best-electric-bikes-scooters https://www.genze.com/fleet/

Featuring a sleek and lightweight aluminum frame design, the 200-Series ebike takes your riding experience to greater heights. Available in both black and white this ebike comes with a connected app, which allows you to plan activities, map distances and routes while also allowing connections with fellow riders.

Price: $2099.00

Available countries

The Genze 200 series e-Bike is available at GenZe retail locations across the U.S or online via GenZe.com website. Customers from outside the US can ship the product while incurring the relevant charges.

Features

  • 2 Frame Options
  • 2 Sizes
  • Integrated/Removable Battery
  • Throttle and Pedal Assist Ride Modes
  • Integrated LCD Display
  • Connected App
  • 24 month warranty
  • GPS navigation
  • Bluetooth connectivity

Specifications

  • Maximum speed: 20 mph with throttle
  • Range per charge: 15-18 miles w/ throttle and 30-50 miles w/ pedal assist
  • Charging time: 3.5 hours
  • Motor type: Brushless Rear Hub Motor
  • Gears: Microshift Thumb Shifter
  • Battery type: Removable Samsung 36V, 9.6AH Li-Ion battery pack
  • Battery capacity: 36V and 350 Wh
  • Weight: 46 pounds
  • Derailleur: 8-speed Shimano
  • Brakes: Dual classic
  • Wheels: 26 x 20 inches
  • Frame: 16, and 18 inches
  • Operating Mode: Analog mode 5 levels of Pedal Assist Thrott­le Mode

Norco from eBikestore

norco-best-electric-bikes-scooters https://ebikestore.com/shop/norco-vlt-s2/

The Norco VLT S2 is a front suspension e-Bike with solid components alongside the reliable Bosch Performance Line Power systems that offer precise pedal assistance during any riding situation.

Price: $2,699.00

Available countries

This item is available via the various Norco bikes international distributors.

Features

  • VLT aluminum frame- for stiffness and wheel security.
  • Bosch e-bike system – for their reliability and performance.
  • E-bike components – for added durability.
  • Hydraulic disc brakes – offer riders more stopping power for safety and control at higher speeds.
  • Practical design features – to add convenience and versatility.

Specifications

  • Maximum speed: KMC X9 9spd
  • Motor type: Bosch Active Line
  • Gears: Shimano Altus RD-M2000, SGS, 9 Speed
  • Battery type: Power Pack 400
  • Battery capacity: 396Wh
  • Suspension: SR Suntour suspension fork
  • Frame: Norco VLT, Aluminum, 12x142mm TA Dropouts

Bodo EV

bodo-best-electric-bikes-scootershttp://www.bodoevs.com/bodoev/products_show.asp?product_id=13

Manufactured by Bodo Vehicle Group Limited, the Bodo EV is specially designed for strong power and extraordinary long service to facilitate super amazing rides. The Bodo Vehicle Company is a striking top in electric vehicles brand field in China and across the globe. Their Bodo EV will no doubt provide your riders with high-level riding satisfaction owing to its high-quality design, strength, breaking stability and speed.

Price: $799

Available countries

This item ships from China with buyers bearing the shipping costs and other variables prior to delivery.

Features

  • Reliable
  • Environment friendly
  • Comfortable riding
  • Fashionable
  • Economical
  • Durable – long service life
  • Braking stability
  • LED lighting technology

Specifications

  • Maximum speed: 45km/h
  • Range per charge: 50km per person
  • Charging time: 8 hours
  • Maximum Power: 3000W
  • Motor type: Brushless DC Motor
  • Load capacity: 100kg
  • Battery type: Lead-acid battery
  • Battery capacity: 60V 20AH
  • Weight: w/o battery 47kg

#android app #autorent #entrepreneurship #ios app #minimum viable product (mvp) #mobile app development #news #app like bird #app like bounce #app like lime #autorent #best electric bikes 2020 #best electric bikes for rental business #best electric kick scooters 2020 #best electric kickscooters for rental business #best electric scooters 2020 #best electric scooters for rental business #bird scooter business model #bird scooter rental #bird scooter rental cost #bird scooter rental price #clone app like bird #clone app like bounce #clone app like lime #electric rental scooters #electric scooter company #electric scooter rental business #how do you start a moped #how to start a moped #how to start a scooter rental business #how to start an electric company #how to start electric scooterrental business #lime scooter business model #scooter franchise #scooter rental business #scooter rental business for sale #scooter rental business insurance #scooters franchise cost #white label app like bird #white label app like bounce #white label app like lime

Rufus Scheduler: Job Scheduler for Ruby (at, Cron, in and Every Jobs)

rufus-scheduler

Job scheduler for Ruby (at, cron, in and every jobs).

It uses threads.

Note: maybe are you looking for the README of rufus-scheduler 2.x? (especially if you're using Dashing which is stuck on rufus-scheduler 2.0.24)

Quickstart:

# quickstart.rb

require 'rufus-scheduler'

scheduler = Rufus::Scheduler.new

scheduler.in '3s' do
  puts 'Hello... Rufus'
end

scheduler.join
  #
  # let the current thread join the scheduler thread
  #
  # (please note that this join should be removed when scheduling
  # in a web application (Rails and friends) initializer)

(run with ruby quickstart.rb)

Various forms of scheduling are supported:

require 'rufus-scheduler'

scheduler = Rufus::Scheduler.new

# ...

scheduler.in '10d' do
  # do something in 10 days
end

scheduler.at '2030/12/12 23:30:00' do
  # do something at a given point in time
end

scheduler.every '3h' do
  # do something every 3 hours
end
scheduler.every '3h10m' do
  # do something every 3 hours and 10 minutes
end

scheduler.cron '5 0 * * *' do
  # do something every day, five minutes after midnight
  # (see "man 5 crontab" in your terminal)
end

# ...

Rufus-scheduler uses fugit for parsing time strings, et-orbi for pairing time and tzinfo timezones.

non-features

Rufus-scheduler (out of the box) is an in-process, in-memory scheduler. It uses threads.

It does not persist your schedules. When the process is gone and the scheduler instance with it, the schedules are gone.

