@stryker-mutator/core/dist/src/concurrent/pool.js

The extendable JavaScript mutation testing framework

import { notEmpty } from '@stryker-mutator/util';
import { BehaviorSubject, filter, ignoreElements, lastValueFrom, mergeMap, ReplaySubject, Subject, takeUntil, tap, zip, } from 'rxjs';
import { tokens } from 'typed-inject';
import { coreTokens } from '../di/index.js';
const MAX_CONCURRENT_INIT = 2;
createTestRunnerPool.inject = tokens(coreTokens.testRunnerFactory, coreTokens.testRunnerConcurrencyTokens);
export function createTestRunnerPool(factory, concurrencyToken$) {
    return new Pool(factory, concurrencyToken$);
}
createCheckerPool.inject = tokens(coreTokens.checkerFactory, coreTokens.checkerConcurrencyTokens);
export function createCheckerPool(factory, concurrencyToken$) {
    return new Pool(factory, concurrencyToken$);
}
/**
 * Represents a work item: an input with a task and with a `result$` observable where the result (exactly one) will be streamed to.
 */
class WorkItem {
    input;
    task;
    resultSubject = new Subject();
    result$ = this.resultSubject.asObservable();
    /**
     * @param input The input to the ask
     * @param task The task, where a resource and input is presented
     */
    constructor(input, task) {
        this.input = input;
        this.task = task;
    }
    async execute(resource) {
        try {
            const output = await this.task(resource, this.input);
            this.resultSubject.next(output);
            this.resultSubject.complete();
        }
        catch (err) {
            this.resultSubject.error(err);
        }
    }
    reject(error) {
        this.resultSubject.error(error);
    }
    complete() {
        this.resultSubject.complete();
    }
}
/**
 * Represents a pool of resources. Use `schedule` to schedule work to be executed on the resources.
 * The pool will automatically recycle the resources, but will make sure only one task is executed
 * on one resource at any one time. Creates as many resources as the concurrency tokens allow.
 * Also takes care of the initialing of the resources (with `init()`)
 */
export class Pool {
    // The init subject. Using an RxJS subject instead of a promise, so errors are silently ignored when nobody is listening
    initSubject = new ReplaySubject();
    // The disposedSubject emits true when it is disposed, and false when not disposed yet
    disposedSubject = new BehaviorSubject(false);
    // The dispose$ only emits one `true` value when disposed (never emits `false`). Useful for `takeUntil`
    dispose$ = this.disposedSubject.pipe(filter((isDisposed) => isDisposed));
    createdResources = [];
    // The queued work items. This is a replay subject, so scheduled work items can easily be rejected after it was picked up
    todoSubject = new ReplaySubject();
    constructor(factory, concurrencyToken$) {
        // Stream resources that are ready to pick up work
        const resourcesSubject = new Subject();
        // Stream ongoing work.
        zip(resourcesSubject, this.todoSubject)
            .pipe(mergeMap(async ([resource, workItem]) => {
            await workItem.execute(resource);
            resourcesSubject.next(resource); // recycle resource so it can pick up more work
        }), ignoreElements(), takeUntil(this.dispose$))
            .subscribe({
            error: (error) => {
                this.todoSubject.subscribe((workItem) => workItem.reject(error));
            },
        });
        // Create resources
        concurrencyToken$
            .pipe(takeUntil(this.dispose$), mergeMap(async () => {
            if (this.disposedSubject.value) {
                // Don't create new resources when disposed
                return;
            }
            const resource = factory();
            this.createdResources.push(resource);
            await resource.init?.();
            return resource;
        }, MAX_CONCURRENT_INIT), filter(notEmpty), tap({
            complete: () => {
                // Signal init complete
                this.initSubject.next();
                this.initSubject.complete();
            },
            error: (err) => {
                this.initSubject.error(err);
            },
        }))
            .subscribe({
            next: (resource) => resourcesSubject.next(resource),
            error: (err) => resourcesSubject.error(err),
        });
    }
    /**
     * Returns a promise that resolves if all concurrency tokens have resulted in initialized resources.
     * This is optional, resources will get initialized either way.
     */
    async init() {
        await lastValueFrom(this.initSubject);
    }
    /**
     * Schedules a task to be executed on resources in the pool. Each input is paired with a resource, which allows async work to be done.
     * @param input$ The inputs to pair up with a resource.
     * @param task The task to execute on each resource
     */
    schedule(input$, task) {
        return input$.pipe(mergeMap((input) => {
            const workItem = new WorkItem(input, task);
            this.todoSubject.next(workItem);
            return workItem.result$;
        }));
    }
    /**
     * Dispose the pool
     */
    async dispose() {
        if (!this.disposedSubject.value) {
            this.disposedSubject.next(true);
            this.todoSubject.subscribe((workItem) => workItem.complete());
            this.todoSubject.complete();
            await Promise.all(
            // We're mixing promises with undefined values, which triggers the lint warning. We can safely ignore it here.
            // eslint-disable-next-line @typescript-eslint/await-thenable
            this.createdResources.map((resource) => resource.dispose?.()));
        }
    }
}
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