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 */
017package org.apache.activemq.store.kahadb.scheduler;
018
019import java.io.DataInput;
020import java.io.DataOutput;
021import java.io.IOException;
022import java.util.ArrayList;
023import java.util.Iterator;
024import java.util.List;
025import java.util.Map;
026import java.util.concurrent.CopyOnWriteArrayList;
027import java.util.concurrent.atomic.AtomicBoolean;
028
029import javax.jms.MessageFormatException;
030
031import org.apache.activemq.broker.scheduler.CronParser;
032import org.apache.activemq.broker.scheduler.Job;
033import org.apache.activemq.broker.scheduler.JobListener;
034import org.apache.activemq.broker.scheduler.JobScheduler;
035import org.apache.activemq.protobuf.Buffer;
036import org.apache.activemq.store.kahadb.data.KahaAddScheduledJobCommand;
037import org.apache.activemq.store.kahadb.data.KahaRemoveScheduledJobCommand;
038import org.apache.activemq.store.kahadb.data.KahaRemoveScheduledJobsCommand;
039import org.apache.activemq.store.kahadb.data.KahaRescheduleJobCommand;
040import org.apache.activemq.store.kahadb.disk.index.BTreeIndex;
041import org.apache.activemq.store.kahadb.disk.journal.Location;
042import org.apache.activemq.store.kahadb.disk.page.Transaction;
043import org.apache.activemq.store.kahadb.disk.util.LongMarshaller;
044import org.apache.activemq.util.ByteSequence;
045import org.apache.activemq.util.IdGenerator;
046import org.apache.activemq.util.ServiceStopper;
047import org.apache.activemq.util.ServiceSupport;
048import org.slf4j.Logger;
049import org.slf4j.LoggerFactory;
050
051public class JobSchedulerImpl extends ServiceSupport implements Runnable, JobScheduler {
052
053    private static final Logger LOG = LoggerFactory.getLogger(JobSchedulerImpl.class);
054    private final JobSchedulerStoreImpl store;
055    private final AtomicBoolean running = new AtomicBoolean();
056    private String name;
057    private BTreeIndex<Long, List<JobLocation>> index;
058    private Thread thread;
059    private final AtomicBoolean started = new AtomicBoolean(false);
060    private final List<JobListener> jobListeners = new CopyOnWriteArrayList<JobListener>();
061    private static final IdGenerator ID_GENERATOR = new IdGenerator();
062    private final ScheduleTime scheduleTime = new ScheduleTime();
063
064    JobSchedulerImpl(JobSchedulerStoreImpl store) {
065        this.store = store;
066    }
067
068    public void setName(String name) {
069        this.name = name;
070    }
071
072    @Override
073    public String getName() {
074        return this.name;
075    }
076
077    @Override
078    public void addListener(JobListener l) {
079        this.jobListeners.add(l);
080    }
081
082    @Override
083    public void removeListener(JobListener l) {
084        this.jobListeners.remove(l);
085    }
086
087    @Override
088    public void schedule(final String jobId, final ByteSequence payload, final long delay) throws IOException {
089        doSchedule(jobId, payload, "", 0, delay, 0);
090    }
091
092    @Override
093    public void schedule(final String jobId, final ByteSequence payload, final String cronEntry) throws Exception {
094        doSchedule(jobId, payload, cronEntry, 0, 0, 0);
095    }
096
097    @Override
098    public void schedule(final String jobId, final ByteSequence payload, final String cronEntry, final long delay, final long period, final int repeat) throws IOException {
099        doSchedule(jobId, payload, cronEntry, delay, period, repeat);
100    }
101
102    @Override
103    public void remove(final long time) throws IOException {
104        doRemoveRange(time, time);
105    }
106
107    @Override
108    public void remove(final String jobId) throws IOException {
109        doRemove(-1, jobId);
110    }
111
112    @Override
113    public void removeAllJobs() throws IOException {
114        doRemoveRange(0, Long.MAX_VALUE);
115    }
116
117    @Override
118    public void removeAllJobs(final long start, final long finish) throws IOException {
119        doRemoveRange(start, finish);
120    }
121
122    @Override
123    public long getNextScheduleTime() throws IOException {
124        this.store.readLockIndex();
125        try {
126            Map.Entry<Long, List<JobLocation>> first = this.index.getFirst(this.store.getPageFile().tx());
127            return first != null ? first.getKey() : -1l;
128        } finally {
129            this.store.readUnlockIndex();
130        }
131    }
132
133    @Override
134    public List<Job> getNextScheduleJobs() throws IOException {
