/
MessageChannel.cpp
1755 lines (1459 loc) · 51.6 KB
/
MessageChannel.cpp
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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/. */
#include "mozilla/ipc/MessageChannel.h"
#include "mozilla/ipc/ProtocolUtils.h"
#include "mozilla/Assertions.h"
#include "mozilla/DebugOnly.h"
#include "mozilla/Move.h"
#include "nsDebug.h"
#include "nsISupportsImpl.h"
// Undo the damage done by mozzconf.h
#undef compress
using namespace mozilla;
using namespace std;
using mozilla::MonitorAutoLock;
using mozilla::MonitorAutoUnlock;
template<>
struct RunnableMethodTraits<mozilla::ipc::MessageChannel>
{
static void RetainCallee(mozilla::ipc::MessageChannel* obj) { }
static void ReleaseCallee(mozilla::ipc::MessageChannel* obj) { }
};
#define IPC_ASSERT(_cond, ...) \
do { \
if (!(_cond)) \
DebugAbort(__FILE__, __LINE__, #_cond,## __VA_ARGS__); \
} while (0)
namespace mozilla {
namespace ipc {
const int32_t MessageChannel::kNoTimeout = INT32_MIN;
// static
bool MessageChannel::sIsPumpingMessages = false;
enum Direction
{
IN_MESSAGE,
OUT_MESSAGE
};
class MessageChannel::InterruptFrame
{
private:
enum Semantics
{
INTR_SEMS,
SYNC_SEMS,
ASYNC_SEMS
};
public:
InterruptFrame(Direction direction, const Message* msg)
: mMessageName(strdup(msg->name())),
mMessageRoutingId(msg->routing_id()),
mMesageSemantics(msg->is_interrupt() ? INTR_SEMS :
msg->is_sync() ? SYNC_SEMS :
ASYNC_SEMS),
mDirection(direction),
mMoved(false)
{
MOZ_ASSERT(mMessageName);
}
InterruptFrame(InterruptFrame&& aOther)
{
MOZ_ASSERT(aOther.mMessageName);
mMessageName = aOther.mMessageName;
aOther.mMessageName = nullptr;
aOther.mMoved = true;
mMessageRoutingId = aOther.mMessageRoutingId;
mMesageSemantics = aOther.mMesageSemantics;
mDirection = aOther.mDirection;
}
~InterruptFrame()
{
MOZ_ASSERT_IF(!mMessageName, mMoved);
if (mMessageName)
free(const_cast<char*>(mMessageName));
}
InterruptFrame& operator=(InterruptFrame&& aOther)
{
MOZ_ASSERT(&aOther != this);
this->~InterruptFrame();
new (this) InterruptFrame(mozilla::Move(aOther));
return *this;
}
bool IsInterruptIncall() const
{
return INTR_SEMS == mMesageSemantics && IN_MESSAGE == mDirection;
}
bool IsInterruptOutcall() const
{
return INTR_SEMS == mMesageSemantics && OUT_MESSAGE == mDirection;
}
void Describe(int32_t* id, const char** dir, const char** sems,
const char** name) const
{
*id = mMessageRoutingId;
*dir = (IN_MESSAGE == mDirection) ? "in" : "out";
*sems = (INTR_SEMS == mMesageSemantics) ? "intr" :
(SYNC_SEMS == mMesageSemantics) ? "sync" :
"async";
*name = mMessageName;
}
private:
const char* mMessageName;
int32_t mMessageRoutingId;
Semantics mMesageSemantics;
Direction mDirection;
DebugOnly<bool> mMoved;
// Disable harmful methods.
