packager: worker-farm: isolate stdout/stderr

Reviewed By: davidaurelio

Differential Revision: D5011034

fbshipit-source-id: 81d3d49156775f9781427d3c103d768ccc30fe20

packages/metro-bundler/src/Bundler/index.js

@@ -194,8 +194,15 @@ class Bundler {
 
     const maxWorkerCount = Bundler.getMaxWorkerCount();
 
-    /* $FlowFixMe: in practice it's always here. */
+    this._transformer = new Transformer(
-    this._transformer = new Transformer(opts.transformModulePath, maxWorkerCount);
+      /* $FlowFixMe: in practice it's always here. */
+      opts.transformModulePath,
+      maxWorkerCount,
+      {
+        stdoutChunk: chunk => opts.reporter.update({type: 'worker_stdout_chunk', chunk}),
+        stderrChunk: chunk => opts.reporter.update({type: 'worker_stderr_chunk', chunk}),
+      }
+    );
 
     const getTransformCacheKey = (options) => {
       return transformCacheKey + getCacheKey(options);

packages/metro-bundler/src/JSTransformer/__tests__/Transformer-test.js

@@ -9,6 +9,7 @@
 'use strict';
 
 jest
+  .unmock('stream')
   .unmock('imurmurhash')
   .unmock('../../lib/ModuleTransport')
   .unmock('../');
@@ -24,6 +25,7 @@ jest.setMock('../../worker-farm', workerFarm);
 var Transformer = require('../');
 
 const {any} = jasmine;
+const {Readable} = require('stream');
 
 describe('Transformer', function() {
   let workers, Cache;
@@ -39,7 +41,7 @@ describe('Transformer', function() {
     workerFarm.mockImplementation((opts, path, methods) => {
       const api = workers = {};
       methods.forEach(method => {api[method] = jest.fn();});
-      return api;
+      return {methods: api, stdout: new Readable({read() {}}), stderr: new Readable({read() {}})};
     });
   });
 

packages/metro-bundler/src/JSTransformer/index.js

@@ -50,6 +50,11 @@ function makeFarm(worker, methods, timeout, maxConcurrentWorkers) {
   );
 }
 
+type Reporters = {
+  +stdoutChunk: (chunk: string) => mixed,
+  +stderrChunk: (chunk: string) => mixed,
+};
+
 class Transformer {
 
   _workers: {[name: string]: Function};
@@ -66,16 +71,24 @@ class Transformer {
     sourceMap: MappingsMap,
   ) => Promise<{code: string, map: MappingsMap}>;
 
-  constructor(transformModulePath: string, maxWorkerCount: number) {
+  constructor(transformModulePath: string, maxWorkerCount: number, reporters: Reporters) {
     invariant(path.isAbsolute(transformModulePath), 'transform module path should be absolute');
     this._transformModulePath = transformModulePath;
 
-    this._workers = makeFarm(
+    const farm = makeFarm(
       require.resolve('./worker'),
       ['minify', 'transformAndExtractDependencies'],
       TRANSFORM_TIMEOUT_INTERVAL,
       maxWorkerCount,
     );
+    farm.stdout.on('data', chunk => {
+      reporters.stdoutChunk(chunk.toString('utf8'));
+    });
+    farm.stderr.on('data', chunk => {
+      reporters.stderrChunk(chunk.toString('utf8'));
+    });
+
+    this._workers = farm.methods;
     this._transform = denodeify(this._workers.transformAndExtractDependencies);
     this.minify = denodeify(this._workers.minify);
   }

packages/metro-bundler/src/lib/TerminalReporter.js

@@ -135,7 +135,6 @@ class TerminalReporter {
     }
   }
 
-
   _logPackagerInitializing(port: number, projectRoots: Array<string>) {
     terminal.log(
       formatBanner(
@@ -183,7 +182,6 @@ class TerminalReporter {
     }
   }
 
