ipc/ipc_sync_message_filter.cc

   1 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 #include "ipc/ipc_sync_message_filter.h"
   6
   7 #include "base/bind.h"
   8 #include "base/location.h"
   9 #include "base/logging.h"
  10 #include "base/message_loop_proxy.h"
  11 #include "base/synchronization/waitable_event.h"
  12 #include "ipc/ipc_sync_message.h"
  13
  14 using base::MessageLoopProxy;
  15
  16 namespace IPC {
  17
  18 SyncMessageFilter::SyncMessageFilter(base::WaitableEvent* shutdown_event)
  19     : channel_(NULL),
  20       listener_loop_(MessageLoopProxy::current()),
  21       shutdown_event_(shutdown_event) {
  22 }
  23
  24 bool SyncMessageFilter::Send(Message* message) {
  25   {
  26     base::AutoLock auto_lock(lock_);
  27     if (!io_loop_) {
  28       delete message;
  29       return false;
  30     }
  31   }
  32
  33   if (!message->is_sync()) {
  34     io_loop_->PostTask(
  35       FROM_HERE, base::Bind(&SyncMessageFilter::SendOnIOThread, this, message));
  36     return true;
  37   }
  38
  39   base::WaitableEvent done_event(true, false);
  40   PendingSyncMsg pending_message(
  41       SyncMessage::GetMessageId(*message),
  42       reinterpret_cast<SyncMessage*>(message)->GetReplyDeserializer(),
  43       &done_event);
  44
  45   {
  46     base::AutoLock auto_lock(lock_);
  47     // Can't use this class on the main thread or else it can lead to deadlocks.
  48     // Also by definition, can't use this on IO thread since we're blocking it.
  49     DCHECK(MessageLoopProxy::current() != listener_loop_);
  50     DCHECK(MessageLoopProxy::current() != io_loop_);
  51     pending_sync_messages_.insert(&pending_message);
  52   }
  53
  54   io_loop_->PostTask(
  55       FROM_HERE, base::Bind(&SyncMessageFilter::SendOnIOThread, this, message));
  56
  57   base::WaitableEvent* events[2] = { shutdown_event_, &done_event };
  58   base::WaitableEvent::WaitMany(events, 2);
  59
  60   {
  61     base::AutoLock auto_lock(lock_);
  62     delete pending_message.deserializer;
  63     pending_sync_messages_.erase(&pending_message);
  64   }
  65
  66   return pending_message.send_result;
  67 }
  68
  69 void SyncMessageFilter::OnFilterAdded(Channel* channel) {
  70   channel_ = channel;
  71   base::AutoLock auto_lock(lock_);
  72   io_loop_ = MessageLoopProxy::current();
  73 }
  74
  75 void SyncMessageFilter::OnChannelError() {
  76   channel_ = NULL;
  77   SignalAllEvents();
  78 }
  79
  80 void SyncMessageFilter::OnChannelClosing() {
  81   channel_ = NULL;
  82   SignalAllEvents();
  83 }
  84
  85 bool SyncMessageFilter::OnMessageReceived(const Message& message) {
  86   base::AutoLock auto_lock(lock_);
  87   for (PendingSyncMessages::iterator iter = pending_sync_messages_.begin();
  88        iter != pending_sync_messages_.end(); ++iter) {
  89     if (SyncMessage::IsMessageReplyTo(message, (*iter)->id)) {
  90       if (!message.is_reply_error()) {
  91         (*iter)->send_result =
  92             (*iter)->deserializer->SerializeOutputParameters(message);
  93       }
  94       (*iter)->done_event->Signal();
  95       return true;
  96     }
  97   }
  98
  99   return false;
 100 }
 101
 102 SyncMessageFilter::~SyncMessageFilter() {
 103 }
 104
 105 void SyncMessageFilter::SendOnIOThread(Message* message) {
 106   if (channel_) {
 107     channel_->Send(message);
 108     return;
 109   }
 110
 111   if (message->is_sync()) {
 112     // We don't know which thread sent it, but it doesn't matter, just signal
 113     // them all.
 114     SignalAllEvents();
 115   }
 116
 117   delete message;
 118 }
 119
 120 void SyncMessageFilter::SignalAllEvents() {
 121   base::AutoLock auto_lock(lock_);
 122   for (PendingSyncMessages::iterator iter = pending_sync_messages_.begin();
 123        iter != pending_sync_messages_.end(); ++iter) {
 124     (*iter)->done_event->Signal();
 125   }
 126 }
 127
 128 }  // namespace IPC