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
015package 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 */
022public 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    @Override
040    public long firstExecution()
041    {
042        return nextExecution(System.currentTimeMillis());
043    }
044
045    @Override
046    public long nextExecution(long previousExecution)
047    {
048        return previousExecution + interval;
049    }
050}