Bill commented on a change in pull request #5666: URL: https://github.com/apache/geode/pull/5666#discussion_r512967623
########## File path: geode-core/src/main/java/org/apache/geode/internal/net/ByteBufferSharingImpl.java ########## @@ -0,0 +1,142 @@ +/* + * 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 org.apache.geode.internal.net; + +import java.io.IOException; +import java.nio.ByteBuffer; +import java.util.concurrent.TimeUnit; +import java.util.concurrent.atomic.AtomicBoolean; +import java.util.concurrent.atomic.AtomicInteger; +import java.util.concurrent.locks.Lock; +import java.util.concurrent.locks.ReentrantLock; + +import org.apache.geode.annotations.VisibleForTesting; +import org.apache.geode.internal.net.BufferPool.BufferType; + +/** + * An {@link AutoCloseable} meant to be acquired in a try-with-resources statement. The resource (a + * {@link ByteBuffer}) is available (for reading and modification) in the scope of the + * try-with-resources. + */ +class ByteBufferSharingImpl implements ByteBufferSharing { + + static class LockAttemptTimedOut extends Exception { + } + + private final Lock lock; + private final AtomicBoolean isClosed; + // mutable because in general our ByteBuffer may need to be resized (grown or compacted) + private ByteBuffer buffer; + private final BufferType bufferType; + private final AtomicInteger counter; + private final BufferPool bufferPool; + + /** + * This constructor is for use only by the owner of the shared resource (a {@link ByteBuffer}). + * + * A resource owner must invoke {@link #alias()} once for each reference that escapes (is passed + * to an external object or is returned to an external caller.) + * + * This constructor acquires no lock. The reference count will be 1 after this constructor + * completes. + */ + ByteBufferSharingImpl(final ByteBuffer buffer, final BufferType bufferType, + final BufferPool bufferPool) { + this.buffer = buffer; + this.bufferType = bufferType; + this.bufferPool = bufferPool; + lock = new ReentrantLock(); + counter = new AtomicInteger(1); + isClosed = new AtomicBoolean(false); + } + + /** + * The destructor. Called by the resource owner to undo the work of the constructor. + */ + void destruct() { + if (isClosed.compareAndSet(false, true)) { + dropReference(); + } + } + + /** + * This method is for use only by the owner of the shared resource. It's used for handing out + * references to the shared resource. So it does reference counting and also acquires a lock. + * + * Resource owners call this method as the last thing before returning a reference to the caller. + * That caller binds that reference to a variable in a try-with-resources statement and relies on + * the AutoCloseable protocol to invoke close() on the object at the end of the block. + */ + ByteBufferSharing alias() { Review comment: renamed `open()` for symmetry with `close()` ---------------------------------------------------------------- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. For queries about this service, please contact Infrastructure at: [email protected]