A rufus-scheduler instance will go on scheduling while it is present among the objects in a Ruby process. To make it stop scheduling you have to call its #shutdown method.

related and similar gems

  • Whenever - let cron call back your Ruby code, trusted and reliable cron drives your schedule
  • ruby-clock - a clock process / job scheduler for Ruby
  • Clockwork - rufus-scheduler inspired gem
  • Crono - an in-Rails cron scheduler
  • PerfectSched - highly available distributed cron built on Sequel and more

(please note: rufus-scheduler is not a cron replacement)

note about the 3.0 line

It's a complete rewrite of rufus-scheduler.

There is no EventMachine-based scheduler anymore.

I don't know what this Ruby thing is, where are my Rails?

I'll drive you right to the tracks.

notable changes:

  • As said, no more EventMachine-based scheduler
  • scheduler.every('100') { will schedule every 100 seconds (previously, it would have been 0.1s). This aligns rufus-scheduler with Ruby's sleep(100)
  • The scheduler isn't catching the whole of Exception anymore, only StandardError
  • The error_handler is #on_error (instead of #on_exception), by default it now prints the details of the error to $stderr (used to be $stdout)
  • Rufus::Scheduler::TimeOutError renamed to Rufus::Scheduler::TimeoutError
  • Introduction of "interval" jobs. Whereas "every" jobs are like "every 10 minutes, do this", interval jobs are like "do that, then wait for 10 minutes, then do that again, and so on"
  • Introduction of a lockfile: true/filename mechanism to prevent multiple schedulers from executing
  • "discard_past" is on by default. If the scheduler (its host) sleeps for 1 hour and a every '10m' job is on, it will trigger once at wakeup, not 6 times (discard_past was false by default in rufus-scheduler 2.x). No intention to re-introduce discard_past: false in 3.0 for now.
  • Introduction of Scheduler #on_pre_trigger and #on_post_trigger callback points

getting help

So you need help. People can help you, but first help them help you, and don't waste their time. Provide a complete description of the issue. If it works on A but not on B and others have to ask you: "so what is different between A and B" you are wasting everyone's time.

"hello", "please" and "thanks" are not swear words.

Go read how to report bugs effectively, twice.

Update: help_help.md might help help you.

on Gitter

You can find help via chat over at https://gitter.im/floraison/fugit. It's fugit, et-orbi, and rufus-scheduler combined chat room.

Please be courteous.

issues

Yes, issues can be reported in rufus-scheduler issues, I'd actually prefer bugs in there. If there is nothing wrong with rufus-scheduler, a Stack Overflow question is better.

faq

scheduling

Rufus-scheduler supports five kinds of jobs. in, at, every, interval and cron jobs.

Most of the rufus-scheduler examples show block scheduling, but it's also OK to schedule handler instances or handler classes.

in, at, every, interval, cron

In and at jobs trigger once.

require 'rufus-scheduler'

scheduler = Rufus::Scheduler.new

scheduler.in '10d' do
  puts "10 days reminder for review X!"
end

scheduler.at '2014/12/24 2000' do
  puts "merry xmas!"
end

In jobs are scheduled with a time interval, they trigger after that time elapsed. At jobs are scheduled with a point in time, they trigger when that point in time is reached (better to choose a point in the future).

Every, interval and cron jobs trigger repeatedly.

require 'rufus-scheduler'

scheduler = Rufus::Scheduler.new

scheduler.every '3h' do
  puts "change the oil filter!"
end

scheduler.interval '2h' do
  puts "thinking..."
  puts sleep(rand * 1000)
  puts "thought."
end

scheduler.cron '00 09 * * *' do
  puts "it's 9am! good morning!"
end

Every jobs try hard to trigger following the frequency they were scheduled with.

Interval jobs trigger, execute and then trigger again after the interval elapsed. (every jobs time between trigger times, interval jobs time between trigger termination and the next trigger start).

Cron jobs are based on the venerable cron utility (man 5 crontab). They trigger following a pattern given in (almost) the same language cron uses.

 

#schedule_x vs #x

schedule_in, schedule_at, schedule_cron, etc will return the new Job instance.

in, at, cron will return the new Job instance's id (a String).

job_id =
  scheduler.in '10d' do
    # ...
  end
job = scheduler.job(job_id)

# versus

job =
  scheduler.schedule_in '10d' do
    # ...
  end

# also

job =
  scheduler.in '10d', job: true do
    # ...
  end

#schedule and #repeat

Sometimes it pays to be less verbose.

The #schedule methods schedules an at, in or cron job. It just decides based on its input. It returns the Job instance.

scheduler.schedule '10d' do; end.class
  # => Rufus::Scheduler::InJob

scheduler.schedule '2013/12/12 12:30' do; end.class
  # => Rufus::Scheduler::AtJob

scheduler.schedule '* * * * *' do; end.class
  # => Rufus::Scheduler::CronJob

The #repeat method schedules and returns an EveryJob or a CronJob.

scheduler.repeat '10d' do; end.class
  # => Rufus::Scheduler::EveryJob

scheduler.repeat '* * * * *' do; end.class
  # => Rufus::Scheduler::CronJob

(Yes, no combination here gives back an IntervalJob).

schedule blocks arguments (job, time)

A schedule block may be given 0, 1 or 2 arguments.

The first argument is "job", it's simply the Job instance involved. It might be useful if the job is to be unscheduled for some reason.

scheduler.every '10m' do |job|

  status = determine_pie_status

  if status == 'burnt' || status == 'cooked'
    stop_oven
    takeout_pie
    job.unschedule
  end
end

The second argument is "time", it's the time when the job got cleared for triggering (not Time.now).

Note that time is the time when the job got cleared for triggering. If there are mutexes involved, now = mutex_wait_time + time...

"every" jobs and changing the next_time in-flight

It's OK to change the next_time of an every job in-flight:

scheduler.every '10m' do |job|

  # ...

  status = determine_pie_status

  job.next_time = Time.now + 30 * 60 if status == 'burnt'
    #
    # if burnt, wait 30 minutes for the oven to cool a bit
end

It should work as well with cron jobs, not so with interval jobs whose next_time is computed after their block ends its current run.

scheduling handler instances

It's OK to pass any object, as long as it responds to #call(), when scheduling:

class Handler
  def self.call(job, time)
    p "- Handler called for #{job.id} at #{time}"
  end
end

scheduler.in '10d', Handler

# or

class OtherHandler
  def initialize(name)
    @name = name
  end
  def call(job, time)
    p "* #{time} - Handler #{name.inspect} called for #{job.id}"
  end
end

oh = OtherHandler.new('Doe')

scheduler.every '10m', oh
scheduler.in '3d5m', oh

The call method must accept 2 (job, time), 1 (job) or 0 arguments.

