commit 0abc72ebe356c32354b575c48189965a0edc7890
author Jeff Hao <jeffhao@google.com> Tue Aug 13 13:45:14 2013 -0700
committer Jeff Hao <jeffhao@google.com> Tue Aug 13 18:22:13 2013 -0700
tree 7faa419cdcb44353d8f9d8b1d47499d3241924d0
parent 73a79074c06d8b0a8c14946438c59c3821d88fe7

Modify traceview to sample instead of instrumenting methods.

Disabled the method instrumentation in traceview. Now when traceview
is triggered, it starts up a thread which periodically samples all
threads instead, generating method entry/exit events that traceview
can understand.

Change-Id: Ifc4012a4509d8eb9f54941eee2a8b42c411e5e9c

runtime/trace.h

diff --git a/runtime/trace.h b/runtime/trace.h
index bd9c140..d2e6fb1 100644
--- a/runtime/trace.h
+++ b/runtime/trace.h
@@ -20,6 +20,7 @@
 #include <ostream>
 #include <set>
 #include <string>
+#include <vector>
 
 #include "base/macros.h"
 #include "globals.h"
@@ -62,6 +63,9 @@
   bool UseWallClock();
   bool UseThreadCpuClock();
 
+  void CompareAndUpdateStackTrace(Thread* thread, std::vector<mirror::AbstractMethod*>* stack_trace)
+      SHARED_LOCKS_REQUIRED(Locks::mutator_lock_);
+
   virtual void MethodEntered(Thread* thread, mirror::Object* this_object,
                              const mirror::AbstractMethod* method, uint32_t dex_pc)
       SHARED_LOCKS_REQUIRED(Locks::mutator_lock_);
@@ -79,9 +83,13 @@
                                mirror::Throwable* exception_object)
       SHARED_LOCKS_REQUIRED(Locks::mutator_lock_);
 
+  ~Trace();
+
  private:
   explicit Trace(File* trace_file, int buffer_size, int flags);
 
+  static void* RunSamplingThread(void* arg) LOCKS_EXCLUDED(Locks::trace_lock_);
+
   void FinishTracing() SHARED_LOCKS_REQUIRED(Locks::mutator_lock_);
 
   void LogMethodTraceEvent(Thread* thread, const mirror::AbstractMethod* method,
@@ -94,11 +102,23 @@
   void DumpThreadList(std::ostream& os) LOCKS_EXCLUDED(Locks::thread_list_lock_);
 
   // Singleton instance of the Trace or NULL when no method tracing is active.
-  static Trace* the_trace_ GUARDED_BY(Locks::trace_lock_);
+  static Trace* volatile the_trace_ GUARDED_BY(Locks::trace_lock_);
 
   // The default profiler clock source.
   static ProfilerClockSource default_clock_source_;
 
+  // True if traceview should sample instead of instrumenting method entry/exit.
+  static bool sampling_enabled_;
+
+  // Sampling interval in microseconds.
+  static uint32_t sampling_interval_us_;
+
+  // 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::AbstractMethod*>*> thread_stack_trace_map_;
+
   // Maps a thread to its clock base.
   SafeMap<Thread*, uint64_t> thread_clock_base_map_;