InterruptFrame(const InterruptFrame& aOther) MOZ_DELETE;
InterruptFrame& operator=(const InterruptFrame&) MOZ_DELETE;
};
class MOZ_STACK_CLASS MessageChannel::CxxStackFrame
{
public:
CxxStackFrame(MessageChannel& that, Direction direction, const Message* msg)
: mThat(that)
{
mThat.AssertWorkerThread();
if (mThat.mCxxStackFrames.empty())
mThat.EnteredCxxStack();
mThat.mCxxStackFrames.append(InterruptFrame(direction, msg));
const InterruptFrame& frame = mThat.mCxxStackFrames.back();
if (frame.IsInterruptIncall())
mThat.EnteredCall();
mThat.mSawInterruptOutMsg |= frame.IsInterruptOutcall();
}
~CxxStackFrame() {
mThat.AssertWorkerThread();
MOZ_ASSERT(!mThat.mCxxStackFrames.empty());
bool exitingCall = mThat.mCxxStackFrames.back().IsInterruptIncall();
mThat.mCxxStackFrames.shrinkBy(1);
bool exitingStack = mThat.mCxxStackFrames.empty();
// mListener could have gone away if Close() was called while
// MessageChannel code was still on the stack
if (!mThat.mListener)
return;
if (exitingCall)
mThat.ExitedCall();
if (exitingStack)
mThat.ExitedCxxStack();
}
private:
MessageChannel& mThat;
// Disable harmful methods.
CxxStackFrame() MOZ_DELETE;
CxxStackFrame(const CxxStackFrame&) MOZ_DELETE;
CxxStackFrame& operator=(const CxxStackFrame&) MOZ_DELETE;
};
MessageChannel::MessageChannel(MessageListener *aListener)
: mListener(aListener->asWeakPtr()),
mChannelState(ChannelClosed),
mSide(UnknownSide),
mLink(nullptr),
mWorkerLoop(nullptr),
mChannelErrorTask(nullptr),
mWorkerLoopID(-1),
mTimeoutMs(kNoTimeout),
mInTimeoutSecondHalf(false),
mNextSeqno(0),
mPendingSyncReplies(0),
mPendingUrgentReplies(0),
mPendingRPCReplies(0),
mCurrentRPCTransaction(0),
mDispatchingSyncMessage(false),
mDispatchingUrgentMessageCount(0),
mRemoteStackDepthGuess(false),
mSawInterruptOutMsg(false),
mAbortOnError(false)
{
MOZ_COUNT_CTOR(ipc::MessageChannel);
#ifdef OS_WIN
mTopFrame = nullptr;
mIsSyncWaitingOnNonMainThread = false;
#endif
mDequeueOneTask = new RefCountedTask(NewRunnableMethod(
this,
&MessageChannel::OnMaybeDequeueOne));
#ifdef OS_WIN
mEvent = CreateEventW(nullptr, TRUE, FALSE, nullptr);
NS_ASSERTION(mEvent, "CreateEvent failed! Nothing is going to work!");
#endif
}
MessageChannel::~MessageChannel()
{
MOZ_COUNT_DTOR(ipc::MessageChannel);
IPC_ASSERT(mCxxStackFrames.empty(), "mismatched CxxStackFrame ctor/dtors");
#ifdef OS_WIN
DebugOnly<BOOL> ok = CloseHandle(mEvent);
MOZ_ASSERT(ok);
#endif
Clear();
}
static void
PrintErrorMessage(Side side, const char* channelName, const char* msg)
{
const char *from = (side == ChildSide)
? "Child"
: ((side == ParentSide) ? "Parent" : "Unknown");
printf_stderr("\n###!!! [%s][%s] Error: %s\n\n", from, channelName, msg);
}
bool
MessageChannel::Connected() const
{
mMonitor->AssertCurrentThreadOwns();
// The transport layer allows us to send messages before
// receiving the "connected" ack from the remote side.
return (ChannelOpening == mChannelState || ChannelConnected == mChannelState);
}
bool
MessageChannel::CanSend() const
{
MonitorAutoLock lock(*mMonitor);
return Connected();
}
void
MessageChannel::Clear()
{
// Don't clear mWorkerLoopID; we use it in AssertLinkThread() and
// AssertWorkerThread().
//
// Also don't clear mListener. If we clear it, then sending a message
// through this channel after it's Clear()'ed can cause this process to
// crash.