135        final List<Job> result = new ArrayList<Job>();
136        this.store.readLockIndex();
137        try {
138            this.store.getPageFile().tx().execute(new Transaction.Closure<IOException>() {
139                @Override
140                public void execute(Transaction tx) throws IOException {
141                    Map.Entry<Long, List<JobLocation>> first = index.getFirst(tx);
142                    if (first != null) {
143                        for (JobLocation jl : first.getValue()) {
144                            ByteSequence bs = getPayload(jl.getLocation());
145                            Job job = new JobImpl(jl, bs);
146                            result.add(job);
147                        }
148                    }
149                }
150            });
151        } finally {
152            this.store.readUnlockIndex();
153        }
154        return result;
155    }
156
157    private Map.Entry<Long, List<JobLocation>> getNextToSchedule() throws IOException {
158        this.store.readLockIndex();
159        try {
160            if (!this.store.isStopped() && !this.store.isStopping()) {
161                Map.Entry<Long, List<JobLocation>> first = this.index.getFirst(this.store.getPageFile().tx());
162                return first;
163            }
164        } finally {
165            this.store.readUnlockIndex();
166        }
167        return null;
168    }
169
170    @Override
171    public List<Job> getAllJobs() throws IOException {
172        final List<Job> result = new ArrayList<Job>();
173        this.store.readLockIndex();
174        try {
175            this.store.getPageFile().tx().execute(new Transaction.Closure<IOException>() {
176                @Override
177                public void execute(Transaction tx) throws IOException {
178                    Iterator<Map.Entry<Long, List<JobLocation>>> iter = index.iterator(store.getPageFile().tx());
179                    while (iter.hasNext()) {
180                        Map.Entry<Long, List<JobLocation>> next = iter.next();
181                        if (next != null) {
182                            for (JobLocation jl : next.getValue()) {
183                                ByteSequence bs = getPayload(jl.getLocation());
184                                Job job = new JobImpl(jl, bs);
185                                result.add(job);
186                            }
187                        } else {
188                            break;
189                        }
190                    }
191                }
192            });
193        } finally {
194            this.store.readUnlockIndex();
195        }
196        return result;
197    }
198
199    @Override
200    public List<Job> getAllJobs(final long start, final long finish) throws IOException {
201        final List<Job> result = new ArrayList<Job>();
202        this.store.readLockIndex();
203        try {
204            this.store.getPageFile().tx().execute(new Transaction.Closure<IOException>() {
205                @Override
206                public void execute(Transaction tx) throws IOException {
207                    Iterator<Map.Entry<Long, List<JobLocation>>> iter = index.iterator(tx, start);
208                    while (iter.hasNext()) {
209                        Map.Entry<Long, List<JobLocation>> next = iter.next();
210                        if (next != null && next.getKey().longValue() <= finish) {
211                            for (JobLocation jl : next.getValue()) {
212                                ByteSequence bs = getPayload(jl.getLocation());
213                                Job job = new JobImpl(jl, bs);
214                                result.add(job);
215                            }
216                        } else {
217                            break;
218                        }
219                    }
220                }
221            });
222        } finally {
223            this.store.readUnlockIndex();
224        }
225        return result;
226    }
227
228    private void doSchedule(final String jobId, final ByteSequence payload, final String cronEntry, long delay, long period, int repeat) throws IOException {
229        long startTime = System.currentTimeMillis();
230        // round startTime - so we can schedule more jobs
231        // at the same time
232        startTime = (startTime / 1000) * 1000;
233        long time = 0;
234        if (cronEntry != null && cronEntry.length() > 0) {
235            try {
236                time = CronParser.getNextScheduledTime(cronEntry, startTime);
