Add flag to control number of stack frames collected by profiler

runtime/vm/profiler.h

Index: runtime/vm/profiler.h
diff --git a/runtime/vm/profiler.h b/runtime/vm/profiler.h
index 706e64aab973de36abf5729989a9ba211ec42f4f..6c27c2d4bae71f2c6c85bbd6b1a3aaa93cfd750c 100644
--- a/runtime/vm/profiler.h
+++ b/runtime/vm/profiler.h
@@ -18,6 +18,7 @@ class JSONArray;
 class JSONStream;
 class ProfilerCodeRegionTable;
 struct Sample;
+class SampleBuffer;
 
 // Profiler
 class Profiler : public AllStatic {
@@ -82,21 +83,26 @@ class IsolateProfilerData {
 
 // Profile sample.
 struct Sample {

[siva, 2014/01/16 23:34:23]

why not just make it class Sample ?

[Cutch, 2014/01/17 16:02:25]

Done.

-  static const intptr_t kNumStackFrames = 6;
   enum SampleType {
-    kIsolateStart,
-    kIsolateStop,
     kIsolateSample,
   };
+
   int64_t timestamp;
   ThreadId tid;
   Isolate* isolate;
-  uintptr_t pcs[kNumStackFrames];
   SampleType type;
   uint16_t vm_tags;
   uint16_t runtime_tags;
+  uintptr_t pcs[0];

[siva, 2014/01/16 23:34:23]

Document that this needs to be the last field, no fields should be added after
this.

[Cutch, 2014/01/17 16:02:25]

Done.

 
   void Init(SampleType type, Isolate* isolate, int64_t timestamp, ThreadId tid);
+  void CopyInto(Sample* dst) const;
+
+  static Sample* Allocate();
+  static intptr_t InstanceSize();
+
+ private:
+  DISALLOW_COPY_AND_ASSIGN(Sample);
 };
 
 
@@ -109,14 +115,9 @@ class SampleBuffer {
   ~SampleBuffer();
 
   intptr_t capacity() const { return capacity_; }
-
   Sample* ReserveSample();
-
-  Sample GetSample(intptr_t i) const {
-    ASSERT(i >= 0);
-    ASSERT(i < capacity_);
-    return samples_[i];
-  }
+  void CopySample(intptr_t i, Sample* sample) const;
+  Sample* At(intptr_t idx) const;
 
  private:
   Sample* samples_;