//
// In practice, mListener owns the channel, so the channel gets deleted
// before mListener. But just to be safe, mListener is a weak pointer.
mDequeueOneTask->Cancel();
mWorkerLoop = nullptr;
delete mLink;
mLink = nullptr;
if (mChannelErrorTask) {
mChannelErrorTask->Cancel();
mChannelErrorTask = nullptr;
}
// Free up any memory used by pending messages.
mPending.clear();
mPendingUrgentRequest = nullptr;
mPendingRPCCall = nullptr;
mOutOfTurnReplies.clear();
while (!mDeferred.empty()) {
mDeferred.pop();
}
}
bool
MessageChannel::Open(Transport* aTransport, MessageLoop* aIOLoop, Side aSide)
{
NS_PRECONDITION(!mLink, "Open() called > once");
mMonitor = new RefCountedMonitor();
mWorkerLoop = MessageLoop::current();
mWorkerLoopID = mWorkerLoop->id();
ProcessLink *link = new ProcessLink(this);
link->Open(aTransport, aIOLoop, aSide); // :TODO: n.b.: sets mChild
mLink = link;
return true;
}
bool
MessageChannel::Open(MessageChannel *aTargetChan, MessageLoop *aTargetLoop, Side aSide)
{
// Opens a connection to another thread in the same process.
// This handshake proceeds as follows:
// - Let A be the thread initiating the process (either child or parent)
// and B be the other thread.
// - A spawns thread for B, obtaining B's message loop
// - A creates ProtocolChild and ProtocolParent instances.
// Let PA be the one appropriate to A and PB the side for B.
// - A invokes PA->Open(PB, ...):
// - set state to mChannelOpening
// - this will place a work item in B's worker loop (see next bullet)
// and then spins until PB->mChannelState becomes mChannelConnected
// - meanwhile, on PB's worker loop, the work item is removed and:
// - invokes PB->SlaveOpen(PA, ...):
// - sets its state and that of PA to Connected
NS_PRECONDITION(aTargetChan, "Need a target channel");
NS_PRECONDITION(ChannelClosed == mChannelState, "Not currently closed");
CommonThreadOpenInit(aTargetChan, aSide);
Side oppSide = UnknownSide;
switch(aSide) {
case ChildSide: oppSide = ParentSide; break;
case ParentSide: oppSide = ChildSide; break;
case UnknownSide: break;
}
mMonitor = new RefCountedMonitor();
MonitorAutoLock lock(*mMonitor);
mChannelState = ChannelOpening;
aTargetLoop->PostTask(
FROM_HERE,
NewRunnableMethod(aTargetChan, &MessageChannel::OnOpenAsSlave, this, oppSide));
while (ChannelOpening == mChannelState)
mMonitor->Wait();
NS_ASSERTION(ChannelConnected == mChannelState, "not connected when awoken");
return (ChannelConnected == mChannelState);
}
void
MessageChannel::OnOpenAsSlave(MessageChannel *aTargetChan, Side aSide)
{
// Invoked when the other side has begun the open.
