001/**
002 * Licensed to the Apache Software Foundation (ASF) under one or more
003 * contributor license agreements.  See the NOTICE file distributed with
004 * this work for additional information regarding copyright ownership.
005 * The ASF licenses this file to You under the Apache License, Version 2.0
006 * (the "License"); you may not use this file except in compliance with
007 * the License.  You may obtain a copy of the License at
008 *
009 *      http://www.apache.org/licenses/LICENSE-2.0
010 *
011 * Unless required by applicable law or agreed to in writing, software
012 * distributed under the License is distributed on an "AS IS" BASIS,
013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
014 * See the License for the specific language governing permissions and
015 * limitations under the License.
016 */
017package org.apache.camel;
018
019/**
020 * Strategy that allows {@link Consumer}s to influence the {@link PollingConsumer}.
021 * <p/>
022 * For example this is used by schedule based consumers to be able to suspend/resume
023 * upon polling using a {@link PollingConsumer}.
024 *
025 * @see org.apache.camel.impl.EventDrivenPollingConsumer
026 */
027public interface PollingConsumerPollingStrategy {
028
029    /**
030     * Callback invoked when the consumer is initialized such as when the {@link PollingConsumer} starts.
031     *
032     * @throws Exception can be thrown if error initializing.
033     */
034    void onInit() throws Exception;
035
036    /**
037     * Callback invoked before the poll.
038     *
039     * @param timeout the timeout
040     * @throws Exception can be thrown if error occurred
041     * @return timeout to be used, this allows returning a higher timeout value
042     * to ensure at least one poll is being performed
043     */
044    long beforePoll(long timeout) throws Exception;
045
046    /**
047     * Callback invoked after the poll.
048     *
049     * @throws Exception can be thrown if error occurred
050     */
051    void afterPoll() throws Exception;
052}