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Bug 648935: Need to use the "remote stack depth view" when deciding whether to undefer, too. r=bsmedberg

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This commit is contained in:
Chris Jones 2011-05-04 15:55:54 -05:00
parent 2724d954fd
commit 705e9bc07a
2 changed files with 21 additions and 9 deletions
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18
ipc/glue/RPCChannel.cpp
View File

@ -330,7 +330,7 @@ RPCChannel::MaybeUndeferIncall()
RPC_ASSERT(mDeferred.top().rpc_remote_stack_depth_guess() <= stackDepth,
"fatal logic error");
if (mDeferred.top().rpc_remote_stack_depth_guess() < stackDepth)
if (mDeferred.top().rpc_remote_stack_depth_guess() < RemoteViewOfStackDepth(stackDepth))
return;
// maybe time to process this message
@ -435,6 +435,13 @@ RPCChannel::OnMaybeDequeueOne()
return true;
}
size_t
RPCChannel::RemoteViewOfStackDepth(size_t stackDepth) const
{
AssertWorkerThread();
return stackDepth - mOutOfTurnReplies.size();
}
void
RPCChannel::Incall(const Message& call, size_t stackDepth)
{
@ -445,14 +452,7 @@ RPCChannel::Incall(const Message& call, size_t stackDepth)
// Race detection: see the long comment near
// mRemoteStackDepthGuess in RPCChannel.h. "Remote" stack depth
// means our side, and "local" means other side.
//
// We compare the remote stack depth guess against the "remote
// view of stack depth" because of out-of-turn replies. When we
// receive one, our actual RPC stack depth doesn't decrease, but
// the other side (that sent the reply) thinks it has. So, just
// adjust down by the number of out-of-turn replies.
size_t remoteViewOfStackDepth = (stackDepth - mOutOfTurnReplies.size());
if (call.rpc_remote_stack_depth_guess() != remoteViewOfStackDepth) {
if (call.rpc_remote_stack_depth_guess() != RemoteViewOfStackDepth(stackDepth)) {
// RPC in-calls have raced.
// the "winner", if there is one, gets to defer processing of
// the other side's in-call

12
ipc/glue/RPCChannel.h
View File

@ -207,6 +207,18 @@ protected:
*/
bool OnMaybeDequeueOne();
/**
* The "remote view of stack depth" can be different than the
* actual stack depth when there are out-of-turn replies. When we
* receive one, our actual RPC stack depth doesn't decrease, but
* the other side (that sent the reply) thinks it has. So, the
* "view" returned here is |stackDepth| minus the number of
* out-of-turn replies.
*
* Only called from the worker thread.
*/
size_t RemoteViewOfStackDepth(size_t stackDepth) const;
void Incall(const Message& call, size_t stackDepth);
void DispatchIncall(const Message& call);