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      1 /*
      2  * Copyright (C) 2012 The Android Open Source Project
      3  *
      4  * Licensed under the Apache License, Version 2.0 (the "License");
      5  * you may not use this file except in compliance with the License.
      6  * You may obtain a copy of the License at
      7  *
      8  *      http://www.apache.org/licenses/LICENSE-2.0
      9  *
     10  * Unless required by applicable law or agreed to in writing, software
     11  * distributed under the License is distributed on an "AS IS" BASIS,
     12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
     13  * See the License for the specific language governing permissions and
     14  * limitations under the License.
     15  */
     16 
     17 package com.android.contacts.common.util;
     18 
     19 import android.util.Log;
     20 
     21 import com.google.common.collect.Lists;
     22 
     23 import java.util.ArrayList;
     24 
     25 /**
     26  * A {@link StopWatch} records start, laps and stop, and print them to logcat.
     27  */
     28 public class StopWatch {
     29 
     30     private final String mLabel;
     31 
     32     private final ArrayList<Long> mTimes = Lists.newArrayList();
     33     private final ArrayList<String> mLapLabels = Lists.newArrayList();
     34 
     35     private StopWatch(String label) {
     36         mLabel = label;
     37         lap("");
     38     }
     39 
     40     /**
     41      * Create a new instance and start it.
     42      */
     43     public static StopWatch start(String label) {
     44         return new StopWatch(label);
     45     }
     46 
     47     /**
     48      * Record a lap.
     49      */
     50     public void lap(String lapLabel) {
     51         mTimes.add(System.currentTimeMillis());
     52         mLapLabels.add(lapLabel);
     53     }
     54 
     55     /**
     56      * Stop it and log the result, if the total time >= {@code timeThresholdToLog}.
     57      */
     58     public void stopAndLog(String TAG, int timeThresholdToLog) {
     59 
     60         lap("");
     61 
     62         final long start = mTimes.get(0);
     63         final long stop = mTimes.get(mTimes.size() - 1);
     64 
     65         final long total = stop - start;
     66         if (total < timeThresholdToLog) return;
     67 
     68         final StringBuilder sb = new StringBuilder();
     69         sb.append(mLabel);
     70         sb.append(",");
     71         sb.append(total);
     72         sb.append(": ");
     73 
     74         long last = start;
     75         for (int i = 1; i < mTimes.size(); i++) {
     76             final long current = mTimes.get(i);
     77             sb.append(mLapLabels.get(i));
     78             sb.append(",");
     79             sb.append((current - last));
     80             sb.append(" ");
     81             last = current;
     82         }
     83         Log.v(TAG, sb.toString());
     84     }
     85 
     86     /**
     87      * Return a dummy instance that does no operations.
     88      */
     89     public static StopWatch getNullStopWatch() {
     90         return NullStopWatch.INSTANCE;
     91     }
     92 
     93     private static class NullStopWatch extends StopWatch {
     94         public static final NullStopWatch INSTANCE = new NullStopWatch();
     95 
     96         public NullStopWatch() {
     97             super(null);
     98         }
     99 
    100         @Override
    101         public void lap(String lapLabel) {
    102             // noop
    103         }
    104 
    105         @Override
    106         public void stopAndLog(String TAG, int timeThresholdToLog) {
    107             // noop
    108         }
    109     }
    110 }
    111