1 /* 2 * Copyright (C) 2009 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.quicksearchbox; 18 19 import android.os.SystemClock; 20 21 /** 22 * Tracks latency in wall-clock time. Since {@link #getLatency} returns an {@code int}, 23 * latencies over 2^31 ms (~ 25 days) cannot be measured. 24 * This class uses {@link SystemClock#uptimeMillis} which does not advance during deep sleep. 25 */ 26 public class LatencyTracker { 27 28 /** 29 * Start time, in milliseconds as returned by {@link SystemClock#uptimeMillis}. 30 */ 31 private long mStartTime; 32 33 /** 34 * Creates a new latency tracker and sets the start time. 35 */ 36 public LatencyTracker() { 37 mStartTime = SystemClock.uptimeMillis(); 38 } 39 40 /** 41 * Resets the start time. 42 */ 43 public void reset() { 44 mStartTime = SystemClock.uptimeMillis(); 45 } 46 47 /** 48 * Gets the number of milliseconds since the object was created, or {@link #reset} was called. 49 */ 50 public int getLatency() { 51 long now = SystemClock.uptimeMillis(); 52 return (int) (now - mStartTime); 53 } 54 55 } 56
