gecko-dev/ipc/glue/SyncChannel.h

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/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*-
* vim: sw=4 ts=4 et :
*/
/* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
#ifndef ipc_glue_SyncChannel_h
#define ipc_glue_SyncChannel_h 1
#include "mozilla/ipc/AsyncChannel.h"
namespace mozilla {
namespace ipc {
//-----------------------------------------------------------------------------
class SyncChannel : public AsyncChannel
{
protected:
typedef IPC::Message::msgid_t msgid_t;
public:
static const int32_t kNoTimeout;
class /*NS_INTERFACE_CLASS*/ SyncListener :
public AsyncChannel::AsyncListener
{
public:
virtual ~SyncListener() { }
virtual void OnChannelClose() = 0;
virtual void OnChannelError() = 0;
virtual Result OnMessageReceived(const Message& aMessage) = 0;
virtual void OnProcessingError(Result aError) = 0;
virtual int32_t GetProtocolTypeId() = 0;
virtual bool OnReplyTimeout() = 0;
virtual Result OnMessageReceived(const Message& aMessage,
Message*& aReply) = 0;
virtual void OnChannelConnected(int32_t peer_pid) {}
};
SyncChannel(SyncListener* aListener);
virtual ~SyncChannel();
virtual bool Send(Message* msg) MOZ_OVERRIDE {
return AsyncChannel::Send(msg);
}
// Synchronously send |msg| (i.e., wait for |reply|)
virtual bool Send(Message* msg, Message* reply);
// Set channel timeout value. Since this is broken up into
// two period, the minimum timeout value is 2ms.
void SetReplyTimeoutMs(int32_t aTimeoutMs) {
AssertWorkerThread();
mTimeoutMs = (aTimeoutMs <= 0) ? kNoTimeout :
// timeouts are broken up into two periods
(int32_t)ceil((double)aTimeoutMs/2.0);
}
static bool IsPumpingMessages() {
return sIsPumpingMessages;
}
static void SetIsPumpingMessages(bool aIsPumping) {
sIsPumpingMessages = aIsPumping;
}
#ifdef OS_WIN
public:
struct MOZ_STACK_CLASS SyncStackFrame
{
SyncStackFrame(SyncChannel* channel, bool rpc);
~SyncStackFrame();
bool mRPC;
bool mSpinNestedEvents;
bool mListenerNotified;
SyncChannel* mChannel;
/* the previous stack frame for this channel */
SyncStackFrame* mPrev;
/* the previous stack frame on any channel */
SyncStackFrame* mStaticPrev;
};
friend struct SyncChannel::SyncStackFrame;
static bool IsSpinLoopActive() {
for (SyncStackFrame* frame = sStaticTopFrame;
frame;
frame = frame->mPrev) {
if (frame->mSpinNestedEvents)
return true;
}
return false;
}
protected:
/* the deepest sync stack frame for this channel */
SyncStackFrame* mTopFrame;
/* the deepest sync stack frame on any channel */
static SyncStackFrame* sStaticTopFrame;
#endif // OS_WIN
protected:
// Executed on the link thread
// Override the AsyncChannel handler so we can dispatch sync messages
virtual void OnMessageReceivedFromLink(const Message& msg) MOZ_OVERRIDE;
virtual void OnChannelErrorFromLink() MOZ_OVERRIDE;
// Executed on the worker thread
bool ProcessingSyncMessage() const {
return mProcessingSyncMessage;
}
void OnDispatchMessage(const Message& aMsg);
//
// Return true if the wait ended because a notification was
// received. That is, true => event received.
//
// Return false if the time elapsed from when we started the
// process of waiting until afterwards exceeded the currently
// allotted timeout. That *DOES NOT* mean false => "no event" (==
// timeout); there are many circumstances that could cause the
// measured elapsed time to exceed the timeout EVEN WHEN we were
// notified.
//
// So in sum: true is a meaningful return value; false isn't,
// necessarily.
//
bool WaitForNotify();
bool ShouldContinueFromTimeout();
// Executed on the IO thread.
void NotifyWorkerThread();
// On both
bool AwaitingSyncReply() const {
mMonitor->AssertCurrentThreadOwns();
return mPendingReply != 0;
}
Message TakeReply() {
Message reply = mRecvd;
mRecvd = Message();
return reply;
}
int32_t NextSeqno() {
AssertWorkerThread();
return mChild ? --mNextSeqno : ++mNextSeqno;
}
msgid_t mPendingReply;
bool mProcessingSyncMessage;
Message mRecvd;
// This is only accessed from the worker thread; seqno's are
// completely opaque to the IO thread.
int32_t mNextSeqno;
static bool sIsPumpingMessages;
// Timeout periods are broken up in two to prevent system suspension from
// triggering an abort. This method (called by WaitForNotify with a 'did
// timeout' flag) decides if we should wait again for half of mTimeoutMs
// or give up.
bool WaitResponse(bool aWaitTimedOut);
bool mInTimeoutSecondHalf;
int32_t mTimeoutMs;
std::deque<Message> mUrgent;
#ifdef OS_WIN
HANDLE mEvent;
#endif
private:
bool EventOccurred();
bool ProcessUrgentMessages();
};
} // namespace ipc
} // namespace mozilla
#endif // ifndef ipc_glue_SyncChannel_h