237            } catch (MessageFormatException e) {
238                throw new IOException(e.getMessage());
239            }
240        }
241
242        if (time == 0) {
243            // start time not set by CRON - so it it to the current time
244            time = startTime;
245        }
246
247        if (delay > 0) {
248            time += delay;
249        } else {
250            time += period;
251        }
252
253        KahaAddScheduledJobCommand newJob = new KahaAddScheduledJobCommand();
254        newJob.setScheduler(name);
255        newJob.setJobId(jobId);
256        newJob.setStartTime(startTime);
257        newJob.setCronEntry(cronEntry);
258        newJob.setDelay(delay);
259        newJob.setPeriod(period);
260        newJob.setRepeat(repeat);
261        newJob.setNextExecutionTime(time);
262        newJob.setPayload(new Buffer(payload.getData(), payload.getOffset(), payload.getLength()));
263
264        this.store.store(newJob);
265    }
266
267    private void doReschedule(final String jobId, long executionTime, long nextExecutionTime, int rescheduledCount) throws IOException {
268        KahaRescheduleJobCommand update = new KahaRescheduleJobCommand();
269        update.setScheduler(name);
270        update.setJobId(jobId);
271        update.setExecutionTime(executionTime);
272        update.setNextExecutionTime(nextExecutionTime);
273        update.setRescheduledCount(rescheduledCount);
274        this.store.store(update);
275    }
276
277    private void doRemove(final long executionTime, final List<JobLocation> jobs) throws IOException {
278        for (JobLocation job : jobs) {
279            doRemove(executionTime, job.getJobId());
280        }
281    }
282
283    private void doRemove(long executionTime, final String jobId) throws IOException {
284        KahaRemoveScheduledJobCommand remove = new KahaRemoveScheduledJobCommand();
285        remove.setScheduler(name);
286        remove.setJobId(jobId);
287        remove.setNextExecutionTime(executionTime);
288        this.store.store(remove);
289    }
290
291    private void doRemoveRange(long start, long end) throws IOException {
292        KahaRemoveScheduledJobsCommand destroy = new KahaRemoveScheduledJobsCommand();
293        destroy.setScheduler(name);
294        destroy.setStartTime(start);
295        destroy.setEndTime(end);
296        this.store.store(destroy);
297    }
298
299    /**
300     * Adds a new Scheduled job to the index.  Must be called under index lock.
301     *
302     * This method must ensure that a duplicate add is not processed into the scheduler.  On index
303     * recover some adds may be replayed and we don't allow more than one instance of a JobId to
304     * exist at any given scheduled time, so filter these out to ensure idempotence.
305     *
306     * @param tx
307     *      Transaction in which the update is performed.
308     * @param command
309     *      The new scheduled job command to process.
310     * @param location
311     *      The location where the add command is stored in the journal.
312     *
313     * @throws IOException if an error occurs updating the index.
314     */
315    protected void process(final Transaction tx, final KahaAddScheduledJobCommand command, Location location) throws IOException {
316        JobLocation jobLocation = new JobLocation(location);
317        jobLocation.setJobId(command.getJobId());
318        jobLocation.setStartTime(command.getStartTime());
319        jobLocation.setCronEntry(command.getCronEntry());
320        jobLocation.setDelay(command.getDelay());
321        jobLocation.setPeriod(command.getPeriod());
322        jobLocation.setRepeat(command.getRepeat());
323
324        long nextExecutionTime = command.getNextExecutionTime();
325
326        List<JobLocation> values = null;
327        jobLocation.setNextTime(nextExecutionTime);
328        if (this.index.containsKey(tx, nextExecutionTime)) {
329            values = this.index.remove(tx, nextExecutionTime);
330        }
331        if (values == null) {
332            values = new ArrayList<JobLocation>();
333        }
334
335        // There can never be more than one instance of the same JobId scheduled at any
336        // given time, when it happens its probably the result of index recovery and this
337        // method must be idempotent so check for it first.
338        if (!values.contains(jobLocation)) {
339            values.add(jobLocation);
340
341            // Reference the log file where the add command is stored to prevent GC.
