Mojo: add javascript bindings for request/response

mojo/public/bindings/js/connector.js

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 define("mojo/public/bindings/js/connector", [
   "mojo/public/bindings/js/codec",
   "mojo/bindings/js/core",
   "mojo/bindings/js/support",
 ], function(codec, core, support) {
 
   function Connector(handle) {
     this.handle_ = handle;
+    this.dropWrites_ = false;
     this.error_ = false;
     this.incomingReceiver_ = null;
     this.readWaitCookie_ = null;
+
+    this.waitToReadMore_();
   }
 
   Connector.prototype.close = function() {
     if (this.readWaitCookie_) {
       support.cancelWait(this.readWaitCookie_);
       this.readWaitCookie_ = null;
     }
     if (this.handle_ != core.kInvalidHandle) {
       core.close(this.handle_);
       this.handle_ = core.kInvalidHandle;
     }
   };
 
   Connector.prototype.accept = function(message) {
     if (this.error_)
       return false;
-    this.write_(message);
-    return !this.error_;
+
+    if (this.dropWrites_)
+      return true;
+
+    var result = core.writeMessage(this.handle_,
+                                   message.memory,
+                                   message.handles,
+                                   core.WRITE_MESSAGE_FLAG_NONE);
+
+    switch (result) {
+      case core.RESULT_OK:
+        // The handles were successfully transferred, so we don't own them
+        // anymore.
+        message.handles = [];
+        break;
+      case core.RESULT_FAILED_PRECONDITION:
+        // There's no point in continuing to write to this pipe since the other
+        // end is gone. Avoid writing any future messages. Hide write failures
+        // from the caller since we'd like them to continue consuming any
+        // backlog of incoming messages before regarding the message pipe as
+        // closed.
+        dropWrites_ = true;

[abarth-chromium, 2014/03/26 18:26:32]

Sorry for being unclear.  You need to write "this." if you want to store this
value in a field of this object.  As written, this line of code should throw an
exception in the unit test environment because we run in strict mode.  Are we
missing test coverage for this line?

+        break;
+      default:
+        // This particular write was rejected, presumably because of bad input.
+        // The pipe is not necessarily in a bad state.
+        return false;
+    }
+    return true;
   };
 
   Connector.prototype.setIncomingReceiver = function(receiver) {
     this.incomingReceiver_ = receiver;
-    if (this.incomingReceiver_)
-      this.waitToReadMore_();
-  };
-
-  Connector.prototype.write_ = function(message) {
-    var result = core.writeMessage(this.handle_,
-                                   message.memory,
-                                   message.handles,
-                                   core.WRITE_MESSAGE_FLAG_NONE);
-    if (result != core.RESULT_OK) {
-      this.error_ = true
-      return;
-    }
-    // The handles were successfully transferred, so we don't own them anymore.
-    message.handles = [];
   };
 
   Connector.prototype.waitToReadMore_ = function() {
     this.readWaitCookie_ = support.asyncWait(this.handle_,
                                              core.WAIT_FLAG_READABLE,
                                              this.readMore_.bind(this));
   };
 
   Connector.prototype.readMore_ = function(result) {
     for (;;) {
       var read = core.readMessage(this.handle_,
                                   core.READ_MESSAGE_FLAG_NONE);
       if (read.result == core.RESULT_SHOULD_WAIT) {
         this.waitToReadMore_();
         return;
       }
       if (read.result != core.RESULT_OK) {
         this.error_ = true;
         return;
       }
       // TODO(abarth): Should core.readMessage return a Uint8Array?
       var memory = new Uint8Array(read.buffer);
       var message = new codec.Message(memory, read.handles);
-      this.incomingReceiver_.accept(message);
+      if (this.incomingReceiver_)
+        this.incomingReceiver_.accept(message);
     }
   };
 
-  function Connection(handle, localFactory, remoteFactory) {
-    this.connector_ = new Connector(handle);
-    this.remote = new remoteFactory(this.connector_);
-    this.local = new localFactory(this.remote);
-    this.connector_.setIncomingReceiver(this.local);
-  }
-
-  Connection.prototype.close = function() {
-    this.connector_.close();
-    this.connector_ = null;
-    this.local = null;
-    this.remote = null;
-  };
-
   var exports = {};
-  exports.Connection = Connection;
+  exports.Connector = Connector;
   return exports;
 });