    001// Licensed under the Apache License, Version 2.0 (the "License");
    002// you may not use this file except in compliance with the License.
    003// You may obtain a copy of the License at
    004//
    005// http://www.apache.org/licenses/LICENSE-2.0
    006//
    007// Unless required by applicable law or agreed to in writing, software
    008// distributed under the License is distributed on an "AS IS" BASIS,
    009// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    010// See the License for the specific language governing permissions and
    011// limitations under the License.
    012
    013package org.apache.tapestry5.ioc.services.cron;
    014
    015/**
    016 * Used with {@link PeriodicExecutor} to control the schedule for when jobs execute.
    017 */
    018public interface Schedule
    019{
    020    /**
    021     * For a newly created job, what is the start time for the job.  Often, the current clock time is returned, to start
    022     * a job as soon as possible.
    023     *
    024     * @return start time for new job, in system clock millis
    025     */
    026    long firstExecution();
    027
    028    /**
    029     * Computes the next execution time for a job.
    030     *
    031     * @param previousExecution time of previous execution (in system clock millis)
    032     * @return time of next execution (in system clock millis) or a value &lt;= 0 to cancel the job's execution
    033     */
    034    long nextExecution(long previousExecution);
    035}