GH-1146 - Improve lookup of event publications in progress.

Instead of iterating over all publications currently in progress we now use a map to look them up by key.

Baseline
--------
Benchmark                        Mode  Cnt        Score      Error  Units
….inProgressPublicationsAccess  thrpt   50      312,155 ±    7,428  ops/s

Fixed
-----
Benchmark                        Mode  Cnt        Score      Error  Units
….inProgressPublicationsAccess  thrpt   50  2328732,504 ± 7809,092  ops/s

spring-modulith-events/spring-modulith-events-core/src/main/java/org/springframework/modulith/events/core/DefaultEventPublicationRegistry.java

@@ -19,10 +19,9 @@ import java.time.Clock;
 import java.time.Duration;
 import java.time.Instant;
 import java.util.Collection;
-import java.util.HashSet;
 import java.util.Iterator;
+import java.util.Map;
 import java.util.Optional;
-import java.util.Set;
 import java.util.concurrent.ConcurrentHashMap;
 import java.util.function.Consumer;
 import java.util.function.Predicate;
@@ -296,7 +295,7 @@ public class DefaultEventPublicationRegistry
 	 */
 	static class PublicationsInProgress implements Iterable<TargetEventPublication> {
 
-		private final Set<TargetEventPublication> publications = ConcurrentHashMap.newKeySet();
+		private final Map<Key, TargetEventPublication> publications = new ConcurrentHashMap<>();
 
 		/**
 		 * Registers the given {@link TargetEventPublication} as currently processed.
@@ -308,7 +307,7 @@ public class DefaultEventPublicationRegistry
 
 			Assert.notNull(publication, "TargetEventPublication must not be null!");
 
-			publications.add(publication);
+			publications.put(new Key(publication), publication);
 
 			return publication;
 		}
@@ -325,8 +324,7 @@ public class DefaultEventPublicationRegistry
 			Assert.notNull(event, "Event must not be null!");
 			Assert.notNull(identifier, "PublicationTargetIdentifier must not be null!");
 
-			getPublication(event, identifier)
-					.ifPresent(publications::remove);
+			publications.remove(new Key(event, identifier));
 		}
 
 		/**
@@ -338,7 +336,7 @@ public class DefaultEventPublicationRegistry
 
 			Assert.notNull(publication, "TargetEventPublication must not be null!");
 
-			publications.remove(publication);
+			publications.remove(new Key(publication));
 		}
 
 		/**
@@ -354,9 +352,7 @@ public class DefaultEventPublicationRegistry
 			Assert.notNull(event, "Event must not be null!");
 			Assert.notNull(identifier, "PublicationTargetIdentifier must not be null!");
 
-			return publications.stream()
-					.filter(it -> it.isAssociatedWith(event, identifier))
-					.findFirst();
+			return Optional.ofNullable(publications.get(new Key(event, identifier)));
 		}
 
 		/*
@@ -365,7 +361,48 @@ public class DefaultEventPublicationRegistry
 		 */
 		@Override
 		public Iterator<TargetEventPublication> iterator() {
-			return new HashSet<>(publications).iterator();
+			return publications.values().iterator();
+		}
+
+		private record Key(Object event, PublicationTargetIdentifier identifier) {
+
+			public Key(TargetEventPublication publication) {
+				this(publication.getEvent(), publication.getTargetIdentifier());
+			}
+
+			/*
+			 * (non-Javadoc)
+			 * @see org.springframework.modulith.events.core.DefaultEventPublicationRegistry.PublicationsInProgress.Key#equals(java.lang.Object)
+			 */
+			@Override
+			public final boolean equals(Object obj) {
+
+				if (obj == this) {
+					return true;
+				}
+
+				if (!(obj instanceof Key that)) {
+					return false;
+				}
+
+				return this.event == that.event
+						&& this.identifier.equals(identifier);
+			}
+
+			/*
+			 * (non-Javadoc)
+			 * @see org.springframework.modulith.events.core.DefaultEventPublicationRegistry.PublicationsInProgress.Key#hashCode()
+			 */
+			@Override
+			public final int hashCode() {
+
+				int result = 7;
+
+				result += 31 * System.identityHashCode(event);
+				result += 31 * identifier.hashCode();
+
+				return result;
+			}
 		}
 	}
 }

spring-modulith-events/spring-modulith-events-core/src/test/java/org/springframework/modulith/events/core/DefaultEventPublicationRegistryUnitTests.java

@@ -97,7 +97,6 @@ class DefaultEventPublicationRegistryUnitTests {
 
 		assertThat(inProgress.getPublication(firstEvent, identifier)).containsSame(first);
 		assertThat(inProgress.getPublication(secondEvent, identifier)).containsSame(second);
-
 	}
 
 	private DefaultEventPublicationRegistry createRegistry(Instant instant) {