[mojo-edk] Add MojoWatch and MojoCancelWatch APIs

mojo/edk/system/node_controller.cc

 // Copyright 2016 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.
 
 #include "mojo/edk/system/node_controller.h"
 
 #include <algorithm>
 #include <limits>
 
 #include "base/bind.h"
 #include "base/location.h"
 #include "base/logging.h"
 #include "base/macros.h"
 #include "base/message_loop/message_loop.h"
 #include "base/metrics/histogram_macros.h"
 #include "base/process/process_handle.h"
 #include "crypto/random.h"
 #include "mojo/edk/embedder/embedder_internal.h"
 #include "mojo/edk/embedder/platform_channel_pair.h"
 #include "mojo/edk/system/broker.h"
 #include "mojo/edk/system/broker_host.h"
 #include "mojo/edk/system/core.h"
 #include "mojo/edk/system/ports_message.h"
+#include "mojo/edk/system/request_context.h"
 
 namespace mojo {
 namespace edk {
 
 namespace {
 
 template <typename T>
 void GenerateRandomName(T* out) { crypto::RandBytes(out, sizeof(T)); }
 
 ports::NodeName GetRandomNodeName() {
@@ skipping 675 matching lines @@
     }
   }
 #endif
 
   DVLOG(1) << "Child " << name_ << " accepted by broker " << broker_name;
 }
 
 void NodeController::OnPortsMessage(Channel::MessagePtr channel_message) {
   DCHECK(io_task_runner_->RunsTasksOnCurrentThread());
 
+  // This is a singular chokepoint through which dispatcher port statuses may
+  // be changed without an explicit call to some Mojo system API. We need to
+  // ensure that a RequestContext exists in case a dispatcher has any watchers
+  // to notify.
+  RequestContext request_context;
+
   void* data;
   size_t num_data_bytes;
   NodeChannel::GetPortsMessageData(
       channel_message.get(), &data, &num_data_bytes);
 
   size_t num_header_bytes, num_payload_bytes, num_ports_bytes;
   ports::Message::Parse(data,
                         num_data_bytes,
                         &num_header_bytes,
                         &num_payload_bytes,
@@ skipping 149 matching lines @@
     shutdown_callback_.Reset();
   }
 
   DCHECK(!callback.is_null());
 
   callback.Run();
 }
 
 }  // namespace edk
 }  // namespace mojo