Move talk/examples/* to webrtc/examples.

talk/examples/android/src/org/appspot/apprtc/CpuMonitor.java

-/*
- * libjingle
- * Copyright 2015 Google Inc.
- *
- * Redistribution and use in source and binary forms, with or without
- * modification, are permitted provided that the following conditions are met:
- *
- *  1. Redistributions of source code must retain the above copyright notice,
- *     this list of conditions and the following disclaimer.
- *  2. Redistributions in binary form must reproduce the above copyright notice,
- *     this list of conditions and the following disclaimer in the documentation
- *     and/or other materials provided with the distribution.
- *  3. The name of the author may not be used to endorse or promote products
- *     derived from this software without specific prior written permission.
- *
- * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED
- * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
- * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO
- * EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
- * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
- * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS;
- * OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
- * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR
- * OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
- * ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
- */
-
-package org.appspot.apprtc;
-
-import android.util.Log;
-
-import java.io.BufferedReader;
-import java.io.FileNotFoundException;
-import java.io.FileReader;
-import java.io.IOException;
-import java.util.InputMismatchException;
-import java.util.Scanner;
-
-/**
- * Simple CPU monitor.  The caller creates a CpuMonitor object which can then
- * be used via sampleCpuUtilization() to collect the percentual use of the
- * cumulative CPU capacity for all CPUs running at their nominal frequency.  3
- * values are generated: (1) getCpuCurrent() returns the use since the last
- * sampleCpuUtilization(), (2) getCpuAvg3() returns the use since 3 prior
- * calls, and (3) getCpuAvgAll() returns the use over all SAMPLE_SAVE_NUMBER
- * calls.
- *
- * <p>CPUs in Android are often "offline", and while this of course means 0 Hz
- * as current frequency, in this state we cannot even get their nominal
- * frequency.  We therefore tread carefully, and allow any CPU to be missing.
- * Missing CPUs are assumed to have the same nominal frequency as any close
- * lower-numbered CPU, but as soon as it is online, we'll get their proper
- * frequency and remember it.  (Since CPU 0 in practice always seem to be
- * online, this unidirectional frequency inheritance should be no problem in
- * practice.)
- *
- * <p>Caveats:
- *   o No provision made for zany "turbo" mode, common in the x86 world.
- *   o No provision made for ARM big.LITTLE; if CPU n can switch behind our
- *     back, we might get incorrect estimates.
- *   o This is not thread-safe.  To call asynchronously, create different
- *     CpuMonitor objects.
- *
- * <p>If we can gather enough info to generate a sensible result,
- * sampleCpuUtilization returns true.  It is designed to never through an
- * exception.
- *
- * <p>sampleCpuUtilization should not be called too often in its present form,
- * since then deltas would be small and the percent values would fluctuate and
- * be unreadable. If it is desirable to call it more often than say once per
- * second, one would need to increase SAMPLE_SAVE_NUMBER and probably use
- * Queue<Integer> to avoid copying overhead.
- *
- * <p>Known problems:
- *   1. Nexus 7 devices running Kitkat have a kernel which often output an
- *      incorrect 'idle' field in /proc/stat.  The value is close to twice the
- *      correct value, and then returns to back to correct reading.  Both when
- *      jumping up and back down we might create faulty CPU load readings.
- */
-
-class CpuMonitor {
-  private static final int SAMPLE_SAVE_NUMBER = 10;  // Assumed to be >= 3.
-  private int[] percentVec = new int[SAMPLE_SAVE_NUMBER];
-  private int sum3 = 0;
-  private int sum10 = 0;
-  private static final String TAG = "CpuMonitor";
-  private long[] cpuFreq;
-  private int cpusPresent;
-  private double lastPercentFreq = -1;
-  private int cpuCurrent;
-  private int cpuAvg3;
-  private int cpuAvgAll;
-  private boolean initialized = false;
-  private String[] maxPath;
-  private String[] curPath;
-  ProcStat lastProcStat;
-
-  private class ProcStat {
-    final long runTime;
-    final long idleTime;
-
-    ProcStat(long aRunTime, long aIdleTime) {
-      runTime = aRunTime;
-      idleTime = aIdleTime;
-    }
-  }
-
-  private void init() {
-    try {
-      FileReader fin = new FileReader("/sys/devices/system/cpu/present");
-      try {
-        BufferedReader rdr = new BufferedReader(fin);
-        Scanner scanner = new Scanner(rdr).useDelimiter("[-\n]");
-        scanner.nextInt();  // Skip leading number 0.
