    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.internal.services.cron;
    014
    015import org.apache.tapestry5.commons.util.CollectionFactory;
    016import org.apache.tapestry5.ioc.Invokable;
    017import org.apache.tapestry5.ioc.annotations.PostInjection;
    018import org.apache.tapestry5.ioc.services.ParallelExecutor;
    019import org.apache.tapestry5.ioc.services.RegistryShutdownHub;
    020import org.apache.tapestry5.ioc.services.cron.PeriodicExecutor;
    021import org.apache.tapestry5.ioc.services.cron.PeriodicJob;
    022import org.apache.tapestry5.ioc.services.cron.Schedule;
    023import org.slf4j.Logger;
    024
    025import java.util.HashSet;
    026import java.util.List;
    027import java.util.Set;
    028import java.util.concurrent.atomic.AtomicBoolean;
    029import java.util.concurrent.atomic.AtomicInteger;
    030import java.util.concurrent.locks.Lock;
    031import java.util.concurrent.locks.ReentrantLock;
    032
    033public class PeriodicExecutorImpl implements PeriodicExecutor, Runnable
    034{
    035    private final ParallelExecutor parallelExecutor;
    036
    037    private final Logger logger;
    038
    039    // Synchronized by jobLock
    040    private final List<Job> jobs = CollectionFactory.newList();
    041
    042    private final Thread thread = new Thread(this, "Tapestry PeriodicExecutor");
    043
    044    private transient boolean shutdown;
    045
    046    private static final long FIVE_MINUTES = 5 * 60 * 1000;
    047
    048    private final AtomicInteger jobIdAllocator = new AtomicInteger();
    049
    050    private final AtomicBoolean started = new AtomicBoolean();
    051
    052    private final Lock jobLock = new ReentrantLock();
    053
    054    private class Job implements PeriodicJob, Invokable<Void>
    055    {
    056        final int jobId = jobIdAllocator.incrementAndGet();
    057
    058        private final Schedule schedule;
    059
    060        private final String name;
    061
    062        private final Runnable runnableJob;
    063
    064        private boolean executing, canceled;
    065
    066        private long nextExecution;
    067
    068        public Job(Schedule schedule, String name, Runnable runnableJob)
    069        {
    070            this.schedule = schedule;
    071            this.name = name;
    072            this.runnableJob = runnableJob;
    073
    074            nextExecution = schedule.firstExecution();
    075        }
    076
    077        @Override
    078        public String getName()
    079        {
    080            return name;
    081        }
    082
    083        public long getNextExecution()
    084        {
    085            try
    086            {
    087                jobLock.lock();
    088                return nextExecution;
    089            } finally
    090            {
    091                jobLock.unlock();
    092            }
    093        }
    094
    095
    096        @Override
    097        public boolean isExecuting()
    098        {
    099            try
    100            {
    101                jobLock.lock();
    102                return executing;
    103            } finally
    104            {
    105                jobLock.unlock();
    106            }
    107        }
    108
    109        @Override
    110        public boolean isCanceled()
    111        {
    112            try
    113            {
    114                jobLock.lock();
    115                return canceled;
    116            } finally
    117            {
    118                jobLock.unlock();
    119            }
    120        }
    121
    122        @Override
    123        public void cancel()
    124        {
    125            try
    126            {
    127                jobLock.lock();
    128
    129                canceled = true;
    130
    131                if (!executing)
    132                {
    133                    removeJob(this);
    134                }
    135
    136                // Otherwise, it will be caught when the job finishes execution.
    137            } finally
    138            {
    139                jobLock.unlock();
    140            }
    141        }
    142
    143        @Override
    144        public String toString()
    145        {
    146            StringBuilder builder = new StringBuilder("PeriodicJob[#").append(jobId);
    147
    148            builder.append(", (").append(name).append(')');
    149
    150            if (executing)
    151            {
    152                builder.append(", executing");
    153            }
    154
    155            if (canceled)
    156            {
    157                builder.append(", canceled");
    158            } else
    159            {
    160                builder.append(String.format(", next execution %Tk:%<TM:%<TS+%<TL", nextExecution));
    161            }
    162
    163            return builder.append(']').toString();
    164        }
    165
    166        /**
    167         * Starts execution of the job; this sets the executing flag, calculates the next execution time,
    168         * and uses the ParallelExecutor to run the job.
    169         */
    170        void start()
    171        {
    172            try
    173            {
    174                jobLock.lock();
    175                executing = true;
    176
    177                // This is a bit naive; it assumes there will not be a delay waiting to execute. There's a lot of options
    178                // here, such as basing the next execution on the actual start time, or event actual completion time, or allowing
    179                // overlapping executions of the Job on a more rigid schedule.  Use Quartz.
    180
    181                nextExecution = schedule.nextExecution(nextExecution);
    182
    183                parallelExecutor.invoke(this);
    184            } finally
    185            {
    186                jobLock.unlock();
    187            }
    188
    189            if (logger.isTraceEnabled())
    190            {
    191                logger.trace(this + " sent for execution");
    192            }
    193        }
    194
    195        void cleanupAfterExecution()
    196        {
    197            try
    198            {
    199                if (logger.isTraceEnabled())
    200                {
    201                    logger.trace(this + " execution complete");
    202                }
    203
    204                executing = false;
    205
    206                if (canceled)
    207                {
    208                    removeJob(this);
    209                } else
    210                {
    211                    // Again, naive but necessary.
