chromium/base/sampling_heap_profiler/poisson_allocation_sampler.h

// Copyright 2018 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#ifndef BASE_SAMPLING_HEAP_PROFILER_POISSON_ALLOCATION_SAMPLER_H_
#define BASE_SAMPLING_HEAP_PROFILER_POISSON_ALLOCATION_SAMPLER_H_

#include <atomic>
#include <vector>

#include "base/allocator/dispatcher/notification_data.h"
#include "base/allocator/dispatcher/reentry_guard.h"
#include "base/allocator/dispatcher/subsystem.h"
#include "base/base_export.h"
#include "base/compiler_specific.h"
#include "base/gtest_prod_util.h"
#include "base/memory/raw_ptr_exclusion.h"
#include "base/no_destructor.h"
#include "base/sampling_heap_profiler/lock_free_address_hash_set.h"
#include "base/synchronization/lock.h"
#include "base/thread_annotations.h"

namespace base {

class SamplingHeapProfilerTest;

// This singleton class implements Poisson sampling of the incoming allocations
// stream. It hooks onto base::allocator and base::PartitionAlloc.
// The only control parameter is sampling interval that controls average value
// of the sampling intervals. The actual intervals between samples are
// randomized using Poisson distribution to mitigate patterns in the allocation
// stream.
// Once accumulated allocation sizes fill up the current sample interval,
// a sample is generated and sent to the observers via |SampleAdded| call.
// When the corresponding memory that triggered the sample is freed observers
// get notified with |SampleRemoved| call.
//
class BASE_EXPORT PoissonAllocationSampler { … };

ALWAYS_INLINE void PoissonAllocationSampler::OnAllocation(
    const base::allocator::dispatcher::AllocationNotificationData&
        allocation_data) { … }

ALWAYS_INLINE void PoissonAllocationSampler::OnFree(
    const base::allocator::dispatcher::FreeNotificationData& free_data) { … }

}  // namespace base

#endif  // BASE_SAMPLING_HEAP_PROFILER_POISSON_ALLOCATION_SAMPLER_H_