342            this.store.incrementJournalCount(tx, location);
343            this.index.put(tx, nextExecutionTime, values);
344            this.scheduleTime.newJob();
345        } else {
346            this.index.put(tx, nextExecutionTime, values);
347            LOG.trace("Job {} already in scheduler at this time {}",
348                      jobLocation.getJobId(), jobLocation.getNextTime());
349        }
350    }
351
352    /**
353     * Reschedules a Job after it has be fired.
354     *
355     * For jobs that are repeating this method updates the job in the index by adding it to the
356     * jobs list for the new execution time.  If the job is not a cron type job then this method
357     * will reduce the repeat counter if the job has a fixed number of repeats set.  The Job will
358     * be removed from the jobs list it just executed on.
359     *
360     * This method must also update the value of the last update location in the JobLocation
361     * instance so that the checkpoint worker doesn't drop the log file in which that command lives.
362     *
363     * This method must ensure that an reschedule command that references a job that doesn't exist
364     * does not cause an error since it's possible that on recover the original add might be gone
365     * and so the job should not reappear in the scheduler.
366     *
367     * @param tx
368     *      The TX under which the index is updated.
369     * @param command
370     *      The reschedule command to process.
371     * @param location
372     *      The location in the index where the reschedule command was stored.
373     *
374     * @throws IOException if an error occurs during the reschedule.
375     */
376    protected void process(final Transaction tx, final KahaRescheduleJobCommand command, Location location) throws IOException {
377        JobLocation result = null;
378        final List<JobLocation> current = this.index.remove(tx, command.getExecutionTime());
379        if (current != null) {
380            for (int i = 0; i < current.size(); i++) {
381                JobLocation jl = current.get(i);
382                if (jl.getJobId().equals(command.getJobId())) {
383                    current.remove(i);
384                    if (!current.isEmpty()) {
385                        this.index.put(tx, command.getExecutionTime(), current);
386                    }
387                    result = jl;
388                    break;
389                }
390            }
391        } else {
392            LOG.debug("Process reschedule command for job {} non-existent executime time {}.",
393                      command.getJobId(), command.getExecutionTime());
394        }
395
396        if (result != null) {
397            Location previousUpdate = result.getLastUpdate();
398
399            List<JobLocation> target = null;
400            result.setNextTime(command.getNextExecutionTime());
401            result.setLastUpdate(location);
402            result.setRescheduledCount(command.getRescheduledCount());
403            if (!result.isCron() && result.getRepeat() > 0) {
404                result.setRepeat(result.getRepeat() - 1);
405            }
406            if (this.index.containsKey(tx, command.getNextExecutionTime())) {
407                target = this.index.remove(tx, command.getNextExecutionTime());
408            }
409            if (target == null) {
410                target = new ArrayList<JobLocation>();
411            }
412            target.add(result);
413
414            // Track the location of the last reschedule command and release the log file
415            // reference for the previous one if there was one.
416            this.store.incrementJournalCount(tx, location);
417            if (previousUpdate != null) {
418                this.store.decrementJournalCount(tx, previousUpdate);
419            }
420
421            this.index.put(tx, command.getNextExecutionTime(), target);
422            this.scheduleTime.newJob();
423        } else {
424            LOG.debug("Process reschedule command for non-scheduled job {} at executime time {}.",
425                      command.getJobId(), command.getExecutionTime());
426        }
427    }
428
429    /**
430     * Removes a scheduled job from the scheduler.
431     *
432     * The remove operation can be of two forms.  The first is that there is a job Id but no set time
433     * (-1) in which case the jobs index is searched until the target job Id is located.  The alternate
434     * form is that a job Id and execution time are both set in which case the given time is checked
435     * for a job matching that Id.  In either case once an execution time is identified the job is
436     * removed and the index updated.
437     *
438     * This method should ensure that if the matching job is not found that no error results as it
439     * is possible that on a recover the initial add command could be lost so the job may not be
440     * rescheduled.
441     *
442     * @param tx
443     *      The transaction under which the index is updated.
444     * @param command
445     *      The remove command to process.
446     * @param location
447     *      The location of the remove command in the Journal.
448     *
449     * @throws IOException if an error occurs while updating the scheduler index.
