nestjs-resilience/dist/strategies/bulkhead.strategy.js

A module for improving the reliability and fault-tolerance of your NestJS applications

"use strict";
Object.defineProperty(exports, "__esModule", { value: true });
exports.BulkheadStrategy = void 0;
const base_strategy_1 = require("./base.strategy");
const rxjs_1 = require("rxjs");
const exceptions_1 = require("../exceptions");
class BulkheadStrategy extends base_strategy_1.Strategy {
    get executionSlots() {
        return this.options.maxConcurrent - this.active;
    }
    get queueSlots() {
        return this.options.maxQueue - this.queue.length;
    }
    constructor(options) {
        super(Object.assign(Object.assign({}, BulkheadStrategy.DEFAULT_OPTIONS), options));
        this.active = 0;
        this.queue = [];
        this.queue$ = new rxjs_1.Subject();
    }
    process(observable) {
        if (this.executionSlots > 0) {
            return this.concurrent(observable);
        }
        if (this.queueSlots > 0) {
            return this.enqueue(observable);
        }
        return (0, rxjs_1.throwError)(() => new exceptions_1.BulkheadRejectedException(this.options.maxConcurrent, this.options.maxQueue));
    }
    concurrent(observable) {
        this.active++;
        return observable.pipe((0, rxjs_1.finalize)(() => {
            this.active--;
            this.dequeue();
        }));
    }
    enqueue(observable) {
        this.queue.push(observable);
        return new rxjs_1.Observable(subscriber => {
            this.queue$.subscribe(queuedObservable => {
                if (queuedObservable === observable) {
                    return this.concurrent(observable).subscribe(subscriber);
                }
            });
        });
    }
    dequeue() {
        if (this.executionSlots === 0) {
            return;
        }
        const observable = this.queue.shift();
        if (!observable) {
            return;
        }
        return this.queue$.next(observable);
    }
}
exports.BulkheadStrategy = BulkheadStrategy;
BulkheadStrategy.DEFAULT_OPTIONS = {
    maxConcurrent: 1,
    maxQueue: 1
};