8 * particular file as subject to the "Classpath" exception as provided
9 * by Oracle in the LICENSE file that accompanied this code.
10 *
11 * This code is distributed in the hope that it will be useful, but WITHOUT
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 *
17 * You should have received a copy of the GNU General Public License version
18 * 2 along with this work; if not, write to the Free Software Foundation,
19 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
20 *
21 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
22 * or visit www.oracle.com if you need additional information or have any
23 * questions.
24 */
25
26 package sun.nio.fs;
27
28 import jdk.internal.misc.Unsafe;
29
30 /**
31 * Factory for native buffers.
32 */
33
34 class NativeBuffers {
35 private NativeBuffers() { }
36
37 private static final Unsafe unsafe = Unsafe.getUnsafe();
38
39 private static final int TEMP_BUF_POOL_SIZE = 3;
40 private static ThreadLocal<NativeBuffer[]> threadLocal =
41 new ThreadLocal<NativeBuffer[]>();
42
43 /**
44 * Allocates a native buffer, of at least the given size, from the heap.
45 */
46 static NativeBuffer allocNativeBuffer(int size) {
47 // Make a new one of at least 2k
48 if (size < 2048) size = 2048;
49 return new NativeBuffer(size);
50 }
51
52 /**
53 * Returns a native buffer, of at least the given size, from the thread
54 * local cache.
55 */
56 static NativeBuffer getNativeBufferFromCache(int size) {
57 // return from cache if possible
58 NativeBuffer[] buffers = threadLocal.get();
59 if (buffers != null) {
60 for (int i=0; i<TEMP_BUF_POOL_SIZE; i++) {
61 NativeBuffer buffer = buffers[i];
62 if (buffer != null && buffer.size() >= size) {
63 buffers[i] = null;
64 return buffer;
65 }
66 }
67 }
68 return null;
69 }
70
71 /**
72 * Returns a native buffer, of at least the given size. The native buffer
73 * is taken from the thread local cache if possible; otherwise it is
74 * allocated from the heap.
75 */
76 static NativeBuffer getNativeBuffer(int size) {
77 NativeBuffer buffer = getNativeBufferFromCache(size);
78 if (buffer != null) {
79 buffer.setOwner(null);
80 return buffer;
81 } else {
82 return allocNativeBuffer(size);
83 }
84 }
85
86 /**
87 * Releases the given buffer. If there is space in the thread local cache
88 * then the buffer goes into the cache; otherwise the memory is deallocated.
89 */
90 static void releaseNativeBuffer(NativeBuffer buffer) {
91 // create cache if it doesn't exist
92 NativeBuffer[] buffers = threadLocal.get();
93 if (buffers == null) {
94 buffers = new NativeBuffer[TEMP_BUF_POOL_SIZE];
95 buffers[0] = buffer;
96 threadLocal.set(buffers);
97 return;
98 }
99 // Put it in an empty slot if such exists
100 for (int i=0; i<TEMP_BUF_POOL_SIZE; i++) {
101 if (buffers[i] == null) {
102 buffers[i] = buffer;
103 return;
104 }
105 }
106 // Otherwise replace a smaller one in the cache if such exists
107 for (int i=0; i<TEMP_BUF_POOL_SIZE; i++) {
108 NativeBuffer existing = buffers[i];
109 if (existing.size() < buffer.size()) {
110 existing.free();
111 buffers[i] = buffer;
112 return;
|
8 * particular file as subject to the "Classpath" exception as provided
9 * by Oracle in the LICENSE file that accompanied this code.
10 *
11 * This code is distributed in the hope that it will be useful, but WITHOUT
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 *
17 * You should have received a copy of the GNU General Public License version
18 * 2 along with this work; if not, write to the Free Software Foundation,
19 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
20 *
21 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
22 * or visit www.oracle.com if you need additional information or have any
23 * questions.
24 */
25
26 package sun.nio.fs;
27
28 import jdk.internal.misc.JavaLangAccess;
29 import jdk.internal.misc.SharedSecrets;
30 import jdk.internal.misc.Unsafe;
31
32 /**
33 * Factory for native buffers.
34 */
35
36 class NativeBuffers {
37 private static JavaLangAccess JLA = SharedSecrets.getJavaLangAccess();
38
39 private static final Unsafe unsafe = Unsafe.getUnsafe();
40
41 private static final int TEMP_BUF_POOL_SIZE = 3;
42 private static ThreadLocal<NativeBuffer[]> threadLocal =
43 new ThreadLocal<NativeBuffer[]>();
44
45 private NativeBuffers() { }
46
47 /**
48 * Allocates a native buffer, of at least the given size, from the heap.
49 */
50 static NativeBuffer allocNativeBuffer(int size) {
51 // Make a new one of at least 2k
52 if (size < 2048) size = 2048;
53 return new NativeBuffer(size);
54 }
55
56 /**
57 * Returns a native buffer, of at least the given size, from the thread
58 * local cache.
59 */
60 static NativeBuffer getNativeBufferFromCache(int size) {
61 // return from cache if possible
62 NativeBuffer[] buffers = JLA.getKernelThreadLocal(threadLocal);
63 if (buffers != null) {
64 for (int i=0; i<TEMP_BUF_POOL_SIZE; i++) {
65 NativeBuffer buffer = buffers[i];
66 if (buffer != null && buffer.size() >= size) {
67 buffers[i] = null;
68 return buffer;
69 }
70 }
71 }
72 return null;
73 }
74
75 /**
76 * Returns a native buffer, of at least the given size. The native buffer
77 * is taken from the thread local cache if possible; otherwise it is
78 * allocated from the heap.
79 */
80 static NativeBuffer getNativeBuffer(int size) {
81 NativeBuffer buffer = getNativeBufferFromCache(size);
82 if (buffer != null) {
83 buffer.setOwner(null);
84 return buffer;
85 } else {
86 return allocNativeBuffer(size);
87 }
88 }
89
90 /**
91 * Releases the given buffer. If there is space in the thread local cache
92 * then the buffer goes into the cache; otherwise the memory is deallocated.
93 */
94 static void releaseNativeBuffer(NativeBuffer buffer) {
95 // create cache if it doesn't exist
96 NativeBuffer[] buffers = JLA.getKernelThreadLocal(threadLocal);
97 if (buffers == null) {
98 buffers = new NativeBuffer[TEMP_BUF_POOL_SIZE];
99 buffers[0] = buffer;
100 threadLocal.set(buffers);
101 return;
102 }
103 // Put it in an empty slot if such exists
104 for (int i=0; i<TEMP_BUF_POOL_SIZE; i++) {
105 if (buffers[i] == null) {
106 buffers[i] = buffer;
107 return;
108 }
109 }
110 // Otherwise replace a smaller one in the cache if such exists
111 for (int i=0; i<TEMP_BUF_POOL_SIZE; i++) {
112 NativeBuffer existing = buffers[i];
113 if (existing.size() < buffer.size()) {
114 existing.free();
115 buffers[i] = buffer;
116 return;
|