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/*
* Copyright (c) 2008, 2009, Oracle and/or its affiliates. All rights reserved.
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
* This code is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License version 2 only, as
* published by the Free Software Foundation. Oracle designates this
* particular file as subject to the "Classpath" exception as provided
* by Oracle in the LICENSE file that accompanied this code.
*
* This code is distributed in the hope that it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
* version 2 for more details (a copy is included in the LICENSE file that
* accompanied this code).
*
* You should have received a copy of the GNU General Public License version
* 2 along with this work; if not, write to the Free Software Foundation,
* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
*
* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
* or visit www.oracle.com if you need additional information or have any
* questions.
*/
package sun.nio.fs;
import sun.misc.Unsafe;
/**
* Factory for native buffers.
*/
class NativeBuffers {
private NativeBuffers() { }
private static final Unsafe unsafe = Unsafe.getUnsafe();
private static final int TEMP_BUF_POOL_SIZE = 3;
private static ThreadLocal<NativeBuffer[]> threadLocal =
new ThreadLocal<NativeBuffer[]>();
/**
* Allocates a native buffer, of at least the given size, from the heap.
*/
static NativeBuffer allocNativeBuffer(int size) {
// Make a new one of at least 2k
if (size < 2048) size = 2048;
return new NativeBuffer(size);
}
/**
* Returns a native buffer, of at least the given size, from the thread
* local cache.
*/
static NativeBuffer getNativeBufferFromCache(int size) {
// return from cache if possible
NativeBuffer[] buffers = threadLocal.get();
if (buffers != null) {
for (int i=0; i<TEMP_BUF_POOL_SIZE; i++) {
NativeBuffer buffer = buffers[i];
if (buffer != null && buffer.size() >= size) {
buffers[i] = null;
return buffer;
}
}
}
return null;
}
/**
* Returns a native buffer, of at least the given size. The native buffer
* is taken from the thread local cache if possible; otherwise it is
* allocated from the heap.
*/
static NativeBuffer getNativeBuffer(int size) {
NativeBuffer buffer = getNativeBufferFromCache(size);
if (buffer != null) {
buffer.setOwner(null);
return buffer;
} else {
return allocNativeBuffer(size);
}
}
/**
* Releases the given buffer. If there is space in the thread local cache
* then the buffer goes into the cache; otherwise the memory is deallocated.
*/
static void releaseNativeBuffer(NativeBuffer buffer) {
// create cache if it doesn't exist
NativeBuffer[] buffers = threadLocal.get();
if (buffers == null) {
buffers = new NativeBuffer[TEMP_BUF_POOL_SIZE];
buffers[0] = buffer;
threadLocal.set(buffers);
return;
}
// Put it in an empty slot if such exists
for (int i=0; i<TEMP_BUF_POOL_SIZE; i++) {
if (buffers[i] == null) {
buffers[i] = buffer;
return;
}
}
// Otherwise replace a smaller one in the cache if such exists
for (int i=0; i<TEMP_BUF_POOL_SIZE; i++) {
NativeBuffer existing = buffers[i];
if (existing.size() < buffer.size()) {
existing.cleaner().clean();
buffers[i] = buffer;
return;
}
}
// free it
buffer.cleaner().clean();
}
/**
* Copies a byte array and zero terminator into a given native buffer.
*/
static void copyCStringToNativeBuffer(byte[] cstr, NativeBuffer buffer) {
// Android-removed: We don't have Unsafe.copyMemory yet, so use putByte.
// long offset = Unsafe.ARRAY_BYTE_BASE_OFFSET;
long len = cstr.length;
assert buffer.size() >= (len + 1);
// BEGIN Android-changed: We don't have Unsafe.copyMemory yet, so use putByte.
// unsafe.copyMemory(cstr, offset, null, buffer.address(), len);
for (int i = 0; i < len; ++i) {
unsafe.putByte(buffer.address() + i, cstr[i]);
}
// END Android-changed: We don't have Unsafe.copyMemory yet, so use putByte.
unsafe.putByte(buffer.address() + len, (byte)0);
}
/**
* Copies a byte array and zero terminator into a native buffer, returning
* the buffer.
*/
static NativeBuffer asNativeBuffer(byte[] cstr) {
NativeBuffer buffer = getNativeBuffer(cstr.length+1);
copyCStringToNativeBuffer(cstr, buffer);
return buffer;
}
}
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