Support narrowing a cpu profile to a given time window

runtime/vm/profiler.h

 // Copyright (c) 2013, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 #ifndef VM_PROFILER_H_
 #define VM_PROFILER_H_
 
 #include "vm/allocation.h"
 #include "vm/bitfield.h"
 #include "vm/code_observers.h"
@@ skipping 73 matching lines @@
  private:
   Isolate* isolate_;
   intptr_t visited_;
 
   DISALLOW_IMPLICIT_CONSTRUCTORS(SampleVisitor);
 };
 
 
 class SampleFilter : public ValueObject {
  public:
-  explicit SampleFilter(Isolate* isolate) : isolate_(isolate) { }
+  explicit SampleFilter(Isolate* isolate,
+                        int64_t time_origin_micros = -1,
+                        int64_t time_extent_micros = -1)

[siva, 2015/12/21 20:43:27]

I don't see any place where SampleFilter is constructed with just one argument
passed in, why not make time_origin_micros and time_extent_micros regular params
without any default values?

[Cutch, 2015/12/21 22:07:38]

Done.

+      : isolate_(isolate),
+        time_origin_micros_(time_origin_micros),
+        time_extent_micros_(time_extent_micros) { }

[siva, 2015/12/21 20:43:28]

ASSERT(time_origin_micros >= 0);
ASSERT(time_extent_micros >= 0);

because of the math done in the implementation of TimeFilterSample

[Cutch, 2015/12/21 22:07:38]

When these are -1 it means we don't have a TimeFilterSample.

[siva, 2015/12/22 17:08:23]

Sorry I meant :
ASSERT(time_origin_micros >= -1);
ASSERT(time_extent_micros >= -1);

   virtual ~SampleFilter() { }
 
   // Override this function.
   // Return |true| if |sample| passes the filter.
   virtual bool FilterSample(Sample* sample) {
     return true;
   }
 
   Isolate* isolate() const {
     return isolate_;
   }
 
+  // Returns |true| if |sample| passes the time filter.
+  bool TimeFilterSample(Sample* sample);
+
  private:
   Isolate* isolate_;
+
+  int64_t time_origin_micros_;
+  int64_t time_extent_micros_;
 };
 
 
 class ClearProfileVisitor : public SampleVisitor {
  public:
   explicit ClearProfileVisitor(Isolate* isolate);
 
   virtual void VisitSample(Sample* sample);
 };
 
@@ skipping 499 matching lines @@
  private:
   ZoneGrowableArray<ProcessedSample*> samples_;
   CodeLookupTable* code_lookup_table_;
 
   DISALLOW_COPY_AND_ASSIGN(ProcessedSampleBuffer);
 };
 
 }  // namespace dart
 
 #endif  // VM_PROFILER_H_