op-queue

A simple module for operations in queue.

Push operations to queue, they will execute one by one synchronous.

Support async functions or functions returned Promise.

Intall

npm install op-queue --save

Usage

const OpQueue = require('op-queue').default;
let myQ = new OpQueue();

function promiseOperation(...args) {
    return new Promise((resolve: any, reject: any) => {
        // ...
    });
}

async function asyncOperation(...args) {
    // ...
}

let myPromiseOp = OpQueue.buildOperation(promiseOperation);
let myAsyncOp = OpQueue.buildOperation(asyncOperation);

myQ.push(myPromiseOp(...args), (err. data) => {
    // ... handle returns of function "promiseOperation"
});
myQ.push(myAsyncOp(...args), (err, data) => {
    // ... handle returns of function "asyncOperation"
});

Events

done

myQ.on('done', (data) => {
    console.log('event.done:', data);
});

op_error

myQ.on('op_error', (error) => {
    console.log('event.error:', error);
});

API

const OpQueue = require('op-queue').default;
let myQ = new OpQueue(opt);

opt:

• manualStart: boolean, default false. If set true, operations pushed in queue will not execute until you call start() method. Use this when you want to push all operations in queue then start from first one and execute one by one.

OpQueue.buildOperation(fn)

• fn: async function or function returned Promise

length

let l = myQ.length

Get length of operations pending in queue (exclude the operation in processing)

push(op, callback)

Push operation to queue

• op value returned by OpQueue.buildOperation(fn)
• callback returns of op, optional, (error, data) => {} error: error op rejected, or null if op resolved, data: value op resolved.

start()

Start execute operations in queue. (only work when option manualStart is true)

const OpQueue = require('op-queue').default;
let myQ = new OpQueue({ manualStart: true });
myQ.push(...);
myQ.push(...);
myQ.push(...);
// operations will start execute after call start() method
myQ.start();

Example

typescript example:

import OpQueue from 'op-queue';

let myQ = new OpQueue();

myQ.on('done', (p: any) => {
    console.log('event.done:', p);
});

myQ.on('op_error', (e: any) => {
    console.log('event.error:', e);
});

async function sleep(ms: number) {
    return new Promise((resolve: any, reject: any) => {
        setTimeout(resolve, ms);
    });
}

function promiseOperation(a: any) {
    return new Promise((resolve: any, reject: any) => {
        resolve({a: a});
    });
}

let myPromiseOp = OpQueue.buildOperation(promiseOperation);

async function asyncOperation(ms: number) {
    console.log('sleep start');
    await sleep(ms);
    console.log('sleep done');
    return ms;
}

let myAsyncOp = OpQueue.buildOperation(asyncOperation);

myQ.push(myAsyncOp(2000));
myQ.push(myPromiseOp(222));
myQ.push(myAsyncOp(3000));
myQ.push(myPromiseOp(333), (error: any, p: any) => {
    if (error) {
        console.log('cb.error', error);
    } else {
        console.log('cb.done', p);
    }
});

// output should be:
// sleep start
// sleep done
// event.done: 2000
// event.done: { a: 222 }
// sleep start
// sleep done
// event.done: 3000
// event.done: { a: 333 }
// cb.done { a: 333 }

Test

npm test