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     */
017    package 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     */
027    public 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    }