450     */
451    void process(final Transaction tx, final KahaRemoveScheduledJobCommand command, Location location) throws IOException {
452
453        // Case 1: JobId and no time value means find the job and remove it.
454        // Case 2: JobId and a time value means find exactly this scheduled job.
455
456        Long executionTime = command.getNextExecutionTime();
457
458        List<JobLocation> values = null;
459
460        if (executionTime == -1) {
461            for (Iterator<Map.Entry<Long, List<JobLocation>>> i = this.index.iterator(tx); i.hasNext();) {
462                Map.Entry<Long, List<JobLocation>> entry = i.next();
463                List<JobLocation> candidates = entry.getValue();
464                if (candidates != null) {
465                    for (JobLocation jl : candidates) {
466                        if (jl.getJobId().equals(command.getJobId())) {
467                            LOG.trace("Entry {} contains the remove target: {}", entry.getKey(), command.getJobId());
468                            executionTime = entry.getKey();
469                            values = this.index.remove(tx, executionTime);
470                            break;
471                        }
472                    }
473                }
474            }
475        } else {
476            values = this.index.remove(tx, executionTime);
477        }
478
479        JobLocation removed = null;
480
481        // Remove the job and update the index if there are any other jobs scheduled at this time.
482        if (values != null) {
483            for (JobLocation job : values) {
484                if (job.getJobId().equals(command.getJobId())) {
485                    removed = job;
486                    values.remove(removed);
487                    break;
488                }
489            }
490
491            if (!values.isEmpty()) {
492                this.index.put(tx, executionTime, values);
493            }
494        }
495
496        if (removed != null) {
497            LOG.trace("{} removed from scheduler {}", removed, this);
498
499            // Remove the references for add and reschedule commands for this job
500            // so that those logs can be GC'd when free.
501            this.store.decrementJournalCount(tx, removed.getLocation());
502            if (removed.getLastUpdate() != null) {
503                this.store.decrementJournalCount(tx, removed.getLastUpdate());
504            }
505
506            // now that the job is removed from the index we can store the remove info and
507            // then dereference the log files that hold the initial add command and the most
508            // recent update command.
509            this.store.referenceRemovedLocation(tx, location, removed);
510        }
511    }
512
513    /**
514     * Removes all scheduled jobs within a given time range.
515     *
516     * The method can be used to clear the entire scheduler index by specifying a range that
517     * encompasses all time [0...Long.MAX_VALUE] or a single execution time can be removed by
518     * setting start and end time to the same value.
519     *
520     * @param tx
521     *      The transaction under which the index is updated.
522     * @param command
523     *      The remove command to process.
524     * @param location
525     *      The location of the remove command in the Journal.
526     *
527     * @throws IOException if an error occurs while updating the scheduler index.
528     */
529    protected void process(final Transaction tx, final KahaRemoveScheduledJobsCommand command, Location location) throws IOException {
530        removeInRange(tx, command.getStartTime(), command.getEndTime(), location);
531    }
532
533    /**
534     * Removes all jobs from the schedulers index.  Must be called with the index locked.
535     *
536     * @param tx
537     *      The transaction under which the index entries for this scheduler are removed.
538     *
539     * @throws IOException if an error occurs removing the jobs from the scheduler index.
540     */
541    protected void removeAll(Transaction tx) throws IOException {
542        this.removeInRange(tx, 0, Long.MAX_VALUE, null);
543    }
544
545    /**
546     * Removes all scheduled jobs within the target range.
547     *
548     * This method can be used to remove all the stored jobs by passing a range of [0...Long.MAX_VALUE]
549     * or it can be used to remove all jobs at a given scheduled time by passing the same time value
550     * for both start and end.  If the optional location parameter is set then this method will update
551     * the store's remove location tracker with the location value and the Jobs that are being removed.
552     *
553     * This method must be called with the store index locked for writes.
554     *
555     * @param tx
556     *      The transaction under which the index is to be updated.
557     * @param start
558     *      The start time for the remove operation.
559     * @param finish
560     *      The end time for the remove operation.
561     * @param location (optional)
562     *      The location of the remove command that triggered this remove.
