bool
SyncChannel::Send(Message* msg, Message* reply)
{
AssertWorkerThread();
mMonitor.AssertNotCurrentThreadOwns();
NS_ABORT_IF_FALSE(!ProcessingSyncMessage(),
"violation of sync handler invariant");
NS_ABORT_IF_FALSE(msg->is_sync(), "can only Send() sync messages here");
#ifdef OS_WIN
SyncStackFrame frame(this, false);
#endif
msg->set_seqno(NextSeqno());
MonitorAutoLock lock(mMonitor);
if (!Connected()) {
ReportConnectionError("SyncChannel");
return false;
}
mPendingReply = msg->type() + 1;
int32 msgSeqno = msg->seqno();
SendThroughTransport(msg);
while (1) {
bool maybeTimedOut = !SyncChannel::WaitForNotify();
if (EventOccurred())
break;
if (maybeTimedOut && !ShouldContinueFromTimeout())
return false;
}
if (!Connected()) {
ReportConnectionError("SyncChannel");
return false;
}
// we just received a synchronous message from the other side.
// If it's not the reply we were awaiting, there's a serious
// error: either a mistimed/malformed message or a sync in-message
// that raced with our sync out-message.
// (NB: IPDL prevents the latter from occuring in actor code)
// FIXME/cjones: real error handling
NS_ABORT_IF_FALSE(mRecvd.is_sync() && mRecvd.is_reply() &&
(mRecvd.is_reply_error() ||
(mPendingReply == mRecvd.type() &&
msgSeqno == mRecvd.seqno())),
"unexpected sync message");
mPendingReply = 0;
*reply = mRecvd;
mRecvd = Message();
return true;
}
bool
RPCChannel::Call(Message* _msg, Message* reply)
{
RPC_ASSERT(!mPendingReply, "should not be waiting for a reply");
nsAutoPtr<Message> msg(_msg);
AssertWorkerThread();
mMonitor->AssertNotCurrentThreadOwns();
RPC_ASSERT(!ProcessingSyncMessage() || msg->priority() == IPC::Message::PRIORITY_HIGH,
"violation of sync handler invariant");
RPC_ASSERT(msg->is_rpc(), "can only Call() RPC messages here");
#ifdef OS_WIN
SyncStackFrame frame(this, true);
#endif
Message copy = *msg;
CxxStackFrame f(*this, OUT_MESSAGE, ©);
MonitorAutoLock lock(*mMonitor);
if (!Connected()) {
ReportConnectionError("RPCChannel");
return false;
}
bool urgent = (copy.priority() == IPC::Message::PRIORITY_HIGH);
msg->set_seqno(NextSeqno());
msg->set_rpc_remote_stack_depth_guess(mRemoteStackDepthGuess);
msg->set_rpc_local_stack_depth(1 + StackDepth());
mStack.push(*msg);
mLink->SendMessage(msg.forget());
while (1) {
// 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("RPCChannel");
return false;
}
// now might be the time to process a message deferred because
// of race resolution
MaybeUndeferIncall();
// here we're waiting for something to happen. see long
// comment about the queue in RPCChannel.h
while (!EventOccurred()) {
bool maybeTimedOut = !RPCChannel::WaitForNotify();
if (EventOccurred() ||
// we might have received a "subtly deferred" message
// in a nested loop that it's now time to process
(!maybeTimedOut &&
(!mDeferred.empty() || !mOutOfTurnReplies.empty())))
break;
if (maybeTimedOut && !ShouldContinueFromTimeout())
return false;
}
if (!Connected()) {
ReportConnectionError("RPCChannel");
return false;
}
Message recvd;
MessageMap::iterator it;
if (!mOutOfTurnReplies.empty() &&
((it = mOutOfTurnReplies.find(mStack.top().seqno())) !=
mOutOfTurnReplies.end())) {
recvd = it->second;
mOutOfTurnReplies.erase(it);
}
else if (!mUrgent.empty()) {
recvd = mUrgent.front();
mUrgent.pop_front();
}
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 (!recvd.is_rpc()) {
if (urgent && recvd.priority() != IPC::Message::PRIORITY_HIGH) {
// If we're waiting for an urgent reply, don't process any
// messages yet.
mNonUrgentDeferred.push_back(recvd);
} else if (recvd.is_sync()) {
RPC_ASSERT(mPending.empty(),
"other side should have been blocked");
MonitorAutoUnlock unlock(*mMonitor);
CxxStackFrame f(*this, IN_MESSAGE, &recvd);
SyncChannel::OnDispatchMessage(recvd);
} else {
MonitorAutoUnlock unlock(*mMonitor);
CxxStackFrame f(*this, IN_MESSAGE, &recvd);
AsyncChannel::OnDispatchMessage(recvd);
}
continue;
}
RPC_ASSERT(recvd.is_rpc(), "wtf???");
if (recvd.is_reply()) {
RPC_ASSERT(0 < mStack.size(), "invalid RPC stack");
const Message& outcall = mStack.top();
// in the parent, seqno's increase from 0, and in the
// child, they decrease from 0
if ((!mChild && recvd.seqno() < outcall.seqno()) ||
(mChild && recvd.seqno() > outcall.seqno())) {
mOutOfTurnReplies[recvd.seqno()] = recvd;
continue;
}
// FIXME/cjones: handle error
RPC_ASSERT(
recvd.is_reply_error() ||
(recvd.type() == (outcall.type()+1) &&
recvd.seqno() == outcall.seqno()),
"somebody's misbehavin'", "rpc", true);
// we received a reply to our most recent outstanding
// call. pop this frame and return the reply
mStack.pop();
bool isError = recvd.is_reply_error();
if (!isError) {
*reply = recvd;
}
if (0 == StackDepth()) {
RPC_ASSERT(
mOutOfTurnReplies.empty(),
"still have pending replies with no pending out-calls",
"rpc", true);
}
// finished with this RPC stack frame
return !isError;
}
// in-call. process in a new stack frame.
// "snapshot" the current stack depth while we own the Monitor
size_t stackDepth = StackDepth();
{
MonitorAutoUnlock unlock(*mMonitor);
// someone called in to us from the other side. handle the call
CxxStackFrame f(*this, IN_MESSAGE, &recvd);
Incall(recvd, stackDepth);
// FIXME/cjones: error handling
}
}
return true;
}
