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Copy path4-priority.js
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162 lines (142 loc) · 3.39 KB
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'use strict';
class Queue {
constructor(concurrency) {
this.paused = false;
this.concurrency = concurrency;
this.count = 0;
this.waiting = [];
this.onProcess = null;
this.onDone = null;
this.onSuccess = null;
this.onFailure = null;
this.onDrain = null;
this.waitTimeout = Infinity;
this.processTimeout = Infinity;
this.priorityMode = false;
}
static channels(concurrency) {
return new Queue(concurrency);
}
wait(msec) {
this.waitTimeout = msec;
return this;
}
timeout(msec) {
this.processTimeout = msec;
return this;
}
add(task, priority = 0) {
if (!this.paused) {
const hasChannel = this.count < this.concurrency;
if (hasChannel) {
this.next(task);
return;
}
}
this.waiting.push({ task, start: Date.now(), priority });
if (this.priorityMode) {
this.waiting.sort((a, b) => b.priority - a.priority);
}
}
next(task) {
this.count++;
let timer = null;
let finished = false;
const { processTimeout, onProcess } = this;
const finish = (err, res) => {
if (finished) return;
finished = true;
if (timer) clearTimeout(timer);
this.count--;
this.finish(err, res);
if (!this.paused && this.waiting.length > 0) this.takeNext();
};
if (processTimeout !== Infinity) {
const err = new Error('Process timed out');
timer = setTimeout(finish, processTimeout, err, task);
}
onProcess(task, finish);
}
takeNext() {
const { waiting, waitTimeout } = this;
const { task, start } = waiting.shift();
if (waitTimeout !== Infinity) {
const delay = Date.now() - start;
if (delay > waitTimeout) {
const err = new Error('Waiting timed out');
this.finish(err, task);
if (waiting.length > 0) {
setTimeout(() => {
if (!this.paused && waiting.length > 0) this.takeNext();
}, 0);
}
return;
}
}
const hasChannel = this.count < this.concurrency;
if (hasChannel) this.next(task);
}
finish(err, res) {
const { onFailure, onSuccess, onDone, onDrain } = this;
if (err) {
onFailure?.(err, res);
} else {
onSuccess?.(res);
}
onDone?.(err, res);
if (this.count === 0) onDrain?.();
}
process(listener) {
this.onProcess = listener;
return this;
}
done(listener) {
this.onDone = listener;
return this;
}
success(listener) {
this.onSuccess = listener;
return this;
}
failure(listener) {
this.onFailure = listener;
return this;
}
drain(listener) {
this.onDrain = listener;
return this;
}
pause() {
this.paused = true;
return this;
}
resume() {
if (this.waiting.length > 0) {
const channels = this.concurrency - this.count;
for (let i = 0; i < channels; i++) {
this.takeNext();
}
}
this.paused = false;
return this;
}
priority(flag = true) {
this.priorityMode = flag;
return this;
}
}
// Usage
const job = (task, next) => {
setTimeout(next, task.interval, null, task);
};
const queue = Queue.channels(3)
.process(job)
.priority()
.done((error, task) => {
if (error) console.error(error);
console.log(`Done: ${task.name}`);
})
.drain(() => void console.log('Queue drain'));
for (let i = 0; i < 10; i++) {
queue.add({ name: `Task${i}`, interval: 1000 }, i);
}