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1 /*
2  * Copyright (C) 2010 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 dalvik.system.profiler;
18 
19 import dalvik.system.VMStack;
20 import java.util.Arrays;
21 
22 class DalvikThreadSampler implements ThreadSampler {
23 
24     private int depth;
25 
26     /**
27      * Reusable storage for sampling sized for the specified depth.
28      */
29     private StackTraceElement[][] mutableStackTraceElements;
30 
setDepth(int depth)31     @Override public void setDepth(int depth) {
32         this.depth = depth;
33         this.mutableStackTraceElements = new StackTraceElement[depth+1][];
34         for (int i = 1; i < mutableStackTraceElements.length; i++) {
35             this.mutableStackTraceElements[i] = new StackTraceElement[i];
36         }
37     }
38 
getStackTrace(Thread thread)39     @Override public StackTraceElement[] getStackTrace(Thread thread) {
40         int count = VMStack.fillStackTraceElements(thread, mutableStackTraceElements[depth]);
41         if (count == 0) {
42             return null;
43         }
44         if (count < depth) {
45             System.arraycopy(mutableStackTraceElements[depth], 0,
46                              mutableStackTraceElements[count], 0,
47                              count);
48         }
49         return mutableStackTraceElements[count];
50     }
51 }
52