Send progress events via multipart response

Summary:
Context: I'm trying to add support for sending packager progress events to the client that is downloading the bundle over HTTP multipart response.

The idea is for the client to send `Accept: multipart/mixed` header, and if present the server will stream progress events to the client. This will ensure the change is backwards-compatible - the clients who don't know about progress events won't receive them.

In the future we can use this approach to download RAM bundle modules in one request.

Reviewed By: davidaurelio

Differential Revision: D3926984

fbshipit-source-id: 39a6e38e40a79f7a2f2cf40765a0655fb13b7918

packager/react-packager/src/Server/MultipartResponse.js

@@ -0,0 +1,84 @@
+/**
+ * Copyright (c) 2015-present, Facebook, Inc.
+ * All rights reserved.
+ *
+ * This source code is licensed under the BSD-style license found in the
+ * LICENSE file in the root directory of this source tree. An additional grant
+ * of patent rights can be found in the PATENTS file in the same directory.
+ */
+'use strict';
+
+const CRLF = '\r\n';
+const BOUNDARY = '3beqjf3apnqeu3h5jqorms4i';
+
+class MultipartResponse {
+  static wrap(req, res) {
+    if (acceptsMultipartResponse(req)) {
+      return new MultipartResponse(res);
+    }
+    // Ugly hack, ideally wrap function should always return a proxy
+    // object with the same interface
+    res.writeChunk = () => {}; // noop
+    return res;
+  }
+
+  constructor(res) {
+    this.res = res;
+    this.headers = {};
+
+    res.writeHead(200, {
+      'Content-Type': `multipart/mixed; boundary="${BOUNDARY}"`,
+    });
+    res.write('If you are seeing this, your client does not support multipart response');
+  }
+
+  writeChunk(headers, data, isLast = false) {
+    let chunk = `${CRLF}--${BOUNDARY}${CRLF}`;
+    if (headers) {
+      chunk += MultipartResponse.serializeHeaders(headers) + CRLF + CRLF;
+    }
+
+    if (data) {
+      chunk += data;
+    }
+
+    if (isLast) {
+      chunk += `${CRLF}--${BOUNDARY}--${CRLF}`;
+    }
+
+    this.res.write(chunk);
+  }
+
+  writeHead(status, headers) {
+    // We can't actually change the response HTTP status code
+    // because the headers have already been sent
+    this.setHeader('X-Http-Status', status);
+    if (!headers) {
+      return;
+    }
+    for (let key in headers) {
+      this.setHeader(key, headers[key]);
+    }
+  }
+
+  setHeader(name, value) {
+    this.headers[name] = value;
+  }
+
+  end(data) {
+    this.writeChunk(this.headers, data, true);
+    this.res.end();
+  }
+
+  static serializeHeaders(headers) {
+    return Object.keys(headers)
+      .map((key) => `${key}: ${headers[key]}`)
+      .join(CRLF);
+  }
+}
+
+function acceptsMultipartResponse(req) {
+  return req.headers && req.headers['accept'] === 'multipart/mixed';
+}
+
+module.exports = MultipartResponse;

