Introduce InterfaceEndpointClient(IEC), InterfaceEndpointHandle and

mojo/public/js/lib/interface_endpoint_client.js

+// Copyright 2017 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/js/lib/interface_endpoint_client", [
+  "console",
+  "mojo/public/js/codec",
+  "mojo/public/js/lib/control_message_handler",
+  "mojo/public/js/lib/control_message_proxy",
+  "mojo/public/js/lib/interface_endpoint_handle",
+  "mojo/public/js/validator",
+  "timer",
+], function(console, codec, controlMessageHandler, controlMessageProxy,

[yzshen1, 2017/03/24 21:20:12]

Style nit: For function definitions (as opposed to function calls), when
parameters cannot fit on one line, typically we put each on a separate line.

function(param1,
         param2,
         ...) {
}

(here and elsewhere in this patch.)

[wangjimmy, 2017/03/27 16:51:28]

Done.

+  interfaceEndpointHandle, validator, timer) {
+
+  var ControlMessageHandler = controlMessageHandler.ControlMessageHandler;
+  var ControlMessageProxy = controlMessageProxy.ControlMessageProxy;
+  var MessageReader = codec.MessageReader;
+  var Validator = validator.Validator;
+  var InterfaceEndpointHandle = interfaceEndpointHandle.InterfaceEndpointHandle;
+
+  function InterfaceEndpointClient(interfaceEndpointHandle, receiver,
+      interfaceVersion) {
+    this.controller_ = null;
+    this.encounteredError_ = false;
+    this.handle_ = interfaceEndpointHandle;
+    this.incomingReceiver_ = receiver;
+
+    if (interfaceEndpointHandle.pendingAssociation()) {

[yzshen1, 2017/03/24 21:20:13]

Please move this block to the end, after declaration of all member variables.

[wangjimmy, 2017/03/27 16:51:27]

Done.

+      interfaceEndpointHandle.setAssociationEventHandler(
+          this.onAssociationEvent.bind(this));
+    } else {
+      this.initControllerIfNecessary();
+    }
+
+    if (interfaceVersion !== undefined) {
+      this.controlMessageHandler_ = new ControlMessageHandler(
+          interfaceVersion);
+    } else {
+      this.controlMessageProxy_ = new ControlMessageProxy(this);
+    }
+
+    this.nextRequestID_ = 0;
+    this.completers_ = new Map();
+    this.payloadValidators_ = [];
+    this.connectionErrorHandler_ = undefined;

[yzshen1, 2017/03/24 21:20:13]

I noticed that some fields are inited as "undefined" but some are "null". Why is
the difference?

I usually use "null". They are defined just not yet refer to a valid object.

[wangjimmy, 2017/03/27 16:51:28]

Done. I was trying to use undefined for callbacks. But using null for everything
would be more consistent, thanks!

+  }
+
+  InterfaceEndpointClient.prototype.initControllerIfNecessary = function() {

[yzshen1, 2017/03/24 21:20:12]

private functions should end with trailing underscore.

[wangjimmy, 2017/03/27 16:51:27]

Done.

+    if (this.controller_ || this.handle_.pendingAssociation()) {
+      return;
+    }
+
+    this.controller_ = this.handle_.groupController().attachEndpointClient(
+        this.handle_, this);
+  };
+
+  InterfaceEndpointClient.prototype.onAssociationEvent = function(
+      associationEvent) {
+    if (associationEvent ===
+      InterfaceEndpointHandle.AssociationEvent.ASSOCIATED) {

[yzshen1, 2017/03/24 21:20:12]

Indent should be 4 spaces.

[wangjimmy, 2017/03/27 16:51:28]

Done.

+      this.initControllerIfNecessary();
+    } else if (associationEvent ===
+      InterfaceEndpointHandle.AssociationEvent.PEER_CLOSED_BEFORE_ASSOCIATION) {

[yzshen1, 2017/03/24 21:20:12]

ditto

[wangjimmy, 2017/03/27 16:51:27]

Done.

+      timer.createOneShot(0, this.notifyError.bind(this,
+          this.handle_.disconnectReason()));
+    }
+  };
+
+  InterfaceEndpointClient.prototype.passHandle = function() {
+    if (!this.handle_.isValid()) {
+      return new InterfaceEndpointHandle();
+    }
+
+    // Used to clear the previously set callback.
+    this.handle_.setAssociationEventHandler(undefined);
+
+    if (this.controller_) {
+      this.controller_ = null;
+      this.handle_.groupController().detachEndpointClient(this.handle_);
+    }
+    var handle = this.handle_;
+    this.handle_ = null;
+    return handle;
+  };
+
+  InterfaceEndpointClient.prototype.closeWithReason = function(reason) {
+    var handle = this.passHandle();
+    handle.reset(reason);
+  };
+
+  InterfaceEndpointClient.prototype.accept = function(message) {
+    if (this.encounteredError_) {
+      return false;
+    }
+
+    this.initControllerIfNecessary();
+    return this.controller_.sendMessage(message);
+  };
+
+  InterfaceEndpointClient.prototype.acceptAndExpectResponse = function(message)
+  {

[yzshen1, 2017/03/24 21:20:12]

{ should be on the same line as the parameter list.

