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/*
* Copyright (C) 2009 The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package com.android.camera;
import android.util.Log;
// A simple counter to measure the time to run a code fragment. Example:
//
// TimeCounter mDrawCounter = TimeCounter("Draw", 128);
// ...
// mDrawCounter.begin()
// // drawing code
// mDrawCounter.end()
//
// In this example, the counter will report (using Log.d) average time
// between begin() and end() every 128 times.
public class TimeCounter {
private static final String TAG = "TimeCounter";
private final String mName;
private int mSamples;
private final int mPeriod;
// To avoid overflow, these values are in microseconds.
private long mSum;
private long mSumSquare;
private long mBeginTime;
private long mMax;
private long mMin;
public TimeCounter(String name, int period) {
mName = name;
mPeriod = period;
reset();
}
public void reset() {
mSamples = 0;
mSum = 0;
mSumSquare = 0;
mMax = Long.MIN_VALUE;
mMin = Long.MAX_VALUE;
}
public void begin() {
mBeginTime = System.nanoTime();
}
public void end() {
long delta = (System.nanoTime() - mBeginTime) / 1000;
mSum += delta;
mSumSquare += delta * delta;
if (delta > mMax) mMax = delta;
if (delta < mMin) mMin = delta;
mSamples++;
if (mSamples == mPeriod) {
report();
reset();
}
}
public void report() {
double avg = mSum / (double) mSamples;
double stddev = Math.sqrt(mSumSquare / (double) mSamples - avg * avg);
Log.d(TAG, "Counter " + mName
+ ": Avg = " + avg
+ ", StdDev = " + stddev
+ ", Max = " + mMax
+ ", Min = " + mMin);
}
}
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