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本文主要研究一下artemis的maxDeliveryAttempts
maxDeliveryAttempts
activemq-artemis-2.11.0/artemis-server/src/main/java/org/apache/activemq/artemis/core/settings/impl/AddressSettings.java
public class AddressSettings implements Mergeable<AddressSettings>, Serializable, EncodingSupport {
//......
public static final int DEFAULT_MAX_DELIVERY_ATTEMPTS = 10;
private Integer maxDeliveryAttempts = null;
private SimpleString deadLetterAddress = null;
//......
public int getMaxDeliveryAttempts() {
return maxDeliveryAttempts != null ? maxDeliveryAttempts : AddressSettings.DEFAULT_MAX_DELIVERY_ATTEMPTS;
}
public AddressSettings setMaxDeliveryAttempts(final int maxDeliveryAttempts) {
this.maxDeliveryAttempts = maxDeliveryAttempts;
return this;
}
public SimpleString getDeadLetterAddress() {
return deadLetterAddress;
}
public AddressSettings setDeadLetterAddress(final SimpleString deadLetterAddress) {
this.deadLetterAddress = deadLetterAddress;
return this;
}
//......
}
- AddressSettings定义了maxDeliveryAttempts及deadLetterAddress属性，其getMaxDeliveryAttempts方法在maxDeliveryAttempts为null时返回AddressSettings.DEFAULT_MAX_DELIVERY_ATTEMPTS，默认值为10
checkRedelivery
activemq-artemis-2.11.0/artemis-server/src/main/java/org/apache/activemq/artemis/core/server/impl/QueueImpl.java
public class QueueImpl extends CriticalComponentImpl implements Queue {
//......
public Pair<Boolean, Boolean> checkRedelivery(final MessageReference reference,
final long timeBase,
final boolean ignoreRedeliveryDelay) throws Exception {
Message message = reference.getMessage();
if (internalQueue) {
if (logger.isTraceEnabled()) {
logger.trace("Queue " + this.getName() + " is an internal queue, no checkRedelivery");
}
// no DLQ check on internal queues
return new Pair<>(true, false);
}
if (!internalQueue && reference.isDurable() && isDurable() && !reference.isPaged()) {
storageManager.updateDeliveryCount(reference);
}
AddressSettings addressSettings = addressSettingsRepository.getMatch(address.toString());
int maxDeliveries = addressSettings.getMaxDeliveryAttempts();
int deliveryCount = reference.getDeliveryCount();
// First check DLA
if (maxDeliveries > 0 && deliveryCount >= maxDeliveries) {
if (logger.isTraceEnabled()) {
logger.trace("Sending reference " + reference + " to DLA = " + addressSettings.getDeadLetterAddress() + " since ref.getDeliveryCount=" + reference.getDeliveryCount() + "and maxDeliveries=" + maxDeliveries + " from queue=" + this.getName());
}
boolean dlaResult = sendToDeadLetterAddress(null, reference, addressSettings.getDeadLetterAddress());
return new Pair<>(false, dlaResult);
} else {
// Second check Redelivery Delay
long redeliveryDelay = addressSettings.getRedeliveryDelay();
if (!ignoreRedeliveryDelay && redeliveryDelay > 0) {
redeliveryDelay = calculateRedeliveryDelay(addressSettings, deliveryCount);
if (logger.isTraceEnabled()) {
logger.trace("Setting redeliveryDelay=" + redeliveryDelay + " on reference=" + reference);
}
reference.setScheduledDeliveryTime(timeBase + redeliveryDelay);
if (!reference.isPaged() && reference.isDurable() && isDurable()) {
storageManager.updateScheduledDeliveryTime(reference);
}
}
decDelivering(reference);
return new Pair<>(true, false);
}
}
//......
}
- QueueImpl的checkRedelivery方法会对比deliveryCount与maxDeliveries，当deliveryCount大于0且大于等于maxDeliveries时会执行sendToDeadLetterAddress
sendToDeadLetterAddress
activemq-artemis-2.11.0/artemis-server/src/main/java/org/apache/activemq/artemis/core/server/impl/QueueImpl.java
public class QueueImpl extends CriticalComponentImpl implements Queue {
//......
private boolean sendToDeadLetterAddress(final Transaction tx,
final MessageReference ref,
final SimpleString deadLetterAddress) throws Exception {
if (deadLetterAddress != null) {
Bindings bindingList = postOffice.lookupBindingsForAddress(deadLetterAddress);
if (bindingList == null || bindingList.getBindings().isEmpty()) {
ActiveMQServerLogger.LOGGER.messageExceededMaxDelivery(ref, deadLetterAddress);
ref.acknowledge(tx, AckReason.KILLED, null);
} else {
ActiveMQServerLogger.LOGGER.messageExceededMaxDeliverySendtoDLA(ref, deadLetterAddress, name);
move(tx, deadLetterAddress, null, ref, false, AckReason.KILLED, null);
return true;
}
} else {
ActiveMQServerLogger.LOGGER.messageExceededMaxDeliveryNoDLA(ref, name);
ref.acknowledge(tx, AckReason.KILLED, null);
}
return false;
}
private void move(final Transaction originalTX,
final SimpleString address,
final Binding binding,
final MessageReference ref,
final boolean rejectDuplicate,
final AckReason reason,
final ServerConsumer consumer) throws Exception {
Transaction tx;
if (originalTX != null) {
tx = originalTX;
} else {
// if no TX we create a new one to commit at the end
tx = new TransactionImpl(storageManager);
}
Message copyMessage = makeCopy(ref, reason == AckReason.EXPIRED);
copyMessage.setAddress(address);
postOffice.route(copyMessage, tx, false, rejectDuplicate, binding);
acknowledge(tx, ref, reason, consumer);
if (originalTX == null) {
tx.commit();
}
}
//......
