qpid/java/common/src/main/java/org/apache/qpid/util/concurrent/SynchRecord.java

package org.apache.qpid.util.concurrent;
/*
 * 
 * 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.
 * 
 */


/**
 * SynchRecord associates a data item from a {@link BatchSynchQueue} with its producer. This enables the data item data
 * item to be put back on the queue without unblocking its producer, or to send exceptions to the producer.
 *
 * <p/><table id="crc"><caption>CRC Card</caption>
 * <tr><th> Responsibilities <th> Collaborations
 * <tr><td> Get the underlying data element.
 * <tr><td> Put the data element back on the queue without unblocking its producer.
 * <tr><td> Send and exception to the data elements producer.
 * </table>
 */
public interface SynchRecord<E>
{
    /**
     * Gets the data element contained by this record.
     *
     * @return The data element contained by this record.
     */
    public E getElement();

    /**
     * Tells the synch queue to put this element back onto the queue instead of releasing its producer.
     * The element is not requeued immediately but upon calling the {@link SynchRef#unblockProducers()} method.
     *
     * <p/>This method will raise a runtime exception {@link AlreadyUnblockedException} if the producer for this element
     * has already been unblocked.
     */
    public void reQueue();

    /**
     * Immediately releases the producer of this data record. Consumers can bring the synchronization time of
     * producers to a minimum by using this method to release them at the earliest possible moment when batch
     * consuming records from sychronized producers.
     */
    public void releaseImmediately();

    /**
     * Tells the synch queue to raise an exception with this elements producer. The exception is not raised immediately
     * but upon calling the {@link SynchRef#unblockProducers()} method. The exception will be wrapped in a
     * {@link SynchException} before it is raised on the producer.
     *
     * <p/>This method is unusual in that it accepts an exception as an argument. This is non-standard but is used
     * because the exception is to be passed onto a different thread.
     *
     * <p/>This method will raise a runtime exception {@link AlreadyUnblockedException} if the producer for this element
     * has already been unblocked.
     *
     * @param e The exception to raise on the producer.
     */
    public void inError(Exception e);
}