commit 61f157c8528c2b46f3234b4eea5a44df531d857d
author Ben Murdoch <benm@google.com> Fri Sep 16 13:49:30 2016 +0100
committer Dirk Vogt <dirk@fairphone.com> Fri Mar 17 16:06:52 2017 +0100
tree 3fa142ce2609b1fdf9d001275350184f71860fa3
parent c5610438f36f65235862a5f5020a739d29a5c32e

Merge V8 5.3.332.45.  DO NOT MERGE

Test: Manual

FPIIM-449

Change-Id: Id3254828b068abdea3cb10442e0172a8c9a98e03
(cherry picked from commit 13e2dadd00298019ed862f2b2fc5068bba730bcf)

src/libsampler/v8-sampler.h

diff --git a/src/libsampler/v8-sampler.h b/src/libsampler/v8-sampler.h
new file mode 100644
index 0000000..7ae3c8c
--- /dev/null
+++ b/src/libsampler/v8-sampler.h
@@ -0,0 +1,103 @@
+// Copyright 2016 the V8 project authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef V8_LIBSAMPLER_SAMPLER_H_
+#define V8_LIBSAMPLER_SAMPLER_H_
+
+#include "include/v8.h"
+
+#include "src/base/atomicops.h"
+#include "src/base/macros.h"
+
+namespace v8 {
+namespace sampler {
+
+// ----------------------------------------------------------------------------
+// Sampler
+//
+// A sampler periodically samples the state of the VM and optionally
+// (if used for profiling) the program counter and stack pointer for
+// the thread that created it.
+
+class Sampler {
+ public:
+  static const int kMaxFramesCountLog2 = 8;
+  static const unsigned kMaxFramesCount = (1u << kMaxFramesCountLog2) - 1;
+
+  // Initializes the Sampler support. Called once at VM startup.
+  static void SetUp();
+  static void TearDown();
+
+  // Initialize sampler.
+  explicit Sampler(Isolate* isolate);
+  virtual ~Sampler();
+
+  Isolate* isolate() const { return isolate_; }
+
+  // Performs stack sampling.
+  // Clients should override this method in order to do something on samples,
+  // for example buffer samples in a queue.
+  virtual void SampleStack(const v8::RegisterState& regs) = 0;
+
+  // Start and stop sampler.
+  void Start();
+  void Stop();
+
+  // Whether the sampling thread should use this Sampler for CPU profiling?
+  bool IsProfiling() const {
+    return base::NoBarrier_Load(&profiling_) > 0 &&
+        !base::NoBarrier_Load(&has_processing_thread_);
+  }
+  void IncreaseProfilingDepth();
+  void DecreaseProfilingDepth();
+
+  // Whether the sampler is running (that is, consumes resources).
+  bool IsActive() const { return base::NoBarrier_Load(&active_); }
+
+  // CpuProfiler collects samples by calling DoSample directly
+  // without calling Start. To keep it working, we register the sampler
+  // with the CpuProfiler.
+  bool IsRegistered() const { return base::NoBarrier_Load(&registered_); }
+
+  void DoSample();
+
+  void SetHasProcessingThread(bool value) {
+    base::NoBarrier_Store(&has_processing_thread_, value);
+  }
+
+  // Used in tests to make sure that stack sampling is performed.
+  unsigned js_sample_count() const { return js_sample_count_; }
+  unsigned external_sample_count() const { return external_sample_count_; }
+  void StartCountingSamples() {
+    js_sample_count_ = 0;
+    external_sample_count_ = 0;
+    is_counting_samples_ = true;
+  }
+
+  class PlatformData;
+  PlatformData* platform_data() const { return data_; }
+
+ protected:
+  // Counts stack samples taken in various VM states.
+  bool is_counting_samples_;
+  unsigned js_sample_count_;
+  unsigned external_sample_count_;
+
+ private:
+  void SetActive(bool value) { base::NoBarrier_Store(&active_, value); }
+  void SetRegistered(bool value) { base::NoBarrier_Store(&registered_, value); }
+
+  Isolate* isolate_;
+  base::Atomic32 profiling_;
+  base::Atomic32 has_processing_thread_;
+  base::Atomic32 active_;
+  base::Atomic32 registered_;
+  PlatformData* data_;  // Platform specific data.
+  DISALLOW_IMPLICIT_CONSTRUCTORS(Sampler);
+};
+
+}  // namespace sampler
+}  // namespace v8
+
+#endif  // V8_LIBSAMPLER_SAMPLER_H_