    212                    thread.interrupt();
    213                }
    214            } finally
    215            {
    216                jobLock.unlock();
    217            }
    218        }
    219
    220        @Override
    221        public Void invoke()
    222        {
    223            logger.debug("Executing job #{} ({})", jobId, name);
    224
    225            try
    226            {
    227                runnableJob.run();
    228            } finally
    229            {
    230                cleanupAfterExecution();
    231            }
    232
    233            return null;
    234        }
    235
    236    }
    237
    238    public PeriodicExecutorImpl(ParallelExecutor parallelExecutor, Logger logger)
    239    {
    240        this.parallelExecutor = parallelExecutor;
    241        this.logger = logger;
    242    }
    243
    244    @PostInjection
    245    public void start(RegistryShutdownHub hub)
    246    {
    247        hub.addRegistryShutdownListener(new Runnable()
    248        {
    249            @Override
    250            public void run()
    251            {
    252                registryDidShutdown();
    253            }
    254        });
    255
    256    }
    257
    258    public void init()
    259    {
    260        if (!started.get())
    261        {
    262            started.set(true);
    263            thread.start();
    264        }
    265    }
    266
    267    void removeJob(Job job)
    268    {
    269        if (logger.isDebugEnabled())
    270        {
    271            logger.debug("Removing " + job);
    272        }
    273
    274        try
    275        {
    276            jobLock.lock();
    277            jobs.remove(job);
    278        } finally
    279        {
    280            jobLock.unlock();
    281        }
    282    }
    283
    284
    285    @Override
    286    public PeriodicJob addJob(Schedule schedule, String name, Runnable job)
    287    {
    288        assert schedule != null;
    289        assert name != null;
    290        assert job != null;
    291
    292        Job periodicJob = new Job(schedule, name, job);
    293
    294        try
    295        {
    296            jobLock.lock();
    297
    298            jobs.add(periodicJob);
    299        } finally
    300        {
    301            jobLock.unlock();
    302        }
    303
    304        if (logger.isDebugEnabled())
    305        {
    306            logger.debug("Added " + periodicJob);
    307        }
    308
    309        // Wake the thread so that it can start the job, if necessary.
    310
    311        // Technically, this is only necessary if the new job is scheduled earlier
    312        // than any job currently in the list of jobs, but this naive implementation
    313        // is simpler.
    314        thread.interrupt();
    315
    316        return periodicJob;
    317    }
    318
    319    @Override
    320    public void run()
    321    {
    322        while (!shutdown)
    323        {
    324            long nextExecution = executeCurrentBatch();
    325
    326            try
    327            {
    328                long delay = nextExecution - System.currentTimeMillis();
    329
    330                if (logger.isTraceEnabled())
    331                {
    332                    logger.trace(String.format("Sleeping for %,d ms", delay));
    333                }
    334
    335                if (delay > 0)
    336                {
    337                    Thread.sleep(delay);
    338                }
    339            } catch (InterruptedException
    340                    ex)
    341            {
    342                // Ignored; the thread is interrupted() to shut it down,
    343                // or to have it execute a new batch.
    344
    345                logger.trace("Interrupted");
    346            }
    347        }
    348    }
    349
    350    private void registryDidShutdown()
    351    {
    352        shutdown = true;
    353
    354        thread.interrupt();
    355    }
    356
    357    /**
    358     * Finds jobs and executes jobs that are ready to be executed.
    359     *
    360     * @return the next execution time (from the non-executing job that is scheduled earliest for execution).
    361     */
    362    private long executeCurrentBatch()
    363    {
    364        long now = System.currentTimeMillis();
    365        long nextExecution = now + FIVE_MINUTES;
    366
    367        try
    368        {
    369            jobLock.lock();
    370            // TAP5-2455
    371            Set<Job> jobsToCancel = null;
    372
    373            for (Job job : jobs)
    374            {
    375                if (job.isExecuting())
    376                {
    377                    continue;
    378                }
    379
    380                long jobNextExecution = job.getNextExecution();
    381
    382                if (jobNextExecution <= 0)
    383                {
    384                    if (jobsToCancel == null)
    385                    {
    386                        jobsToCancel = new HashSet<PeriodicExecutorImpl.Job>();
    387                    }
    388                    jobsToCancel.add(job);
    389                } else if (jobNextExecution <= now)
    390                {
    391                    job.start();
    392                } else
    393                {
    394                    nextExecution = Math.min(nextExecution, jobNextExecution);
    395                }
    396            }
    397            if (jobsToCancel != null)
    398            {
    399                for (Job job : jobsToCancel)
    400                {
    401                    job.cancel();
    402                }
    403            }
    404        } finally
    405        {
    406            jobLock.unlock();
    407        }
    408
    409        return nextExecution;
    410    }
    411
    412
    413}