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8  * particular file as subject to the "Classpath" exception as provided
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12  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
13  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
14  * version 2 for more details (a copy is included in the LICENSE file that
15  * accompanied this code).
16  *
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24  */
25 
26 package sun.nio.fs;
27 
28 import sun.misc.Unsafe;
29 import sun.misc.Cleaner;
30 
31 /**
32  * A light-weight buffer in native memory.
33  */
34 
35 class NativeBuffer {
36     private static final Unsafe unsafe = Unsafe.getUnsafe();
37 
38     private final long address;
39     private final int size;
40     private final Cleaner cleaner;
41 
42     // optional "owner" to avoid copying
43     // (only safe for use by thread-local caches)
44     private Object owner;
45 
46     private static class Deallocator implements Runnable {
47         private final long address;
Deallocator(long address)48         Deallocator(long address) {
49             this.address = address;
50         }
run()51         public void run() {
52             unsafe.freeMemory(address);
53         }
54     }
55 
NativeBuffer(int size)56     NativeBuffer(int size) {
57         this.address = unsafe.allocateMemory(size);
58         this.size = size;
59         this.cleaner = Cleaner.create(this, new Deallocator(address));
60     }
61 
62     // Android-note: releaseNativeBuffer() ensures that its argument is strongly reachable.
release()63     void release() {
64         NativeBuffers.releaseNativeBuffer(this);
65     }
66 
67     // BEGIN Android-note: Lifecycle contract of NativeBuffer.address() relative to release().
68     // We require that:
69     // 1) NativeBuffer is ALWAYS explicitly release()ed before being dropped, and
70     // 2) The result of address() is only used before release() is called.
71     // END Android-note: Lifecycle contract of NativeBuffer.address() relative to release().
address()72     long address() {
73         return address;
74     }
75 
size()76     int size() {
77         return size;
78     }
79 
cleaner()80     Cleaner cleaner() {
81         return cleaner;
82     }
83 
84     // not synchronized; only safe for use by thread-local caches
setOwner(Object owner)85     void setOwner(Object owner) {
86         this.owner = owner;
87     }
88 
89     // not synchronized; only safe for use by thread-local caches
owner()90     Object owner() {
91         return owner;
92     }
93 }
94