Mojo: Make some attempts towards fixing remote message pipe closure.

mojo/system/proxy_message_pipe_endpoint.cc

 // Copyright 2013 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/system/proxy_message_pipe_endpoint.h"
 
 #include <string.h>
 
 #include "base/logging.h"
 #include "mojo/system/channel.h"
 #include "mojo/system/local_message_pipe_endpoint.h"
 #include "mojo/system/message_pipe_dispatcher.h"
 
 namespace mojo {
 namespace system {
 
 ProxyMessagePipeEndpoint::ProxyMessagePipeEndpoint()
     : local_id_(MessageInTransit::kInvalidEndpointId),
       remote_id_(MessageInTransit::kInvalidEndpointId),
-      is_open_(true),
       is_peer_open_(true) {
 }
 
 ProxyMessagePipeEndpoint::ProxyMessagePipeEndpoint(
     LocalMessagePipeEndpoint* local_message_pipe_endpoint,
     bool is_peer_open)
     : local_id_(MessageInTransit::kInvalidEndpointId),
       remote_id_(MessageInTransit::kInvalidEndpointId),
-      is_open_(true),
       is_peer_open_(is_peer_open),
       paused_message_queue_(MessageInTransitQueue::PassContents(),
                             local_message_pipe_endpoint->message_queue()) {
   local_message_pipe_endpoint->Close();
 }
 
 ProxyMessagePipeEndpoint::~ProxyMessagePipeEndpoint() {
   DCHECK(!is_running());
   DCHECK(!is_attached());
   AssertConsistentState();
   DCHECK(paused_message_queue_.IsEmpty());
 }
 
 MessagePipeEndpoint::Type ProxyMessagePipeEndpoint::GetType() const {
   return kTypeProxy;
 }
 
-void ProxyMessagePipeEndpoint::Close() {
-  DCHECK(is_open_);
-  is_open_ = false;
-
-  DCHECK(is_attached());
-  channel_->DetachMessagePipeEndpoint(local_id_);
-  channel_ = NULL;
-  local_id_ = MessageInTransit::kInvalidEndpointId;
-  remote_id_ = MessageInTransit::kInvalidEndpointId;
-  paused_message_queue_.Clear();
-}
-
-void ProxyMessagePipeEndpoint::OnPeerClose() {
-  DCHECK(is_open_);
+bool ProxyMessagePipeEndpoint::OnPeerClose() {
   DCHECK(is_peer_open_);
 
   is_peer_open_ = false;
-  EnqueueMessage(make_scoped_ptr(
-      new MessageInTransit(MessageInTransit::kTypeMessagePipe,
-                           MessageInTransit::kSubtypeMessagePipePeerClosed,
-                           0, 0, NULL)));
+
+  // If our outgoing message queue isn't empty, we shouldn't be destroyed yet.
+  if (!paused_message_queue_.IsEmpty())
+    return true;
+
+  if (is_attached()) {
+    if (!is_running()) {
+      // If we're not running yet, we can't be destroyed yet, because we're
+      // still waiting for the "run" message from the other side.
+      return true;
+    }
+
+    Detach();
+  }
+
+  return false;
 }
 
 // Note: We may have to enqueue messages even when our (local) peer isn't open
 // -- it may have been written to and closed immediately, before we were ready.
 // This case is handled in |Run()| (which will call us).
 void ProxyMessagePipeEndpoint::EnqueueMessage(
     scoped_ptr<MessageInTransit> message) {
-  DCHECK(is_open_);
-
   if (is_running()) {
     message->SerializeAndCloseDispatchers(channel_.get());
 
     message->set_source_id(local_id_);
     message->set_destination_id(remote_id_);
     if (!channel_->WriteMessage(message.Pass()))
       LOG(WARNING) << "Failed to write message to channel";
   } else {
     paused_message_queue_.AddMessage(message.Pass());
   }
 }
 
 void ProxyMessagePipeEndpoint::Attach(scoped_refptr<Channel> channel,
                                       MessageInTransit::EndpointId local_id) {
   DCHECK(channel.get());
   DCHECK_NE(local_id, MessageInTransit::kInvalidEndpointId);
 
   DCHECK(!is_attached());
 
   AssertConsistentState();
   channel_ = channel;
   local_id_ = local_id;
   AssertConsistentState();
 }
 
-void ProxyMessagePipeEndpoint::Run(MessageInTransit::EndpointId remote_id) {
+bool ProxyMessagePipeEndpoint::Run(MessageInTransit::EndpointId remote_id) {
   // Assertions about arguments:
   DCHECK_NE(remote_id, MessageInTransit::kInvalidEndpointId);
 
   // Assertions about current state:
   DCHECK(is_attached());
   DCHECK(!is_running());
 
   AssertConsistentState();
   remote_id_ = remote_id;
   AssertConsistentState();
 
   while (!paused_message_queue_.IsEmpty())
     EnqueueMessage(paused_message_queue_.GetMessage());
+
+  if (is_peer_open_)
+    return true;  // Stay alive.
+
+  // We were just waiting to die.
+  Detach();
+  return false;
+}
+
+void ProxyMessagePipeEndpoint::OnRemove() {
+  Detach();
+}
+
+void ProxyMessagePipeEndpoint::Detach() {
+  DCHECK(is_attached());
+
+  AssertConsistentState();
+  channel_->DetachMessagePipeEndpoint(local_id_, remote_id_);
+  channel_ = NULL;
+  local_id_ = MessageInTransit::kInvalidEndpointId;
+  remote_id_ = MessageInTransit::kInvalidEndpointId;
+  paused_message_queue_.Clear();
+  AssertConsistentState();
 }
 
 #ifndef NDEBUG
 void ProxyMessagePipeEndpoint::AssertConsistentState() const {
   if (is_attached()) {
     DCHECK_NE(local_id_, MessageInTransit::kInvalidEndpointId);
   } else {  // Not attached.
     DCHECK_EQ(local_id_, MessageInTransit::kInvalidEndpointId);
     DCHECK_EQ(remote_id_, MessageInTransit::kInvalidEndpointId);
   }
 }
 #endif
 
 }  // namespace system
 }  // namespace mojo