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// Copyright 2012 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_METRICS_SPARSE_HISTOGRAM_H_
#define BASE_METRICS_SPARSE_HISTOGRAM_H_
#include <stddef.h>
#include <stdint.h>
#include <map>
#include <memory>
#include <string>
#include "base/base_export.h"
#include "base/metrics/histogram_base.h"
#include "base/metrics/histogram_samples.h"
#include "base/synchronization/lock.h"
#include "base/values.h"
namespace base {
class HistogramSamples;
class PersistentHistogramAllocator;
class Pickle;
class PickleIterator;
class BASE_EXPORT SparseHistogram : public HistogramBase {
public:
// If there's one with same name, return the existing one. If not, create a
// new one.
static HistogramBase* FactoryGet(std::string_view name, int32_t flags);
// Create a histogram using data in persistent storage. The allocator must
// live longer than the created sparse histogram.
static std::unique_ptr<HistogramBase> PersistentCreate(
PersistentHistogramAllocator* allocator,
DurableStringView name,
uint64_t name_hash,
HistogramSamples::Metadata* meta,
HistogramSamples::Metadata* logged_meta);
SparseHistogram(const SparseHistogram&) = delete;
SparseHistogram& operator=(const SparseHistogram&) = delete;
~SparseHistogram() override;
// HistogramBase:
uint64_t name_hash() const override;
HistogramType GetHistogramType() const override;
bool HasConstructionArguments(Sample32 expected_minimum,
Sample32 expected_maximum,
size_t expected_bucket_count) const override;
void Add(Sample32 value) override;
void AddCount(Sample32 value, int count) override;
bool AddSamples(const HistogramSamples& samples) override;
bool AddSamplesFromPickle(base::PickleIterator* iter) override;
std::unique_ptr<HistogramSamples> SnapshotSamples() const override;
std::unique_ptr<HistogramSamples> SnapshotUnloggedSamples() const override;
void MarkSamplesAsLogged(const HistogramSamples& samples) override;
std::unique_ptr<HistogramSamples> SnapshotDelta() override;
std::unique_ptr<HistogramSamples> SnapshotFinalDelta() const override;
base::Value::Dict ToGraphDict() const override;
protected:
// HistogramBase:
void SerializeInfoImpl(base::Pickle* pickle) const override;
private:
// Clients should always use FactoryGet to create SparseHistogram.
explicit SparseHistogram(DurableStringView name);
// Same as above, but takes a pre-computed `name_hash`. This function is more
// efficient as it avoids recomputing the hash if it's already known. The
// `name_hash` must be the hash of `name`, this is enforced with a DCHECK.
SparseHistogram(DurableStringView name, uint64_t name_hash);
SparseHistogram(PersistentHistogramAllocator* allocator,
DurableStringView name,
uint64_t name_hash,
HistogramSamples::Metadata* meta,
HistogramSamples::Metadata* logged_meta);
friend BASE_EXPORT HistogramBase* DeserializeHistogramInfo(
base::PickleIterator* iter);
static HistogramBase* DeserializeInfoImpl(base::PickleIterator* iter);
// Writes the type of the sparse histogram in the |params|.
Value::Dict GetParameters() const override;
// For constructor calling.
friend class SparseHistogramTest;
friend class HistogramThreadsafeTest;
// Protects access to |samples_|.
mutable base::Lock lock_;
// Flag to indicate if PrepareFinalDelta has been previously called.
mutable bool final_delta_created_ = false;
std::unique_ptr<HistogramSamples> unlogged_samples_;
std::unique_ptr<HistogramSamples> logged_samples_;
};
} // namespace base
#endif // BASE_METRICS_SPARSE_HISTOGRAM_H_
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