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      1 /*
      2  * Copyright (C) 2018 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.google.android.setupcompat.logging;
     18 
     19 import android.util.Log;
     20 import com.google.android.setupcompat.internal.ClockProvider;
     21 import com.google.android.setupcompat.internal.Preconditions;
     22 
     23 /** Convenience utility to log duration events. Please note that this class is not thread-safe. */
     24 public final class Timer {
     25   /** Creates a new instance of timer for the given {@code metricKey}. */
     26   public Timer(MetricKey metricKey) {
     27     this.metricKey = metricKey;
     28   }
     29 
     30   /**
     31    * Starts the timer and notes the current clock time.
     32    *
     33    * @throws IllegalStateException if the timer was stopped.
     34    */
     35   public void start() {
     36     Preconditions.checkState(!isStopped(), "Timer cannot be started once stopped.");
     37     if (isStarted()) {
     38       Log.wtf(
     39           TAG,
     40           String.format(
     41               "Timer instance was already started for: %s at [%s].", metricKey, startInNanos));
     42       return;
     43     }
     44     startInNanos = ClockProvider.timeInNanos();
     45   }
     46 
     47   /**
     48    * Stops the watch and the current clock time is noted.
     49    *
     50    * @throws IllegalStateException if the watch was not started.
     51    */
     52   public void stop() {
     53     Preconditions.checkState(isStarted(), "Timer must be started before it can be stopped.");
     54     if (isStopped()) {
     55       Log.wtf(
     56           TAG,
     57           String.format(
     58               "Timer instance was already stopped for: %s at [%s]", metricKey, stopInNanos));
     59       return;
     60     }
     61     stopInNanos = ClockProvider.timeInNanos();
     62   }
     63 
     64   boolean isStopped() {
     65     return stopInNanos != 0;
     66   }
     67 
     68   private boolean isStarted() {
     69     return startInNanos != 0;
     70   }
     71 
     72   long getDurationInNanos() {
     73     return stopInNanos - startInNanos;
     74   }
     75 
     76   MetricKey getMetricKey() {
     77     return metricKey;
     78   }
     79 
     80   private long startInNanos;
     81   private long stopInNanos;
     82   private final MetricKey metricKey;
     83 
     84   private static final String TAG = "SetupCompat.Timer";
     85 }
     86