Note that time is the time when the job got cleared for triggering. If there are mutexes involved, now = mutex_wait_time + time...

scheduling handler classes

One can pass a handler class to rufus-scheduler when scheduling. Rufus will instantiate it and that instance will be available via job#handler.

class MyHandler
  attr_reader :count
  def initialize
    @count = 0
  end
  def call(job)
    @count += 1
    puts ". #{self.class} called at #{Time.now} (#{@count})"
  end
end

job = scheduler.schedule_every '35m', MyHandler

job.handler
  # => #<MyHandler:0x000000021034f0>
job.handler.count
  # => 0

If you want to keep that "block feeling":

job_id =
  scheduler.every '10m', Class.new do
    def call(job)
      puts ". hello #{self.inspect} at #{Time.now}"
    end
  end

pause and resume the scheduler

The scheduler can be paused via the #pause and #resume methods. One can determine if the scheduler is currently paused by calling #paused?.

While paused, the scheduler still accepts schedules, but no schedule will get triggered as long as #resume isn't called.

job options

name: string

Sets the name of the job.

scheduler.cron '*/15 8 * * *', name: 'Robert' do |job|
  puts "A, it's #{Time.now} and my name is #{job.name}"
end

job1 =
  scheduler.schedule_cron '*/30 9 * * *', n: 'temporary' do |job|
    puts "B, it's #{Time.now} and my name is #{job.name}"
  end
# ...
job1.name = 'Beowulf'

blocking: true

By default, jobs are triggered in their own, new threads. When blocking: true, the job is triggered in the scheduler thread (a new thread is not created). Yes, while a blocking job is running, the scheduler is not scheduling.

overlap: false

Since, by default, jobs are triggered in their own new threads, job instances might overlap. For example, a job that takes 10 minutes and is scheduled every 7 minutes will have overlaps.

To prevent overlap, one can set overlap: false. Such a job will not trigger if one of its instances is already running.

The :overlap option is considered before the :mutex option when the scheduler is reviewing jobs for triggering.

mutex: mutex_instance / mutex_name / array of mutexes

When a job with a mutex triggers, the job's block is executed with the mutex around it, preventing other jobs with the same mutex from entering (it makes the other jobs wait until it exits the mutex).

This is different from overlap: false, which is, first, limited to instances of the same job, and, second, doesn't make the incoming job instance block/wait but give up.

:mutex accepts a mutex instance or a mutex name (String). It also accept an array of mutex names / mutex instances. It allows for complex relations between jobs.

Array of mutexes: original idea and implementation by Rainux Luo

Note: creating lots of different mutexes is OK. Rufus-scheduler will place them in its Scheduler#mutexes hash... And they won't get garbage collected.

The :overlap option is considered before the :mutex option when the scheduler is reviewing jobs for triggering.

timeout: duration or point in time

It's OK to specify a timeout when scheduling some work. After the time specified, it gets interrupted via a Rufus::Scheduler::TimeoutError.

scheduler.in '10d', timeout: '1d' do
  begin
    # ... do something
  rescue Rufus::Scheduler::TimeoutError
    # ... that something got interrupted after 1 day
  end
end

The :timeout option accepts either a duration (like "1d" or "2w3d") or a point in time (like "2013/12/12 12:00").

:first_at, :first_in, :first, :first_time

This option is for repeat jobs (cron / every) only.

It's used to specify the first time after which the repeat job should trigger for the first time.

In the case of an "every" job, this will be the first time (modulo the scheduler frequency) the job triggers. For a "cron" job as well, the :first will point to the first time the job has to trigger, the following trigger times are then determined by the cron string.

scheduler.every '2d', first_at: Time.now + 10 * 3600 do
  # ... every two days, but start in 10 hours
end

scheduler.every '2d', first_in: '10h' do
  # ... every two days, but start in 10 hours
end

scheduler.cron '00 14 * * *', first_in: '3d' do
  # ... every day at 14h00, but start after 3 * 24 hours
end

:first, :first_at and :first_in all accept a point in time or a duration (number or time string). Use the symbol you think makes your schedule more readable.

Note: it's OK to change the first_at (a Time instance) directly:

job.first_at = Time.now + 10
job.first_at = Rufus::Scheduler.parse('2029-12-12')

The first argument (in all its flavours) accepts a :now or :immediately value. That schedules the first occurrence for immediate triggering. Consider:

require 'rufus-scheduler'

s = Rufus::Scheduler.new

n = Time.now; p [ :scheduled_at, n, n.to_f ]

s.every '3s', first: :now do
  n = Time.now; p [ :in, n, n.to_f ]
end

s.join

that'll output something like:

[:scheduled_at, 2014-01-22 22:21:21 +0900, 1390396881.344438]
[:in, 2014-01-22 22:21:21 +0900, 1390396881.6453865]
[:in, 2014-01-22 22:21:24 +0900, 1390396884.648807]
[:in, 2014-01-22 22:21:27 +0900, 1390396887.651686]
[:in, 2014-01-22 22:21:30 +0900, 1390396890.6571937]
...

:last_at, :last_in, :last

This option is for repeat jobs (cron / every) only.

It indicates the point in time after which the job should unschedule itself.

scheduler.cron '5 23 * * *', last_in: '10d' do
  # ... do something every evening at 23:05 for 10 days
end

scheduler.every '10m', last_at: Time.now + 10 * 3600 do
  # ... do something every 10 minutes for 10 hours
end

scheduler.every '10m', last_in: 10 * 3600 do
  # ... do something every 10 minutes for 10 hours
end

:last, :last_at and :last_in all accept a point in time or a duration (number or time string). Use the symbol you think makes your schedule more readable.

