chromium/components/metrics/psi_memory_parser.h

// Copyright 2021 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#ifndef COMPONENTS_METRICS_PSI_MEMORY_PARSER_H_
#define COMPONENTS_METRICS_PSI_MEMORY_PARSER_H_

#include <cstdint>
#include <string>
#include <string_view>

#include "base/gtest_prod_util.h"

namespace metrics {

// Items in internal are - as the name implies - NOT for outside consumption.
// Defined here to allow access to unit test.
namespace internal {

// Finds the bounds for a substring of |content| which is sandwiched between
// the given |prefix| and |suffix| indices. Search only considers
// the portion of the string starting from |search_start|.
// Returns false if the prefix and/or suffix are not found, true otherwise.
// |start| and |end| are output parameters populated with the indices
// for the middle string.
bool FindMiddleString(std::string_view content,
                      size_t search_start,
                      std::string_view prefix,
                      std::string_view suffix,
                      size_t* start,
                      size_t* end);

}  // namespace internal

// Values as logged in the histogram for memory pressure.
constexpr int kMemPressureMin = …;  // As 0 is for underflow.
constexpr int kMemPressureExclusiveMax = …;
constexpr int kMemPressureHistogramBuckets = …;

// Enumeration representing success and various failure modes for parsing PSI
// memory data. These values are persisted to logs. Entries should not be
// renumbered and numeric values should never be reused.
enum class ParsePSIMemStatus { … };

// PSIMemoryParser has logic to parse results from /proc/memory/pressure
// in Linux, which can be used for memory pressure metrics.
class PSIMemoryParser { … };

}  // namespace metrics

#endif  // COMPONENTS_METRICS_PSI_MEMORY_PARSER_H_