| // 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 SERVICES_DEVICE_COMPUTE_PRESSURE_PROCFS_STAT_CPU_PARSER_H_ |
| #define SERVICES_DEVICE_COMPUTE_PRESSURE_PROCFS_STAT_CPU_PARSER_H_ |
| |
| #include <stdint.h> |
| |
| #include <vector> |
| |
| #include "base/files/file_path.h" |
| #include "base/sequence_checker.h" |
| #include "base/strings/string_piece.h" |
| #include "base/thread_annotations.h" |
| #include "services/device/compute_pressure/core_times.h" |
| |
| namespace device { |
| |
| // 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(base::StringPiece stat_line); |
| |
| static void UpdateCore(base::StringPiece 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 device |
| |
| #endif // SERVICES_DEVICE_COMPUTE_PRESSURE_PROCFS_STAT_CPU_PARSER_H_ |