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// Copyright 2013 the V8 project authors. All rights reserved.
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions are
// met:
//
// * Redistributions of source code must retain the above copyright
// notice, this list of conditions and the following disclaimer.
// * Redistributions in binary form must reproduce the above
// copyright notice, this list of conditions and the following
// disclaimer in the documentation and/or other materials provided
// with the distribution.
// * Neither the name of Google Inc. nor the names of its
// contributors may be used to endorse or promote products derived
// from this software without specific prior written permission.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
#ifndef V8_SAMPLER_H_
#define V8_SAMPLER_H_
#include "atomicops.h"
#include "frames.h"
#include "v8globals.h"
namespace v8 {
namespace internal {
class Isolate;
// ----------------------------------------------------------------------------
// 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.
struct RegisterState {
RegisterState() : pc(NULL), sp(NULL), fp(NULL) {}
Address pc; // Instruction pointer.
Address sp; // Stack pointer.
Address fp; // Frame pointer.
};
// TickSample captures the information collected for each sample.
struct TickSample {
TickSample()
: state(OTHER),
pc(NULL),
external_callback(NULL),
frames_count(0),
has_external_callback(false),
top_frame_type(StackFrame::NONE) {}
void Init(Isolate* isolate, const RegisterState& state);
StateTag state; // The state of the VM.
Address pc; // Instruction pointer.
union {
Address tos; // Top stack value (*sp).
Address external_callback;
};
static const int kMaxFramesCount = 64;
Address stack[kMaxFramesCount]; // Call stack.
int frames_count : 8; // Number of captured frames.
bool has_external_callback : 1;
StackFrame::Type top_frame_type : 4;
};
class Sampler {
public:
// Initializes the Sampler support. Called once at VM startup.
static void SetUp();
static void TearDown();
// Initialize sampler.
Sampler(Isolate* isolate, int interval);
virtual ~Sampler();
Isolate* isolate() const { return isolate_; }
int interval() const { return interval_; }
// Performs stack sampling.
void SampleStack(const RegisterState& regs);
// Start and stop sampler.
void Start();
void Stop();
// Is the sampler used for profiling?
bool IsProfiling() const { return NoBarrier_Load(&profiling_) > 0; }
void IncreaseProfilingDepth() { NoBarrier_AtomicIncrement(&profiling_, 1); }
void DecreaseProfilingDepth() { NoBarrier_AtomicIncrement(&profiling_, -1); }
// Whether the sampler is running (that is, consumes resources).
bool IsActive() const { return NoBarrier_Load(&active_); }
// Used in tests to make sure that stack sampling is performed.
int samples_taken() const { return samples_taken_; }
void ResetSamplesTaken() { samples_taken_ = 0; }
class PlatformData;
PlatformData* platform_data() const { return data_; }
protected:
// This method is called for each sampling period with the current
// program counter.
virtual void Tick(TickSample* sample) = 0;
private:
void SetActive(bool value) { NoBarrier_Store(&active_, value); }
Isolate* isolate_;
const int interval_;
Atomic32 profiling_;
Atomic32 active_;
PlatformData* data_; // Platform specific data.
int samples_taken_; // Counts stack samples taken.
DISALLOW_IMPLICIT_CONSTRUCTORS(Sampler);
};
} } // namespace v8::internal
#endif // V8_SAMPLER_H_
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