Home | History | Annotate | Download | only in ipc 
      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/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_.get()) {
     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       static_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().get() != listener_loop_.get());
     50     DCHECK(MessageLoopProxy::current().get() != io_loop_.get());
     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
    129