ravendb/dist/esm/Utility/Semaphore.js

RavenDB client for Node.js

const nextTick = function (fn) {
    setTimeout(fn, 0);
};
export class Semaphore {
    capacity = 1;
    current = 0;
    queue = [];
    firstHere = false;
    constructor(capacity = 1) {
        this.capacity = capacity;
    }
    take(func) {
        let isFirst;
        if (this.firstHere === false) {
            this.current++;
            this.firstHere = true;
            isFirst = 1;
        }
        else {
            isFirst = 0;
        }
        const item = { n: 1, task: func };
        if (this.current + item.n - isFirst > this.capacity) {
            if (isFirst === 1) {
                this.current--;
                this.firstHere = false;
            }
            return this.queue.push(item);
        }
        this.current += item.n - isFirst;
        item.task();
        if (isFirst === 1) {
            this.firstHere = false;
        }
    }
    leave(n = 1) {
        this.current -= n;
        if (!this.queue.length) {
            if (this.current < 0) {
                throw new Error('leave called too many times.');
            }
            return;
        }
        const item = this.queue[0];
        if (item.n + this.current > this.capacity) {
            return;
        }
        this.queue.shift();
        this.current += item.n;
        nextTick(item.task);
    }
    available(n = 1) {
        return this.current + n <= this.capacity;
    }
}
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