Increase debug information for failed monitor exits

CTS has shown IllegalMonitorStateExceptions where they shouldn't occur.
Ratchet up the debug information in the case of unlocks so the kind of
problem can be better diagnosed. This code is only executed in
exceptional cases and so better debugging wins out over performance.

Also, add helper to dump thread state as something human readable.

Also, JNI internal unit test of monitor enter/exit.

Change-Id: I9c06fbce7e6c9ebbb950a4e400f65c791ebe2ba4

1 files changed, 4 insertions, 2 deletions

diff --git a/src/monitor.h b/src/monitor.h
index 4d73e37..a79f6ce 100644
--- a/src/monitor.h
+++ b/src/monitor.h
@@ -89,6 +89,8 @@ class Monitor {
 
   void LogContentionEvent(Thread* self, uint32_t wait_ms, uint32_t sample_percent, const char* owner_filename, uint32_t owner_line_number);
 
+  static void FailedUnlock(Object* obj, Thread* expected_owner, Thread* found_owner, Monitor* mon);
+
   void Lock(Thread* self);
   bool Unlock(Thread* thread);
 
@@ -105,13 +107,13 @@ class Monitor {
   static uint32_t lock_profiling_threshold_;
 
   // Which thread currently owns the lock?
-  Thread* owner_;
+  Thread* volatile owner_;
 
   // Owner's recursive lock depth.
   int lock_count_;
 
   // What object are we part of (for debugging).
-  Object* obj_;
+  Object* const obj_;
 
   // Threads currently waiting on this monitor.
   Thread* wait_set_;