-
   /**
    * This function is only concerned with logging and should not do state
    * or terminal status updates.
@@ -214,9 +212,25 @@ class TerminalReporter {
       case 'transform_cache_reset':
         reporting.logWarning(terminal, 'the transform cache was reset.');
         break;
+      case 'worker_stdout_chunk':
+        this._logWorkerChunk('stdout', event.chunk);
+        break;
+      case 'worker_stderr_chunk':
+        this._logWorkerChunk('stderr', event.chunk);
+        break;
     }
   }
 
+  _logWorkerChunk(origin: 'stdout' | 'stderr', chunk: string) {
+    const lines = chunk.split('\n');
+    if (lines.length >= 1 && lines[lines.length - 1] === '') {
+      lines.splice(lines.length - 1, 1);
+    }
+    lines.forEach(line => {
+      terminal.log(`transform[${origin}]: ${line}`);
+    });
+  }
+
   /**
    * We use Math.pow(ratio, 2) to as a conservative measure of progress because
    * we know the `totalCount` is going to progressively increase as well. We

packages/metro-bundler/src/lib/reporting.js

@@ -59,6 +59,12 @@ export type ReportableEvent = {
   reason: GlobalCacheDisabledReason,
 } | {
   type: 'transform_cache_reset',
+} | {
+  type: 'worker_stdout_chunk',
+  chunk: string,
+} | {
+  type: 'worker_stderr_chunk',
+  chunk: string,
 };
 
 /**

packages/metro-bundler/src/worker-farm/lib/farm.js

@@ -27,10 +27,14 @@ const extend                  = require('xtend')
     , ProcessTerminatedError  = require('errno').create('ProcessTerminatedError')
     , MaxConcurrentCallsError = require('errno').create('MaxConcurrentCallsError')
 
+const mergeStream = require('merge-stream');
+
 function Farm (options: {+execArgv: Array<string>}, path: string) {
   this.options     = extend(DEFAULT_OPTIONS, options)
   this.path        = path
   this.activeCalls = 0
+  this.stdout = mergeStream();
+  this.stderr = mergeStream();
 }
 
 // make a handle to pass back in the form of an external API
@@ -118,6 +122,9 @@ Farm.prototype.startChild = function () {
         , exitCode    : null
       }
 
+  this.stdout.add(forked.child.stdout);
+  this.stderr.add(forked.child.stderr);
+
   forked.child.on('message', this.receive.bind(this))
   forked.child.once('exit', function (code) {
     c.exitCode = code

packages/metro-bundler/src/worker-farm/lib/fork.js

@@ -16,9 +16,10 @@ const childModule = require.resolve('./child/index');
 
 function fork(forkModule: string, options: {|+execArgv: Array<string>|}) {
   const child = childProcess.fork(childModule, {
-    env: process.env,
     cwd: process.cwd(),
+    env: process.env,
     execArgv: options.execArgv,
+    silent: true,
   });
 
   child.send({module: forkModule});

packages/metro-bundler/src/worker-farm/lib/index.js

@@ -12,20 +12,31 @@
 /* eslint-disable */
 const Farm = require('./farm')
 
+import type {Readable} from 'stream';
+
 var farms = [] // keep record of farms so we can end() them if required
 
+export type FarmAPI = {|
+  methods: {[name: string]: Function},
+  stdout: Readable,
+  stderr: Readable,
+|};
+
 function farm(
   options: {+execArgv: Array<string>},
   path: string,
   methods: Array<string>,
-): {[name: string]: Function} {
+): FarmAPI {
   var f   = new Farm(options, path)
     , api = f.setup(methods)
 
   farms.push({ farm: f, api: api })
 
+  // $FlowFixMe: gotta type the Farm class.
+  const {stdout, stderr} = f;
+
   // return the public API
-  return (api: any)
+  return {methods: (api: any), stdout, stderr};
 }
 
 function end (api, callback) {