Note: it's OK to change the last_at (nil or a Time instance) directly:

job.last_at = nil
  # remove the "last" bound

job.last_at = Rufus::Scheduler.parse('2029-12-12')
  # set the last bound

times: nb of times (before auto-unscheduling)

One can tell how many times a repeat job (CronJob or EveryJob) is to execute before unscheduling by itself.

scheduler.every '2d', times: 10 do
  # ... do something every two days, but not more than 10 times
end

scheduler.cron '0 23 * * *', times: 31 do
  # ... do something every day at 23:00 but do it no more than 31 times
end

It's OK to assign nil to :times to make sure the repeat job is not limited. It's useful when the :times is determined at scheduling time.

scheduler.cron '0 23 * * *', times: (nolimit ? nil : 10) do
  # ...
end

The value set by :times is accessible in the job. It can be modified anytime.

job =
  scheduler.cron '0 23 * * *' do
    # ...
  end

# later on...

job.times = 10
  # 10 days and it will be over

Job methods

When calling a schedule method, the id (String) of the job is returned. Longer schedule methods return Job instances directly. Calling the shorter schedule methods with the job: true also returns Job instances instead of Job ids (Strings).

  require 'rufus-scheduler'

  scheduler = Rufus::Scheduler.new

  job_id =
    scheduler.in '10d' do
      # ...
    end

  job =
    scheduler.schedule_in '1w' do
      # ...
    end

  job =
    scheduler.in '1w', job: true do
      # ...
    end

Those Job instances have a few interesting methods / properties:

id, job_id

Returns the job id.

job = scheduler.schedule_in('10d') do; end
job.id
  # => "in_1374072446.8923042_0.0_0"

scheduler

Returns the scheduler instance itself.

opts

Returns the options passed at the Job creation.

job = scheduler.schedule_in('10d', tag: 'hello') do; end
job.opts
  # => { :tag => 'hello' }

original

Returns the original schedule.

job = scheduler.schedule_in('10d', tag: 'hello') do; end
job.original
  # => '10d'

callable, handler

callable() returns the scheduled block (or the call method of the callable object passed in lieu of a block)

handler() returns nil if a block was scheduled and the instance scheduled otherwise.

# when passing a block

job =
  scheduler.schedule_in('10d') do
    # ...
  end

job.handler
  # => nil
job.callable
  # => #<Proc:0x00000001dc6f58@/home/jmettraux/whatever.rb:115>

and

# when passing something else than a block

class MyHandler
  attr_reader :counter
  def initialize
    @counter = 0
  end
  def call(job, time)
    @counter = @counter + 1
  end
end

job = scheduler.schedule_in('10d', MyHandler.new)

job.handler
  # => #<Method: MyHandler#call>
job.callable
  # => #<MyHandler:0x0000000163ae88 @counter=0>

source_location

Added to rufus-scheduler 3.8.0.

Returns the array [ 'path/to/file.rb', 123 ] like Proc#source_location does.

require 'rufus-scheduler'

scheduler = Rufus::Scheduler.new

job = scheduler.schedule_every('2h') { p Time.now }

p job.source_location
  # ==> [ '/home/jmettraux/rufus-scheduler/test.rb', 6 ]

scheduled_at

Returns the Time instance when the job got created.

job = scheduler.schedule_in('10d', tag: 'hello') do; end
job.scheduled_at
  # => 2013-07-17 23:48:54 +0900

last_time

Returns the last time the job triggered (is usually nil for AtJob and InJob).

job = scheduler.schedule_every('10s') do; end

job.scheduled_at
  # => 2013-07-17 23:48:54 +0900
job.last_time
  # => nil (since we've just scheduled it)

# after 10 seconds

job.scheduled_at
  # => 2013-07-17 23:48:54 +0900 (same as above)
job.last_time
  # => 2013-07-17 23:49:04 +0900

previous_time

Returns the previous #next_time

scheduler.every('10s') do |job|
  puts "job scheduled for #{job.previous_time} triggered at #{Time.now}"
  puts "next time will be around #{job.next_time}"
  puts "."
end

last_work_time, mean_work_time

The job keeps track of how long its work was in the last_work_time attribute. For a one time job (in, at) it's probably not very useful.

The attribute mean_work_time contains a computed mean work time. It's recomputed after every run (if it's a repeat job).

next_times(n)

Returns an array of EtOrbi::EoTime instances (Time instances with a designated time zone), listing the n next occurrences for this job.

Please note that for "interval" jobs, a mean work time is computed each time and it's used by this #next_times(n) method to approximate the next times beyond the immediate next time.

unschedule

Unschedule the job, preventing it from firing again and removing it from the schedule. This doesn't prevent a running thread for this job to run until its end.

threads

Returns the list of threads currently "hosting" runs of this Job instance.

kill

Interrupts all the work threads currently running for this job instance. They discard their work and are free for their next run (of whatever job).

Note: this doesn't unschedule the Job instance.

Note: if the job is pooled for another run, a free work thread will probably pick up that next run and the job will appear as running again. You'd have to unschedule and kill to make sure the job doesn't run again.

running?

Returns true if there is at least one running Thread hosting a run of this Job instance.

scheduled?

Returns true if the job is scheduled (is due to trigger). For repeat jobs it should return true until the job gets unscheduled. "at" and "in" jobs will respond with false as soon as they start running (execution triggered).

pause, resume, paused?, paused_at

These four methods are only available to CronJob, EveryJob and IntervalJob instances. One can pause or resume such jobs thanks to these methods.

job =
  scheduler.schedule_every('10s') do
    # ...
  end

job.pause
  # => 2013-07-20 01:22:22 +0900
job.paused?
  # => true
job.paused_at
  # => 2013-07-20 01:22:22 +0900

job.resume
  # => nil

tags

Returns the list of tags attached to this Job instance.

By default, returns an empty array.

job = scheduler.schedule_in('10d') do; end
job.tags
  # => []

job = scheduler.schedule_in('10d', tag: 'hello') do; end
job.tags
  # => [ 'hello' ]

[]=, [], key?, has_key?, keys, values, and entries

Threads have thread-local variables, similarly Rufus-scheduler jobs have job-local variables. Those are more like a dict with thread-safe access.

job =
  @scheduler.schedule_every '1s' do |job|
    job[:timestamp] = Time.now.to_f
    job[:counter] ||= 0
    job[:counter] += 1
  end

sleep 3.6

job[:counter]
  # => 3

job.key?(:timestamp) # => true
job.has_key?(:timestamp) # => true
job.keys # => [ :timestamp, :counter ]

Locals can be set at schedule time:

job0 =
  @scheduler.schedule_cron '*/15 12 * * *', locals: { a: 0 } do
    # ...
  end
job1 =
  @scheduler.schedule_cron '*/15 13 * * *', l: { a: 1 } do
    # ...
  end

One can fetch the Hash directly with Job#locals. Of course, direct manipulation is not thread-safe.

job.locals.entries do |k, v|
  p "#{k}: #{v}"
end

call

Job instances have a #call method. It simply calls the scheduled block or callable immediately.

job =
  @scheduler.schedule_every '10m' do |job|
    # ...
  end

job.call

Warning: the Scheduler#on_error handler is not involved. Error handling is the responsibility of the caller.

