concurrently/dist/lib/flow-control/restart-process.js

Run commands concurrently

import Rx from 'rxjs';
import { defaultIfEmpty, delayWhen, filter, map, skip, take, takeWhile } from 'rxjs/operators';
import * as defaults from '../defaults.js';
/**
 * Restarts commands that fail up to a defined number of times.
 */
export class RestartProcess {
    logger;
    scheduler;
    delay;
    tries;
    constructor({ delay, tries, logger, scheduler, }) {
        this.logger = logger;
        this.delay = delay ?? 0;
        this.tries = tries != null ? +tries : defaults.restartTries;
        this.tries = this.tries < 0 ? Infinity : this.tries;
        this.scheduler = scheduler;
    }
    handle(commands) {
        if (this.tries === 0) {
            return { commands };
        }
        const delayOperator = delayWhen((_, index) => {
            const { delay } = this;
            const value = delay === 'exponential' ? 2 ** index * 1000 : delay;
            return Rx.timer(value, this.scheduler);
        });
        commands
            .map((command) => command.close.pipe(take(this.tries), takeWhile(({ exitCode }) => exitCode !== 0)))
            .forEach((failure, index) => Rx.merge(
        // Delay the emission (so that the restarts happen on time),
        // explicitly telling the subscriber that a restart is needed
        failure.pipe(delayOperator, map(() => true)), 
        // Skip the first N emissions (as these would be duplicates of the above),
        // meaning it will be empty because of success, or failed all N times,
        // and no more restarts should be attempted.
        failure.pipe(skip(this.tries), map(() => false), defaultIfEmpty(false))).subscribe((restart) => {
            const command = commands[index];
            if (restart) {
                this.logger.logCommandEvent(`${command.command} restarted`, command);
                command.start();
            }
        }));
        return {
            commands: commands.map((command) => {
                const closeStream = command.close.pipe(filter(({ exitCode }, emission) => {
                    // We let all success codes pass, and failures only after restarting won't happen again
                    return exitCode === 0 || emission >= this.tries;
                }));
                // Return a proxy so that mutations happen on the original Command object.
                // If either `Object.assign()` or `Object.create()` were used, it'd be hard to
                // reflect the mutations on Command objects referenced by previous flow controllers.
                return new Proxy(command, {
                    get(target, prop) {
                        return prop === 'close' ? closeStream : target[prop];
                    },
                });
            }),
        };
    }
}