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.broker.region.cursors;
018
019import java.util.Iterator;
020import java.util.LinkedList;
021import java.util.ListIterator;
022import java.util.concurrent.CancellationException;
023import java.util.concurrent.Future;
024import java.util.concurrent.TimeUnit;
025import java.util.concurrent.TimeoutException;
026
027import org.apache.activemq.broker.region.Destination;
028import org.apache.activemq.broker.region.MessageReference;
029import org.apache.activemq.broker.region.Subscription;
030import org.apache.activemq.command.Message;
031import org.apache.activemq.command.MessageId;
032import org.apache.activemq.store.MessageRecoveryListener;
033import org.slf4j.Logger;
034import org.slf4j.LoggerFactory;
035
036/**
037 *  Store based cursor
038 *
039 */
040public abstract class AbstractStoreCursor extends AbstractPendingMessageCursor implements MessageRecoveryListener {
041    private static final Logger LOG = LoggerFactory.getLogger(AbstractStoreCursor.class);
042    protected final Destination regionDestination;
043    protected final PendingList batchList;
044    private Iterator<MessageReference> iterator = null;
045    protected boolean batchResetNeeded = false;
046    protected int size;
047    private final LinkedList<MessageId> pendingCachedIds = new LinkedList<>();
048    private static int SYNC_ADD = 0;
049    private static int ASYNC_ADD = 1;
050    final MessageId[] lastCachedIds = new MessageId[2];
051    protected boolean hadSpace = false;
052
053
054
055    protected AbstractStoreCursor(Destination destination) {
056        super((destination != null ? destination.isPrioritizedMessages():false));
057        this.regionDestination=destination;
058        if (this.prioritizedMessages) {
059            this.batchList= new PrioritizedPendingList();
060        } else {
061            this.batchList = new OrderedPendingList();
062        }
063    }
064
065
066    @Override
067    public final synchronized void start() throws Exception{
068        if (!isStarted()) {
069            super.start();
070            resetBatch();
071            resetSize();
072            setCacheEnabled(size==0&&useCache);
073        }
074    }
075
076    protected void resetSize() {
077        this.size = getStoreSize();
078    }
079
080    @Override
081    public void rebase() {
082        resetSize();
083    }
084
085    @Override
086    public final synchronized void stop() throws Exception {
087        resetBatch();
088        super.stop();
089        gc();
090    }
091
092
093    @Override
094    public final boolean recoverMessage(Message message) throws Exception {
095        return recoverMessage(message,false);
096    }
097
098    public synchronized boolean recoverMessage(Message message, boolean cached) throws Exception {
099        boolean recovered = false;
100        message.setRegionDestination(regionDestination);
101        if (recordUniqueId(message.getMessageId())) {
102            if (!cached) {
103                if( message.getMemoryUsage()==null ) {
104                    message.setMemoryUsage(this.getSystemUsage().getMemoryUsage());
105                }
106            }
107            message.incrementReferenceCount();
108            batchList.addMessageLast(message);
109            clearIterator(true);
110            recovered = true;
111        } else if (!cached) {
112            // a duplicate from the store (!cached) - needs to be removed/acked - otherwise it will get re dispatched on restart
113            if (message.isRecievedByDFBridge()) {
114                // expected for messages pending acks with kahadb.concurrentStoreAndDispatchQueues=true
115                if (LOG.isTraceEnabled()) {
116                    LOG.trace("{} store replayed pending message due to concurrentStoreAndDispatchQueues {} seq: {}", this, message.getMessageId(), message.getMessageId().getFutureOrSequenceLong());
117                }
118            } else {
119                LOG.warn("{} - cursor got duplicate from store {} seq: {}", this, message.getMessageId(), message.getMessageId().getFutureOrSequenceLong());
120                duplicate(message);
121            }
122        } else {
123            LOG.warn("{} - cursor got duplicate send {} seq: {}", this, message.getMessageId(), message.getMessageId().getFutureOrSequenceLong());
124            if (message.getMessageId().getEntryLocator() instanceof Long) {
125                // JDBC will store a duplicate (with new sequence id) - it needs an ack  (AMQ4952Test)
126                duplicate(message);
127            }
128        }
129        return recovered;
130    }
131
132    // track for processing outside of store index lock so we can dlq
133    final LinkedList<Message> duplicatesFromStore = new LinkedList<Message>();
134    private void duplicate(Message message) {
135        duplicatesFromStore.add(message);
136    }
137
138    void dealWithDuplicates() {
139        for (Message message : duplicatesFromStore) {
140            regionDestination.duplicateFromStore(message, getSubscription());
141        }
142        duplicatesFromStore.clear();
143    }
144
145    @Override
146    public final synchronized void reset() {
147        if (batchList.isEmpty()) {
148            try {
149                fillBatch();
150            } catch (Exception e) {
151                LOG.error("{} - Failed to fill batch", this, e);
152                throw new RuntimeException(e);
153            }
154        }
155        clearIterator(true);
156        size();
157    }
158
159
160    @Override
161    public synchronized void release() {
