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本文主要研究一下artemis消息的推拉模式
拉模式
receive
activemq-artemis-2.11.0/artemis-jms-client/src/main/java/org/apache/activemq/artemis/jms/client/ActiveMQMessageConsumer.java
public final class ActiveMQMessageConsumer implements QueueReceiver, TopicSubscriber {
//......
@Override
public Message receive() throws JMSException {
return getMessage(0, false);
}
@Override
public Message receive(final long timeout) throws JMSException {
return getMessage(timeout, false);
}
@Override
public Message receiveNoWait() throws JMSException {
return getMessage(0, true);
}
private ActiveMQMessage getMessage(final long timeout, final boolean noWait) throws JMSException {
try {
ClientMessage coreMessage;
if (noWait) {
coreMessage = consumer.receiveImmediate();
} else {
coreMessage = consumer.receive(timeout);
}
ActiveMQMessage jmsMsg = null;
if (coreMessage != null) {
ClientSession coreSession = session.getCoreSession();
boolean needSession = ackMode == Session.CLIENT_ACKNOWLEDGE ||
ackMode == ActiveMQJMSConstants.INDIVIDUAL_ACKNOWLEDGE ||
coreMessage.getType() == ActiveMQObjectMessage.TYPE;
if (coreMessage.getRoutingType() == null) {
coreMessage.setRoutingType(destination.isQueue() ? RoutingType.ANYCAST : RoutingType.MULTICAST);
}
if (session.isEnable1xPrefixes()) {
jmsMsg = ActiveMQCompatibleMessage.createMessage(coreMessage, needSession ? coreSession : null, options);
} else {
jmsMsg = ActiveMQMessage.createMessage(coreMessage, needSession ? coreSession : null, options);
}
try {
jmsMsg.doBeforeReceive();
} catch (IndexOutOfBoundsException ioob) {
((ClientSessionInternal) session.getCoreSession()).markRollbackOnly();
// In case this exception happen you will need to know where it happened.
// it has been a bug here in the past, and this was used to debug it.
// nothing better than keep it for future investigations in case it happened again
IndexOutOfBoundsException newIOOB = new IndexOutOfBoundsException(ioob.getMessage() + "@" + jmsMsg.getCoreMessage());
newIOOB.initCause(ioob);
ActiveMQClientLogger.LOGGER.unableToGetMessage(newIOOB);
throw ioob;
}
// We Do the ack after doBeforeReceive, as in the case of large messages, this may fail so we don't want messages redelivered
// https://issues.jboss.org/browse/JBPAPP-6110
if (session.getAcknowledgeMode() == ActiveMQJMSConstants.INDIVIDUAL_ACKNOWLEDGE) {
jmsMsg.setIndividualAcknowledge();
} else if (session.getAcknowledgeMode() == Session.CLIENT_ACKNOWLEDGE) {
jmsMsg.setClientAcknowledge();
coreMessage.acknowledge();
} else {
coreMessage.acknowledge();
}
}
return jmsMsg;
} catch (ActiveMQException e) {
((ClientSessionInternal) session.getCoreSession()).markRollbackOnly();
throw JMSExceptionHelper.convertFromActiveMQException(e);
} catch (ActiveMQInterruptedException e) {
((ClientSessionInternal) session.getCoreSession()).markRollbackOnly();
throw JMSExceptionHelper.convertFromActiveMQException(e);
}
}
//......
}
- ActiveMQMessageConsumer的receive方法最后调用的是getMessage方法，它对于session.getAcknowledgeMode()为ActiveMQJMSConstants.INDIVIDUAL_ACKNOWLEDGE执行jmsMsg.setIndividualAcknowledge()，其余的都执行coreMessage.acknowledge()
acknowledge
activemq-artemis-2.11.0/artemis-core-client/src/main/java/org/apache/activemq/artemis/core/client/impl/ClientMessageImpl.java
public class ClientMessageImpl extends CoreMessage implements ClientMessageInternal {
//......
public ClientMessageImpl acknowledge() throws ActiveMQException {
if (consumer != null) {
consumer.acknowledge(this);
}
return this;
}
//......
