001    // Copyright 2011 The Apache Software Foundation
002    //
003    // Licensed under the Apache License, Version 2.0 (the "License");
004    // you may not use this file except in compliance with the License.
005    // You may obtain a copy of the License at
006    //
007    // http://www.apache.org/licenses/LICENSE-2.0
008    //
009    // Unless required by applicable law or agreed to in writing, software
010    // distributed under the License is distributed on an "AS IS" BASIS,
011    // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
012    // See the License for the specific language governing permissions and
013    // limitations under the License.
014    
015    package org.apache.tapestry5.ioc.services.cron;
016    
017    /**
018     * A very simple schedule, that simply executes the desired job at fixed intervals.
019     *
020     * @since 5.3
021     */
022    public class IntervalSchedule implements Schedule
023    {
024        private final long interval;
025    
026        /**
027         * Interval at which the schedule should execute jobs. The first execution is delayed from current time
028         * by the interval as well.
029         *
030         * @param interval in milliseconds
031         */
032        public IntervalSchedule(long interval)
033        {
034            assert interval > 0;
035    
036            this.interval = interval;
037        }
038    
039        public long firstExecution()
040        {
041            return nextExecution(System.currentTimeMillis());
042        }
043    
044        public long nextExecution(long previousExecution)
045        {
046            return previousExecution + interval;
047        }
048    }