Add parser for new cpu freq file

chrome/browser/chromeos/power/cpu_data_collector.h

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef CHROME_BROWSER_CHROMEOS_POWER_CPU_DATA_COLLECTOR_H_
 #define CHROME_BROWSER_CHROMEOS_POWER_CPU_DATA_COLLECTOR_H_
 
 #include <stdint.h>
 
 #include <deque>
@@ skipping 25 matching lines @@
     base::Time time;
 
     // Indicates whether the CPU is online.
     bool cpu_online;
 
     // A mapping from a CPU state to time spent in that state in milliseconds.
     // For idle state samples, the name of the state at index i in this vector
     // is the name at index i in the vector returned by cpu_idle_state_names().
     // Similarly, for freq state occupancy, similar information is in the vector
     // returned by cpu_freq_state_names().
     std::vector<int64_t> time_in_state;

[Daniel Erat, 2017/05/02 23:41:10]

if you're up for changing this, it should be either ms_in_state or (even better)
a std::vector<base::TimeDelta>, which is completely unambiguous.

[weidongg, 2017/05/03 21:32:31]

time_in_state here may try to be consistent with the cpu freq file name in linux
kernel.
https://cs.chromium.org/chromium/src/chrome/browser/chromeos/power/cpu_data_c...
Maybe change it to time_in_state_milisecond (which is a little bit long)?

[Daniel Erat, 2017/05/03 22:08:21]

time_in_state_ms would be okay, but using base::TimeDelta is even better. it's
also 64 bits and copyable, but it doesn't have any ambiguity about units.

   };
 
   typedef std::deque<StateOccupancySample> StateOccupancySampleDeque;
 
   const std::vector<std::string>& cpu_idle_state_names() const {
     return cpu_idle_state_names_;
   }
 
   const std::vector<StateOccupancySampleDeque>& cpu_idle_state_data() const {
     return cpu_idle_state_data_;
   }
 
   const std::vector<std::string>& cpu_freq_state_names() const {
     return cpu_freq_state_names_;
   }
 
   const std::vector<StateOccupancySampleDeque>& cpu_freq_state_data() const {
     return cpu_freq_state_data_;
   }
 
   CpuDataCollector();
   ~CpuDataCollector();
 
   // Starts a repeating timer which periodically runs a callback to collect
   // CPU state occupancy samples.
   void Start();
 
+  // Samples the CPU idle state information from sysfs. |cpu_count| is the
+  // number of possible CPUs on the system. Sample at index i in |idle_samples|
+  // corresponds to the idle state information of the i-th CPU.
+  static void SampleCpuIdleData(

[Daniel Erat, 2017/05/02 23:41:10]

only the methods that you're actually calling from tests need to be public
static methods. everything else should only be declared in the .cc file as
before.

[weidongg, 2017/05/03 21:32:31]

Done.

+      int cpu_count,
+      std::vector<std::string>* cpu_idle_state_names,
+      std::vector<CpuDataCollector::StateOccupancySample>* idle_samples);
+
+  // Read CPU frequency data of a specific CPU from the file in |path| and fill
+  // |cpu_freq_state_names| and |freq_sample| with the data.
+  // Sample file looks like:
+  // 126000 223344
+  // 216000 93495
+  // ...
+  // 1800000 321907
+  static bool ReadCpuFreqTimeInState(
+      const std::string& path,
+      std::vector<std::string>* cpu_freq_state_names,
+      CpuDataCollector::StateOccupancySample* freq_sample);
+
+  // Read CPU frequency data of all CPUs from the file in |path| and fill
+  // |cpu_freq_state_names| and |freq_samples| with the data. |cpu_count| is the
+  // number of possible CPUs on the system. Note that |freq_samples| is not
+  // empty and sample at index i in |freq_samples| corresponds to the freq state
+  // information of the i-th CPU. |cpu_online| of each sample must be set before
+  // calling this function.
+  // Sample file looks like:
+  // freq   cpu0    cpu1
+  // 126000   223344    223311
+  // 216000   93495   93450
+  // ...
+  // 1800000    321907    331897
+  static bool ReadCpuFreqAllTimeInState(
+      int cpu_count,
+      const std::string& path,
+      std::vector<std::string>* cpu_freq_state_names,
+      std::vector<CpuDataCollector::StateOccupancySample>* freq_samples);
+
+  // Samples the CPU freq state information from sysfs. |cpu_count| is the
+  // number of possible CPUs on the system. Sample at index i in |freq_samples|
+  // corresponds to the freq state information of the i-th CPU.
+  static void SampleCpuFreqData(

[Daniel Erat, 2017/05/02 23:41:10]

see above

[weidongg, 2017/05/03 21:32:31]

Done.

+      int cpu_count,
+      std::vector<std::string>* cpu_freq_state_names,
+      std::vector<CpuDataCollector::StateOccupancySample>* freq_samples);
+
+  // Samples CPU idle and CPU freq data from sysfs. This function should run on
+  // the blocking pool as reading from sysfs is a blocking task. Elements at
+  // index i in |idle_samples| and |freq_samples| correspond to the idle and
+  // freq samples of CPU i. This also function reads the number of CPUs from
+  // sysfs if *|cpu_count| < 0.
+  static void SampleCpuStateAsync(

[Daniel Erat, 2017/05/02 23:41:10]

see above

[weidongg, 2017/05/03 21:32:31]

Done.

+      int* cpu_count,
+      std::vector<std::string>* cpu_idle_state_names,
+      std::vector<CpuDataCollector::StateOccupancySample>* idle_samples,
+      std::vector<std::string>* cpu_freq_state_names,
+      std::vector<CpuDataCollector::StateOccupancySample>* freq_samples);
+
  private:
   // Posts callbacks to the blocking pool which collect CPU state occupancy
   // samples from the sysfs.
   void PostSampleCpuState();
 
   // This function commits the CPU count and samples read by
   // SampleCpuStateAsync to |cpu_idle_state_data_| and
   // |cpu_freq_state_data_|. Since UI is the consumer of CPU idle and freq data,
   // this function should run on the UI thread.
   void SaveCpuStateSamplesOnUIThread(
@@ skipping 23 matching lines @@
   // hence should be read/written to only from the blocking pool.
   int cpu_count_;
 
   base::WeakPtrFactory<CpuDataCollector> weak_ptr_factory_;
   DISALLOW_COPY_AND_ASSIGN(CpuDataCollector);
 };
 
 }  // namespace chromeos
 
 #endif  // CHROME_BROWSER_CHROMEOS_POWER_CPU_DATA_COLLECTOR_H_