SubscriptionRegistry re-uses channel and handlers if channel type didn't change when subscription is updated

hapi-fhir-jpaserver-subscription/src/main/java/ca/uhn/fhir/jpa/subscription/module/cache/ActiveSubscription.java

@@ -36,7 +36,7 @@ import java.util.HashSet;
 public class ActiveSubscription {
 	private static final Logger ourLog = LoggerFactory.getLogger(ActiveSubscription.class);
 
-	private final CanonicalSubscription mySubscription;
+	private CanonicalSubscription mySubscription;
 	private final SubscribableChannel mySubscribableChannel;
 	private final Collection<MessageHandler> myDeliveryHandlerSet = new HashSet<>();
 
@@ -90,4 +90,8 @@ public class ActiveSubscription {
 	public MessageHandler getDeliveryHandlerForUnitTest() {
 		return myDeliveryHandlerSet.iterator().next();
 	}
+
+	public void setSubscription(CanonicalSubscription theCanonicalizedSubscription) {
+		mySubscription = theCanonicalizedSubscription;
+	}
 }

hapi-fhir-jpaserver-subscription/src/main/java/ca/uhn/fhir/jpa/subscription/module/cache/SubscriptionRegistry.java

@@ -130,6 +130,11 @@ public class SubscriptionRegistry {
 				return false;
 			}
 			ourLog.info("Updating already-registered active subscription {}", theSubscription.getIdElement().toUnqualified().getValue());
+			if (channelTypeSame(existingSubscription.get(), newSubscription)) {
+				ourLog.info("Channel type is same.  Updating active subscription and re-using existing channel and handlers.");
+				updateSubscription(theSubscription);
+				return true;
+			}
 			unregisterSubscription(theSubscription.getIdElement());
 		} else {
 			ourLog.info("Registering active subscription {}", theSubscription.getIdElement().toUnqualified().getValue());
@@ -140,7 +145,23 @@ public class SubscriptionRegistry {
 		} else {
 			return false;
 		}
+	}
 
+	private void updateSubscription(IBaseResource theSubscription) {
+		IIdType theId = theSubscription.getIdElement();
+		Validate.notNull(theId);
+		Validate.notBlank(theId.getIdPart());
+		ActiveSubscription activeSubscription = myActiveSubscriptionCache.get(theId.getIdPart());
+		Validate.notNull(activeSubscription);
+		CanonicalSubscription canonicalized = mySubscriptionCanonicalizer.canonicalize(theSubscription);
+		activeSubscription.setSubscription(canonicalized);
+
+		// Interceptor call: SUBSCRIPTION_AFTER_ACTIVE_SUBSCRIPTION_REGISTERED
+		myInterceptorBroadcaster.callHooks(Pointcut.SUBSCRIPTION_AFTER_ACTIVE_SUBSCRIPTION_REGISTERED, canonicalized);
+	}
+
+	private boolean channelTypeSame(CanonicalSubscription theExistingSubscription, CanonicalSubscription theNewSubscription) {
+		return theExistingSubscription.getChannelType().equals(theNewSubscription.getChannelType());
 	}
 
 	public boolean unregisterSubscriptionIfRegistered(IBaseResource theSubscription, String theStatusString) {

hapi-fhir-jpaserver-subscription/src/test/java/ca/uhn/fhir/jpa/subscription/module/cache/SubscriptionRegistryTest.java