NS_PRECONDITION(ChannelClosed == mChannelState,
"Not currently closed");
NS_PRECONDITION(ChannelOpening == aTargetChan->mChannelState,
"Target channel not in the process of opening");
CommonThreadOpenInit(aTargetChan, aSide);
mMonitor = aTargetChan->mMonitor;
MonitorAutoLock lock(*mMonitor);
NS_ASSERTION(ChannelOpening == aTargetChan->mChannelState,
"Target channel not in the process of opening");
mChannelState = ChannelConnected;
aTargetChan->mChannelState = ChannelConnected;
aTargetChan->mMonitor->Notify();
}
void
MessageChannel::CommonThreadOpenInit(MessageChannel *aTargetChan, Side aSide)
{
mWorkerLoop = MessageLoop::current();
mWorkerLoopID = mWorkerLoop->id();
mLink = new ThreadLink(this, aTargetChan);
mSide = aSide;
}
bool
MessageChannel::Echo(Message* aMsg)
{
nsAutoPtr<Message> msg(aMsg);
AssertWorkerThread();
mMonitor->AssertNotCurrentThreadOwns();
if (MSG_ROUTING_NONE == msg->routing_id()) {
ReportMessageRouteError("MessageChannel::Echo");
return false;
}
MonitorAutoLock lock(*mMonitor);
if (!Connected()) {
ReportConnectionError("MessageChannel");
return false;
}
mLink->EchoMessage(msg.forget());
return true;
}
bool
MessageChannel::Send(Message* aMsg)
{
CxxStackFrame frame(*this, OUT_MESSAGE, aMsg);
nsAutoPtr<Message> msg(aMsg);
AssertWorkerThread();
mMonitor->AssertNotCurrentThreadOwns();
if (MSG_ROUTING_NONE == msg->routing_id()) {
ReportMessageRouteError("MessageChannel::Send");
return false;
}
MonitorAutoLock lock(*mMonitor);
if (!Connected()) {
ReportConnectionError("MessageChannel");
return false;
}
mLink->SendMessage(msg.forget());
return true;
}
bool
MessageChannel::MaybeInterceptSpecialIOMessage(const Message& aMsg)
{
AssertLinkThread();
mMonitor->AssertCurrentThreadOwns();
if (MSG_ROUTING_NONE == aMsg.routing_id() &&
GOODBYE_MESSAGE_TYPE == aMsg.type())
{
// :TODO: Sort out Close() on this side racing with Close() on the
// other side
mChannelState = ChannelClosing;
if (LoggingEnabled()) {
printf("NOTE: %s process received `Goodbye', closing down\n",
(mSide == ChildSide) ? "child" : "parent");
}
return true;
}
return false;
}
void
MessageChannel::OnMessageReceivedFromLink(const Message& aMsg)
{
AssertLinkThread();
mMonitor->AssertCurrentThreadOwns();
if (MaybeInterceptSpecialIOMessage(aMsg))
return;
// Regardless of the Interrupt stack, if we're awaiting a sync or urgent reply,
// we know that it needs to be immediately handled to unblock us.
if ((AwaitingSyncReply() && aMsg.is_sync()) ||
(AwaitingUrgentReply() && aMsg.is_urgent()) ||
(AwaitingRPCReply() && aMsg.is_rpc()))
{
mRecvd = new Message(aMsg);
NotifyWorkerThread();
return;
}
// Urgent messages cannot be compressed.
MOZ_ASSERT(!aMsg.compress() || !aMsg.is_urgent());
bool compress = (aMsg.compress() && !mPending.empty() &&
mPending.back().type() == aMsg.type() &&
mPending.back().routing_id() == aMsg.routing_id());
if (compress) {
// This message type has compression enabled, and the back of the
// queue was the same message type and routed to the same destination.
// Replace it with the newer message.
MOZ_ASSERT(mPending.back().compress());
mPending.pop_back();
}
bool shouldWakeUp = AwaitingInterruptReply() ||
// Allow incoming RPCs to be processed inside an urgent message.
(AwaitingUrgentReply() && aMsg.is_rpc()) ||
// Always process urgent messages while blocked.
((AwaitingSyncReply() || AwaitingRPCReply()) && aMsg.is_urgent());
// There are four cases we're concerned about, relating to the state of the
// main thread:
//
// (1) We are waiting on a sync|rpc reply - main thread is blocked on the
// IPC monitor.
// - If the message is high priority, we wake up the main thread to
// deliver the message. Otherwise, we leave it in the mPending queue,
// posting a task to the main event loop, where it will be processed
// once the synchronous reply has been received.
//
// (2) We are waiting on an Interrupt reply - main thread is blocked on the
// IPC monitor.
// - Always notify and wake up the main thread.
//
// (3) We are not waiting on a reply.
// - We post a task to the main event loop.