563     *
564     * @throws IOException if an error occurs during the remove operation.
565     */
566    protected void removeInRange(Transaction tx, long start, long finish, Location location) throws IOException {
567        List<Long> keys = new ArrayList<Long>();
568        for (Iterator<Map.Entry<Long, List<JobLocation>>> i = this.index.iterator(tx, start); i.hasNext();) {
569            Map.Entry<Long, List<JobLocation>> entry = i.next();
570            if (entry.getKey().longValue() <= finish) {
571                keys.add(entry.getKey());
572            } else {
573                break;
574            }
575        }
576
577        for (Long executionTime : keys) {
578            List<JobLocation> values = this.index.remove(tx, executionTime);
579            if (location != null) {
580                for (JobLocation job : values) {
581                    LOG.trace("Removing {} scheduled at: {}", job, executionTime);
582
583                    // Remove the references for add and reschedule commands for this job
584                    // so that those logs can be GC'd when free.
585                    this.store.decrementJournalCount(tx, job.getLocation());
586                    if (job.getLastUpdate() != null) {
587                        this.store.decrementJournalCount(tx, job.getLastUpdate());
588                    }
589
590                    // now that the job is removed from the index we can store the remove info and
591                    // then dereference the log files that hold the initial add command and the most
592                    // recent update command.
593                    this.store.referenceRemovedLocation(tx, location, job);
594                }
595            }
596        }
597    }
598
599    /**
600     * Removes a Job from the index using it's Id value and the time it is currently set to
601     * be executed.  This method will only remove the Job if it is found at the given execution
602     * time.
603     *
604     * This method must be called under index lock.
605     *
606     * @param tx
607     *        the transaction under which this method is being executed.
608     * @param jobId
609     *        the target Job Id to remove.
610     * @param executionTime
611     *        the scheduled time that for the Job Id that is being removed.
612     *
613     * @returns true if the Job was removed or false if not found at the given time.
614     *
615     * @throws IOException if an error occurs while removing the Job.
616     */
617    protected boolean removeJobAtTime(Transaction tx, String jobId, long executionTime) throws IOException {
618        boolean result = false;
619
620        List<JobLocation> jobs = this.index.remove(tx, executionTime);
621        Iterator<JobLocation> jobsIter = jobs.iterator();
622        while (jobsIter.hasNext()) {
623            JobLocation job = jobsIter.next();
624            if (job.getJobId().equals(jobId)) {
625                jobsIter.remove();
626                // Remove the references for add and reschedule commands for this job
627                // so that those logs can be GC'd when free.
628                this.store.decrementJournalCount(tx, job.getLocation());
629                if (job.getLastUpdate() != null) {
630                    this.store.decrementJournalCount(tx, job.getLastUpdate());
631                }
632                result = true;
633                break;
634            }
635        }
636
637        // Return the list to the index modified or unmodified.
638        this.index.put(tx, executionTime, jobs);
639
640        return result;
641    }
642
643    /**
644     * Walks the Scheduled Job Tree and collects the add location and last update location
645     * for all scheduled jobs.
646     *
647     * This method must be called with the index locked.
648     *
649     * @param tx
650     *        the transaction under which this operation was invoked.
651     *
652     * @return a list of all referenced Location values for this JobSchedulerImpl
653     *
654     * @throws IOException if an error occurs walking the scheduler tree.
655     */
656    protected List<JobLocation> getAllScheduledJobs(Transaction tx) throws IOException {
657        List<JobLocation> references = new ArrayList<JobLocation>();
658
659        for (Iterator<Map.Entry<Long, List<JobLocation>>> i = this.index.iterator(tx); i.hasNext();) {
660            Map.Entry<Long, List<JobLocation>> entry = i.next();
661            List<JobLocation> scheduled = entry.getValue();
662            for (JobLocation job : scheduled) {
663                references.add(job);
664            }
665        }
666
667        return references;
668    }
669
670    @Override
671    public void run() {
672        try {
673            mainLoop();
674        } catch (Throwable e) {
675            if (this.running.get() && isStarted()) {
676                LOG.error("{} Caught exception in mainloop", this, e);
677            }
678        } finally {
679            if (running.get()) {
680                try {
681                    stop();
682                } catch (Exception e) {
683                    LOG.error("Failed to stop {}", this);
684                }
685            }
686        }
687    }
688
689    @Override
690    public String toString() {
691        return "JobScheduler: " + this.name;
692    }
693
694    protected void mainLoop() {
695        while (this.running.get()) {
696            this.scheduleTime.clearNewJob();
697            try {
698                long currentTime = System.currentTimeMillis();
699
700                // Read the list of scheduled events and fire the jobs, reschedule repeating jobs as
701                // needed before firing the job event.