If the call has to be rescued by the error handler of the scheduler, call(true) might help:

require 'rufus-scheduler'

s = Rufus::Scheduler.new

def s.on_error(job, err)
  if job
    p [ 'error in scheduled job', job.class, job.original, err.message ]
  else
    p [ 'error while scheduling', err.message ]
  end
rescue
  p $!
end

job =
  s.schedule_in('1d') do
    fail 'again'
  end

job.call(true)
  #
  # true lets the error_handler deal with error in the job call

AtJob and InJob methods

time

Returns when the job will trigger (hopefully).

next_time

An alias for time.

EveryJob, IntervalJob and CronJob methods

next_time

Returns the next time the job will trigger (hopefully).

count

Returns how many times the job fired.

EveryJob methods

frequency

It returns the scheduling frequency. For a job scheduled "every 20s", it's 20.

It's used to determine if the job frequency is higher than the scheduler frequency (it raises an ArgumentError if that is the case).

IntervalJob methods

interval

Returns the interval scheduled between each execution of the job.

Every jobs use a time duration between each start of their execution, while interval jobs use a time duration between the end of an execution and the start of the next.

CronJob methods

brute_frequency

An expensive method to run, it's brute. It caches its results. By default it runs for 2017 (a non leap-year).

  require 'rufus-scheduler'

  Rufus::Scheduler.parse('* * * * *').brute_frequency
    #
    # => #<Fugit::Cron::Frequency:0x00007fdf4520c5e8
    #      @span=31536000.0, @delta_min=60, @delta_max=60,
    #      @occurrences=525600, @span_years=1.0, @yearly_occurrences=525600.0>
      #
      # Occurs 525600 times in a span of 1 year (2017) and 1 day.
      # There are least 60 seconds between "triggers" and at most 60 seconds.

  Rufus::Scheduler.parse('0 12 * * *').brute_frequency
    # => #<Fugit::Cron::Frequency:0x00007fdf451ec6d0
    #      @span=31536000.0, @delta_min=86400, @delta_max=86400,
    #      @occurrences=365, @span_years=1.0, @yearly_occurrences=365.0>
  Rufus::Scheduler.parse('0 12 * * *').brute_frequency.to_debug_s
    # => "dmin: 1D, dmax: 1D, ocs: 365, spn: 52W1D, spnys: 1, yocs: 365"
      #
      # 365 occurrences, at most 1 day between each, at least 1 day.

The CronJob#frequency method found in rufus-scheduler < 3.5 has been retired.

looking up jobs

Scheduler#job(job_id)

The scheduler #job(job_id) method can be used to look up Job instances.

  require 'rufus-scheduler'

  scheduler = Rufus::Scheduler.new

  job_id =
    scheduler.in '10d' do
      # ...
    end

  # later on...

  job = scheduler.job(job_id)

Scheduler #jobs #at_jobs #in_jobs #every_jobs #interval_jobs and #cron_jobs

Are methods for looking up lists of scheduled Job instances.

Here is an example:

  #
  # let's unschedule all the at jobs

  scheduler.at_jobs.each(&:unschedule)

Scheduler#jobs(tag: / tags: x)

When scheduling a job, one can specify one or more tags attached to the job. These can be used to look up the job later on.

  scheduler.in '10d', tag: 'main_process' do
    # ...
  end
  scheduler.in '10d', tags: [ 'main_process', 'side_dish' ] do
    # ...
  end

  # ...

  jobs = scheduler.jobs(tag: 'main_process')
    # find all the jobs with the 'main_process' tag

  jobs = scheduler.jobs(tags: [ 'main_process', 'side_dish' ]
    # find all the jobs with the 'main_process' AND 'side_dish' tags

Scheduler#running_jobs

Returns the list of Job instance that have currently running instances.

Whereas other "_jobs" method scan the scheduled job list, this method scans the thread list to find the job. It thus comprises jobs that are running but are not scheduled anymore (that happens for at and in jobs).

misc Scheduler methods

Scheduler#unschedule(job_or_job_id)

Unschedule a job given directly or by its id.

Scheduler#shutdown

Shuts down the scheduler, ceases any scheduler/triggering activity.

Scheduler#shutdown(:wait)

Shuts down the scheduler, waits (blocks) until all the jobs cease running.

Scheduler#shutdown(wait: n)

Shuts down the scheduler, waits (blocks) at most n seconds until all the jobs cease running. (Jobs are killed after n seconds have elapsed).

Scheduler#shutdown(:kill)

Kills all the job (threads) and then shuts the scheduler down. Radical.

Scheduler#down?

Returns true if the scheduler has been shut down.

Scheduler#started_at

Returns the Time instance at which the scheduler got started.

Scheduler #uptime / #uptime_s

Returns since the count of seconds for which the scheduler has been running.

#uptime_s returns this count in a String easier to grasp for humans, like "3d12m45s123".

Scheduler#join

Lets the current thread join the scheduling thread in rufus-scheduler. The thread comes back when the scheduler gets shut down.

#join is mostly used in standalone scheduling script (or tiny one file examples). Calling #join from a web application initializer will probably hijack the main thread and prevent the web application from being served. Do not put a #join in such a web application initializer file.

Scheduler#threads

Returns all the threads associated with the scheduler, including the scheduler thread itself.

Scheduler#work_threads(query=:all/:active/:vacant)

Lists the work threads associated with the scheduler. The query option defaults to :all.

  • :all : all the work threads
  • :active : all the work threads currently running a Job
  • :vacant : all the work threads currently not running a Job

Note that the main schedule thread will be returned if it is currently running a Job (ie one of those blocking: true jobs).

Scheduler#scheduled?(job_or_job_id)

Returns true if the arg is a currently scheduled job (see Job#scheduled?).