//
// Note that, we may notify the main thread even though the monitor is not
// blocked. This is okay, since we always check for pending events before
// blocking again.
if (shouldWakeUp && (AwaitingUrgentReply() && aMsg.is_rpc())) {
// If we're receiving an RPC message while blocked on an urgent message,
// we must defer any messages that were not sent as part of the child
// answering the urgent message.
//
// We must also be sure that we will not accidentally defer any RPC
// message that was sent while answering an urgent message. Otherwise,
// we will deadlock.
//
// On the parent side, the current transaction can only transition from 0
// to an ID, either by us issuing an urgent request while not blocked, or
// by receiving an RPC request while not blocked. When we unblock, the
// current transaction is reset to 0.
//
// When the child side receives an urgent message, any RPC messages sent
// before issuing the urgent reply will carry the urgent message's
// transaction ID.
//
// Since AwaitingUrgentReply() implies we are blocked, it also implies
// that we are within a transaction that will not change until we are
// completely unblocked (i.e, the transaction has completed).
if (aMsg.transaction_id() != mCurrentRPCTransaction)
shouldWakeUp = false;
}
if (aMsg.is_urgent()) {
MOZ_ASSERT(!mPendingUrgentRequest);
mPendingUrgentRequest = new Message(aMsg);
} else if (aMsg.is_rpc() && shouldWakeUp) {
// Only use this slot if we need to wake up for an RPC call. Otherwise
// we treat it like a normal async or sync message.
MOZ_ASSERT(!mPendingRPCCall);
mPendingRPCCall = new Message(aMsg);
} else {
mPending.push_back(aMsg);
}
if (shouldWakeUp) {
// Always wake up Interrupt waiters, sync waiters for urgent messages,
// RPC waiters for urgent messages, and urgent waiters for RPCs in the
// same transaction.
NotifyWorkerThread();
} else {
// Worker thread is either not blocked on a reply, or this is an
// incoming Interrupt that raced with outgoing sync, and needs to be
// deferred to a later event-loop iteration.
if (!compress) {
// If we compressed away the previous message, we'll re-use
// its pending task.
mWorkerLoop->PostTask(FROM_HERE, new DequeueTask(mDequeueOneTask));
}
}
}
bool
MessageChannel::Send(Message* aMsg, Message* aReply)
{
// Sanity checks.
AssertWorkerThread();
mMonitor->AssertNotCurrentThreadOwns();
#ifdef OS_WIN
SyncStackFrame frame(this, false);
#endif
CxxStackFrame f(*this, OUT_MESSAGE, aMsg);
MonitorAutoLock lock(*mMonitor);
IPC_ASSERT(aMsg->is_sync(), "can only Send() sync messages here");
IPC_ASSERT(!DispatchingSyncMessage(), "violation of sync handler invariant");
IPC_ASSERT(!DispatchingUrgentMessage(), "sync messages forbidden while handling urgent message");
IPC_ASSERT(!AwaitingSyncReply(), "nested sync messages are not supported");
AutoEnterPendingReply replies(mPendingSyncReplies);
if (!SendAndWait(aMsg, aReply))
return false;
NS_ABORT_IF_FALSE(aReply->is_sync(), "reply is not sync");
return true;
}
bool
MessageChannel::UrgentCall(Message* aMsg, Message* aReply)
{
AssertWorkerThread();
mMonitor->AssertNotCurrentThreadOwns();
