| /* |
| * 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 jdk.internal.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.free(); |
| buffers[i] = buffer; |
| return; |
| } |
| } |
| |
| // free it |
| buffer.free(); |
| } |
| |
| /** |
| * Copies a byte array and zero terminator into a given native buffer. |
| */ |
| static void copyCStringToNativeBuffer(byte[] cstr, NativeBuffer buffer) { |
| long offset = Unsafe.ARRAY_BYTE_BASE_OFFSET; |
| long len = cstr.length; |
| assert buffer.size() >= (len + 1); |
| unsafe.copyMemory(cstr, offset, null, buffer.address(), len); |
| 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; |
| } |
| } |