Optimize ClassNameReader.getClassName via direct ASM API

spring-core/src/jmh/java/org/springframework/cglib/core/ClassNameReaderBenchmark.java

@@ -0,0 +1,133 @@
+/*
+ * Copyright 2002-present the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.springframework.cglib.core;
+
+import java.util.concurrent.TimeUnit;
+
+import org.openjdk.jmh.annotations.Benchmark;
+import org.openjdk.jmh.annotations.BenchmarkMode;
+import org.openjdk.jmh.annotations.Level;
+import org.openjdk.jmh.annotations.Measurement;
+import org.openjdk.jmh.annotations.Mode;
+import org.openjdk.jmh.annotations.OutputTimeUnit;
+import org.openjdk.jmh.annotations.Scope;
+import org.openjdk.jmh.annotations.Setup;
+import org.openjdk.jmh.annotations.State;
+import org.openjdk.jmh.annotations.Warmup;
+
+import org.springframework.asm.ClassReader;
+import org.springframework.cglib.proxy.Enhancer;
+import org.springframework.cglib.proxy.MethodInterceptor;
+
+/**
+ * Benchmarks for {@link ClassNameReader#getClassName(ClassReader)}.
+ * Comparing the legacy {@code getClassInfo(r)[0]} delegation against a direct {@code ClassReader.getClassName()} call.
+ *
+ * @author Daehyeon Kim
+ */
+public class ClassNameReaderBenchmark {
+
+	@BenchmarkMode(Mode.AverageTime)
+	@OutputTimeUnit(TimeUnit.NANOSECONDS)
+	@Warmup(iterations = 5, time = 2)
+	@Measurement(iterations = 5, time = 2)
+	public static class WithoutInterfaces {
+
+		@State(Scope.Benchmark)
+		public static class BenchmarkState {
+
+			public ClassReader classReader;
+
+			@Setup(Level.Trial)
+			public void setup() {
+				this.classReader = generateProxyReader(new Class<?>[0]);
+			}
+		}
+
+		@Benchmark
+		public String viaGetClassInfo(BenchmarkState state) {
+			return ClassNameReader.getClassInfo(state.classReader)[0];
+		}
+
+		@Benchmark
+		public String viaGetClassName(BenchmarkState state) {
+			return state.classReader.getClassName().replace('/', '.');
+		}
+	}
+
+	@BenchmarkMode(Mode.AverageTime)
+	@OutputTimeUnit(TimeUnit.NANOSECONDS)
+	@Warmup(iterations = 5, time = 2)
+	@Measurement(iterations = 5, time = 2)
+	public static class WithInterfaces {
+
+		@State(Scope.Benchmark)
+		public static class BenchmarkState {
+
+			public ClassReader classReader;
+
+			@Setup(Level.Trial)
+			public void setup() {
+				this.classReader = generateProxyReader(
+						new Class<?>[]{Cloneable.class, Comparable.class, Runnable.class}
+				);
+			}
+		}
+
+		@Benchmark
+		public String viaGetClassInfo(BenchmarkState state) {
+			return ClassNameReader.getClassInfo(state.classReader)[0];
+		}
+
+		@Benchmark
+		public String viaGetClassName(BenchmarkState state) {
+			return state.classReader.getClassName().replace('/', '.');
+		}
+	}
+
+	private static ClassReader generateProxyReader(Class<?>[] interfaces) {
+		CapturingGeneratorStrategy strategy = new CapturingGeneratorStrategy();
+		Enhancer enhancer = new Enhancer();
+		enhancer.setSuperclass(ProxyTarget.class);
+		enhancer.setCallbackType(MethodInterceptor.class);
+		enhancer.setUseCache(false);
+		enhancer.setInterfaces(interfaces);
+		enhancer.setStrategy(strategy);
+		enhancer.createClass();
+		return strategy.createClassReader();
+	}
+
+	public static class ProxyTarget {
+	}
+
+	private static class CapturingGeneratorStrategy implements GeneratorStrategy {
+
+		private static final GeneratorStrategy delegate = DefaultGeneratorStrategy.INSTANCE;
+
+		private byte[] captured;
+
+		@Override
+		public byte[] generate(ClassGenerator cg) throws Exception {
+			this.captured = delegate.generate(cg);
+			return this.captured;
+		}
+
+		private ClassReader createClassReader() {
+			return new ClassReader(this.captured);
+		}
+	}
+}

spring-core/src/main/java/org/springframework/cglib/core/ClassNameReader.java

@@ -34,9 +34,11 @@ private ClassNameReader() {
 	private static class EarlyExitException extends RuntimeException {
 	}
 
+	// SPRING PATCH BEGIN
 	public static String getClassName(ClassReader r) {
-		return getClassInfo(r)[0];
+		return r.getClassName().replace('/', '.');
 	}
+	// SPRING PATCH END
 
     public static String[] getClassInfo(ClassReader r) {
         final List<String> array = new ArrayList<>();