IPC_ASSERT(mSide == ParentSide, "cannot send urgent requests from child");
#ifdef OS_WIN
SyncStackFrame frame(this, false);
#endif
CxxStackFrame f(*this, OUT_MESSAGE, aMsg);
MonitorAutoLock lock(*mMonitor);
IPC_ASSERT(!AwaitingInterruptReply(), "urgent calls cannot be issued within Interrupt calls");
IPC_ASSERT(!AwaitingSyncReply(), "urgent calls cannot be issued within sync sends");
AutoEnterRPCTransaction transact(this);
aMsg->set_transaction_id(mCurrentRPCTransaction);
AutoEnterPendingReply replies(mPendingUrgentReplies);
if (!SendAndWait(aMsg, aReply))
return false;
NS_ABORT_IF_FALSE(aReply->is_urgent(), "reply is not urgent");
return true;
}
bool
MessageChannel::RPCCall(Message* aMsg, Message* aReply)
{
AssertWorkerThread();
mMonitor->AssertNotCurrentThreadOwns();
IPC_ASSERT(mSide == ChildSide, "cannot send rpc messages from parent");
#ifdef OS_WIN
SyncStackFrame frame(this, false);
#endif
CxxStackFrame f(*this, OUT_MESSAGE, aMsg);
MonitorAutoLock lock(*mMonitor);
AutoEnterRPCTransaction transact(this);
aMsg->set_transaction_id(mCurrentRPCTransaction);
AutoEnterPendingReply replies(mPendingRPCReplies);
if (!SendAndWait(aMsg, aReply))
return false;
NS_ABORT_IF_FALSE(aReply->is_rpc(), "expected rpc reply");
return true;
}
bool
MessageChannel::SendAndWait(Message* aMsg, Message* aReply)
{
mMonitor->AssertCurrentThreadOwns();
nsAutoPtr<Message> msg(aMsg);
if (!Connected()) {
ReportConnectionError("MessageChannel::SendAndWait");
return false;
}
msg->set_seqno(NextSeqno());
DebugOnly<int32_t> replySeqno = msg->seqno();
DebugOnly<msgid_t> replyType = msg->type() + 1;
mLink->SendMessage(msg.forget());
while (true) {
// Wait for an event to occur.
while (true) {
if (mRecvd || mPendingUrgentRequest || mPendingRPCCall)
break;
bool maybeTimedOut = !WaitForSyncNotify();
if (!Connected()) {
ReportConnectionError("MessageChannel::SendAndWait");
return false;
}
if (maybeTimedOut && !ShouldContinueFromTimeout())
return false;
}
if (mPendingUrgentRequest && !ProcessPendingUrgentRequest())
return false;
if (mPendingRPCCall && !ProcessPendingRPCCall())
return false;
if (mRecvd) {
NS_ABORT_IF_FALSE(mRecvd->is_reply(), "expected reply");
if (mRecvd->is_reply_error()) {
mRecvd = nullptr;
return false;
}
NS_ABORT_IF_FALSE(mRecvd->type() == replyType, "wrong reply type");
NS_ABORT_IF_FALSE(mRecvd->seqno() == replySeqno, "wrong sequence number");
*aReply = *mRecvd;
mRecvd = nullptr;
return true;
}
}
return true;
}
bool
MessageChannel::Call(Message* aMsg, Message* aReply)
{
if (aMsg->is_urgent())
return UrgentCall(aMsg, aReply);
if (aMsg->is_rpc())
return RPCCall(aMsg, aReply);
return InterruptCall(aMsg, aReply);
}
bool
MessageChannel::InterruptCall(Message* aMsg, Message* aReply)
{
AssertWorkerThread();
mMonitor->AssertNotCurrentThreadOwns();
#ifdef OS_WIN
SyncStackFrame frame(this, true);
#endif
// This must come before MonitorAutoLock, as its destructor acquires the
// monitor lock.
CxxStackFrame cxxframe(*this, OUT_MESSAGE, aMsg);
MonitorAutoLock lock(*mMonitor);
if (!Connected()) {
ReportConnectionError("MessageChannel::Call");
return false;
}
// Sanity checks.
