Cache BridgeMethodResolver results

Add a cache to `BridgeMethodResolver` to help with repeated calls to
resolve the same methods. Since bridge method resolution can be somewhat
expensive (especially when resolving generics), and the number of bridge
methods is quite small, a cache generally helps.

This commit also simplifies the code a little by calling `doWithMethods`
directly rather than relying on `ReflectionUtils.getAllDeclaredMethods`
to do so. The methods list is now always created, but we save the list
creation that `getAllDeclaredMethods` used to do.

Closes gh-22579

Author: philwebb

spring-core/src/main/java/org/springframework/core/BridgeMethodResolver.java

@@ -21,10 +21,13 @@
 import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.List;
+import java.util.Map;
 
 import org.springframework.lang.Nullable;
 import org.springframework.util.ClassUtils;
+import org.springframework.util.ConcurrentReferenceHashMap;
 import org.springframework.util.ReflectionUtils;
+import org.springframework.util.ReflectionUtils.MethodFilter;
 
 /**
  * Helper for resolving synthetic {@link Method#isBridge bridge Methods} to the
@@ -47,6 +50,8 @@
  */
 public final class BridgeMethodResolver {
 
+	private static final Map<Method, Method> cache = new ConcurrentReferenceHashMap<>();
+
 	private BridgeMethodResolver() {
 	}
 
@@ -64,32 +69,26 @@ public static Method findBridgedMethod(Method bridgeMethod) {
 		if (!bridgeMethod.isBridge()) {
 			return bridgeMethod;
 		}
-
-		// Gather all methods with matching name and parameter size.
-		List<Method> candidateMethods = new ArrayList<>();
-		Method[] methods = ReflectionUtils.getAllDeclaredMethods(bridgeMethod.getDeclaringClass());
-		for (Method candidateMethod : methods) {
-			if (isBridgedCandidateFor(candidateMethod, bridgeMethod)) {
-				candidateMethods.add(candidateMethod);
+		Method bridgedMethod = cache.get(bridgeMethod);
+		if (bridgedMethod == null) {
+			// Gather all methods with matching name and parameter size.
+			List<Method> candidateMethods = new ArrayList<>();
+			MethodFilter filter = candidateMethod ->
+					isBridgedCandidateFor(candidateMethod, bridgeMethod);
+			ReflectionUtils.doWithMethods(bridgeMethod.getDeclaringClass(), candidateMethods::add, filter);
+			if (!candidateMethods.isEmpty()) {
+				bridgedMethod = candidateMethods.size() == 1 ?
+						candidateMethods.get(0) :
+						searchCandidates(candidateMethods, bridgeMethod);
 			}
+			if (bridgedMethod == null) {
+				// A bridge method was passed in but we couldn't find the bridged method.
+				// Let's proceed with the passed-in method and hope for the best...
+				bridgedMethod = bridgeMethod;
+			}
+			cache.put(bridgeMethod, bridgedMethod);
 		}
-
-		// Now perform simple quick check.
-		if (candidateMethods.size() == 1) {
-			return candidateMethods.get(0);
-		}
-
-		// Search for candidate match.
-		Method bridgedMethod = searchCandidates(candidateMethods, bridgeMethod);
-		if (bridgedMethod != null) {
-			// Bridged method found...
-			return bridgedMethod;
-		}
-		else {
-			// A bridge method was passed in but we couldn't find the bridged method.
-			// Let's proceed with the passed-in method and hope for the best...
-			return bridgeMethod;
-		}
+		return bridgedMethod;
 	}
 
 	/**