}
- sendToDeadLetterAddress方法在bindingList不为空的情况下会执行move操作，move到deadLetterAddress，其AckReason为AckReason.KILLED
incrementDeliveryCount
activemq-artemis-2.11.0/artemis-server/src/main/java/org/apache/activemq/artemis/core/server/impl/ServerConsumerImpl.java
public class ServerConsumerImpl implements ServerConsumer, ReadyListener {
//......
public HandleStatus handle(final MessageReference ref) throws Exception {
// available credits can be set back to null with a flow control option.
AtomicInteger checkInteger = availableCredits;
if (callback != null && !callback.hasCredits(this) || checkInteger != null && checkInteger.get() <= 0) {
if (logger.isDebugEnabled()) {
logger.debug(this + " is busy for the lack of credits. Current credits = " +
availableCredits +
" Can't receive reference " +
ref);
}
return HandleStatus.BUSY;
}
synchronized (lock) {
// If the consumer is stopped then we don't accept the message, it
// should go back into the
// queue for delivery later.
// TCP-flow control has to be done first than everything else otherwise we may lose notifications
if ((callback != null && !callback.isWritable(this, protocolContext)) || !started || transferring) {
return HandleStatus.BUSY;
}
// If there is a pendingLargeMessage we can't take another message
// This has to be checked inside the lock as the set to null is done inside the lock
if (largeMessageDeliverer != null) {
if (logger.isDebugEnabled()) {
logger.debug(this + " is busy delivering large message " +
largeMessageDeliverer +
", can't deliver reference " +
ref);
}
return HandleStatus.BUSY;
}
final Message message = ref.getMessage();
if (!message.acceptsConsumer(sequentialID())) {
return HandleStatus.NO_MATCH;
}
if (filter != null && !filter.match(message)) {
if (logger.isTraceEnabled()) {
logger.trace("Reference " + ref + " is a noMatch on consumer " + this);
}
return HandleStatus.NO_MATCH;
}
if (logger.isTraceEnabled()) {
logger.trace("ServerConsumerImpl::" + this + " Handling reference " + ref);
}
if (!browseOnly) {
if (!preAcknowledge) {
deliveringRefs.add(ref);
}
ref.handled();
ref.setConsumerId(this.id);
ref.incrementDeliveryCount();
// If updateDeliveries = false (set by strict-update),
// the updateDeliveryCountAfterCancel would still be updated after c
if (strictUpdateDeliveryCount && !ref.isPaged()) {
if (ref.getMessage().isDurable() && ref.getQueue().isDurable() &&
!ref.getQueue().isInternalQueue() &&
!ref.isPaged()) {
storageManager.updateDeliveryCount(ref);
}
}
if (preAcknowledge) {
if (message.isLargeMessage()) {
// we must hold one reference, or the file will be deleted before it could be delivered
((LargeServerMessage) message).incrementDelayDeletionCount();
}
// With pre-ack, we ack *before* sending to the client
ref.getQueue().acknowledge(ref, this);
acks++;
}
if (message.isLargeMessage() && this.supportLargeMessage) {
largeMessageDeliverer = new LargeMessageDeliverer((LargeServerMessage) message, ref);
}
}
pendingDelivery.countUp();
return HandleStatus.HANDLED;
}
}
//......
}
- ServerConsumerImpl的handle方法会在非browseOnly的情况下会调用ref.incrementDeliveryCount()来增加deliveryCount；必要的时候会执行storageManager.updateDeliveryCount(ref)
updateDeliveryCount
activemq-artemis-2.11.0/artemis-server/src/main/java/org/apache/activemq/artemis/core/persistence/impl/journal/AbstractJournalStorageManager.java
public abstract class AbstractJournalStorageManager extends CriticalComponentImpl implements StorageManager {
//......
public void updateDeliveryCount(final MessageReference ref) throws Exception {
// no need to store if it's the same value
// otherwise the journal will get OME in case of lots of redeliveries
if (ref.getDeliveryCount() == ref.getPersistedCount()) {
return;
}
ref.setPersistedCount(ref.getDeliveryCount());
DeliveryCountUpdateEncoding updateInfo = new DeliveryCountUpdateEncoding(ref.getQueue().getID(), ref.getDeliveryCount());
readLock();
try {
messageJournal.appendUpdateRecord(ref.getMessage().getMessageID(), JournalRecordIds.UPDATE_DELIVERY_COUNT, updateInfo, syncNonTransactional, getContext(syncNonTransactional));
} finally {
readUnLock();
}
}
//......
}
- AbstractJournalStorageManager的updateDeliveryCount方法会更新persistedCount到storage
小结
AddressSettings定义了maxDeliveryAttempts及deadLetterAddress属性，其getMaxDeliveryAttempts方法在maxDeliveryAttempts为null时返回AddressSettings.DEFAULT_MAX_DELIVERY_ATTEMPTS，默认值为10；QueueImpl的checkRedelivery方法会对比deliveryCount与maxDeliveries，当deliveryCount大于0且大于等于maxDeliveries时会执行sendToDeadLetterAddress；sendToDeadLetterAddress方法在bindingList不为空的情况下会执行move操作，move到deadLetterAddress，其AckReason为AckReason.KILLED
doc
来源：oschina
链接：https://my.oschina.net/go4it/blog/3161549