packager/react-packager/src/Server/__tests__/MultipartResponse-test.js

@@ -0,0 +1,150 @@
+/**
+ * Copyright (c) 2015-present, Facebook, Inc.
+ * All rights reserved.
+ *
+ * This source code is licensed under the BSD-style license found in the
+ * LICENSE file in the root directory of this source tree. An additional grant
+ * of patent rights can be found in the PATENTS file in the same directory.
+ */
+'use strict';
+
+jest.dontMock('../MultipartResponse');
+
+const MultipartResponse = require('../MultipartResponse');
+
+describe('MultipartResponse', () => {
+  it('forwards calls to response', () => {
+    const nreq = mockNodeRequest({accept: 'text/html'});
+    const nres = mockNodeResponse();
+    const res = MultipartResponse.wrap(nreq, nres);
+
+    expect(res).toBe(nres);
+
+    res.writeChunk({}, 'foo');
+    expect(nres.write).not.toBeCalled();
+  });
+
+  it('writes multipart response', () => {
+    const nreq = mockNodeRequest({accept: 'multipart/mixed'});
+    const nres = mockNodeResponse();
+    const res = MultipartResponse.wrap(nreq, nres);
+
+    expect(res).not.toBe(nres);
+
+    res.setHeader('Result-Header-1', 1);
+    res.writeChunk({foo: 'bar'}, 'first chunk');
+    res.writeChunk({test: 2}, 'second chunk');
+    res.writeChunk(null, 'empty headers third chunk');
+    res.setHeader('Result-Header-2', 2);
+    res.end('Hello, world!');
+
+    expect(nres.toString()).toEqual([
+      'HTTP/1.1 200',
+      'Content-Type: multipart/mixed; boundary="3beqjf3apnqeu3h5jqorms4i"',
+      '',
+      'If you are seeing this, your client does not support multipart response',
+      '--3beqjf3apnqeu3h5jqorms4i',
+      'foo: bar',
+      '',
+      'first chunk',
+      '--3beqjf3apnqeu3h5jqorms4i',
+      'test: 2',
+      '',
+      'second chunk',
+      '--3beqjf3apnqeu3h5jqorms4i',
+      'empty headers third chunk',
+      '--3beqjf3apnqeu3h5jqorms4i',
+      'Result-Header-1: 1',
+      'Result-Header-2: 2',
+      '',
+      'Hello, world!',
+      '--3beqjf3apnqeu3h5jqorms4i--',
+      '',
+    ].join('\r\n'));
+  });
+
+  it('sends status code as last chunk header', () => {
+    const nreq = mockNodeRequest({accept: 'multipart/mixed'});
+    const nres = mockNodeResponse();
+    const res = MultipartResponse.wrap(nreq, nres);
+
+    res.writeChunk({foo: 'bar'}, 'first chunk');
+    res.writeHead(500, {
+      'Content-Type': 'application/json; boundary="3beqjf3apnqeu3h5jqorms4i"',
+    });
+    res.end('{}');
+
+    expect(nres.toString()).toEqual([
+      'HTTP/1.1 200',
+      'Content-Type: multipart/mixed; boundary="3beqjf3apnqeu3h5jqorms4i"',
+      '',
+      'If you are seeing this, your client does not support multipart response',
+      '--3beqjf3apnqeu3h5jqorms4i',
+      'foo: bar',
+      '',
+      'first chunk',
+      '--3beqjf3apnqeu3h5jqorms4i',
+      'X-Http-Status: 500',
+      'Content-Type: application/json; boundary="3beqjf3apnqeu3h5jqorms4i"',
+      '',
+      '{}',
+      '--3beqjf3apnqeu3h5jqorms4i--',
+      '',
+    ].join('\r\n'));
+  });
+
+  it('supports empty responses', () => {
+    const nreq = mockNodeRequest({accept: 'multipart/mixed'});
+    const nres = mockNodeResponse();
+    const res = MultipartResponse.wrap(nreq, nres);
+
+    res.writeHead(304, {
+      'Content-Type': 'application/json; boundary="3beqjf3apnqeu3h5jqorms4i"',
+    });
+    res.end();
+
+    expect(nres.toString()).toEqual([
+      'HTTP/1.1 200',
+      'Content-Type: multipart/mixed; boundary="3beqjf3apnqeu3h5jqorms4i"',
+      '',
+      'If you are seeing this, your client does not support multipart response',
+      '--3beqjf3apnqeu3h5jqorms4i',
+      'X-Http-Status: 304',
+      'Content-Type: application/json; boundary="3beqjf3apnqeu3h5jqorms4i"',
+      '',
+      '',
+      '--3beqjf3apnqeu3h5jqorms4i--',
+      '',
+    ].join('\r\n'));
+  });
+});
+
+function mockNodeRequest(headers = {}) {
+  return {headers};
+}
+
+function mockNodeResponse() {
+  let status = 200;
+  let headers = {};
+  let body = '';
+  return {
+    writeHead: jest.fn((st, hdrs) => {
+      status = st;
+      headers = {...headers, ...hdrs};
+    }),
+    setHeader: jest.fn((key, val) => { headers[key] = val; }),
+    write: jest.fn((data) => { body += data; }),
+    end: jest.fn((data) => { body += (data || ''); }),
+
+    // For testing only
+    toString() {
+      return [
+        `HTTP/1.1 ${status}`,
+        MultipartResponse.serializeHeaders(headers),
+        '',
+        body,
+      ].join('\r\n');
+    }
+  };
+}
+

