Mojo C++ bindings: fix Connector teardown.

mojo/public/cpp/bindings/lib/connector.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/public/cpp/bindings/connector.h"
 
 #include <stdint.h>
 #include <utility>
 
 #include "base/bind.h"
 #include "base/location.h"
 #include "base/logging.h"
 #include "base/macros.h"
 #include "base/synchronization/lock.h"
 #include "mojo/public/cpp/bindings/lib/may_auto_lock.h"
 #include "mojo/public/cpp/bindings/sync_handle_watcher.h"
 
 namespace mojo {
 
 Connector::Connector(ScopedMessagePipeHandle message_pipe,
                      ConnectorConfig config,
                      scoped_refptr<base::SingleThreadTaskRunner> runner)
     : message_pipe_(std::move(message_pipe)),
       task_runner_(std::move(runner)),
-      handle_watcher_(task_runner_),
       lock_(config == MULTI_THREADED_SEND ? new base::Lock : nullptr),
       weak_factory_(this) {
   weak_self_ = weak_factory_.GetWeakPtr();
   // Even though we don't have an incoming receiver, we still want to monitor
   // the message pipe to know if is closed or encounters an error.
   WaitToReadMore();
 }
 
 Connector::~Connector() {
   {
     // Allow for quick destruction on any thread if the pipe is already closed.
     base::AutoLock lock(connected_lock_);
     if (!connected_)
       return;
   }
 
   DCHECK(thread_checker_.CalledOnValidThread());
   CancelWait();
 }
 
 void Connector::CloseMessagePipe() {
-  DCHECK(thread_checker_.CalledOnValidThread());
-
-  CancelWait();
-  internal::MayAutoLock locker(lock_.get());
-  message_pipe_.reset();
-
-  base::AutoLock lock(connected_lock_);
-  connected_ = false;
+  // Throw away the returned message pipe.
+  PassMessagePipe();
 }
 
 ScopedMessagePipeHandle Connector::PassMessagePipe() {
   DCHECK(thread_checker_.CalledOnValidThread());
 
   CancelWait();
   internal::MayAutoLock locker(lock_.get());
   ScopedMessagePipeHandle message_pipe = std::move(message_pipe_);
+  weak_factory_.InvalidateWeakPtrs();
+  sync_handle_watcher_callback_count_ = 0;
 
   base::AutoLock lock(connected_lock_);
   connected_ = false;
   return message_pipe;
 }
 
 void Connector::RaiseError() {
   DCHECK(thread_checker_.CalledOnValidThread());
 
   HandleError(true, true);
@@ skipping 114 matching lines @@
 void Connector::OnWatcherHandleReady(MojoResult result) {
   OnHandleReadyInternal(result);
 }
 
 void Connector::OnSyncHandleWatcherHandleReady(MojoResult result) {
   base::WeakPtr<Connector> weak_self(weak_self_);
 
   sync_handle_watcher_callback_count_++;
   OnHandleReadyInternal(result);
   // At this point, this object might have been deleted.
-  if (weak_self)
+  if (weak_self) {
+    DCHECK_LT(0u, sync_handle_watcher_callback_count_);
     sync_handle_watcher_callback_count_--;
+  }
 }
 
 void Connector::OnHandleReadyInternal(MojoResult result) {
   DCHECK(thread_checker_.CalledOnValidThread());
 
   if (result != MOJO_RESULT_OK) {
     HandleError(result != MOJO_RESULT_FAILED_PRECONDITION, false);
     return;
   }
   ReadAllAvailableMessages();
   // At this point, this object might have been deleted. Return.
 }
 
 void Connector::WaitToReadMore() {
   CHECK(!paused_);
-  DCHECK(!handle_watcher_.IsWatching());
+  DCHECK(!handle_watcher_);
 
-  MojoResult rv = handle_watcher_.Start(
+  handle_watcher_.reset(new Watcher(task_runner_));
+  MojoResult rv = handle_watcher_->Start(
       message_pipe_.get(), MOJO_HANDLE_SIGNAL_READABLE,
-      base::Bind(&Connector::OnWatcherHandleReady,
-                 base::Unretained(this)));
+      base::Bind(&Connector::OnWatcherHandleReady, base::Unretained(this)));
 
   if (rv != MOJO_RESULT_OK) {
     // If the watch failed because the handle is invalid or its conditions can
     // no longer be met, we signal the error asynchronously to avoid reentry.
     task_runner_->PostTask(
         FROM_HERE,
         base::Bind(&Connector::OnWatcherHandleReady, weak_self_, rv));
   }
 
   if (allow_woken_up_by_others_) {
     EnsureSyncWatcherExists();
     sync_watcher_->AllowWokenUpBySyncWatchOnSameThread();
   }
 }
 
 bool Connector::ReadSingleMessage(MojoResult* read_result) {
   CHECK(!paused_);
 
   bool receiver_result = false;
 
-  // Detect if |this| was destroyed during message dispatch. Allow for the
-  // possibility of re-entering ReadMore() through message dispatch.
+  // Detect if |this| was destroyed or the message pipe was closed/transferred
+  // during message dispatch.
   base::WeakPtr<Connector> weak_self = weak_self_;
 
   Message message;
   const MojoResult rv = ReadMessage(message_pipe_.get(), &message);
   *read_result = rv;
 
   if (rv == MOJO_RESULT_OK) {
     receiver_result =
         incoming_receiver_ && incoming_receiver_->Accept(&message);
   }
@@ skipping 13 matching lines @@
     HandleError(true, false);
     return false;
   }
   return true;
 }
 
 void Connector::ReadAllAvailableMessages() {
   while (!error_) {
     MojoResult rv;
 
-    // Return immediately if |this| was destroyed. Do not touch any members!
-    if (!ReadSingleMessage(&rv))
+    if (!ReadSingleMessage(&rv)) {
+      // Return immediately without touching any members. |this| may have been
+      // destroyed.
       return;
+    }
 
     if (paused_)
       return;
 
     if (rv == MOJO_RESULT_SHOULD_WAIT)
       break;
   }
 }
 
 void Connector::CancelWait() {
-  handle_watcher_.Cancel();
+  handle_watcher_.reset();
   sync_watcher_.reset();
 }
 
 void Connector::HandleError(bool force_pipe_reset, bool force_async_handler) {
   if (error_ || !message_pipe_.is_valid())
     return;
 
   if (paused_) {
     // Enforce calling the error handler asynchronously if the user has paused
     // receiving messages. We need to wait until the user starts receiving
@@ skipping 27 matching lines @@
 void Connector::EnsureSyncWatcherExists() {
   if (sync_watcher_)
     return;
   sync_watcher_.reset(new SyncHandleWatcher(
       message_pipe_.get(), MOJO_HANDLE_SIGNAL_READABLE,
       base::Bind(&Connector::OnSyncHandleWatcherHandleReady,
                  base::Unretained(this))));
 }
 
 }  // namespace mojo