}
- ClientMessageImpl的acknowledge方法执行的是consumer.acknowledge(this)
推模式
handleMessage
activemq-artemis-2.11.0/artemis-core-client/src/main/java/org/apache/activemq/artemis/core/client/impl/ClientConsumerImpl.java
public final class ClientConsumerImpl implements ClientConsumerInternal {
//......
public synchronized void handleMessage(final ClientMessageInternal message) throws Exception {
if (closing) {
// This is ok - we just ignore the message
return;
}
if (message.getBooleanProperty(Message.HDR_LARGE_COMPRESSED)) {
handleCompressedMessage(message);
} else {
handleRegularMessage(message);
}
}
private void handleRegularMessage(ClientMessageInternal message) {
if (message.getAddress() == null) {
message.setAddress(queueInfo.getAddress());
}
message.onReceipt(this);
if (!ackIndividually && message.getPriority() != 4 && !message.containsProperty(ClientConsumerImpl.FORCED_DELIVERY_MESSAGE)) {
// We have messages of different priorities so we need to ack them individually since the order
// of them in the ServerConsumerImpl delivery list might not be the same as the order they are
// consumed in, which means that acking all up to won't work
ackIndividually = true;
}
// Add it to the buffer
buffer.addTail(message, message.getPriority());
if (handler != null) {
// Execute using executor
if (!stopped) {
queueExecutor();
}
} else {
notify();
}
}
private void queueExecutor() {
if (logger.isTraceEnabled()) {
logger.trace(this + "::Adding Runner on Executor for delivery");
}
sessionExecutor.execute(runner);
}
//......
}
- ClientConsumerImpl的handleRegularMessage会执行buffer.addTail(message, message.getPriority())以及queueExecutor()，queueExecutor通过sessionExecutor执行Runner
callOnMessage
activemq-artemis-2.11.0/artemis-core-client/src/main/java/org/apache/activemq/artemis/core/client/impl/ClientConsumerImpl.java
public final class ClientConsumerImpl implements ClientConsumerInternal {
//......
private final PriorityLinkedList<ClientMessageInternal> buffer = new PriorityLinkedListImpl<>(ClientConsumerImpl.NUM_PRIORITIES);
//......
private class Runner implements Runnable {
@Override
public void run() {
try {
callOnMessage();
} catch (Exception e) {
ActiveMQClientLogger.LOGGER.onMessageError(e);
lastException = e;
}
}
}
private void callOnMessage() throws Exception {
if (closing || stopped) {
return;
}
session.workDone();
// We pull the message from the buffer from inside the Runnable so we can ensure priority
// ordering. If we just added a Runnable with the message to the executor immediately as we get it
// we could not do that
ClientMessageInternal message;
// Must store handler in local variable since might get set to null
// otherwise while this is executing and give NPE when calling onMessage
MessageHandler theHandler = handler;
if (theHandler != null) {
if (rateLimiter != null) {
rateLimiter.limit();
}
failedOver = false;
synchronized (this) {
message = buffer.poll();
}
if (message != null) {
if (message.containsProperty(ClientConsumerImpl.FORCED_DELIVERY_MESSAGE)) {
//Ignore, this could be a relic from a previous receiveImmediate();
return;
}
boolean expired = message.isExpired();
flowControlBeforeConsumption(message);
if (!expired) {
if (logger.isTraceEnabled()) {
logger.trace(this + "::Calling handler.onMessage");
}
final ClassLoader originalLoader = AccessController.doPrivileged(new PrivilegedAction<ClassLoader>() {
@Override
public ClassLoader run() {
ClassLoader originalLoader = Thread.currentThread().getContextClassLoader();
Thread.currentThread().setContextClassLoader(contextClassLoader);
return originalLoader;
}
});
onMessageThread = Thread.currentThread();
try {
theHandler.onMessage(message);
} finally {
try {
AccessController.doPrivileged(new PrivilegedAction<Object>() {
@Override
public Object run() {
Thread.currentThread().setContextClassLoader(originalLoader);
return null;
}
});
} catch (Exception e) {
ActiveMQClientLogger.LOGGER.failedPerformPostActionsOnMessage(e);
}
onMessageThread = null;
}
if (logger.isTraceEnabled()) {
logger.trace(this + "::Handler.onMessage done");
}
if (message.isLargeMessage()) {
message.discardBody();
}
} else {
session.expire(this, message);
}
// If slow consumer, we need to send 1 credit to make sure we get another message
if (clientWindowSize == 0) {
startSlowConsumer();
}
}
}
}
//......