702                Map.Entry<Long, List<JobLocation>> first = getNextToSchedule();
703                if (first != null) {
704                    List<JobLocation> list = new ArrayList<JobLocation>(first.getValue());
705                    List<JobLocation> toRemove = new ArrayList<JobLocation>(list.size());
706                    final long executionTime = first.getKey();
707                    long nextExecutionTime = 0;
708                    if (executionTime <= currentTime) {
709                        for (final JobLocation job : list) {
710
711                            if (!running.get()) {
712                                break;
713                            }
714
715                            int repeat = job.getRepeat();
716                            nextExecutionTime = calculateNextExecutionTime(job, currentTime, repeat);
717                            long waitTime = nextExecutionTime - currentTime;
718                            this.scheduleTime.setWaitTime(waitTime);
719                            if (!job.isCron()) {
720                                fireJob(job);
721                                if (repeat != 0) {
722                                    // Reschedule for the next time, the scheduler will take care of
723                                    // updating the repeat counter on the update.
724                                    doReschedule(job.getJobId(), executionTime, nextExecutionTime, job.getRescheduledCount() + 1);
725                                } else {
726                                    toRemove.add(job);
727                                }
728                            } else {
729                                if (repeat == 0) {
730                                    // This is a non-repeating Cron entry so we can fire and forget it.
731                                    fireJob(job);
732                                }
733
734                                if (nextExecutionTime > currentTime) {
735                                    // Reschedule the cron job as a new event, if the cron entry signals
736                                    // a repeat then it will be stored separately and fired as a normal
737                                    // event with decrementing repeat.
738                                    doReschedule(job.getJobId(), executionTime, nextExecutionTime, job.getRescheduledCount() + 1);
739
740                                    if (repeat != 0) {
741                                        // we have a separate schedule to run at this time
742                                        // so the cron job is used to set of a separate schedule
743                                        // hence we won't fire the original cron job to the
744                                        // listeners but we do need to start a separate schedule
745                                        String jobId = ID_GENERATOR.generateId();
746                                        ByteSequence payload = getPayload(job.getLocation());
747                                        schedule(jobId, payload, "", job.getDelay(), job.getPeriod(), job.getRepeat());
748                                        waitTime = job.getDelay() != 0 ? job.getDelay() : job.getPeriod();
749                                        this.scheduleTime.setWaitTime(waitTime);
750                                    }
751                                } else {
752                                    toRemove.add(job);
753                                }
754                            }
755                        }
756
757                        // now remove all jobs that have not been rescheduled from this execution
758                        // time, if there are no more entries in that time it will be removed.
759                        doRemove(executionTime, toRemove);
760
761                        // If there is a job that should fire before the currently set wait time
762                        // we need to reset wait time otherwise we'll miss it.