packager/react-packager/src/Server/__tests__/Server-test.js

@@ -47,9 +47,11 @@ describe('processRequest', () => {
     reqHandler(
       { url: requrl, headers:{}, ...reqOptions },
       {
+        statusCode: 200,
         headers: {},
         getHeader(header) { return this.headers[header]; },
         setHeader(header, value) { this.headers[header] = value; },
+        writeHead(statusCode) { this.statusCode = statusCode; },
         end(body) {
           this.body = body;
           resolve(this);
@@ -157,6 +159,7 @@ describe('processRequest', () => {
         sourceMapUrl: 'index.ios.includeRequire.map',
         dev: true,
         platform: undefined,
+        onProgress: jasmine.any(Function),
         runBeforeMainModule: ['InitializeJavaScriptAppEngine'],
         unbundle: false,
         entryModuleOnly: false,
@@ -181,6 +184,7 @@ describe('processRequest', () => {
         sourceMapUrl: 'index.map?platform=ios',
         dev: true,
         platform: 'ios',
+        onProgress: jasmine.any(Function),
         runBeforeMainModule: ['InitializeJavaScriptAppEngine'],
         unbundle: false,
         entryModuleOnly: false,
@@ -205,6 +209,7 @@ describe('processRequest', () => {
         sourceMapUrl: 'index.map?assetPlugin=assetPlugin1&assetPlugin=assetPlugin2',
         dev: true,
         platform: undefined,
+        onProgress: jasmine.any(Function),
         runBeforeMainModule: ['InitializeJavaScriptAppEngine'],
         unbundle: false,
         entryModuleOnly: false,

packager/react-packager/src/Server/index.js

@@ -13,6 +13,7 @@ const AssetServer = require('../AssetServer');
 const FileWatcher = require('../node-haste').FileWatcher;
 const getPlatformExtension = require('../node-haste').getPlatformExtension;
 const Bundler = require('../Bundler');
+const MultipartResponse = require('./MultipartResponse');
 const ProgressBar = require('progress');
 const Promise = require('promise');
 const SourceMapConsumer = require('source-map').SourceMapConsumer;
@@ -657,6 +658,7 @@ class Server {
       },
     );
 
+    let consoleProgress = () => {};
     if (process.stdout.isTTY && !this._opts.silent) {
       const bar = new ProgressBar('transformed :current/:total (:percent)', {
         complete: '=',
@@ -664,8 +666,15 @@ class Server {
         width: 40,
         total: 1,
       });
-      options.onProgress = debouncedTick(bar);
+      consoleProgress = debouncedTick(bar);
     }
+
+    const mres = MultipartResponse.wrap(req, res);
+    options.onProgress = (done, total) => {
+      consoleProgress(done, total);
+      mres.writeChunk({'Content-Type': 'application/json'}, JSON.stringify({done, total}));
+    };
+
     debug('Getting bundle for request');
     const building = this._useCachedOrUpdateOrCreateBundle(options);
     building.then(
@@ -678,15 +687,16 @@ class Server {
             dev: options.dev,
           });
           debug('Writing response headers');
-          res.setHeader('Content-Type', 'application/javascript');
-          res.setHeader('ETag', p.getEtag());
-          if (req.headers['if-none-match'] === res.getHeader('ETag')){
+          const etag = p.getEtag();
+          mres.setHeader('Content-Type', 'application/javascript');
+          mres.setHeader('ETag', etag);
+
+          if (req.headers['if-none-match'] === etag) {
             debug('Responding with 304');
-            res.statusCode = 304;
-            res.end();
+            mres.writeHead(304);
+            mres.end();
           } else {
-            debug('Writing request body');
-            res.end(bundleSource);
+            mres.end(bundleSource);
           }
           debug('Finished response');
           Activity.endEvent(startReqEventId);
@@ -700,17 +710,17 @@ class Server {
             sourceMap = JSON.stringify(sourceMap);
           }
 
-          res.setHeader('Content-Type', 'application/json');
-          res.end(sourceMap);
+          mres.setHeader('Content-Type', 'application/json');
+          mres.end(sourceMap);
           Activity.endEvent(startReqEventId);
         } else if (requestType === 'assets') {
           const assetsList = JSON.stringify(p.getAssets());
-          res.setHeader('Content-Type', 'application/json');
-          res.end(assetsList);
+          mres.setHeader('Content-Type', 'application/json');
+          mres.end(assetsList);
           Activity.endEvent(startReqEventId);
         }
       },
-      error => this._handleError(res, this.optionsHash(options), error)
+      error => this._handleError(mres, this.optionsHash(options), error)
     ).catch(error => {
       process.nextTick(() => {
         throw error;