-        cpusPresent = 1 + scanner.nextInt();
-        scanner.close();
-      } catch (Exception e) {
-        Log.e(TAG, "Cannot do CPU stats due to /sys/devices/system/cpu/present parsing problem");
-      } finally {
-        fin.close();
-      }
-    } catch (FileNotFoundException e) {
-      Log.e(TAG, "Cannot do CPU stats since /sys/devices/system/cpu/present is missing");
-    } catch (IOException e) {
-      Log.e(TAG, "Error closing file");
-    }
-
-    cpuFreq = new long [cpusPresent];
-    maxPath = new String [cpusPresent];
-    curPath = new String [cpusPresent];
-    for (int i = 0; i < cpusPresent; i++) {
-      cpuFreq[i] = 0;  // Frequency "not yet determined".
-      maxPath[i] = "/sys/devices/system/cpu/cpu" + i + "/cpufreq/cpuinfo_max_freq";
-      curPath[i] = "/sys/devices/system/cpu/cpu" + i + "/cpufreq/scaling_cur_freq";
-    }
-
-    lastProcStat = new ProcStat(0, 0);
-
-    initialized = true;
-  }
-
-  /**
-   * Re-measure CPU use.  Call this method at an interval of around 1/s.
-   * This method returns true on success.  The fields
-   * cpuCurrent, cpuAvg3, and cpuAvgAll are updated on success, and represents:
-   * cpuCurrent: The CPU use since the last sampleCpuUtilization call.
-   * cpuAvg3: The average CPU over the last 3 calls.
-   * cpuAvgAll: The average CPU over the last SAMPLE_SAVE_NUMBER calls.
-   */
-  public boolean sampleCpuUtilization() {
-    long lastSeenMaxFreq = 0;
-    long cpufreqCurSum = 0;
-    long cpufreqMaxSum = 0;
-
-    if (!initialized) {
-      init();
-    }
-
-    for (int i = 0; i < cpusPresent; i++) {
-      /*
-       * For each CPU, attempt to first read its max frequency, then its
-       * current frequency.  Once as the max frequency for a CPU is found,
-       * save it in cpuFreq[].
-       */
-
-      if (cpuFreq[i] == 0) {
-        // We have never found this CPU's max frequency.  Attempt to read it.
-        long cpufreqMax = readFreqFromFile(maxPath[i]);
-        if (cpufreqMax > 0) {
-          lastSeenMaxFreq = cpufreqMax;
-          cpuFreq[i] = cpufreqMax;
-          maxPath[i] = null;  // Kill path to free its memory.
-        }
-      } else {
-        lastSeenMaxFreq = cpuFreq[i];  // A valid, previously read value.
-      }
-
-      long cpufreqCur = readFreqFromFile(curPath[i]);
-      cpufreqCurSum += cpufreqCur;
-
-      /* Here, lastSeenMaxFreq might come from
-       * 1. cpuFreq[i], or
-       * 2. a previous iteration, or
-       * 3. a newly read value, or
-       * 4. hypothetically from the pre-loop dummy.
-       */
-      cpufreqMaxSum += lastSeenMaxFreq;
-    }
-
-    if (cpufreqMaxSum == 0) {
-      Log.e(TAG, "Could not read max frequency for any CPU");
-      return false;
-    }
-
-    /*
-     * Since the cycle counts are for the period between the last invocation
-     * and this present one, we average the percentual CPU frequencies between
-     * now and the beginning of the measurement period.  This is significantly
-     * incorrect only if the frequencies have peeked or dropped in between the
-     * invocations.