IPC_ASSERT(!AwaitingSyncReply() && !AwaitingUrgentReply(),
"cannot issue Interrupt call whiel blocked on sync or urgent");
IPC_ASSERT(!DispatchingSyncMessage() || aMsg->priority() == IPC::Message::PRIORITY_HIGH,
"violation of sync handler invariant");
IPC_ASSERT(aMsg->is_interrupt(), "can only Call() Interrupt messages here");
nsAutoPtr<Message> msg(aMsg);
msg->set_seqno(NextSeqno());
msg->set_interrupt_remote_stack_depth_guess(mRemoteStackDepthGuess);
msg->set_interrupt_local_stack_depth(1 + InterruptStackDepth());
mInterruptStack.push(*msg);
mLink->SendMessage(msg.forget());
while (true) {
// if a handler invoked by *Dispatch*() spun a nested event
// loop, and the connection was broken during that loop, we
// might have already processed the OnError event. if so,
// trying another loop iteration will be futile because
// channel state will have been cleared
if (!Connected()) {
ReportConnectionError("MessageChannel::InterruptCall");
return false;
}
// Now might be the time to process a message deferred because of race
// resolution.
MaybeUndeferIncall();
// Wait for an event to occur.
while (!InterruptEventOccurred()) {
bool maybeTimedOut = !WaitForInterruptNotify();
// We might have received a "subtly deferred" message in a nested
// loop that it's now time to process.
if (InterruptEventOccurred() ||
(!maybeTimedOut && (!mDeferred.empty() || !mOutOfTurnReplies.empty())))
{
break;
}
if (maybeTimedOut && !ShouldContinueFromTimeout())
return false;
}
Message recvd;
MessageMap::iterator it;
if (mPendingUrgentRequest) {
recvd = *mPendingUrgentRequest;
mPendingUrgentRequest = nullptr;
} else if (mPendingRPCCall) {
recvd = *mPendingRPCCall;
mPendingRPCCall = nullptr;
} else if ((it = mOutOfTurnReplies.find(mInterruptStack.top().seqno()))
!= mOutOfTurnReplies.end())
{
recvd = it->second;
mOutOfTurnReplies.erase(it);
} else if (!mPending.empty()) {
recvd = mPending.front();
mPending.pop_front();
} else {
// because of subtleties with nested event loops, it's possible
// that we got here and nothing happened. or, we might have a
// deferred in-call that needs to be processed. either way, we
// won't break the inner while loop again until something new
// happens.
continue;
}
// If the message is not Interrupt, we can dispatch it as normal.
if (!recvd.is_interrupt()) {
// Other side should be blocked.
IPC_ASSERT(!recvd.is_sync() || mPending.empty(), "other side should be blocked");
{
AutoEnterRPCTransaction transaction(this, &recvd);
MonitorAutoUnlock unlock(*mMonitor);
CxxStackFrame frame(*this, IN_MESSAGE, &recvd);
DispatchMessage(recvd);
}
if (!Connected()) {
ReportConnectionError("MessageChannel::DispatchMessage");
return false;
}
continue;
}
// If the message is an Interrupt reply, either process it as a reply to our
// call, or add it to the list of out-of-turn replies we've received.
if (recvd.is_reply()) {
IPC_ASSERT(!mInterruptStack.empty(), "invalid Interrupt stack");
// If this is not a reply the call we've initiated, add it to our
// out-of-turn replies and keep polling for events.
{
const Message &outcall = mInterruptStack.top();
// Note, In the parent, sequence numbers increase from 0, and
// in the child, they decrease from 0.
if ((mSide == ChildSide && recvd.seqno() > outcall.seqno()) ||
(mSide != ChildSide && recvd.seqno() < outcall.seqno()))
{
mOutOfTurnReplies[recvd.seqno()] = recvd;
continue;
}
IPC_ASSERT(recvd.is_reply_error() ||
(recvd.type() == (outcall.type() + 1) &&
recvd.seqno() == outcall.seqno()),
"somebody's misbehavin'", true);
}
// We received a reply to our most recent outstanding call. Pop
// this frame and return the reply.
mInterruptStack.pop();
if (!recvd.is_reply_error()) {
*aReply = recvd;
}
// If we have no more pending out calls waiting on replies, then
// the reply queue should be empty.
