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      1 /*
      2  * Copyright (C) 2007 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 android.util;
     18 
     19 import java.util.ArrayList;
     20 
     21 import android.os.SystemClock;
     22 
     23 /**
     24  * A utility class to help log timings splits throughout a method call.
     25  * Typical usage is:
     26  *
     27  * TimingLogger timings = new TimingLogger(TAG, "methodA");
     28  * ... do some work A ...
     29  * timings.addSplit("work A");
     30  * ... do some work B ...
     31  * timings.addSplit("work B");
     32  * ... do some work C ...
     33  * timings.addSplit("work C");
     34  * timings.dumpToLog();
     35  *
     36  * The dumpToLog call would add the following to the log:
     37  *
     38  * D/TAG     ( 3459): methodA: begin
     39  * D/TAG     ( 3459): methodA:      9 ms, work A
     40  * D/TAG     ( 3459): methodA:      1 ms, work B
     41  * D/TAG     ( 3459): methodA:      6 ms, work C
     42  * D/TAG     ( 3459): methodA: end, 16 ms
     43  */
     44 public class TimingLogger {
     45 
     46     /**
     47      * The Log tag to use for checking Log.isLoggable and for
     48      * logging the timings.
     49      */
     50     private String mTag;
     51 
     52     /** A label to be included in every log. */
     53     private String mLabel;
     54 
     55     /** Used to track whether Log.isLoggable was enabled at reset time. */
     56     private boolean mDisabled;
     57 
     58     /** Stores the time of each split. */
     59     ArrayList<Long> mSplits;
     60 
     61     /** Stores the labels for each split. */
     62     ArrayList<String> mSplitLabels;
     63 
     64     /**
     65      * Create and initialize a TimingLogger object that will log using
     66      * the specific tag. If the Log.isLoggable is not enabled to at
     67      * least the Log.VERBOSE level for that tag at creation time then
     68      * the addSplit and dumpToLog call will do nothing.
     69      * @param tag the log tag to use while logging the timings
     70      * @param label a string to be displayed with each log
     71      */
     72     public TimingLogger(String tag, String label) {
     73         reset(tag, label);
     74     }
     75 
     76     /**
     77      * Clear and initialize a TimingLogger object that will log using
     78      * the specific tag. If the Log.isLoggable is not enabled to at
     79      * least the Log.VERBOSE level for that tag at creation time then
     80      * the addSplit and dumpToLog call will do nothing.
     81      * @param tag the log tag to use while logging the timings
     82      * @param label a string to be displayed with each log
     83      */
     84     public void reset(String tag, String label) {
     85         mTag = tag;
     86         mLabel = label;
     87         reset();
     88     }
     89 
     90     /**
     91      * Clear and initialize a TimingLogger object that will log using
     92      * the tag and label that was specified previously, either via
     93      * the constructor or a call to reset(tag, label). If the
     94      * Log.isLoggable is not enabled to at least the Log.VERBOSE
     95      * level for that tag at creation time then the addSplit and
     96      * dumpToLog call will do nothing.
     97      */
     98     public void reset() {
     99         mDisabled = !Log.isLoggable(mTag, Log.VERBOSE);
    100         if (mDisabled) return;
    101         if (mSplits == null) {
    102             mSplits = new ArrayList<Long>();
    103             mSplitLabels = new ArrayList<String>();
    104         } else {
    105             mSplits.clear();
    106             mSplitLabels.clear();
    107         }
    108         addSplit(null);
    109     }
    110 
    111     /**
    112      * Add a split for the current time, labeled with splitLabel. If
    113      * Log.isLoggable was not enabled to at least the Log.VERBOSE for
    114      * the specified tag at construction or reset() time then this
    115      * call does nothing.
    116      * @param splitLabel a label to associate with this split.
    117      */
    118     public void addSplit(String splitLabel) {
    119         if (mDisabled) return;
    120         long now = SystemClock.elapsedRealtime();
    121         mSplits.add(now);
    122         mSplitLabels.add(splitLabel);
    123     }
    124 
    125     /**
    126      * Dumps the timings to the log using Log.d(). If Log.isLoggable was
    127      * not enabled to at least the Log.VERBOSE for the specified tag at
    128      * construction or reset() time then this call does nothing.
    129      */
    130     public void dumpToLog() {
    131         if (mDisabled) return;
    132         Log.d(mTag, mLabel + ": begin");
    133         final long first = mSplits.get(0);
    134         long now = first;
    135         for (int i = 1; i < mSplits.size(); i++) {
    136             now = mSplits.get(i);
    137             final String splitLabel = mSplitLabels.get(i);
    138             final long prev = mSplits.get(i - 1);
    139 
    140             Log.d(mTag, mLabel + ":      " + (now - prev) + " ms, " + splitLabel);
    141         }
    142         Log.d(mTag, mLabel + ": end, " + (now - first) + " ms");
    143     }
    144 }
    145