/* Licensed to the Apache Software Foundation (ASF) under one or more * contributor license agreements. See the NOTICE file distributed with * this work for additional information regarding copyright ownership. * The ASF licenses this file to You under the Apache License, Version 2.0 * (the "License"); you may not use this file except in compliance with * the License. You may obtain a copy of the License at * * http://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. * See the License for the specific language governing permissions and * limitations under the License. */ package java.nio; import org.apache.harmony.luni.platform.PlatformAddress; /** * Helper class for operations on direct ByteBuffer * * @see java.nio.ByteBuffer */ class DirectByteBuffers { /** * Explicitly frees the memory used by the given direct byte buffer. *
* If the memory is known to already have been freed then this is a no-op.
* Once the memory has been freed then operations requiring access to the
* memory will throw an IllegalStateException
.
*
* Note this is is possible that the memory is freed by code that reaches
* into the address and explicitly frees it 'beneith' us -- this is bad
* form.
*
* @param directBuffer
* the direct byte buffer memory to free
* @throws IllegalArgumentException
* if the buffer is null
or is not a
* direct byte buffer.
*/
public static void free(ByteBuffer directBuffer) {
if ((directBuffer == null) || (!directBuffer.isDirect())) {
throw new IllegalArgumentException();
}
DirectByteBuffer buf = (DirectByteBuffer) directBuffer;
buf.free();
}
/**
* Returns the platform address of the start of this buffer instance.
* You must not attempt to free the returned address!! It may not
* be an address that was explicitly malloc'ed (i.e. if this buffer is the
* result of a split); and it may be memory shared by multiple buffers.
*
* If you can guarantee that you want to free the underlying memory call the * #free() method on this instance -- generally applications will rely on * the garbage collector to autofree this memory. * * @param directBuffer * the direct byte buffer * @return the effective address of the start of the buffer. * @throws IllegalStateException * if this buffer address is known to have been freed * previously. */ public static PlatformAddress getEffectiveAddress(ByteBuffer directBuffer) { return toDirectBuffer(directBuffer).getEffectiveAddress(); } private static DirectByteBuffer toDirectBuffer(ByteBuffer directBuffer) { if ((directBuffer == null) || (!directBuffer.isDirect())) { throw new IllegalArgumentException(); } return (DirectByteBuffer) directBuffer; } }