@@ -0,0 +1,78 @@
+package ca.uhn.fhir.jpa.subscription.module.cache;
+
+
+import ca.uhn.fhir.jpa.subscription.module.BaseSubscriptionDstu3Test;
+import org.hl7.fhir.dstu3.model.Subscription;
+import org.junit.After;
+import org.junit.Test;
+import org.springframework.beans.factory.annotation.Autowired;
+
+import static org.junit.Assert.*;
+
+public class SubscriptionRegistryTest extends BaseSubscriptionDstu3Test {
+	public static final String SUBSCRIPTION_ID = "1";
+	public static final String ORIG_CRITERIA = "Patient?";
+	public static final String NEW_CRITERIA = "Observation?";
+	@Autowired
+	SubscriptionRegistry mySubscriptionRegistry;
+
+	@After
+	public void clearRegistry() {
+		mySubscriptionRegistry.unregisterAllSubscriptions();
+	}
+
+	@Test
+	public void updateSubscriptionReusesActiveSubscription() {
+		Subscription subscription = createSubscription();
+		assertEquals(0, mySubscriptionRegistry.size());
+		mySubscriptionRegistry.registerSubscriptionUnlessAlreadyRegistered(subscription);
+		assertEquals(1, mySubscriptionRegistry.size());
+		ActiveSubscription origActiveSubscription = mySubscriptionRegistry.get(SUBSCRIPTION_ID);
+		assertEquals(ORIG_CRITERIA, origActiveSubscription.getCriteriaString());
+
+		subscription.setCriteria(NEW_CRITERIA);
+		assertEquals(ORIG_CRITERIA, origActiveSubscription.getCriteriaString());
+		mySubscriptionRegistry.registerSubscriptionUnlessAlreadyRegistered(subscription);
+		assertEquals(1, mySubscriptionRegistry.size());
+		ActiveSubscription newActiveSubscription = mySubscriptionRegistry.get(SUBSCRIPTION_ID);
+		assertEquals(NEW_CRITERIA, newActiveSubscription.getCriteriaString());
+		// The same object
+		assertTrue(newActiveSubscription == origActiveSubscription);
+	}
+
+	@Test
+	public void updateSubscriptionDoesntReusesActiveSubscriptionWhenChannelChanges() {
+		Subscription subscription = createSubscription();
+		assertEquals(0, mySubscriptionRegistry.size());
+		mySubscriptionRegistry.registerSubscriptionUnlessAlreadyRegistered(subscription);
+		assertEquals(1, mySubscriptionRegistry.size());
+		ActiveSubscription origActiveSubscription = mySubscriptionRegistry.get(SUBSCRIPTION_ID);
+		assertEquals(ORIG_CRITERIA, origActiveSubscription.getCriteriaString());
+
+		setChannel(subscription, Subscription.SubscriptionChannelType.EMAIL);
+
+		assertEquals(ORIG_CRITERIA, origActiveSubscription.getCriteriaString());
+		mySubscriptionRegistry.registerSubscriptionUnlessAlreadyRegistered(subscription);
+		assertEquals(1, mySubscriptionRegistry.size());
+		ActiveSubscription newActiveSubscription = mySubscriptionRegistry.get(SUBSCRIPTION_ID);
+		// A new object
+		assertFalse(newActiveSubscription == origActiveSubscription);
+	}
+
+	private Subscription createSubscription() {
+		Subscription subscription = new Subscription();
+		subscription.setId(SUBSCRIPTION_ID);
+		subscription.setCriteria(ORIG_CRITERIA);
+		subscription.setStatus(Subscription.SubscriptionStatus.ACTIVE);
+		setChannel(subscription, Subscription.SubscriptionChannelType.RESTHOOK);
+		return subscription;
+	}
+
+	private void setChannel(Subscription theSubscription, Subscription.SubscriptionChannelType theResthook) {
+		Subscription.SubscriptionChannelComponent channel = new Subscription.SubscriptionChannelComponent();
+		channel.setType(theResthook);
+		channel.setPayload("application/json");
+		channel.setEndpoint("http://unused.test.endpoint/");
+		theSubscription.setChannel(channel);
+	}
+}

src/changes/changes.xml

@@ -26,6 +26,9 @@
 				enabled after the refactoring of how Subscriptions are enabled that
 				occurred in HAPI FHIR 3.7.0. Thanks to Volker Schmidt for the pull request!
 			</action>
+			<action type="change">
+				Re-use subscription channel and handlers when a subscription is updated (unless the channel type changed).
+			</action>
 		</release>
 		<release version="3.7.0" date="2019-02-06" description="Gale">
 			<action type="add">