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https://issues.apache.org/jira/browse/AMQ-4148?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]
Stirling Chow updated AMQ-4148:
-------------------------------
Attachment: AMQ4148.patch
Patch that, once applied, allows AMQ4148Test to pass.
> Static subscriptions from network bridges do not respect TTL (off by one in
> calculation), resulting in duplicate consumers.
> ---------------------------------------------------------------------------------------------------------------------------
>
> Key: AMQ-4148
> URL: https://issues.apache.org/jira/browse/AMQ-4148
> Project: ActiveMQ
> Issue Type: Bug
> Affects Versions: 5.8.0
> Reporter: Stirling Chow
> Attachments: AMQ4148.patch, AMQ4148Test.java
>
>
> Symptom
> =======
> The remote broker path is not set on network consumers that result from
> static subscriptions; as a result, they are forwarded to other bridges even
> when the network TTL on the bridges is 1. In an n+1 hub-and-spoke network,
> the next broker to join receives n subscriptions instead of 1.
> Cause
> =====
> A consumer for a static subscriptions is created by the following code:
> {code:title=DemandForwardingBridgeSupport.java}
> private void startLocalBridge() throws Throwable {
> ...
> if (!disposed.get()) {
> setupStaticDestinations();
> } else {
> LOG.warn("Network connection between " + localBroker + " and " +
> remoteBroker + "(" + remoteBrokerName + ") was interrupted during
> establishment.");
> }
> }
> }
> /**
> * Subscriptions for these destinations are always created
> */
> protected void setupStaticDestinations() {
> ...
> DemandSubscription sub = createDemandSubscription(dest);
> try {
> addSubscription(sub);
> } catch (IOException e) {
> LOG.error("Failed to add static destination " + dest, e);
> }
> if (LOG.isTraceEnabled()) {
> LOG.trace("bridging messages for static destination: " +
> dest);
> }
> }
> }
> }
> final protected DemandSubscription
> createDemandSubscription(ActiveMQDestination destination) {
> ConsumerInfo info = new ConsumerInfo();
> info.setDestination(destination);
> // the remote info held by the DemandSubscription holds the original
> consumerId,
> // the local info get's overwritten
> info.setConsumerId(new ConsumerId(localSessionInfo.getSessionId(),
> consumerIdGenerator.getNextSequenceId()));
> DemandSubscription result = null;
> try {
> result = createDemandSubscription(info);
> } catch (IOException e) {
> LOG.error("Failed to create DemandSubscription ", e);
> }
> return result;
> }
> {code}
> Note how the broker path is *not* set on the {{ConsumerInfo}} that is used
> for the subscription.
> In contrast, a consumer for a dynamic subscription does have its broker path
> updated to indicate that it is from a remote broker:
> {code:title=DemandForwardingBridgeSupport.java}
> protected void serviceRemoteCommand(Command command) {
> if (!disposed.get()) {
> try {
> if (command.isMessageDispatch()) {
> safeWaitUntilStarted();
> MessageDispatch md = (MessageDispatch) command;
>
> serviceRemoteConsumerAdvisory(md.getMessage().getDataStructure());
> ackAdvisory(md.getMessage());
> ...
> private void serviceRemoteConsumerAdvisory(DataStructure data) throws
> IOException {
> ...
> if (addConsumerInfo(info)) {
> if (LOG.isDebugEnabled()) {
> LOG.debug(configuration.getBrokerName() + " bridged sub
> on " + localBroker + " from " + remoteBrokerName + " : " + info);
> }
> } else {
> if (LOG.isDebugEnabled()) {
> LOG.debug(configuration.getBrokerName() + " Ignoring sub
> from " + remoteBrokerName + " as already subscribed to matching destination :
> " + info);
> }
> }
> }
> ...
> protected boolean addConsumerInfo(final ConsumerInfo consumerInfo) throws
> IOException {
> boolean consumerAdded = false;
> ConsumerInfo info = consumerInfo.copy();
> addRemoteBrokerToBrokerPath(info);
> ...
> {code}
> Because of this difference, a static subscription will be forwarded to new
> bridges with a {{null}} brokerPath while a dynamic subscription to the same
> queue will be forwarded with a singleton brokerPath. As a result, static
> subscriptions will be propagated one further hop than their dynamic
> counterparts. In the case of a network TTL of 1, the static subscription
> consumers from existing bridges are unexpectedly propagated to new bridges,
> while the dynamic subscription consumers are correctly suppressed.
> Solution
> ========
> There should be no logical difference between a network consumer created for
> a static subscription vs. a dynamic subscription. In either case, the bridge
> creates a consumer on behalf of the remote broker. As such, the consumer for
> a static subscription should have the remote broker in its broker path
> because it represents a subscription from that remote broker (even if there
> is no consumer).
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