src/xwalk/runtime/android/java/src/org/xwalk/runtime/extension/api/device_capabilities/DeviceCapabilitiesCPU.java

   1 // Copyright (c) 2013 Intel Corporation. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 package org.xwalk.runtime.extension.api.device_capabilities;
   6
   7 import android.util.Log;
   8
   9 import java.io.RandomAccessFile;
  10 import java.io.IOException;
  11
  12 import org.json.JSONException;
  13 import org.json.JSONObject;
  14 import org.xwalk.runtime.extension.XWalkExtensionContext;
  15
  16 class DeviceCapabilitiesCPU {
  17     private static final String SYSTEM_INFO_STAT_FILE = "/proc/stat";
  18     private static final String TAG = "DeviceCapabilitiesCPU";
  19
  20     private DeviceCapabilities mDeviceCapabilities;
  21
  22     private int mCoreNum = 0;
  23     private String mCPUArch = "Unknown";
  24     private double mCPULoad = 0.0;
  25
  26     public DeviceCapabilitiesCPU(DeviceCapabilities instance,
  27                                  XWalkExtensionContext context) {
  28         mDeviceCapabilities = instance;
  29
  30         // Get arch and core number at constructor since they won't change time to time.
  31         mCoreNum = Runtime.getRuntime().availableProcessors();
  32         mCPUArch = System.getProperty("os.arch");
  33     }
  34
  35     public JSONObject getInfo() {
  36         getCPULoad();
  37
  38         JSONObject out = new JSONObject();
  39         try {
  40             out.put("numOfProcessors", mCoreNum);
  41             out.put("archName", mCPUArch);
  42             out.put("load", mCPULoad);
  43         } catch (JSONException e) {
  44             return mDeviceCapabilities.setErrorMessage(e.toString());
  45         }
  46
  47         return out;
  48     }
  49
  50     /**
  51      * The algorithm here can be found at:
  52      * http://stackoverflow.com/questions/3017162/how-to-get-total-cpu-usage-in-linux-c
  53      */
  54     private boolean getCPULoad() {
  55         try {
  56             RandomAccessFile file = new RandomAccessFile(SYSTEM_INFO_STAT_FILE, "r");
  57             String line = file.readLine();
  58
  59             String[] arrs = line.split("\\s+");
  60             long total1 = 0;
  61             for (int i = 1; i < arrs.length; ++i) {
  62                 total1 += Long.parseLong(arrs[i]);
  63             }
  64             // arrs[4] is the time spent in idle tasks.
  65             long used1 = total1 - Long.parseLong(arrs[4]);
  66             try {
  67                 Thread.sleep(1000);
  68             } catch (Exception e) {
  69                 mCPULoad = 0.0;
  70                 return false;
  71             }
  72
  73             file.seek(0);
  74             line = file.readLine();
  75             file.close();
  76
  77             arrs = line.split("\\s+");
  78             long total2 = 0;
  79             for (int i = 1; i < arrs.length; ++i) {
  80                 total2 += Long.parseLong(arrs[i]);
  81             }
  82             // arrs[4] is the time spent in idle tasks.
  83             long used2 = total2 - Long.parseLong(arrs[4]);
  84             if (total2 == total1) {
  85                 mCPULoad = 0.0;
  86             } else {
  87                 mCPULoad = (double) (used2 - used1) / (total2 - total1);
  88             }
  89         } catch (IOException e) {
  90             mCPULoad = 0.0;
  91             return false;
  92         }
  93         return true;
  94     }
  95 }