Scheduler#occurrences(time0, time1)

Returns a hash { job => [ t0, t1, ... ] } mapping jobs to their potential trigger time within the [ time0, time1 ] span.

Please note that, for interval jobs, the #mean_work_time is used, so the result is only a prediction.

Scheduler#timeline(time0, time1)

Like #occurrences but returns a list [ [ t0, job0 ], [ t1, job1 ], ... ] of time + job pairs.

dealing with job errors

The easy, job-granular way of dealing with errors is to rescue and deal with them immediately. The two next sections show examples. Skip them for explanations on how to deal with errors at the scheduler level.

block jobs

As said, jobs could take care of their errors themselves.

scheduler.every '10m' do
  begin
    # do something that might fail...
  rescue => e
    $stderr.puts '-' * 80
    $stderr.puts e.message
    $stderr.puts e.stacktrace
    $stderr.puts '-' * 80
  end
end

callable jobs

Jobs are not only shrunk to blocks, here is how the above would look like with a dedicated class.

scheduler.every '10m', Class.new do
  def call(job)
    # do something that might fail...
  rescue => e
    $stderr.puts '-' * 80
    $stderr.puts e.message
    $stderr.puts e.stacktrace
    $stderr.puts '-' * 80
  end
end

TODO: talk about callable#on_error (if implemented)

(see scheduling handler instances and scheduling handler classes for more about those "callable jobs")

Rufus::Scheduler#stderr=

By default, rufus-scheduler intercepts all errors (that inherit from StandardError) and dumps abundant details to $stderr.

If, for example, you'd like to divert that flow to another file (descriptor), you can reassign $stderr for the current Ruby process

$stderr = File.open('/var/log/myapplication.log', 'ab')

or, you can limit that reassignement to the scheduler itself

scheduler.stderr = File.open('/var/log/myapplication.log', 'ab')

Rufus::Scheduler#on_error(job, error)

We've just seen that, by default, rufus-scheduler dumps error information to $stderr. If one needs to completely change what happens in case of error, it's OK to overwrite #on_error

def scheduler.on_error(job, error)

  Logger.warn("intercepted error in #{job.id}: #{error.message}")
end

On Rails, the on_error method redefinition might look like:

def scheduler.on_error(job, error)

  Rails.logger.error(
    "err#{error.object_id} rufus-scheduler intercepted #{error.inspect}" +
    " in job #{job.inspect}")
  error.backtrace.each_with_index do |line, i|
    Rails.logger.error(
      "err#{error.object_id} #{i}: #{line}")
  end
end

Callbacks

Rufus::Scheduler #on_pre_trigger and #on_post_trigger callbacks

One can bind callbacks before and after jobs trigger:

s = Rufus::Scheduler.new

def s.on_pre_trigger(job, trigger_time)
  puts "triggering job #{job.id}..."
end

def s.on_post_trigger(job, trigger_time)
  puts "triggered job #{job.id}."
end

s.every '1s' do
  # ...
end

The trigger_time is the time at which the job triggers. It might be a bit before Time.now.

Warning: these two callbacks are executed in the scheduler thread, not in the work threads (the threads where the job execution really happens).

Rufus::Scheduler#around_trigger

One can create an around callback which will wrap a job:

def s.around_trigger(job)
  t = Time.now
  puts "Starting job #{job.id}..."
  yield
  puts "job #{job.id} finished in #{Time.now-t} seconds."
end

The around callback is executed in the thread.

Rufus::Scheduler#on_pre_trigger as a guard

Returning false in on_pre_trigger will prevent the job from triggering. Returning anything else (nil, -1, true, ...) will let the job trigger.

Note: your business logic should go in the scheduled block itself (or the scheduled instance). Don't put business logic in on_pre_trigger. Return false for admin reasons (backend down, etc), not for business reasons that are tied to the job itself.

def s.on_pre_trigger(job, trigger_time)

  return false if Backend.down?

  puts "triggering job #{job.id}..."
end

Rufus::Scheduler.new options

:frequency

By default, rufus-scheduler sleeps 0.300 second between every step. At each step it checks for jobs to trigger and so on.

The :frequency option lets you change that 0.300 second to something else.

scheduler = Rufus::Scheduler.new(frequency: 5)

It's OK to use a time string to specify the frequency.

scheduler = Rufus::Scheduler.new(frequency: '2h10m')
  # this scheduler will sleep 2 hours and 10 minutes between every "step"

Use with care.

lockfile: "mylockfile.txt"

This feature only works on OSes that support the flock (man 2 flock) call.

Starting the scheduler with lockfile: '.rufus-scheduler.lock' will make the scheduler attempt to create and lock the file .rufus-scheduler.lock in the current working directory. If that fails, the scheduler will not start.

The idea is to guarantee only one scheduler (in a group of schedulers sharing the same lockfile) is running.

This is useful in environments where the Ruby process holding the scheduler gets started multiple times.

If the lockfile mechanism here is not sufficient, you can plug your custom mechanism. It's explained in advanced lock schemes below.

:scheduler_lock

(since rufus-scheduler 3.0.9)

The scheduler lock is an object that responds to #lock and #unlock. The scheduler calls #lock when starting up. If the answer is false, the scheduler stops its initialization work and won't schedule anything.

Here is a sample of a scheduler lock that only lets the scheduler on host "coffee.example.com" start:

class HostLock
  def initialize(lock_name)
    @lock_name = lock_name
  end
  def lock
    @lock_name == `hostname -f`.strip
  end
  def unlock
    true
  end
end

scheduler =
  Rufus::Scheduler.new(scheduler_lock: HostLock.new('coffee.example.com'))

By default, the scheduler_lock is an instance of Rufus::Scheduler::NullLock, with a #lock that returns true.

:trigger_lock

(since rufus-scheduler 3.0.9)

The trigger lock in an object that responds to #lock. The scheduler calls that method on the job lock right before triggering any job. If the answer is false, the trigger doesn't happen, the job is not done (at least not in this scheduler).

Here is a (stupid) PingLock example, it'll only trigger if an "other host" is not responding to ping. Do not use that in production, you don't want to fork a ping process for each trigger attempt...

class PingLock
  def initialize(other_host)
    @other_host = other_host
  end
  def lock
    ! system("ping -c 1 #{@other_host}")
  end
end

scheduler =
  Rufus::Scheduler.new(trigger_lock: PingLock.new('main.example.com'))

By default, the trigger_lock is an instance of Rufus::Scheduler::NullLock, with a #lock that always returns true.