}
- Runner的run方法会执行callOnMessage方法，它会从buffer.poll()消息，如果不为null且非expired则执行theHandler.onMessage(message)
onMessage
activemq-artemis-2.11.0/artemis-jms-client/src/main/java/org/apache/activemq/artemis/jms/client/JMSMessageListenerWrapper.java
public class JMSMessageListenerWrapper implements MessageHandler {
private final ConnectionFactoryOptions options;
private final ActiveMQConnection connection;
private final ActiveMQSession session;
private final MessageListener listener;
private final ClientConsumer consumer;
private final boolean transactedOrClientAck;
private final boolean individualACK;
private final boolean clientACK;
protected JMSMessageListenerWrapper(final ConnectionFactoryOptions options,
final ActiveMQConnection connection,
final ActiveMQSession session,
final ClientConsumer consumer,
final MessageListener listener,
final int ackMode) {
this.options = options;
this.connection = connection;
this.session = session;
this.consumer = consumer;
this.listener = listener;
transactedOrClientAck = (ackMode == Session.SESSION_TRANSACTED || ackMode == Session.CLIENT_ACKNOWLEDGE) || session.isXA();
individualACK = (ackMode == ActiveMQJMSConstants.INDIVIDUAL_ACKNOWLEDGE);
clientACK = (ackMode == Session.CLIENT_ACKNOWLEDGE);
}
/**
* In this method we apply the JMS acknowledgement and redelivery semantics
* as per JMS spec
*/
@Override
public void onMessage(final ClientMessage message) {
ActiveMQMessage msg;
if (session.isEnable1xPrefixes()) {
msg = ActiveMQCompatibleMessage.createMessage(message, session.getCoreSession(), options);
} else {
msg = ActiveMQMessage.createMessage(message, session.getCoreSession(), options);
}
if (individualACK) {
msg.setIndividualAcknowledge();
}
if (clientACK) {
msg.setClientAcknowledge();
}
try {
msg.doBeforeReceive();
} catch (Exception e) {
ActiveMQJMSClientLogger.LOGGER.errorPreparingMessageForReceipt(msg.getCoreMessage().toString(), e);
return;
}
if (transactedOrClientAck) {
try {
message.acknowledge();
} catch (ActiveMQException e) {
((ClientSessionInternal) session.getCoreSession()).markRollbackOnly();
ActiveMQJMSClientLogger.LOGGER.errorProcessingMessage(e);
}
}
try {
connection.getThreadAwareContext().setCurrentThread(false);
listener.onMessage(msg);
} catch (RuntimeException e) {
// See JMS 1.1 spec, section 4.5.2
ActiveMQJMSClientLogger.LOGGER.onMessageError(e);
if (!transactedOrClientAck) {
try {
if (individualACK) {
message.individualAcknowledge();
}
session.getCoreSession().rollback(true);
session.setRecoverCalled(true);
} catch (Exception e2) {
ActiveMQJMSClientLogger.LOGGER.errorRecoveringSession(e2);
}
}
} finally {
connection.getThreadAwareContext().clearCurrentThread(false);
}
if (!session.isRecoverCalled() && !individualACK) {
try {
// We don't want to call this if the consumer was closed from inside onMessage
if (!consumer.isClosed() && !transactedOrClientAck) {
message.acknowledge();
}
} catch (ActiveMQException e) {
((ClientSessionInternal) session.getCoreSession()).markRollbackOnly();
ActiveMQJMSClientLogger.LOGGER.errorProcessingMessage(e);
}
}
session.setRecoverCalled(false);
}
}
- onMessage方法在transactedOrClientAck为true时会执行message.acknowledge()；在触发listener.onMessage(msg)之后会在非session.isRecoverCalled()且非individualACK且非consumer.isClosed()且非transactedOrClientAck时执行message.acknowledge()
acknowledge
activemq-artemis-2.11.0/artemis-core-client/src/main/java/org/apache/activemq/artemis/core/client/impl/ClientMessageImpl.java
public class ClientMessageImpl extends CoreMessage implements ClientMessageInternal {
//......
public ClientMessageImpl acknowledge() throws ActiveMQException {
if (consumer != null) {
consumer.acknowledge(this);
}
return this;
}
//......
