commit c604d731730b43231f63040c8db1d58304da0cf3
author Ian Rogers <irogers@google.com> Sun Oct 14 16:09:54 2012 -0700
committer Ian Rogers <irogers@google.com> Mon Oct 15 15:36:32 2012 -0700
tree bb9cd6aa56eb3ba88ff27967efc3cc08da150b87
parent 0b0b515934b83385e1cea448113783e0b22849ed

Implement mutex requeueing for cv broadcasts.

Make the mutex guarding a condition variable part of its state. On a
broadcast requeue waiters on the mutex so they are awoken as the mutex
is unlocked (thereby avoiding thundering herds). Explicit futex use
still guarded behind ART_USE_FUTEXES which remains disabled as I'm
unhappy with some of the warts of mutex usage. Uploading so that the API
changes can stabilize.

Change-Id: Iedb601856ccd8bbc3a64da4ba0cee82246e7bcbf

src/signal_catcher.cc

diff --git a/src/signal_catcher.cc b/src/signal_catcher.cc
index b6f6a41..80c37d4 100644
--- a/src/signal_catcher.cc
+++ b/src/signal_catcher.cc
@@ -62,7 +62,7 @@
 SignalCatcher::SignalCatcher(const std::string& stack_trace_file)
     : stack_trace_file_(stack_trace_file),
       lock_("SignalCatcher lock"),
-      cond_("SignalCatcher::cond_"),
+      cond_("SignalCatcher::cond_", lock_),
       thread_(NULL) {
   SetHaltFlag(false);
 
@@ -72,7 +72,7 @@
   Thread* self = Thread::Current();
   MutexLock mu(self, lock_);
   while (thread_ == NULL) {
-    cond_.Wait(self, lock_);
+    cond_.Wait(self);
   }
 }
 
@@ -190,7 +190,7 @@
   {
     MutexLock mu(self, signal_catcher->lock_);
     signal_catcher->thread_ = self;
-    signal_catcher->cond_.Broadcast();
+    signal_catcher->cond_.Broadcast(self);
   }
 
   // Set up mask with signals we want to handle.