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52 lines
1.5 KiB
JavaScript
52 lines
1.5 KiB
JavaScript
/*
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* decaffeinate suggestions:
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* DS101: Remove unnecessary use of Array.from
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* DS102: Remove unnecessary code created because of implicit returns
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* Full docs: https://github.com/decaffeinate/decaffeinate/blob/master/docs/suggestions.md
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*/
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// A synchronous processing queue. The queue calls process on the arguments,
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// ensuring that process() is only executing once at a time.
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//
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// process(data, callback) _MUST_ eventually call its callback.
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//
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// Example:
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//
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// queue = require 'syncqueue'
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//
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// fn = queue (data, callback) ->
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// asyncthing data, ->
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// callback(321)
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//
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// fn(1)
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// fn(2)
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// fn(3, (result) -> console.log(result))
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//
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// ^--- async thing will only be running once at any time.
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module.exports = function(process) {
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if (typeof process !== 'function') { throw new Error('process is not a function'); }
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const queue = [];
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const enqueue = function(data, callback) {
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queue.push([data, callback]);
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return flush();
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};
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enqueue.busy = false;
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var flush = function() {
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if (enqueue.busy || (queue.length === 0)) { return; }
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enqueue.busy = true;
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const [data, callback] = Array.from(queue.shift());
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return process(data, function(...result) { // TODO: Make this not use varargs - varargs are really slow.
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enqueue.busy = false;
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// This is called after busy = false so a user can check if enqueue.busy is set in the callback.
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if (callback) { callback.apply(null, result); }
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return flush();
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});
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};
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return enqueue;
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};
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