162        clearIterator(false);
163    }
164
165    private synchronized void clearIterator(boolean ensureIterator) {
166        boolean haveIterator = this.iterator != null;
167        this.iterator=null;
168        if(haveIterator&&ensureIterator) {
169            ensureIterator();
170        }
171    }
172
173    private synchronized void ensureIterator() {
174        if(this.iterator==null) {
175            this.iterator=this.batchList.iterator();
176        }
177    }
178
179
180    public final void finished() {
181    }
182
183
184    @Override
185    public final synchronized boolean hasNext() {
186        if (batchList.isEmpty()) {
187            try {
188                fillBatch();
189            } catch (Exception e) {
190                LOG.error("{} - Failed to fill batch", this, e);
191                throw new RuntimeException(e);
192            }
193        }
194        ensureIterator();
195        return this.iterator.hasNext();
196    }
197
198
199    @Override
200    public final synchronized MessageReference next() {
201        MessageReference result = null;
202        if (!this.batchList.isEmpty()&&this.iterator.hasNext()) {
203            result = this.iterator.next();
204        }
205        last = result;
206        if (result != null) {
207            result.incrementReferenceCount();
208        }
209        return result;
210    }
211
212    @Override
213    public synchronized boolean tryAddMessageLast(MessageReference node, long wait) throws Exception {
214        boolean disableCache = false;
215        if (hasSpace()) {
216            if (!isCacheEnabled() && size==0 && isStarted() && useCache) {
217                if (LOG.isTraceEnabled()) {
218                    LOG.trace("{} - enabling cache for empty store {} {}", this, node.getMessageId(), node.getMessageId().getFutureOrSequenceLong());
219                }
220                setCacheEnabled(true);
221            }
222            if (isCacheEnabled()) {
223                if (recoverMessage(node.getMessage(),true)) {
224                    trackLastCached(node);
225                } else {
226                    dealWithDuplicates();
227                    return false;
228                }
229            }
230        } else {
231            disableCache = true;
232        }
233
234        if (disableCache && isCacheEnabled()) {
235            if (LOG.isTraceEnabled()) {
236                LOG.trace("{} - disabling cache on add {} {}", this, node.getMessageId(), node.getMessageId().getFutureOrSequenceLong());
237            }
238            syncWithStore(node.getMessage());
239            setCacheEnabled(false);
240        }
241        size++;
242        return true;
243    }
244
245    private void syncWithStore(Message currentAdd) throws Exception {
246        pruneLastCached();
247        if (lastCachedIds[SYNC_ADD] == null) {
248            // possibly only async adds, lets wait on the potential last add and reset from there
249            for (ListIterator<MessageId> it = pendingCachedIds.listIterator(pendingCachedIds.size()); it.hasPrevious(); ) {
250                MessageId lastPending = it.previous();
251                Object futureOrLong = lastPending.getFutureOrSequenceLong();
252                if (futureOrLong instanceof Future) {
253                    Future future = (Future) futureOrLong;
254                    if (future.isCancelled()) {
255                        continue;
256                    }
257                    try {
258                        future.get(5, TimeUnit.SECONDS);
259                        setLastCachedId(ASYNC_ADD, lastPending);
260                    } catch (CancellationException ok) {
261                        continue;
262                    } catch (TimeoutException potentialDeadlock) {
263                        LOG.debug("{} timed out waiting for async add", this, potentialDeadlock);
264                    } catch (Exception worstCaseWeReplay) {
265                        LOG.debug("{} exception waiting for async add", this, worstCaseWeReplay);
266                    }
267                } else {
268                    setLastCachedId(ASYNC_ADD, lastPending);
269                }
270                break;
271            }
272            if (lastCachedIds[ASYNC_ADD] != null) {
273                // ensure we don't skip current possibly sync add b/c we waited on the future
274                if (isAsync(currentAdd) || Long.compare(((Long) currentAdd.getMessageId().getFutureOrSequenceLong()), ((Long) lastCachedIds[ASYNC_ADD].getFutureOrSequenceLong())) > 0) {
275                    setBatch(lastCachedIds[ASYNC_ADD]);
276                }
277            }
278        } else {
279            setBatch(lastCachedIds[SYNC_ADD]);
280        }
281        // cleanup
282        lastCachedIds[SYNC_ADD] = lastCachedIds[ASYNC_ADD] = null;
283        pendingCachedIds.clear();
284    }
285
286    private void trackLastCached(MessageReference node) {
287        if (isAsync(node.getMessage())) {
288            pruneLastCached();
289            pendingCachedIds.add(node.getMessageId());
290        } else {
291            setLastCachedId(SYNC_ADD, node.getMessageId());
292        }
293    }
294
295    private static final boolean isAsync(Message message) {
296        return message.isRecievedByDFBridge() || message.getMessageId().getFutureOrSequenceLong() instanceof Future;
297    }
298
299    private void pruneLastCached() {
300        for (Iterator<MessageId> it = pendingCachedIds.iterator(); it.hasNext(); ) {
301            MessageId candidate = it.next();
302            final Object futureOrLong = candidate.getFutureOrSequenceLong();