}
- acknowledge方法执行的是consumer.acknowledge(this)方法
ClientConsumerImpl.acknowledge
activemq-artemis-2.11.0/artemis-core-client/src/main/java/org/apache/activemq/artemis/core/client/impl/ClientConsumerImpl.java
public final class ClientConsumerImpl implements ClientConsumerInternal {
//......
public void acknowledge(final ClientMessage message) throws ActiveMQException {
ClientMessageInternal cmi = (ClientMessageInternal) message;
if (ackIndividually) {
individualAcknowledge(message);
} else {
ackBytes += message.getEncodeSize();
if (logger.isTraceEnabled()) {
logger.trace(this + "::acknowledge ackBytes=" + ackBytes + " and ackBatchSize=" + ackBatchSize + ", encodeSize=" + message.getEncodeSize());
}
if (ackBytes >= ackBatchSize) {
if (logger.isTraceEnabled()) {
logger.trace(this + ":: acknowledge acking " + cmi);
}
doAck(cmi);
} else {
if (logger.isTraceEnabled()) {
logger.trace(this + ":: acknowledge setting lastAckedMessage = " + cmi);
}
lastAckedMessage = cmi;
}
}
}
private void doAck(final ClientMessageInternal message) throws ActiveMQException {
ackBytes = 0;
lastAckedMessage = null;
if (logger.isTraceEnabled()) {
logger.trace(this + "::Acking message " + message);
}
session.acknowledge(this, message);
}
//......
}
- ClientConsumerImpl的acknowledge方法执行的是doAck方法，而doAck方法执行的是session.acknowledge(this, message)
ClientSessionImpl.acknowledge
activemq-artemis-2.11.0/artemis-core-client/src/main/java/org/apache/activemq/artemis/core/client/impl/ClientSessionImpl.java
public final class ClientSessionImpl implements ClientSessionInternal, FailureListener {
//......
public void acknowledge(final ClientConsumer consumer, final Message message) throws ActiveMQException {
// if we're pre-acknowledging then we don't need to do anything
if (preAcknowledge) {
return;
}
checkClosed();
if (logger.isDebugEnabled()) {
logger.debug("client ack messageID = " + message.getMessageID());
}
startCall();
try {
sessionContext.sendACK(false, blockOnAcknowledge, consumer, message);
} finally {
endCall();
}
}
//......
}
- ClientSessionImpl的acknowledge方法通过sessionContext.sendACK来发送ack
小结
- ActiveMQMessageConsumer的receive采用的是拉模式，它对于session.getAcknowledgeMode()为ActiveMQJMSConstants.INDIVIDUAL_ACKNOWLEDGE执行jmsMsg.setIndividualAcknowledge()，其余的都执行coreMessage.acknowledge()；ClientMessageImpl的acknowledge方法执行的是consumer.acknowledge(this)
- ClientConsumerImpl的handleMessage采用的是推模式，它会执行buffer.addTail(message, message.getPriority())以及queueExecutor()，queueExecutor通过sessionExecutor执行Runner；Runner的run方法会执行callOnMessage方法，它会从buffer.poll()消息，如果不为null且非expired则执行theHandler.onMessage(message)；最后触发的是执行的是consumer.acknowledge(this)方法
- ClientConsumerImpl的acknowledge方法执行的是doAck方法，而doAck方法执行的是session.acknowledge(this, message)；ClientSessionImpl的acknowledge方法通过sessionContext.sendACK来发送ack
doc
来源：oschina
链接：https://my.oschina.net/go4it/blog/3161281