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      1 /*
      2  * Copyright (C) 2016 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 android.os.Build;
     20 import android.os.SystemClock;
     21 import android.os.Trace;
     22 
     23 import java.util.ArrayDeque;
     24 import java.util.Deque;
     25 
     26 /**
     27  * Helper class for reporting boot and shutdown timing metrics.
     28  * <p>Note: This class is not thread-safe. Use a separate copy for other threads</p>
     29  * @hide
     30  */
     31 public class TimingsTraceLog {
     32     // Debug boot time for every step if it's non-user build.
     33     private static final boolean DEBUG_BOOT_TIME = !Build.IS_USER;
     34     private final Deque<Pair<String, Long>> mStartTimes =
     35             DEBUG_BOOT_TIME ? new ArrayDeque<>() : null;
     36     private final String mTag;
     37     private long mTraceTag;
     38     private long mThreadId;
     39 
     40     public TimingsTraceLog(String tag, long traceTag) {
     41         mTag = tag;
     42         mTraceTag = traceTag;
     43         mThreadId = Thread.currentThread().getId();
     44     }
     45 
     46     /**
     47      * Begin tracing named section
     48      * @param name name to appear in trace
     49      */
     50     public void traceBegin(String name) {
     51         assertSameThread();
     52         Trace.traceBegin(mTraceTag, name);
     53         if (DEBUG_BOOT_TIME) {
     54             mStartTimes.push(Pair.create(name, SystemClock.elapsedRealtime()));
     55         }
     56     }
     57 
     58     /**
     59      * End tracing previously {@link #traceBegin(String) started} section.
     60      * Also {@link #logDuration logs} the duration.
     61      */
     62     public void traceEnd() {
     63         assertSameThread();
     64         Trace.traceEnd(mTraceTag);
     65         if (!DEBUG_BOOT_TIME) {
     66             return;
     67         }
     68         if (mStartTimes.peek() == null) {
     69             Slog.w(mTag, "traceEnd called more times than traceBegin");
     70             return;
     71         }
     72         Pair<String, Long> event = mStartTimes.pop();
     73         logDuration(event.first, (SystemClock.elapsedRealtime() - event.second));
     74     }
     75 
     76     private void assertSameThread() {
     77         final Thread currentThread = Thread.currentThread();
     78         if (currentThread.getId() != mThreadId) {
     79             throw new IllegalStateException("Instance of TimingsTraceLog can only be called from "
     80                     + "the thread it was created on (tid: " + mThreadId + "), but was from "
     81                     + currentThread.getName() + " (tid: " + currentThread.getId() + ")");
     82         }
     83     }
     84 
     85     /**
     86      * Log the duration so it can be parsed by external tools for performance reporting
     87      */
     88     public void logDuration(String name, long timeMs) {
     89         Slog.d(mTag, name + " took to complete: " + timeMs + "ms");
     90     }
     91 }
     92