Revisit AuditEventRepository interface

Update AuditEventRepository to restore support for `null` arguments and
explicitly Javadoc their meaning.

See gh-5854

spring-boot-actuator/src/main/java/org/springframework/boot/actuate/audit/AuditEventRepository.java

@@ -27,9 +27,16 @@ import java.util.List;
  */
 public interface AuditEventRepository {
 
+	/**
+	 * Log an event.
+	 * @param event the audit event to log
+	 */
+	void add(AuditEvent event);
+
 	/**
 	 * Find audit events since the time provided.
-	 * @param after timestamp of earliest result required
+	 * @param after timestamp of earliest result required (or {@code null} if
+	 * unrestricted)
 	 * @return audit events
 	 * @since 1.4.0
 	 */
@@ -37,8 +44,9 @@ public interface AuditEventRepository {
 
 	/**
 	 * Find audit events relating to the specified principal since the time provided.
-	 * @param principal the principal name to search for
-	 * @param after timestamp of earliest result required
+	 * @param principal the principal name to search for (or {@code null} if unrestricted)
+	 * @param after timestamp of earliest result required (or {@code null} if
+	 * unrestricted)
 	 * @return audit events relating to the principal
 	 */
 	List<AuditEvent> find(String principal, Date after);
@@ -46,18 +54,13 @@ public interface AuditEventRepository {
 	/**
 	 * Find audit events of specified type relating to the specified principal since the
 	 * time provided.
-	 * @param principal the principal name to search for
-	 * @param after timestamp of earliest result required
-	 * @param type the event type to search for
+	 * @param principal the principal name to search for (or {@code null} if unrestricted)
+	 * @param after timestamp of earliest result required (or {@code null} if
+	 * unrestricted)
+	 * @param type the event type to search for (or {@code null} if unrestricted)
 	 * @return audit events of specified type relating to the principal
 	 * @since 1.4.0
 	 */
 	List<AuditEvent> find(String principal, Date after, String type);
 
-	/**
-	 * Log an event.
-	 * @param event the audit event to log
-	 */
-	void add(AuditEvent event);
-
 }

spring-boot-actuator/src/main/java/org/springframework/boot/actuate/audit/InMemoryAuditEventRepository.java

@@ -56,59 +56,41 @@ public class InMemoryAuditEventRepository implements AuditEventRepository {
 		this.events = new AuditEvent[capacity];
 	}
 
+	@Override
+	public synchronized void add(AuditEvent event) {
+		Assert.notNull(event, "AuditEvent must not be null");
+		this.tail = (this.tail + 1) % this.events.length;
+		this.events[this.tail] = event;
+	}
+
 	@Override
 	public synchronized List<AuditEvent> find(Date after) {
-		LinkedList<AuditEvent> events = new LinkedList<AuditEvent>();
-		for (int i = 0; i < this.events.length; i++) {
-			AuditEvent event = resolveTailEvent(i);
-			if (event == null) {
-				break;
-			}
-			if (isMatch(event, after)) {
-				events.addFirst(event);
-			}
-		}
-		return events;
+		return find(null, after, null);
 	}
 
 	@Override
 	public synchronized List<AuditEvent> find(String principal, Date after) {
-		Assert.notNull(principal, "Principal must not be null");
-		LinkedList<AuditEvent> events = new LinkedList<AuditEvent>();
-		for (int i = 0; i < this.events.length; i++) {
-			AuditEvent event = resolveTailEvent(i);
-			if (event == null) {
-				break;
-			}
-			if (isMatch(event, principal, after)) {
-				events.addFirst(event);
-			}
-		}
-		return events;
+		return find(principal, after, null);
 	}
 
 	@Override
 	public synchronized List<AuditEvent> find(String principal, Date after, String type) {
-		Assert.notNull(principal, "Principal must not be null");
-		Assert.notNull(type, "Type must not be null");
 		LinkedList<AuditEvent> events = new LinkedList<AuditEvent>();
 		for (int i = 0; i < this.events.length; i++) {
 			AuditEvent event = resolveTailEvent(i);
-			if (event == null) {
-				break;
-			}
-			if (isMatch(event, principal, type, after)) {
+			if (event != null && isMatch(principal, after, type, event)) {
 				events.addFirst(event);
 			}
 		}
 		return events;
 	}
 
-	@Override
-	public synchronized void add(AuditEvent event) {
-		Assert.notNull(event, "AuditEvent must not be null");
-		this.tail = (this.tail + 1) % this.events.length;
-		this.events[this.tail] = event;
+	private boolean isMatch(String principal, Date after, String type, AuditEvent event) {
+		boolean match = true;
+		match &= (principal == null || event.getPrincipal().equals(principal));
+		match &= (after == null || event.getTimestamp().compareTo(after) >= 0);
+		match &= (type == null || event.getType().equals(type));
+		return match;
 	}
 
 	private AuditEvent resolveTailEvent(int offset) {
@@ -116,16 +98,4 @@ public class InMemoryAuditEventRepository implements AuditEventRepository {
 		return this.events[index];
 	}
 
-	private boolean isMatch(AuditEvent event, Date after) {
-		return (after == null || event.getTimestamp().compareTo(after) >= 0);
-	}
-
-	private boolean isMatch(AuditEvent event, String principal, Date after) {
-		return (event.getPrincipal().equals(principal) && isMatch(event, after));
-	}
-
-	private boolean isMatch(AuditEvent event, String principal, String type, Date after) {
-		return (event.getType().equals(type) && isMatch(event, principal, after));
-	}
-
 }

spring-boot-actuator/src/main/java/org/springframework/boot/actuate/audit/listener/AuditApplicationEvent.java

@@ -89,4 +89,5 @@ public class AuditApplicationEvent extends ApplicationEvent {
 	public AuditEvent getAuditEvent() {
 		return this.auditEvent;
 	}
+
 }