Addressing PR review -s

Signed-off-by: Sanghyeok An <[email protected]>

Author: chickenchickenlove

spring-kafka/src/main/java/org/springframework/kafka/support/AbstractKafkaHeaderMapper.java

@@ -66,9 +66,11 @@ public abstract class AbstractKafkaHeaderMapper implements KafkaHeaderMapper {
 
 	private final List<HeaderMatcher> matchers = new ArrayList<>();
 
+	private final ConcurrentLruCache<String, Boolean> matcherResultCache = new ConcurrentLruCache<>(1000, this::doesMatchInternal);
+
 	private final List<HeaderMatcher> multiValueHeaderMatchers = new ArrayList<>();
 
-	private final HeaderPatternMatchCache headerMatchedCache = new HeaderPatternMatchCache();
+	private final ConcurrentLruCache<String, Boolean> multiValueMatcherResultCache = new ConcurrentLruCache<>(1000, this::doesMatchMultiValueHeaderInternal);
 
 	private final Map<String, Boolean> rawMappedHeaders = new HashMap<>();
 
@@ -243,13 +245,17 @@ protected boolean matchesForInbound(String header) {
 	}
 
 	private boolean doesMatch(String header) {
+		return this.matcherResultCache.get(header);
+	}
+
+	private boolean doesMatchInternal(String header) {
 		for (HeaderMatcher matcher : this.matchers) {
 			if (matcher.matchHeader(header)) {
 				return !matcher.isNegated();
 			}
 		}
 		this.logger.debug(() -> MessageFormat.format("headerName=[{0}] WILL NOT be mapped; matched no patterns",
-				header));
+													header));
 		return false;
 	}
 
@@ -269,28 +275,25 @@ protected Object headerValueToAddOut(String key, Object value) {
 	}
 
 	/**
-	 * Check whether the header value should be mapped to multiple values.
+	 * Determine whether the given header name should be mapped to multiple values.
+	 * This method first checks if the mapping result is already cached.
+	 * If a cached result exists, it is returned immediately.
+	 * If not, {@code doesMatchInternal(headerName)} is called to compute the result,
+	 * which is then cached and returned.
 	 * @param headerName the header name.
 	 * @return True for multiple values at the same key.
 	 * @since 4.0
 	 */
 	protected boolean doesMatchMultiValueHeader(String headerName) {
-		if (this.headerMatchedCache.isMultiValuePattern(headerName)) {
-			return true;
-		}
-
-		if (this.headerMatchedCache.isSingleValuePattern(headerName)) {
-			return false;
-		}
+		return this.multiValueMatcherResultCache.get(headerName);
+	}
 
+	private boolean doesMatchMultiValueHeaderInternal(String headerName) {
 		for (HeaderMatcher headerMatcher : this.multiValueHeaderMatchers) {
 			if (headerMatcher.matchHeader(headerName)) {
-				this.headerMatchedCache.cacheAsMultiValueHeader(headerName);
 				return true;
 			}
 		}
-
-		this.headerMatchedCache.cacheAsSingleValueHeader(headerName);
 		return false;
 	}
 
@@ -441,33 +444,4 @@ public boolean isNegated() {
 
 	}
 
-	/**
-	 * A Cache that remembers whether a header name matches the multi-value pattern.
-	 */
-	private static final class HeaderPatternMatchCache {
-
-		private static final int MAX_SIZE = 1000;
-
-		private final ConcurrentLruCache<String, Boolean> multiValueHeaderPatternMatchCache = new ConcurrentLruCache<>(MAX_SIZE, key -> Boolean.TRUE);
-
-		private final ConcurrentLruCache<String, Boolean> singleValueHeaderPatternMatchCache = new ConcurrentLruCache<>(MAX_SIZE, key -> Boolean.TRUE);
-
-		boolean isMultiValuePattern(String headerName) {
-			return this.multiValueHeaderPatternMatchCache.contains(headerName);
-		}
-
-		boolean isSingleValuePattern(String headerName) {
-			return this.singleValueHeaderPatternMatchCache.contains(headerName);
-		}
-
-		void cacheAsSingleValueHeader(String headerName) {
-			this.singleValueHeaderPatternMatchCache.get(headerName);
-		}
-
-		void cacheAsMultiValueHeader(String headerName) {
-			this.multiValueHeaderPatternMatchCache.get(headerName);
-		}
-
-	}
-
 }