As explained in advanced lock schemes, another way to tune that behaviour is by overriding the scheduler's #confirm_lock method. (You could also do that with an #on_pre_trigger callback).

:max_work_threads

In rufus-scheduler 2.x, by default, each job triggering received its own, brand new, thread of execution. In rufus-scheduler 3.x, execution happens in a pooled work thread. The max work thread count (the pool size) defaults to 28.

One can set this maximum value when starting the scheduler.

scheduler = Rufus::Scheduler.new(max_work_threads: 77)

It's OK to increase the :max_work_threads of a running scheduler.

scheduler.max_work_threads += 10

Rufus::Scheduler.singleton

Do not want to store a reference to your rufus-scheduler instance? Then Rufus::Scheduler.singleton can help, it returns a singleton instance of the scheduler, initialized the first time this class method is called.

Rufus::Scheduler.singleton.every '10s' { puts "hello, world!" }

It's OK to pass initialization arguments (like :frequency or :max_work_threads) but they will only be taken into account the first time .singleton is called.

Rufus::Scheduler.singleton(max_work_threads: 77)
Rufus::Scheduler.singleton(max_work_threads: 277) # no effect

The .s is a shortcut for .singleton.

Rufus::Scheduler.s.every '10s' { puts "hello, world!" }

advanced lock schemes

As seen above, rufus-scheduler proposes the :lockfile system out of the box. If in a group of schedulers only one is supposed to run, the lockfile mechanism prevents schedulers that have not set/created the lockfile from running.

There are situations where this is not sufficient.

By overriding #lock and #unlock, one can customize how schedulers lock.

This example was provided by Eric Lindvall:

class ZookeptScheduler < Rufus::Scheduler

  def initialize(zookeeper, opts={})
    @zk = zookeeper
    super(opts)
  end

  def lock
    @zk_locker = @zk.exclusive_locker('scheduler')
    @zk_locker.lock # returns true if the lock was acquired, false else
  end

  def unlock
    @zk_locker.unlock
  end

  def confirm_lock
    return false if down?
    @zk_locker.assert!
  rescue ZK::Exceptions::LockAssertionFailedError => e
    # we've lost the lock, shutdown (and return false to at least prevent
    # this job from triggering
    shutdown
    false
  end
end

This uses a zookeeper to make sure only one scheduler in a group of distributed schedulers runs.

The methods #lock and #unlock are overridden and #confirm_lock is provided, to make sure that the lock is still valid.

The #confirm_lock method is called right before a job triggers (if it is provided). The more generic callback #on_pre_trigger is called right after #confirm_lock.

:scheduler_lock and :trigger_lock

(introduced in rufus-scheduler 3.0.9).

Another way of prodiving #lock, #unlock and #confirm_lock to a rufus-scheduler is by using the :scheduler_lock and :trigger_lock options.

See :trigger_lock and :scheduler_lock.

The scheduler lock may be used to prevent a scheduler from starting, while a trigger lock prevents individual jobs from triggering (the scheduler goes on scheduling).

One has to be careful with what goes in #confirm_lock or in a trigger lock, as it gets called before each trigger.

Warning: you may think you're heading towards "high availability" by using a trigger lock and having lots of schedulers at hand. It may be so if you limit yourself to scheduling the same set of jobs at scheduler startup. But if you add schedules at runtime, they stay local to their scheduler. There is no magic that propagates the jobs to all the schedulers in your pack.

parsing cronlines and time strings

(Please note that fugit does the heavy-lifting parsing work for rufus-scheduler).

Rufus::Scheduler provides a class method .parse to parse time durations and cron strings. It's what it's using when receiving schedules. One can use it directly (no need to instantiate a Scheduler).

require 'rufus-scheduler'

Rufus::Scheduler.parse('1w2d')
  # => 777600.0
Rufus::Scheduler.parse('1.0w1.0d')
  # => 777600.0

Rufus::Scheduler.parse('Sun Nov 18 16:01:00 2012').strftime('%c')
  # => 'Sun Nov 18 16:01:00 2012'

Rufus::Scheduler.parse('Sun Nov 18 16:01:00 2012 Europe/Berlin').strftime('%c %z')
  # => 'Sun Nov 18 15:01:00 2012 +0000'

Rufus::Scheduler.parse(0.1)
  # => 0.1

Rufus::Scheduler.parse('* * * * *')
  # => #<Fugit::Cron:0x00007fb7a3045508
  #      @original="* * * * *", @cron_s=nil,
  #      @seconds=[0], @minutes=nil, @hours=nil, @monthdays=nil, @months=nil,
  #      @weekdays=nil, @zone=nil, @timezone=nil>

It returns a number when the input is a duration and a Fugit::Cron instance when the input is a cron string.

It will raise an ArgumentError if it can't parse the input.

Beyond .parse, there are also .parse_cron and .parse_duration, for finer granularity.

There is an interesting helper method named .to_duration_hash:

require 'rufus-scheduler'

Rufus::Scheduler.to_duration_hash(60)
  # => { :m => 1 }
Rufus::Scheduler.to_duration_hash(62.127)
  # => { :m => 1, :s => 2, :ms => 127 }

Rufus::Scheduler.to_duration_hash(62.127, drop_seconds: true)
  # => { :m => 1 }

cronline notations specific to rufus-scheduler

first Monday, last Sunday et al

To schedule something at noon every first Monday of the month:

scheduler.cron('00 12 * * mon#1') do
  # ...
end

To schedule something at noon the last Sunday of every month:

scheduler.cron('00 12 * * sun#-1') do
  # ...
end
#
# OR
#
scheduler.cron('00 12 * * sun#L') do
  # ...
end

Such cronlines can be tested with scripts like:

require 'rufus-scheduler'

Time.now
  # => 2013-10-26 07:07:08 +0900
Rufus::Scheduler.parse('* * * * mon#1').next_time.to_s
  # => 2013-11-04 00:00:00 +0900

L (last day of month)

L can be used in the "day" slot:

In this example, the cronline is supposed to trigger every last day of the month at noon:

require 'rufus-scheduler'
Time.now
  # => 2013-10-26 07:22:09 +0900
Rufus::Scheduler.parse('00 12 L * *').next_time.to_s
  # => 2013-10-31 12:00:00 +0900

negative day (x days before the end of the month)

It's OK to pass negative values in the "day" slot:

scheduler.cron '0 0 -5 * *' do
  # do it at 00h00 5 days before the end of the month...
end

Negative ranges (-10--5-: 10 days before the end of the month to 5 days before the end of the month) are OK, but mixed positive / negative ranges will raise an ArgumentError.

