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co-flow

Flexible execution flow addons (all, any, wait) for co.

Quickstart

const all = require('co-flow').all;
const any = require('co-flow').any;
const wait = require('co-flow').wait;
 
const allResults = yield all([runnable1, runnable2, …]);  // returns an array with the results of all runnables
const anyResult  = yield any([runnable1, runnable2, …]);  // returns the result for the runnable which succeeded first
 
yield wait(500);  // just what you expect

Usage

all (runnables, [options])

Executes all runnables and waits for all of them to complete.

Returns an array with the result of each runnable, in the same order.
If options.failsWhenAnyFailed is false then the returned array will also contain errors for each runnable which failed.

Returns an empty array if runnables evaluates to false or is an empty array.

Parameters

• runnables - An array of runnables to be executed.

• options.concurrency - Specifies the maximum number of runnables which will be executed concurrently (similar to tasks in a thread pool).
  true executes all runnables in parallel and false is like 1 and runs all runnables serially in order.
  Defaults to true.

• options.failsWhenAnyFailed - If true then the function will fail if any runnable failed.
  The error of the first runnable which failed will be passed along.
  Defaults to true.

• options.failsWhenAllFailed - If true then the function will fail if all runnables failed.
  The error of the first runnable which failed will be passed along.
  Defaults to false.

• options.structured - If true then the function's result data will be wrapped with { error: … } or { data: … }, respectively.
  Defaults to false.

• options.this - Value for this when executing runnables or options.unusedResultHandler.

• options.unusedResultHandler - Callback for each runnable whose result was not returned by the function (due to options.failsWhenAnyFailed or options.failsWhenAllFailed).
  The callback will be called after the function returned and in the order of the runnables.

Example

Load multiple URLs concurrently.

const all = require('co-flow').all;
const co = require('co');
const request = require('co-request');
 
co(function*() {
    try {
        // request all URLs concurrently and wait for all of them to complete
        const results = yield all([
            request('https://raw.github.com/fluidsonic/co-flow/master/README.md'),
            request('https://raw.github.com/fluidsonic/co-flow/master/index.js'),
            request('https://raw.github.com/fluidsonic/co-flow/master/package.json')
        ]);
 
        // output response of each request
        results.forEach(function(result) {
            console.log('\n  ###### %s responded:\n', result.request.uri.href);
            console.log('%s', result.body);
        });
    }
    catch (e) {
        // any request failed
        console.error('Cannot load request:', e);
    }
});

any (runnables, [options])

Executes all runnables and only waits for one of them to complete successfully.

Returns the result data of the first runnable which completes successfully or else the error of the first runnable which failed if options.failsWhen(Any/All)Failed are both false.

Returns the result data undefined if runnables evaluates to false or is an empty array.

Parameters

• runnables - An array of runnables to be executed.

• options.concurrency - Specifies the maximum number of runnables which will be executed concurrently (similar to tasks in a thread pool).
  true executes all runnables in parallel and false is like 1 and runs all runnables serially in order.
  Defaults to true.

• options.failsWhenAnyFailed - If true then the function will fail as soon as any runnable failed.
  As a consequence a successful completion of the function will be delayed until all runnables have completed.
  The error of the first runnable which failed will be passed along.
  Defaults to false.

• options.failsWhenAllFailed - If true then the function will fail if all runnables failed (instead of returning the error as result data).
  The error of the first runnable which failed will be passed along.
  Defaults to true.

• options.structured - If true then the function's result data will be wrapped with { error: … } or { data: … }, respectively.
  Defaults to false.

• options.this - Value for this when executing runnables or options.unusedResultHandler.

• options.unusedResultHandler - Callback for each runnable whose result was not returned by the function.
  The callback will be called after the function returned and all runnables have completed. It will be called in the order of the runnables.

Example

Request multiple URLs concurrently and only wait for one request complete successfully.

const any = require('co-flow').any;
const co = require('co');
const request = require('co-request');
 
co(function*() {
    try {
        // request all URLs concurrently and wait for one of them to complete successfully
        const result = yield any([
            request('https://raw.github.com/fluidsonic/co-flow/master/README.md'),
            request('https://raw.github.com/fluidsonic/co-flow/master/README.md'),
            request('https://rawgithub.com/fluidsonic/co-flow/master/README.md'),
            request('http://rawgithub.com/fluidsonic/co-flow/master/README.md')
        ]);
 
        // output response of the first request which finished
        console.log('\n  ###### %s responded first:\n', result.request.uri.href);
        console.log('%s', result.body);
    }
    catch (e) {
        // all requests failed
        console.error('Cannot load README:', e);
    }
});

wait (delay)

Pauses execution for the given delay - like setTimeout in generator style.

Parameters

• delay - Time in milliseconds before the function returns and execution continues.

Example

const co = require('co');
const wait = require('co-flow').wait;
 
co(function*() {
    console.log('Wait');
    yield wait(500);
    console.log('just');
    yield wait(500);
    console.log('does');
    yield wait(500);
    console.log('what');
    yield wait(500);
    console.log('it');
    yield wait(500);
    console.log('says.');
});

Installation

$ npm install co-flow

Requirements

Node 0.11+, run with --harmony flag.

Testing

$ npm install
$ npm test

License

MIT