forked from jestjs/jest
/
ChildProcessWorker.ts
190 lines (161 loc) Β· 5.39 KB
/
ChildProcessWorker.ts
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/**
* Copyright (c) Facebook, Inc. and its affiliates. All Rights Reserved.
*
* This source code is licensed under the MIT license found in the
* LICENSE file in the root directory of this source tree.
*/
import childProcess, {ChildProcess} from 'child_process';
import supportsColor from 'supports-color';
import {
CHILD_MESSAGE_INITIALIZE,
PARENT_MESSAGE_CLIENT_ERROR,
PARENT_MESSAGE_SETUP_ERROR,
PARENT_MESSAGE_OK,
WorkerInterface,
ChildMessage,
OnEnd,
OnStart,
WorkerOptions,
ParentMessage,
} from '../types';
/**
* This class wraps the child process and provides a nice interface to
* communicate with. It takes care of:
*
* - Re-spawning the process if it dies.
* - Queues calls while the worker is busy.
* - Re-sends the requests if the worker blew up.
*
* The reason for queueing them here (since childProcess.send also has an
* internal queue) is because the worker could be doing asynchronous work, and
* this would lead to the child process to read its receiving buffer and start a
* second call. By queueing calls here, we don't send the next call to the
* children until we receive the result of the previous one.
*
* As soon as a request starts to be processed by a worker, its "processed"
* field is changed to "true", so that other workers which might encounter the
* same call skip it.
*/
export default class ChildProcessWorker implements WorkerInterface {
private _child!: ChildProcess;
private _options: WorkerOptions;
private _onProcessEnd!: OnEnd;
private _request: ChildMessage | null;
private _retries!: number;
constructor(options: WorkerOptions) {
this._options = options;
this._request = null;
this.initialize();
}
initialize() {
const forceColor = supportsColor.stdout ? {FORCE_COLOR: '1'} : {};
const child = childProcess.fork(require.resolve('./processChild'), [], {
cwd: process.cwd(),
env: {
...process.env,
JEST_WORKER_ID: String(this._options.workerId),
...forceColor,
} as NodeJS.ProcessEnv,
// Suppress --debug / --inspect flags while preserving others (like --harmony).
execArgv: process.execArgv.filter(v => !/^--(debug|inspect)/.test(v)),
silent: true,
...this._options.forkOptions,
});
child.on('message', this.onMessage.bind(this));
child.on('exit', this.onExit.bind(this));
child.send([
CHILD_MESSAGE_INITIALIZE,
false,
this._options.workerPath,
this._options.setupArgs,
]);
this._child = child;
this._retries++;
// If we exceeded the amount of retries, we will emulate an error reply
// coming from the child. This avoids code duplication related with cleaning
// the queue, and scheduling the next call.
if (this._retries > this._options.maxRetries) {
const error = new Error('Call retries were exceeded');
this.onMessage([
PARENT_MESSAGE_CLIENT_ERROR,
error.name,
error.message,
error.stack!,
{type: 'WorkerError'},
]);
}
}
onMessage(response: ParentMessage) {
let error;
switch (response[0]) {
case PARENT_MESSAGE_OK:
this._onProcessEnd(null, response[1]);
break;
case PARENT_MESSAGE_CLIENT_ERROR:
error = response[4];
if (error != null && typeof error === 'object') {
const extra = error;
// @ts-ignore: no index
const NativeCtor = global[response[1]];
const Ctor = typeof NativeCtor === 'function' ? NativeCtor : Error;
error = new Ctor(response[2]);
error.type = response[1];
error.stack = response[3];
for (const key in extra) {
// @ts-ignore: adding custom properties to errors.
error[key] = extra[key];
}
}
this._onProcessEnd(error, null);
break;
case PARENT_MESSAGE_SETUP_ERROR:
error = new Error('Error when calling setup: ' + response[2]);
// @ts-ignore: adding custom properties to errors.
error.type = response[1];
error.stack = response[3];
this._onProcessEnd(error, null);
break;
default:
throw new TypeError('Unexpected response from worker: ' + response[0]);
}
}
onExit(exitCode: number) {
if (exitCode !== 0) {
this.initialize();
if (this._request) {
this._child.send(this._request);
}
}
}
send(request: ChildMessage, onProcessStart: OnStart, onProcessEnd: OnEnd) {
onProcessStart(this);
this._onProcessEnd = (...args) => {
// Clean the request to avoid sending past requests to workers that fail
// while waiting for a new request (timers, unhandled rejections...)
this._request = null;
return onProcessEnd(...args);
};
this._request = request;
this._retries = 0;
this._child.send(request);
}
getWorkerId(): number {
return this._options.workerId;
}
getStdout(): NodeJS.ReadableStream {
if (this._child.stdout === null) {
throw new Error(
'stdout is null - this should never happen. Please open up an issue at https://github.com/facebook/jest',
);
}
return this._child.stdout;
}
getStderr(): NodeJS.ReadableStream {
if (this._child.stderr === null) {
throw new Error(
'stderr is null - this should never happen. Please open up an issue at https://github.com/facebook/jest',
);
}
return this._child.stderr;
}
}