Negative ranges with increments (-10---2/2) are accepted as well.

Descending day ranges are not accepted (10-8 or -8--10 for example).

a note about timezones

Cron schedules and at schedules support the specification of a timezone.

scheduler.cron '0 22 * * 1-5 America/Chicago' do
  # the job...
end

scheduler.at '2013-12-12 14:00 Pacific/Samoa' do
  puts "it's tea time!"
end

# or even

Rufus::Scheduler.parse("2013-12-12 14:00 Pacific/Saipan")
  # => #<Rufus::Scheduler::ZoTime:0x007fb424abf4e8 @seconds=1386820800.0, @zone=#<TZInfo::DataTimezone: Pacific/Saipan>, @time=nil>

I get "zotime.rb:41:in `initialize': cannot determine timezone from nil"

For when you see an error like:

rufus-scheduler/lib/rufus/scheduler/zotime.rb:41:
  in `initialize':
    cannot determine timezone from nil (etz:nil,tnz:"中国标准时间",tzid:nil)
      (ArgumentError)
    from rufus-scheduler/lib/rufus/scheduler/zotime.rb:198:in `new'
    from rufus-scheduler/lib/rufus/scheduler/zotime.rb:198:in `now'
    from rufus-scheduler/lib/rufus/scheduler.rb:561:in `start'
    ...

It may happen on Windows or on systems that poorly hint to Ruby which timezone to use. It should be solved by setting explicitly the ENV['TZ'] before the scheduler instantiation:

ENV['TZ'] = 'Asia/Shanghai'
scheduler = Rufus::Scheduler.new
scheduler.every '2s' do
  puts "#{Time.now} Hello #{ENV['TZ']}!"
end

On Rails you might want to try with:

ENV['TZ'] = Time.zone.name # Rails only
scheduler = Rufus::Scheduler.new
scheduler.every '2s' do
  puts "#{Time.now} Hello #{ENV['TZ']}!"
end

(Hat tip to Alexander in gh-230)

Rails sets its timezone under config/application.rb.

Rufus-Scheduler 3.3.3 detects the presence of Rails and uses its timezone setting (tested with Rails 4), so setting ENV['TZ'] should not be necessary.

The value can be determined thanks to https://en.wikipedia.org/wiki/List_of_tz_database_time_zones.

Use a "continent/city" identifier (for example "Asia/Shanghai"). Do not use an abbreviation (not "CST") and do not use a local time zone name (not "中国标准时间" nor "Eastern Standard Time" which, for instance, points to a time zone in America and to another one in Australia...).

If the error persists (and especially on Windows), try to add the tzinfo-data to your Gemfile, as in:

gem 'tzinfo-data'

or by manually requiring it before requiring rufus-scheduler (if you don't use Bundler):

require 'tzinfo/data'
require 'rufus-scheduler'

so Rails?

Yes, I know, all of the above is boring and you're only looking for a snippet to paste in your Ruby-on-Rails application to schedule...

Here is an example initializer:

#
# config/initializers/scheduler.rb

require 'rufus-scheduler'

# Let's use the rufus-scheduler singleton
#
s = Rufus::Scheduler.singleton


# Stupid recurrent task...
#
s.every '1m' do

  Rails.logger.info "hello, it's #{Time.now}"
  Rails.logger.flush
end

And now you tell me that this is good, but you want to schedule stuff from your controller.

Maybe:

class ScheController < ApplicationController

  # GET /sche/
  #
  def index

    job_id =
      Rufus::Scheduler.singleton.in '5s' do
        Rails.logger.info "time flies, it's now #{Time.now}"
      end

    render text: "scheduled job #{job_id}"
  end
end

The rufus-scheduler singleton is instantiated in the config/initializers/scheduler.rb file, it's then available throughout the webapp via Rufus::Scheduler.singleton.

Warning: this works well with single-process Ruby servers like Webrick and Thin. Using rufus-scheduler with Passenger or Unicorn requires a bit more knowledge and tuning, gently provided by a bit of googling and reading, see Faq above.

avoid scheduling when running the Ruby on Rails console

(Written in reply to gh-186)

If you don't want rufus-scheduler to trigger anything while running the Ruby on Rails console, running for tests/specs, or running from a Rake task, you can insert a conditional return statement before jobs are added to the scheduler instance:

#
# config/initializers/scheduler.rb

require 'rufus-scheduler'

return if defined?(Rails::Console) || Rails.env.test? || File.split($PROGRAM_NAME).last == 'rake'
  #
  # do not schedule when Rails is run from its console, for a test/spec, or
  # from a Rake task

# return if $PROGRAM_NAME.include?('spring')
  #
  # see https://github.com/jmettraux/rufus-scheduler/issues/186

s = Rufus::Scheduler.singleton

s.every '1m' do
  Rails.logger.info "hello, it's #{Time.now}"
  Rails.logger.flush
end

(Beware later version of Rails where Spring takes care pre-running the initializers. Running spring stop or disabling Spring might be necessary in some cases to see changes to initializers being taken into account.)

rails server -d

(Written in reply to https://github.com/jmettraux/rufus-scheduler/issues/165 )

There is the handy rails server -d that starts a development Rails as a daemon. The annoying thing is that the scheduler as seen above is started in the main process that then gets forked and daemonized. The rufus-scheduler thread (and any other thread) gets lost, no scheduling happens.

I avoid running -d in development mode and bother about daemonizing only for production deployment.

These are two well crafted articles on process daemonization, please read them:

If, anyway, you need something like rails server -d, why not try bundle exec unicorn -D instead? In my (limited) experience, it worked out of the box (well, had to add gem 'unicorn' to Gemfile first).

executor / reloader

You might benefit from wraping your scheduled code in the executor or reloader. Read more here: https://guides.rubyonrails.org/threading_and_code_execution.html

support

see getting help above.


Author: jmettraux
Source code: https://github.com/jmettraux/rufus-scheduler
License: MIT license

#ruby