netty-incubator-buffer-api/src/main/java/io/netty/buffer/api/BufferRef.java

89 lines
2.9 KiB
Java

/*
* Copyright 2020 The Netty Project
*
* The Netty Project 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:
*
* https://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 io.netty.buffer.api;
import java.lang.invoke.VarHandle;
/**
* A mutable reference to a buffer.
*/
public final class BufferRef extends BufferHolder<BufferRef> {
/**
* Create a reference to the given {@linkplain Buffer buffer}.
* This increments the reference count of the buffer.
*
* @param buf The buffer to reference.
*/
public BufferRef(Buffer buf) {
super(buf);
// BufferRef is meant to be atomic, so we need to add a fence to get the semantics of a volatile store.
VarHandle.fullFence();
}
/**
* Create a reference that holds the exclusive ownership of the sent buffer.
*
* @param send The {@linkplain Send sent} buffer to take ownership of.
*/
public BufferRef(Send<Buffer> send) {
super(send);
// BufferRef is meant to be atomic, so we need to add a fence to get the semantics of a volatile store.
VarHandle.fullFence();
}
@Override
protected BufferRef receive(Buffer buf) {
return new BufferRef(buf);
}
/**
* Replace the underlying referenced buffer with the given buffer.
* <p>
* <strong>Note:</strong> this method decreases the reference count of the current buffer,
* and increases the reference count of the new buffer.
* <p>
* The buffer assignment is performed using a volatile store.
*
* @param newBuf The new {@link Buffer} instance that is replacing the currently held buffer.
*/
public void replace(Buffer newBuf) {
replaceBufVolatile(newBuf);
}
/**
* Replace the underlying referenced buffer with the given buffer.
* <p>
* <strong>Note:</strong> this method decreases the reference count of the current buffer,
* and takes exclusive ownership of the sent buffer.
* <p>
* The buffer assignment is performed using a volatile store.
*
* @param send The {@link Send} with the new {@link Buffer} instance that is replacing the currently held buffer.
*/
public void replace(Send<Buffer> send) {
replaceBufVolatile(send);
}
/**
* Access the buffer in this reference.
*
* @return The buffer held by the reference.
*/
public Buffer contents() {
return getBufVolatile();
}
}