Clean up sampling tracing.

- Moved maps to fields within thread.
- Created temp trace field to lessen amount of traces allocated and freed.

Change-Id: I23fe25a85ad2894cc6917f87d4046cdececf0739

1 files changed, 7 insertions, 5 deletions

diff --git a/runtime/trace.h b/runtime/trace.h
index 5733929..9fe2cc6 100644
--- a/runtime/trace.h
+++ b/runtime/trace.h
@@ -83,6 +83,11 @@ class Trace : public instrumentation::InstrumentationListener {
                                mirror::Throwable* exception_object)
       SHARED_LOCKS_REQUIRED(Locks::mutator_lock_);
 
+  // Reuse an old stack trace if it exists, otherwise allocate a new one.
+  static std::vector<mirror::ArtMethod*>* AllocStackTrace();
+  // Clear and store an old stack trace for later use.
+  static void FreeStackTrace(std::vector<mirror::ArtMethod*>* stack_trace);
+
   ~Trace();
 
  private:
@@ -116,11 +121,8 @@ class Trace : public instrumentation::InstrumentationListener {
   // Sampling thread, non-zero when sampling.
   static pthread_t sampling_pthread_;
 
-  // Maps a thread to its most recent stack trace sample.
-  SafeMap<Thread*, std::vector<mirror::ArtMethod*>*> thread_stack_trace_map_;
-
-  // Maps a thread to its clock base.
-  SafeMap<Thread*, uint64_t> thread_clock_base_map_;
+  // Used to remember an unused stack trace to avoid re-allocation during sampling.
+  static UniquePtr<std::vector<mirror::ArtMethod*> > temp_stack_trace_;
 
   // File to write trace data out to, NULL if direct to ddms.
   UniquePtr<File> trace_file_;