[react-packager] onchange endpoint that informs of changes

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

@@ -45,6 +45,7 @@ describe('processRequest', function() {
   var invalidatorFunc = jest.genMockFunction();
   var watcherFunc = jest.genMockFunction();
   var requestHandler;
+  var triggerFileChange;
 
   beforeEach(function() {
     Packager = require('../../Packager');
@@ -61,7 +62,15 @@ describe('processRequest', function() {
       });
     };
 
-    FileWatcher.prototype.on = watcherFunc;
+
+    FileWatcher.prototype.on = function(eventType, callback) {
+      if (eventType !== 'all') {
+        throw new Error('Can only handle "all" event in watcher.');
+      }
+      watcherFunc.apply(this, arguments);
+      triggerFileChange = callback;
+      return this;
+    };
 
     Packager.prototype.invalidateFile = invalidatorFunc;
 
@@ -109,17 +118,6 @@ describe('processRequest', function() {
 
 
   describe('file changes', function() {
-    var triggerFileChange;
-    beforeEach(function() {
-      FileWatcher.prototype.on = function(eventType, callback) {
-        if (eventType !== 'all') {
-          throw new Error('Can only handle "all" event in watcher.');
-        }
-        triggerFileChange = callback;
-        return this;
-      };
-    });
-
     pit('invalides files in package when file is updated', function() {
       return makeRequest(
         requestHandler,
@@ -175,4 +173,36 @@ describe('processRequest', function() {
         });
     });
   });
+
+  describe('/onchange endpoint', function() {
+    var EventEmitter;
+    var req;
+    var res;
+
+    beforeEach(function() {
+      EventEmitter = require.requireActual('events').EventEmitter;
+      req = new EventEmitter();
+      req.url = '/onchange';
+      res = {
+        writeHead: jest.genMockFn(),
+        end: jest.genMockFn()
+      };
+    });
+
+    it('should hold on to request and inform on change', function() {
+      server.processRequest(req, res);
+      triggerFileChange('all', 'path/file.js', options.projectRoots[0]);
+      jest.runAllTimers();
+      expect(res.end).toBeCalledWith(JSON.stringify({changed: true}));
+    });
+
+    it('should not inform changes on disconnected clients', function() {
+      server.processRequest(req, res);
+      req.emit('close');
+      jest.runAllTimers();
+      triggerFileChange('all', 'path/file.js', options.projectRoots[0]);
+      jest.runAllTimers();
+      expect(res.end).not.toBeCalled();
+    });
+  });
 });

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

@@ -50,6 +50,7 @@ function Server(options) {
   this._projectRoots = opts.projectRoots;
   this._packages = Object.create(null);
   this._packager = new Packager(opts);
+  this._changeWatchers = [];
 
   this._fileWatcher = options.nonPersistent
     ? FileWatcher.createDummyWatcher()
@@ -65,6 +66,7 @@ Server.prototype._onFileChange = function(type, filepath, root) {
   // Make sure the file watcher event runs through the system before
   // we rebuild the packages.
   setImmediate(this._rebuildPackages.bind(this, absPath));
+  setImmediate(this._informChangeWatchers.bind(this));
 };
 
 Server.prototype._rebuildPackages = function() {
@@ -83,6 +85,20 @@ Server.prototype._rebuildPackages = function() {
   });
 };
 
+Server.prototype._informChangeWatchers = function() {
+  var watchers = this._changeWatchers;
+  var headers = {
+    'Content-Type': 'application/json; charset=UTF-8',
+  };
+
+  watchers.forEach(function(w) {
+    w.res.writeHead(205, headers);
+    w.res.end(JSON.stringify({ changed: true }));
+  });
+
+  this._changeWatchers = [];
+};
+
 Server.prototype.end = function() {
   q.all([
     this._fileWatcher.end(),
@@ -142,6 +158,24 @@ Server.prototype._processDebugRequest = function(reqUrl, res) {
   }
 };
 
+Server.prototype._processOnChangeRequest = function(req, res) {
+  var watchers = this._changeWatchers;
+
+  watchers.push({
+    req: req,
+    res: res,
+  });
+
+  req.on('close', function() {
+    for (var i = 0; i < watchers.length; i++) {
+      if (watchers[i] && watchers[i].req === req) {
+        watchers.splice(i, 1);
+        break;
+      }
+    }
+  });
+};
+
 Server.prototype.processRequest = function(req, res, next) {
   var urlObj = url.parse(req.url, true);
   var pathname = urlObj.pathname;
@@ -154,6 +188,9 @@ Server.prototype.processRequest = function(req, res, next) {
   } else if (pathname.match(/^\/debug/)) {
     this._processDebugRequest(req.url, res);
     return;
+  } else if (pathname.match(/^\/onchange\/?$/)) {
+    this._processOnChangeRequest(req, res);
+    return;
   } else {
     next();
     return;