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| author | ruki <waruqi@gmail.com> | 2018-11-08 00:38:48 +0800 |
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| committer | ruki <waruqi@gmail.com> | 2018-11-07 21:53:09 +0800 |
| commit | 26105034da4fcce7ac883c899d781f016559310d (patch) | |
| tree | c459a5dc4e3aa0972d9919033ece511ce76dd129 /node_modules/async-limiter/readme.md | |
| parent | 2c77f00f1a7ecb6c8192f9c16d3b2001b254a107 (diff) | |
| download | xmake-docs-26105034da4fcce7ac883c899d781f016559310d.tar.gz xmake-docs-26105034da4fcce7ac883c899d781f016559310d.zip | |
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diff --git a/node_modules/async-limiter/readme.md b/node_modules/async-limiter/readme.md new file mode 100644 index 00000000..dcf4932f --- /dev/null +++ b/node_modules/async-limiter/readme.md @@ -0,0 +1,132 @@ +# Async-Limiter + +A module for limiting concurrent asynchronous actions in flight. Forked from [queue](https://github.com/jessetane/queue). + +[](http://www.npmjs.org/async-limiter) +[](https://travis-ci.org/STRML/async-limiter) +[](https://coveralls.io/r/STRML/async-limiter) + +This module exports a class `Limiter` that implements some of the `Array` API. +Pass async functions (ones that accept a callback or return a promise) to an instance's additive array methods. + +## Motivation + +Certain functions, like `zlib`, have [undesirable behavior](https://github.com/nodejs/node/issues/8871#issuecomment-250915913) when +run at infinite concurrency. + +In this case, it is actually faster, and takes far less memory, to limit concurrency. + +This module should do the absolute minimum work necessary to queue up functions. PRs are welcome that would +make this module faster or lighter, but new functionality is not desired. + +Style should confirm to nodejs/node style. + +## Example + +``` javascript +var Limiter = require('async-limiter') + +var t = new Limiter({concurrency: 2}); +var results = [] + +// add jobs using the familiar Array API +t.push(function (cb) { + results.push('two') + cb() +}) + +t.push( + function (cb) { + results.push('four') + cb() + }, + function (cb) { + results.push('five') + cb() + } +) + +t.unshift(function (cb) { + results.push('one') + cb() +}) + +t.splice(2, 0, function (cb) { + results.push('three') + cb() +}) + +// Jobs run automatically. If you want a callback when all are done, +// call 'onDone()'. +t.onDone(function () { + console.log('all done:', results) +}) +``` + +## Zlib Example + +```js +const zlib = require('zlib'); +const Limiter = require('async-limiter'); + +const message = {some: "data"}; +const payload = new Buffer(JSON.stringify(message)); + +// Try with different concurrency values to see how this actually +// slows significantly with higher concurrency! +// +// 5: 1398.607ms +// 10: 1375.668ms +// Infinity: 4423.300ms +// +const t = new Limiter({concurrency: 5}); +function deflate(payload, cb) { + t.push(function(done) { + zlib.deflate(payload, function(err, buffer) { + done(); + cb(err, buffer); + }); + }); +} + +console.time('deflate'); +for(let i = 0; i < 30000; ++i) { + deflate(payload, function (err, buffer) {}); +} +q.onDone(function() { + console.timeEnd('deflate'); +}); +``` + +## Install + +`npm install async-limiter` + +## Test + +`npm test` + +## API + +### `var t = new Limiter([opts])` +Constructor. `opts` may contain inital values for: +* `q.concurrency` + +## Instance methods + +### `q.onDone(fn)` +`fn` will be called once and only once, when the queue is empty. + +## Instance methods mixed in from `Array` +Mozilla has docs on how these methods work [here](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array). +### `q.push(element1, ..., elementN)` +### `q.unshift(element1, ..., elementN)` +### `q.splice(index , howMany[, element1[, ...[, elementN]]])` + +## Properties +### `q.concurrency` +Max number of jobs the queue should process concurrently, defaults to `Infinity`. + +### `q.length` +Jobs pending + jobs to process (readonly). + |