763                        Map.Entry<Long, List<JobLocation>> nextUp = getNextToSchedule();
764                        if (nextUp != null) {
765                            final long timeUntilNextScheduled = nextUp.getKey() - currentTime;
766                            if (timeUntilNextScheduled < this.scheduleTime.getWaitTime()) {
767                                this.scheduleTime.setWaitTime(timeUntilNextScheduled);
768                            }
769                        }
770                    } else {
771                        this.scheduleTime.setWaitTime(executionTime - currentTime);
772                    }
773                }
774
775                this.scheduleTime.pause();
776            } catch (Exception ioe) {
777                LOG.error("{} Failed to schedule job", this.name, ioe);
778                try {
779                    this.store.stop();
780                } catch (Exception e) {
781                    LOG.error("{} Failed to shutdown JobSchedulerStore", this.name, e);
782                }
783            }
784        }
785    }
786
787    void fireJob(JobLocation job) throws IllegalStateException, IOException {
788        LOG.debug("Firing: {}", job);
789        ByteSequence bs = this.store.getPayload(job.getLocation());
790        for (JobListener l : jobListeners) {
791            l.scheduledJob(job.getJobId(), bs);
792        }
793    }
794
795    @Override
796    public void startDispatching() throws Exception {
797        if (!this.running.get()) {
798            return;
799        }
800
801        if (started.compareAndSet(false, true)) {
802            this.thread = new Thread(this, "JobScheduler:" + this.name);
803            this.thread.setDaemon(true);
804            this.thread.start();
805        }
806    }
807
808    @Override
809    public void stopDispatching() throws Exception {
810        if (started.compareAndSet(true, false)) {
811            this.scheduleTime.wakeup();
812            Thread t = this.thread;
813            this.thread = null;
814            if (t != null) {
815                t.join(3000);
816            }
817        }
818    }
819
820    @Override
821    protected void doStart() throws Exception {
822        this.running.set(true);
823    }
824
825    @Override
826    protected void doStop(ServiceStopper stopper) throws Exception {
827        this.running.set(false);
828        stopDispatching();
829    }
830
831    private ByteSequence getPayload(Location location) throws IllegalStateException, IOException {
832        return this.store.getPayload(location);
833    }
834
835    long calculateNextExecutionTime(final JobLocation job, long currentTime, int repeat) throws MessageFormatException {
836        long result = currentTime;
837        String cron = job.getCronEntry();
838        if (cron != null && cron.length() > 0) {
839            result = CronParser.getNextScheduledTime(cron, result);
840        } else if (job.getRepeat() != 0) {
841            result += job.getPeriod();
842        }
843        return result;
844    }
845
846    void createIndexes(Transaction tx) throws IOException {
847        this.index = new BTreeIndex<Long, List<JobLocation>>(this.store.getPageFile(), tx.allocate().getPageId());
848    }
849
850    void load(Transaction tx) throws IOException {
851        this.index.setKeyMarshaller(LongMarshaller.INSTANCE);
852        this.index.setValueMarshaller(JobLocationsMarshaller.INSTANCE);
853        this.index.load(tx);
854    }
855
856    void read(DataInput in) throws IOException {
857        this.name = in.readUTF();
858        this.index = new BTreeIndex<Long, List<JobLocation>>(this.store.getPageFile(), in.readLong());
859        this.index.setKeyMarshaller(LongMarshaller.INSTANCE);
860        this.index.setValueMarshaller(JobLocationsMarshaller.INSTANCE);
861    }
862
863    public void write(DataOutput out) throws IOException {
864        out.writeUTF(name);
865        out.writeLong(this.index.getPageId());
866    }
867
868    static class ScheduleTime {
869        private final int DEFAULT_WAIT = 500;
870        private final int DEFAULT_NEW_JOB_WAIT = 100;
871        private boolean newJob;
872        private long waitTime = DEFAULT_WAIT;
873        private final Object mutex = new Object();
874
875        /**
876         * @return the waitTime
877         */
878        long getWaitTime() {
879            return this.waitTime;
880        }
881
882        /**
883         * @param waitTime
884         *            the waitTime to set
885         */
886        void setWaitTime(long waitTime) {
887            if (!this.newJob) {
888                this.waitTime = waitTime > 0 ? waitTime : DEFAULT_WAIT;
889            }
890        }
891
892        void pause() {
893            synchronized (mutex) {
894                try {
895                    mutex.wait(this.waitTime);
896                } catch (InterruptedException e) {
897                }
898            }
899        }
900
901        void newJob() {
902            this.newJob = true;
903            this.waitTime = DEFAULT_NEW_JOB_WAIT;
904            wakeup();
905        }
906
907        void clearNewJob() {
908            this.newJob = false;
909        }
910
911        void wakeup() {
912            synchronized (this.mutex) {
913                mutex.notifyAll();
914            }
915        }
916    }
917}