IPC_ASSERT(!mInterruptStack.empty() || mOutOfTurnReplies.empty(),
"still have pending replies with no pending out-calls",
true);
return !recvd.is_reply_error();
}
// Dispatch an Interrupt in-call. Snapshot the current stack depth while we
// own the monitor.
size_t stackDepth = InterruptStackDepth();
{
MonitorAutoUnlock unlock(*mMonitor);
CxxStackFrame frame(*this, IN_MESSAGE, &recvd);
DispatchInterruptMessage(recvd, stackDepth);
}
if (!Connected()) {
ReportConnectionError("MessageChannel::DispatchInterruptMessage");
return false;
}
}
return true;
}
bool
MessageChannel::InterruptEventOccurred()
{
AssertWorkerThread();
mMonitor->AssertCurrentThreadOwns();
IPC_ASSERT(InterruptStackDepth() > 0, "not in wait loop");
return (!Connected() ||
!mPending.empty() ||
mPendingUrgentRequest ||
mPendingRPCCall ||
(!mOutOfTurnReplies.empty() &&
mOutOfTurnReplies.find(mInterruptStack.top().seqno()) !=
mOutOfTurnReplies.end()));
}
bool
MessageChannel::ProcessPendingUrgentRequest()
{
AssertWorkerThread();
mMonitor->AssertCurrentThreadOwns();
// Note that it is possible we could have sent a sync message at
// the same time the parent process sent an urgent message, and
// therefore mPendingUrgentRequest is set *and* mRecvd is set as
// well, because the link thread received both before the worker
// thread woke up.
//
// In this case, we process the urgent message first, but we need
// to save the reply.
nsAutoPtr<Message> savedReply(mRecvd.forget());
// We're the child process. We should not be receiving RPC calls.
IPC_ASSERT(!mPendingRPCCall, "unexpected RPC call");
nsAutoPtr<Message> recvd(mPendingUrgentRequest.forget());
{
// In order to send the parent RPC messages and guarantee it will
// wake up, we must re-use its transaction.
AutoEnterRPCTransaction transaction(this, recvd);
MonitorAutoUnlock unlock(*mMonitor);
DispatchUrgentMessage(*recvd);
}
if (!Connected()) {
ReportConnectionError("MessageChannel::DispatchUrgentMessage");
return false;
}
// In between having dispatched our reply to the parent process, and
// re-acquiring the monitor, the parent process could have already
// processed that reply and sent the reply to our sync message. If so,
// our saved reply should be empty.
IPC_ASSERT(!mRecvd || !savedReply, "unknown reply");
if (!mRecvd)
mRecvd = savedReply.forget();
return true;
}
bool
MessageChannel::ProcessPendingRPCCall()
{
AssertWorkerThread();
mMonitor->AssertCurrentThreadOwns();
// See comment above re: mRecvd replies and incoming calls.
nsAutoPtr<Message> savedReply(mRecvd.forget());
IPC_ASSERT(!mPendingUrgentRequest, "unexpected urgent message");
nsAutoPtr<Message> recvd(mPendingRPCCall.forget());
{
// If we are not currently in a transaction, this will begin one,
// and the link thread will not wake us up for any RPC messages not
// apart of this transaction. If we are already in a transaction,
// then this will assert that we're still in the same transaction.
AutoEnterRPCTransaction transaction(this, recvd);
MonitorAutoUnlock unlock(*mMonitor);
DispatchRPCMessage(*recvd);
}
if (!Connected()) {
ReportConnectionError("MessageChannel::DispatchRPCMessage");
return false;
}
// In between having dispatched our reply to the parent process, and
// re-acquiring the monitor, the parent process could have already
// processed that reply and sent the reply to our sync message. If so,
// our saved reply should be empty.
IPC_ASSERT(!mRecvd || !savedReply, "unknown reply");
if (!mRecvd)
mRecvd = savedReply.forget();
return true;
}
bool
MessageChannel::DequeueOne(Message *recvd)
{
AssertWorkerThread();
mMonitor->AssertCurrentThreadOwns();
if (!Connected()) {
ReportConnectionError("OnMaybeDequeueOne");
return false;
}
if (mPendingUrgentRequest) {
*recvd = *mPendingUrgentRequest;