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// 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_SYSTEM_CPU_PROCFS_STAT_CPU_PARSER_H_
#define COMPONENTS_SYSTEM_CPU_PROCFS_STAT_CPU_PARSER_H_
#include <stdint.h>
#include <string_view>
#include <vector>
#include "base/files/file_path.h"
#include "base/sequence_checker.h"
#include "base/thread_annotations.h"
#include "components/system_cpu/core_times.h"
namespace system_cpu {
// Parses CPU time usage stats from procfs (/proc/stat).
//
// This class is not thread-safe. Each instance must be used on the same
// sequence, which must allow blocking I/O. The constructor may be used on a
// different sequence.
class ProcfsStatCpuParser {
public:
// The "production" `procfs_path` value for the constructor.
static constexpr base::FilePath::CharType kProcfsStatPath[] =
FILE_PATH_LITERAL("/proc/stat");
// `stat_path` is exposed for testing. Production instances should be
// constructed using base::FilePath(kProcfsStatPath).
explicit ProcfsStatCpuParser(base::FilePath stat_path);
~ProcfsStatCpuParser();
ProcfsStatCpuParser(const ProcfsStatCpuParser&) = delete;
ProcfsStatCpuParser& operator=(const ProcfsStatCpuParser&) = delete;
const std::vector<CoreTimes>& core_times() const {
DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);
return core_times_;
}
// Reads /proc/stat and updates the vector returned by core_times().
//
// Returns false if parsing fails. This only happens if /proc/stat is not
// accessible. Invalid data is ignored.
//
// Cores without entries in /proc/stat will remain unchanged. Counters that
// decrease below the last parsed value are ignored.
bool Update();
private:
// Returns -1 if the line does not include any CPU.
static int CoreIdFromLine(std::string_view stat_line);
static void UpdateCore(std::string_view core_line, CoreTimes& core_times);
SEQUENCE_CHECKER(sequence_checker_);
const base::FilePath stat_path_;
std::vector<CoreTimes> core_times_ GUARDED_BY_CONTEXT(sequence_checker_);
};
} // namespace system_cpu
#endif // COMPONENTS_SYSTEM_CPU_PROCFS_STAT_CPU_PARSER_H_
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