bsw

BSW is a Node.js framework for beanstalkd workers

Table of Contents

• Requirements
• Quick Start
• Handler Function
  • Jobs processing
  • Post processing
• BSW Consumer class
  • async start() function
  • stop() function
  • async stopGracefully(timeout) function
• BSW Producer class
• Full example
• Contributors

Requirements

Node.js v10 or above is required.

Changelog

3.0

Updated dependencies and dropped node 8 support.

Quick Start

Consumer

const {Consumer} = require('bsw');
 
(async () => {
    const consumer = new Consumer({
        host: '127.0.0.1',
        port: 27017,
        tube: 'example',
        handler: async function (payload, job_info) {
            console.log('processing job: ', payload);
            return 'success';
        }
    });
 
    // handling errors
    consumer.on('error', (e) => {
        console.log('error:', e);
    });
 
    await consumer.start();
})();

Producer

const {Producer} = require('bsw');
 
(async () => {
    const producer = new Producer({
        host: '127.0.0.1',
        port: 27017,
        tube: 'example'
    });
 
    // handling errors
    consumer.on('error', (e) => {
        console.log('error:', e);
    });
 
    await producer.start();
 
    await producer.putJob({
        payload: JSON.stringify({throw: true, result: 'success'}),
        priority: 0,
        delay: 0,
        ttr: 60
    });
 
    producer.stop();
})();

Handler Function

In v2, handler must be an async function(https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Statements/async_function)

handler interface:

async handler(payload, job_info)

• payload: beanstalk job payload string or object (if job is a valid JSON)
• job_info: job details
• job_info.id: job id
• job_info.tube: job tube

handler definition examples:

async handler(payload, job_info) {
    console.log('Hello world!');
}

Jobs processing

After job reservation, handler would be called. Each job must get one of the following status after processing:

• success: job processed succesfully and must be deleted from beanstalkd
• bury: job processing failed, it must be marked as buried in beanstalkd
• release + delay: job must be reserved again after delay

To report the job status, it must be returned or thrown from handler function:

// delete job
return 'success';
throw 'success';
 
// bury job
return 'bury';
throw 'bury';
 
// reput job without delay
return 'release';
throw 'release';
 
// reput job with 10s delay
return ['release', 10];
throw ['release', 10];

Default statuses:

• success if handler returned with unknown keyword
• bury if handler thrown with unknown keyword

For example:

async handler(payload, job_info) {
    try {
        await mayThrow();
    } catch (e) {
        return 'bury'
    }
    return 'success';
}

equals to

async handler(payload, job_info) {
    await mayThrow();
}

Post processing

You may add an optional post processing of jobs, to do this add final function to the handler with the following interface:

NOTE: post processing apply after job status was sent to beanstalkd

async final(status, delay, result)

• status: job status (success, release or bury)
• delay: job delay in seconds for release or null
• result: a value returned/thowrn from handler

BSW Consumer class

BSW Consumer class is used to connect to beanstalkd server and subscribe to a tube

The Consumer constructor takes configuration object:

• host: beanstalkd host (default: '127.0.0.1')
• port: beanstalkd port (default: 11300)
• tube: beanstalkd tube (default: 'default')
• enable_logging: enable logging to console (default value false)
• reserve_timeout: timeout value(in seconds) of job reservation (default value 30)
• max_processing_jobs: max number of simultaneous jobs reserved (default: 1)
• auto_reconnect: flag for reconnection behavior when connection is accidentally closed, which means it's not closed by client side and fivebeans will fire a close event (default value false)
• handler: handler async function (mandatory, MUST be an async function)
• final: final async function (optional, MUST be an async function)

async start() function

Start the worker.

• NOTE async function can be called directly, or called inside another async function with await key word.
• If call consumer.start() directly, it will return immediately and process the actual start action asynchonously
• If call await consumer.start() inside an async function, it will wait until the start process finishes and then process the code at the back

Example:

const consumer = new Consumer({
    host: '127.0.0.1',
    port: 27017,
    tube: 'example',
    handler: async function (payload, job_info) {
        console.log('processing job: ', payload);
        return 'success';
    }
});
 
// could be called directly without await
consumer.start();
// this line will be immediately called because start() is async function
console.log('do something');
 
// or could be called inside async function context
(async () => {
    await consumer.start();
    // this line will be called after start() returns
    console.log('do something');
})();

stop() function

Stop the consumer immediately, and any processing jobs won't report to beanstalk. Example

consumer.stop();

async stopGracefully(timeout) function

Stop the consumer in a more graceful way. Will wait until all the processing jobs are done and reported to beanstalk, or wait for a user-specific timeout value.

Example

// stop the consumer gracefully within 3s
await consumer.stopGracefully(3000);

BSW Producer class

BSW Producer class is used to connect to beanstalkd server and put jobs to a tube

The Producer constructor takes configuration object:

• host: beanstalkd host (default: '127.0.0.1')
• port: beanstalkd port (default: 11300)
• tube: beanstalkd tube (default: 'default')
• enable_logging: enable logging to console (default value false)

async start() function

Same as Consumer class.

stop() function

Same as Consumer class.

async putJob(job) function

Put jobs to the tube. Receives an job object which has the following attributes:

• payload: job payload, type is String
• priority: job priority, 0 is highest, type is Integer
• delay: time(in seconds) for a job to transfer from Delayed state to Ready state, type is Integer
• ttr: time(in seconds) for a reserved job to become Ready state, type is Integer

Example:

await producer.putJob({
    payload: JSON.stringify({key: 'value'}),
    priority: 0,
    delay: 0,
    ttr: 60
});

Full example

Find the full example in example directory:

To run, clone the project, then:

> npm install
(If you have `yarn` installed in your machine, we recommand you use `yarn install` instead)
> cd example
> node producer.js
> node consumer.js

Contributors

• Fedor Korshunov (for v1) - view contributions
• Vence Lin (for v2) - view contributions