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// Copyright (c) 2011 The Chromium 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 BASE_WIN_SAMPLING_PROFILER_H_
#define BASE_WIN_SAMPLING_PROFILER_H_
#include <vector>
#include "base/basictypes.h"
#include "base/time.h"
#include "base/win/scoped_handle.h"
namespace base {
namespace win {
// This class exposes the functionality of Window's built-in sampling profiler.
// Each profiler instance covers a range of memory, and while the profiler is
// running, its buckets will count the number of times the instruction counter
// lands in the associated range of memory on a sample.
// The sampling interval is settable, but the setting is system-wide.
class BASE_EXPORT SamplingProfiler {
public:
// Create an uninitialized sampling profiler.
SamplingProfiler();
~SamplingProfiler();
// Initializes the profiler to cover the memory range |start| through
// |start| + |size|, in the process |process_handle| with bucket size
// |2^log2_bucket_size|, |log2_bucket_size| must be in the range 2-31,
// for bucket sizes of 4 bytes to 2 gigabytes.
// The process handle must grant at least PROCESS_QUERY_INFORMATION.
// The memory range should be exectuable code, like e.g. the text segment
// of an exectuable (whether DLL or EXE).
// Returns true on success.
bool Initialize(HANDLE process_handle,
void* start,
size_t size,
size_t log2_bucket_size);
// Start this profiler, which must be initialized and not started.
bool Start();
// Stop this profiler, which must be started.
bool Stop();
// Get and set the sampling interval.
// Note that this is a system-wide setting.
static bool SetSamplingInterval(base::TimeDelta sampling_interval);
static bool GetSamplingInterval(base::TimeDelta* sampling_interval);
// Accessors.
bool is_started() const { return is_started_; }
// It is safe to read the counts in the sampling buckets at any time.
// Note however that there's no guarantee that you'll read consistent counts
// until the profiler has been stopped, as the counts may be updating on other
// CPU cores.
const std::vector<ULONG>& buckets() const { return buckets_; }
private:
// Handle to the corresponding kernel object.
ScopedHandle profile_handle_;
// True iff this profiler is started.
bool is_started_;
std::vector<ULONG> buckets_;
DISALLOW_COPY_AND_ASSIGN(SamplingProfiler);
};
} // namespace win
} // namespace base
#endif // BASE_WIN_SAMPLING_PROFILER_H_
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