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GeezerVison is showing github.com — ConcurrentQueue/JavaScript/1-channels.js at master · HowProgrammingWorks/ConcurrentQueue

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'use strict';
class Queue {
constructor(concurrency) {
this.concurrency = concurrency;
this.count = 0;
this.waiting = [];
this.onProcess = null;
this.onDone = null;
this.onSuccess = null;
this.onFailure = null;
this.onDrain = null;
}
static channels(concurrency) {
return new Queue(concurrency);
}
add(task) {
const hasChannel = this.count < this.concurrency;
if (hasChannel) return void this.next(task);
this.waiting.push(task);
}
next(task) {
this.count++;
this.onProcess(task, (error, result) => {
if (error) {
this.onFailure?.(error);
} else {
this.onSuccess?.(result);
}
this.onDone?.(error, result);
this.count--;
if (this.waiting.length > 0) {
const task = this.waiting.shift();
this.next(task);
return;
}
if (this.count === 0 && this.onDrain) {
this.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;
}
}
// Usage
const job = (task, next) => {
console.log(`Process: ${task.name}`);
setTimeout(next, task.interval, null, task);
};
const queue = Queue.channels(3)
.process(job)
.done((error, res) => {
if (error) console.log(`Done with error: ${error}`);
const { count } = queue;
const waiting = queue.waiting.length;
console.log(`Done: ${res.name}, count: ${count}, waiting: ${waiting}`);
})
.success((res) => void console.log(`Success: ${res.name}`))
.failure((error) => void console.log(`Failure: ${error}`))
.drain(() => void console.log('Queue drain'));
for (let i = 0; i < 10; i++) {
queue.add({ name: `Task${i}`, interval: i * 1000 });
}
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