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// Copyright 2015 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.
#include <memory>
#include "base/base_export.h"
#include "base/macros.h"
#include "base/profiler/stack_sampling_profiler.h"
#include "base/threading/platform_thread.h"
namespace base {
class NativeStackSamplerTestDelegate;
// NativeStackSampler is an implementation detail of StackSamplingProfiler. It
// abstracts the native implementation required to record a stack sample for a
// given thread.
class NativeStackSampler {
// This class contains a buffer for stack copies that can be shared across
// multiple instances of NativeStackSampler.
class StackBuffer {
StackBuffer(size_t buffer_size);
void* buffer() const { return buffer_.get(); }
size_t size() const { return size_; }
// The word-aligned buffer.
const std::unique_ptr<uintptr_t[]> buffer_;
// The size of the buffer.
const size_t size_;
// The callback type used to add annotations to a sample during collection.
// This is passed to the native sampler to be applied at the most appropriate
// time. It is a simple function-pointer because the generated code must be
// completely predictable and do nothing that could acquire a mutex; a
// Callback object is code outside the control of this object and could,
// for example, acquire a mutex as part of allocating memory for a LOG
// message.
using AnnotateCallback = void (*)(StackSamplingProfiler::Sample*);
virtual ~NativeStackSampler();
// Creates a stack sampler that records samples for |thread_handle|. Returns
// null if this platform does not support stack sampling.
static std::unique_ptr<NativeStackSampler> Create(
PlatformThreadId thread_id,
AnnotateCallback annotator,
NativeStackSamplerTestDelegate* test_delegate);
// Gets the required size of the stack buffer.
static size_t GetStackBufferSize();
// Creates an instance of the a stack buffer that can be used for calls to
// any NativeStackSampler object.
static std::unique_ptr<StackBuffer> CreateStackBuffer();
// The following functions are all called on the SamplingThread (not the
// thread being sampled).
// Notifies the sampler that we're starting to record a new profile. Modules
// shared across samples in the profile should be recorded in |modules|.
virtual void ProfileRecordingStarting(
std::vector<StackSamplingProfiler::Module>* modules) = 0;
// Records a stack sample to |sample|.
virtual void RecordStackSample(StackBuffer* stackbuffer,
StackSamplingProfiler::Sample* sample) = 0;
// Notifies the sampler that we've stopped recording the current
// profile.
virtual void ProfileRecordingStopped(StackBuffer* stackbuffer) = 0;
// NativeStackSamplerTestDelegate provides seams for test code to execute during
// stack collection.
class BASE_EXPORT NativeStackSamplerTestDelegate {
virtual ~NativeStackSamplerTestDelegate();
// Called after copying the stack and resuming the target thread, but prior to
// walking the stack. Invoked on the SamplingThread.
virtual void OnPreStackWalk() = 0;
} // namespace base