303            if (futureOrLong instanceof Future) {
304                Future future = (Future) futureOrLong;
305                if (future.isCancelled()) {
306                    it.remove();
307                } else {
308                    // we don't want to wait for work to complete
309                    break;
310                }
311            } else {
312                // complete
313                setLastCachedId(ASYNC_ADD, candidate);
314
315                // keep lock step with sync adds while order is preserved
316                if (lastCachedIds[SYNC_ADD] != null) {
317                    long next = 1 + (Long)lastCachedIds[SYNC_ADD].getFutureOrSequenceLong();
318                    if (Long.compare((Long)futureOrLong, next) == 0) {
319                        setLastCachedId(SYNC_ADD, candidate);
320                    }
321                }
322                it.remove();
323            }
324        }
325    }
326
327    private void setLastCachedId(final int index, MessageId candidate) {
328        MessageId lastCacheId = lastCachedIds[index];
329        if (lastCacheId == null) {
330            lastCachedIds[index] = candidate;
331        } else {
332            Object lastCacheFutureOrSequenceLong = lastCacheId.getFutureOrSequenceLong();
333            Object candidateOrSequenceLong = candidate.getFutureOrSequenceLong();
334            if (lastCacheFutureOrSequenceLong == null) { // possibly null for topics
335                lastCachedIds[index] = candidate;
336            } else if (candidateOrSequenceLong != null &&
337                    Long.compare(((Long) candidateOrSequenceLong), ((Long) lastCacheFutureOrSequenceLong)) > 0) {
338                lastCachedIds[index] = candidate;
339            }
340        }
341    }
342
343    protected void setBatch(MessageId messageId) throws Exception {
344    }
345
346
347    @Override
348    public synchronized void addMessageFirst(MessageReference node) throws Exception {
349        setCacheEnabled(false);
350        size++;
351    }
352
353
354    @Override
355    public final synchronized void remove() {
356        size--;
357        if (iterator!=null) {
358            iterator.remove();
359        }
360        if (last != null) {
361            last.decrementReferenceCount();
362        }
363    }
364
365
366    @Override
367    public final synchronized void remove(MessageReference node) {
368        if (batchList.remove(node) != null) {
369            size--;
370            setCacheEnabled(false);
371        }
372    }
373
374
375    @Override
376    public final synchronized void clear() {
377        gc();
378    }
379
380
381    @Override
382    public synchronized void gc() {
383        for (MessageReference msg : batchList) {
384            rollback(msg.getMessageId());
385            msg.decrementReferenceCount();
386        }
387        batchList.clear();
388        clearIterator(false);
389        batchResetNeeded = true;
390        setCacheEnabled(false);
391    }
392
393    @Override
394    protected final synchronized void fillBatch() {
395        if (LOG.isTraceEnabled()) {
396            LOG.trace("{} fillBatch", this);
397        }
398        if (batchResetNeeded) {
399            resetSize();
400            setMaxBatchSize(Math.min(regionDestination.getMaxPageSize(), size));
401            resetBatch();
402            this.batchResetNeeded = false;
403        }
404        if (this.batchList.isEmpty() && this.size >0) {
405            try {
406                doFillBatch();
407            } catch (Exception e) {
408                LOG.error("{} - Failed to fill batch", this, e);
409                throw new RuntimeException(e);
410            }
411        }
412    }
413
414
415    @Override
416    public final synchronized boolean isEmpty() {
417        // negative means more messages added to store through queue.send since last reset
418        return size == 0;
419    }
420
421
422    @Override
423    public final synchronized boolean hasMessagesBufferedToDeliver() {
424        return !batchList.isEmpty();
425    }
426
427
428    @Override
429    public final synchronized int size() {
430        if (size < 0) {
431            this.size = getStoreSize();
432        }
433        return size;
434    }
435
436    @Override
437    public final synchronized long messageSize() {
438        return getStoreMessageSize();
439    }
440
441    @Override
442    public String toString() {
443        return super.toString() + ":" + regionDestination.getActiveMQDestination().getPhysicalName() + ",batchResetNeeded=" + batchResetNeeded
444                    + ",size=" + this.size + ",cacheEnabled=" + isCacheEnabled()
445                    + ",maxBatchSize:" + maxBatchSize + ",hasSpace:" + hasSpace() + ",pendingCachedIds.size:" + pendingCachedIds.size()
446                    + ",lastSyncCachedId:" + lastCachedIds[SYNC_ADD] + ",lastSyncCachedId-seq:" + (lastCachedIds[SYNC_ADD] != null ? lastCachedIds[SYNC_ADD].getFutureOrSequenceLong() : "null")
447                    + ",lastAsyncCachedId:" + lastCachedIds[ASYNC_ADD] + ",lastAsyncCachedId-seq:" + (lastCachedIds[ASYNC_ADD] != null ? lastCachedIds[ASYNC_ADD].getFutureOrSequenceLong() : "null");
448    }
449
450    protected abstract void doFillBatch() throws Exception;
451
452    protected abstract void resetBatch();
453
454    protected abstract int getStoreSize();
455
456    protected abstract long getStoreMessageSize();
457
458    protected abstract boolean isStoreEmpty();
459
460    public Subscription getSubscription() {
461        return null;
462    }
463}