1 /*
2  * Licensed to the Apache Software Foundation (ASF) under one or more
3  * contributor license agreements.  See the NOTICE file distributed with
4  * this work for additional information regarding copyright ownership.
5  * The ASF licenses this file to You under the Apache License, Version 2.0
6  * (the "License"); you may not use this file except in compliance with
7  * the License.  You may obtain a copy of the License at
8  *
9  *     http://www.apache.org/licenses/LICENSE-2.0
10  *
11  * Unless required by applicable law or agreed to in writing, software
12  * distributed under the License is distributed on an "AS IS" BASIS,
13  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
14  * See the License for the specific language governing permissions and
15  * limitations under the License.
16  */
17 /*
18  * Copyright (C) 2012 The Android Open Source Project
19  *
20  * Licensed under the Apache License, Version 2.0 (the "License");
21  * you may not use this file except in compliance with the License.
22  * You may obtain a copy of the License at
23  *
24  *      http://www.apache.org/licenses/LICENSE-2.0
25  *
26  * Unless required by applicable law or agreed to in writing, software
27  * distributed under the License is distributed on an "AS IS" BASIS,
28  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
29  * See the License for the specific language governing permissions and
30  * limitations under the License.
31  */
32 
33 package java.lang;
34 
35 import com.android.dex.Dex;
36 
37 /**
38  * A dex cache holds resolved copies of strings, fields, methods, and classes from the dexfile.
39  */
40 final class DexCache {
41     /** Lazily initialized dex file wrapper. Volatile to avoid double-check locking issues. */
42     private volatile Dex dex;
43 
44     /** The location of the associated dex file. */
45     String location;
46 
47     /** Holds C pointer to dexFile. */
48     private long dexFile;
49 
50     /**
51      * References to fields (C array pointer) as they become resolved following
52      * interpreter semantics. May refer to fields defined in other dex files.
53      */
54     private long resolvedFields;
55 
56     /**
57      * References to methods (C array pointer) as they become resolved following
58      * interpreter semantics. May refer to methods defined in other dex files.
59      */
60     private long resolvedMethods;
61 
62     /**
63      * References to types (C array pointer) as they become resolved following
64      * interpreter semantics. May refer to types defined in other dex files.
65      */
66     private long resolvedTypes;
67 
68     /**
69      * References to strings (C array pointer) as they become resolved following
70      * interpreter semantics. All strings are interned.
71      */
72     private long strings;
73 
74     /**
75      * The number of elements in the native resolvedFields array.
76      */
77     private int numResolvedFields;
78 
79     /**
80      * The number of elements in the native resolvedMethods array.
81      */
82     private int numResolvedMethods;
83 
84     /**
85      * The number of elements in the native resolvedTypes array.
86      */
87     private int numResolvedTypes;
88 
89     /**
90      * The number of elements in the native strings array.
91      */
92     private int numStrings;
93 
94     // Only created by the VM.
DexCache()95     private DexCache() {}
96 
getDex()97     Dex getDex() {
98         Dex result = dex;
99         if (result == null) {
100             synchronized (this) {
101                 result = dex;
102                 if (result == null) {
103                     dex = result = getDexNative();
104                 }
105             }
106         }
107         return result;
108     }
109 
getResolvedType(int typeIndex)110     native Class<?> getResolvedType(int typeIndex);
getResolvedString(int stringIndex)111     native String getResolvedString(int stringIndex);
setResolvedType(int typeIndex, Class<?> type)112     native void setResolvedType(int typeIndex, Class<?> type);
setResolvedString(int stringIndex, String string)113     native void setResolvedString(int stringIndex, String string);
getDexNative()114     private native Dex getDexNative();
115 }
116 
117