-     */
-    double newPercentFreq = 100.0 * cpufreqCurSum / cpufreqMaxSum;
-    double percentFreq;
-    if (lastPercentFreq > 0) {
-      percentFreq = (lastPercentFreq + newPercentFreq) * 0.5;
-    } else {
-      percentFreq = newPercentFreq;
-    }
-    lastPercentFreq = newPercentFreq;
-
-    ProcStat procStat = readIdleAndRunTime();
-    if (procStat == null) {
-      return false;
-    }
-
-    long diffRunTime = procStat.runTime - lastProcStat.runTime;
-    long diffIdleTime = procStat.idleTime - lastProcStat.idleTime;
-
-    // Save new measurements for next round's deltas.
-    lastProcStat = procStat;
-
-    long allTime = diffRunTime + diffIdleTime;
-    int percent = allTime == 0 ? 0 : (int) Math.round(percentFreq * diffRunTime / allTime);
-    percent = Math.max(0, Math.min(percent, 100));
-
-    // Subtract old relevant measurement, add newest.
-    sum3 += percent - percentVec[2];
-    // Subtract oldest measurement, add newest.
-    sum10 += percent - percentVec[SAMPLE_SAVE_NUMBER - 1];
-
-    // Rotate saved percent values, save new measurement in vacated spot.
-    for (int i = SAMPLE_SAVE_NUMBER - 1; i > 0; i--) {
-      percentVec[i] = percentVec[i - 1];
-    }
-    percentVec[0] = percent;
-
-    cpuCurrent = percent;
-    cpuAvg3 = sum3 / 3;
-    cpuAvgAll = sum10 / SAMPLE_SAVE_NUMBER;
-
-    return true;
-  }
-
-  public int getCpuCurrent() {
-    return cpuCurrent;
-  }
-
-  public int getCpuAvg3() {
-    return cpuAvg3;
-  }
-
-  public int getCpuAvgAll() {
-    return cpuAvgAll;
-  }
-
-  /**
-   * Read a single integer value from the named file.  Return the read value
-   * or if an error occurs return 0.
-   */
-  private long readFreqFromFile(String fileName) {
-    long number = 0;
-    try {
-      FileReader fin = new FileReader(fileName);
-      try {
-        BufferedReader rdr = new BufferedReader(fin);
-        Scanner scannerC = new Scanner(rdr);
-        number = scannerC.nextLong();
-        scannerC.close();
-      } catch (Exception e) {
-        // CPU presumably got offline just after we opened file.
-      } finally {
-        fin.close();
-      }
-    } catch (FileNotFoundException e) {
-      // CPU is offline, not an error.
-    } catch (IOException e) {
-      Log.e(TAG, "Error closing file");
-    }
-    return number;
-  }
-
-  /*
-   * Read the current utilization of all CPUs using the cumulative first line
-   * of /proc/stat.
-   */
-  private ProcStat readIdleAndRunTime() {
-    long runTime = 0;
-    long idleTime = 0;
-    try {
-      FileReader fin = new FileReader("/proc/stat");
-      try {
-        BufferedReader rdr = new BufferedReader(fin);
-        Scanner scanner = new Scanner(rdr);
-        scanner.next();
-        long user = scanner.nextLong();
-        long nice = scanner.nextLong();
-        long sys = scanner.nextLong();
-        runTime = user + nice + sys;
-        idleTime = scanner.nextLong();
-        scanner.close();
-      } catch (Exception e) {
-        Log.e(TAG, "Problems parsing /proc/stat");
-        return null;
-      } finally {
-        fin.close();
-      }
-    } catch (FileNotFoundException e) {
-      Log.e(TAG, "Cannot open /proc/stat for reading");
-      return null;
-    } catch (IOException e) {
-      Log.e(TAG, "Problems reading /proc/stat");
-      return null;
-    }
-    return new ProcStat(runTime, idleTime);
-  }
-}