[wangjimmy, 2017/03/27 16:51:27]

Done.

+    if (this.encounteredError_) {
+      return Promise.reject();
+    }
+
+    this.initControllerIfNecessary();
+
+    // Reserve 0 in case we want it to convey special meaning in the future.
+    var requestID = this.nextRequestID_++;
+    if (requestID === 0)
+      requestID = this.nextRequestID_++;
+
+    message.setRequestID(requestID);
+    var result = this.controller_.sendMessage(message);
+    if (!result)
+      return Promise.reject(Error("Connection error"));
+
+    var completer = {};
+    this.completers_.set(requestID, completer);
+    return new Promise(function(resolve, reject) {
+      completer.resolve = resolve;
+      completer.reject = reject;
+    });
+  };
+
+  InterfaceEndpointClient.prototype.reject = function(message) {

[yzshen1, 2017/03/24 21:20:13]

How is this used?

[wangjimmy, 2017/03/27 16:51:27]

This method is never used.
Looking at the git blame, this TODO was added as part of
https://chromium.googlesource.com/chromium/src/+/5243bce526df42358983d4068647...

I don't see a way to transmit errors over a Connection in connector.cc or
multiplex_router.cc either so I think it's safe to remove this.

+    // TODO(mpcomplete): no way to trasmit errors over a Connection.
+  };
+
+  InterfaceEndpointClient.prototype.setPayloadValidators = function(
+    payloadValidators) {

[yzshen1, 2017/03/24 21:20:12]

4-space indent.

[wangjimmy, 2017/03/27 16:51:27]

Done.

+    this.payloadValidators_ = payloadValidators;
+  };
+
+  InterfaceEndpointClient.prototype.setIncomingReceiver = function(receiver) {
+    this.incomingReceiver_ = receiver;
+  };
+
+  InterfaceEndpointClient.prototype.setConnectionErrorHandler =
+    function(handler) {

[yzshen1, 2017/03/24 21:20:12]

ditto

[wangjimmy, 2017/03/27 16:51:27]

Done.

+    this.connectionErrorHandler_ = handler;
+  };
+
+  InterfaceEndpointClient.prototype.handleIncomingMessage_ = function(message)
+  {

[yzshen1, 2017/03/24 21:20:12]

{ should be on the same line as parameter list.

[wangjimmy, 2017/03/27 16:51:27]

Done.

+    var noError = validator.validationError.NONE;
+    var messageValidator = new Validator(message);
+    var err = noError;
+    for (var i = 0; err === noError && i < this.payloadValidators_.length; ++i)
+      err = this.payloadValidators_[i](messageValidator);
+
+    if (err == noError) {
+      return this.handleValidIncomingMessage_(message);
+    }
+    else {

[yzshen1, 2017/03/24 21:20:12]

This should be on the same line as the previous "}".

[wangjimmy, 2017/03/27 16:51:27]

Done.

+      validator.reportValidationError(err);
+      return false;
+    }
+  };
+
+  InterfaceEndpointClient.prototype.handleValidIncomingMessage_ = function(
+      message) {
+    if (validator.isTestingMode()) {
+      return true;
+    }
+
+    if (this.encounteredError_) {
+      return false;
+    }
+
+    var ok = false;
+
+    if (message.expectsResponse()) {
+      if (controlMessageHandler.isControlMessage(message) &&
+          this.controlMessageHandler_) {
+        ok = this.controlMessageHandler_.acceptWithResponder(message, this);
+      } else if (this.incomingReceiver_) {
+        ok = this.incomingReceiver_.acceptWithResponder(message, this);
+      }
+    } else if (message.isResponse()) {
+      var reader = new MessageReader(message);
+      var requestID = reader.requestID;
+      var completer = this.completers_.get(requestID);
+      if (completer) {
+        this.completers_.delete(requestID);
+        completer.resolve(message);
+        ok = true;
+      } else {
+        console.log("Unexpected response with request ID: " + requestID);
+      }
+    } else {
+      if (controlMessageHandler.isControlMessage(message) &&
+        this.controlMessageHandler_) {

[yzshen1, 2017/03/24 21:20:13]

wrong indent.

[wangjimmy, 2017/03/27 16:51:27]

Done.

+        ok = this.controlMessageHandler_.accept(message);
+      } else if (this.incomingReceiver_) {
+        ok = this.incomingReceiver_.accept(message);
+      }
+    }
+    return ok;
+  };
+
+  InterfaceEndpointClient.prototype.notifyError = function(reason) {
+    if (this.encounteredError_) {
+      return;
+    }
+    this.encounteredError_ = true;
+
+    this.completers_.forEach(function(value) {
+      value.reject();
+    });
+    this.completers_.clear();  // Drop any responders.
+
+    if (this.connectionErrorHandler_) {
+      this.connectionErrorHandler_(reason);
+    }
+  };
+
+  InterfaceEndpointClient.prototype.queryVersion = function() {
+    return this.controlMessageProxy_.queryVersion();
+  };
+
+  InterfaceEndpointClient.prototype.requireVersion = function(version) {
+    this.controlMessageProxy_.requireVersion(version);
+  };
+
+  var exports = {};
+  exports.InterfaceEndpointClient = InterfaceEndpointClient;
+
+  return exports;
+});