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| 1 | +'use strict'; |
| 2 | + |
| 3 | +class Queue { |
| 4 | + constructor(concurrency) { |
| 5 | + this.paused = false; |
| 6 | + this.concurrency = concurrency; |
| 7 | + this.count = 0; |
| 8 | + this.waiting = []; |
| 9 | + this.onProcess = null; |
| 10 | + this.onDone = null; |
| 11 | + this.onSuccess = null; |
| 12 | + this.onFailure = null; |
| 13 | + this.onDrain = null; |
| 14 | + this.waitTimeout = Infinity; |
| 15 | + this.processTimeout = Infinity; |
| 16 | + this.priorityMode = false; |
| 17 | + this.destination = null; |
| 18 | + } |
| 19 | + static channels(concurrency) { |
| 20 | + return new Queue(concurrency); |
| 21 | + } |
| 22 | + wait(msec) { |
| 23 | + this.waitTimeout = msec; |
| 24 | + return this; |
| 25 | + } |
| 26 | + timeout(msec) { |
| 27 | + this.processTimeout = msec; |
| 28 | + return this; |
| 29 | + } |
| 30 | + add(task, priority = 0) { |
| 31 | + if (!this.paused) { |
| 32 | + const hasChannel = this.count < this.concurrency; |
| 33 | + if (hasChannel) { |
| 34 | + this.next(task); |
| 35 | + return; |
| 36 | + } |
| 37 | + } |
| 38 | + this.waiting.push({ task, start: Date.now(), priority }); |
| 39 | + if (this.priorityMode) { |
| 40 | + this.waiting.sort((a, b) => b.priority - a.priority); |
| 41 | + } |
| 42 | + } |
| 43 | + next(task) { |
| 44 | + this.count++; |
| 45 | + let timer = null; |
| 46 | + let finished = false; |
| 47 | + const { processTimeout, onProcess } = this; |
| 48 | + const finish = (err, res) => { |
| 49 | + if (finished) return; |
| 50 | + finished = true; |
| 51 | + if (timer) clearTimeout(timer); |
| 52 | + this.count--; |
| 53 | + this.finish(err, res); |
| 54 | + if (!this.paused && this.waiting.length > 0) this.takeNext(); |
| 55 | + }; |
| 56 | + if (processTimeout !== Infinity) { |
| 57 | + const err = new Error('Process timed out'); |
| 58 | + timer = setTimeout(finish, processTimeout, err, task); |
| 59 | + } |
| 60 | + onProcess(task, finish); |
| 61 | + } |
| 62 | + takeNext() { |
| 63 | + const { waiting, waitTimeout } = this; |
| 64 | + const { task, start } = waiting.shift(); |
| 65 | + if (waitTimeout !== Infinity) { |
| 66 | + const delay = Date.now() - start; |
| 67 | + if (delay > waitTimeout) { |
| 68 | + const err = new Error('Waiting timed out'); |
| 69 | + this.finish(err, task); |
| 70 | + if (waiting.length > 0) { |
| 71 | + setTimeout(() => { |
| 72 | + if (this.paused && waiting.length > 0) this.takeNext(); |
| 73 | + }, 0); |
| 74 | + } |
| 75 | + return; |
| 76 | + } |
| 77 | + } |
| 78 | + const hasChannel = this.count < this.concurrency; |
| 79 | + if (hasChannel) this.next(task); |
| 80 | + return; |
| 81 | + } |
| 82 | + finish(err, res) { |
| 83 | + const { onFailure, onSuccess, onDone, onDrain } = this; |
| 84 | + if (err) { |
| 85 | + if (onFailure) onFailure(err, res); |
| 86 | + } else { |
| 87 | + if (onSuccess) onSuccess(res); |
| 88 | + if (this.destination) this.destination.add(res); |
| 89 | + } |
| 90 | + if (onDone) onDone(err, res); |
| 91 | + if (this.count === 0 && onDrain) onDrain(); |
| 92 | + } |
| 93 | + process(listener) { |
| 94 | + this.onProcess = listener; |
| 95 | + return this; |
| 96 | + } |
| 97 | + done(listener) { |
| 98 | + this.onDone = listener; |
| 99 | + return this; |
| 100 | + } |
| 101 | + success(listener) { |
| 102 | + this.onSuccess = listener; |
| 103 | + return this; |
| 104 | + } |
| 105 | + failure(listener) { |
| 106 | + this.onFailure = listener; |
| 107 | + return this; |
| 108 | + } |
| 109 | + drain(listener) { |
| 110 | + this.onDrain = listener; |
| 111 | + return this; |
| 112 | + } |
| 113 | + pause() { |
| 114 | + this.paused = true; |
| 115 | + return this; |
| 116 | + } |
| 117 | + resume() { |
| 118 | + this.paused = false; |
| 119 | + if (this.waiting.length > 0) { |
| 120 | + const hasChannel = this.count < this.concurrency; |
| 121 | + if (hasChannel) this.takeNext(); |
| 122 | + } |
| 123 | + return this; |
| 124 | + } |
| 125 | + priority(flag = true) { |
| 126 | + this.priorityMode = flag; |
| 127 | + return this; |
| 128 | + } |
| 129 | + pipe(destination) { |
| 130 | + this.destination = destination; |
| 131 | + return this; |
| 132 | + } |
| 133 | +} |
| 134 | + |
| 135 | +// Usage |
| 136 | + |
| 137 | +const destination = Queue.channels(2) |
| 138 | + .wait(5000) |
| 139 | + .process((task, next) => next(null, { ...task, processed: true })) |
| 140 | + .done((err, task) => console.log({ task })); |
| 141 | + |
| 142 | +const source = Queue.channels(3) |
| 143 | + .timeout(4000) |
| 144 | + .process((task, next) => setTimeout(next, task.interval, null, task)) |
| 145 | + .pipe(destination); |
| 146 | + |
| 147 | +for (let i = 0; i < 10; i++) { |
| 148 | + source.add({ name: `Task${i}`, interval: 1000 }); |
| 149 | +} |
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