Add a systrace support for lock contention logging.

- Now several ART executables like oatdump need to link with libcutils
  as the mutex code is shared among them.
- The blocking thread ID and lock owner thread ID are passed to
  ScopedContentionRecorder in the correct order.

Bug: 9986464
Change-Id: Id766de23fbc4af1d8ba2de051595e365b04f5ae7

1 files changed, 9 insertions, 0 deletions

diff --git a/runtime/base/mutex-inl.h b/runtime/base/mutex-inl.h
index 7f3b459..a559d63 100644
--- a/runtime/base/mutex-inl.h
+++ b/runtime/base/mutex-inl.h
@@ -19,7 +19,10 @@
 
 #include "mutex.h"
 
+#define ATRACE_TAG ATRACE_TAG_DALVIK
+
 #include "cutils/atomic-inline.h"
+#include "cutils/trace.h"
 #include "runtime.h"
 #include "thread.h"
 
@@ -45,10 +48,16 @@ class ScopedContentionRecorder {
         blocked_tid_(kLogLockContentions ? blocked_tid : 0),
         owner_tid_(kLogLockContentions ? owner_tid : 0),
         start_nano_time_(kLogLockContentions ? NanoTime() : 0) {
+    if (kLogLockContentions) {
+      std::string msg = StringPrintf("Lock contention on %s (owner tid: %llu)",
+                                     mutex->GetName(), owner_tid);
+      ATRACE_BEGIN(msg.c_str());
+    }
   }
 
   ~ScopedContentionRecorder() {
     if (kLogLockContentions) {
+      ATRACE_END();
       uint64_t end_nano_time = NanoTime();
       mutex_->RecordContention(blocked_tid_, owner_tid_, end_nano_time - start_nano_time_);
     }