kylixs commented on a change in pull request #4858: URL: https://github.com/apache/skywalking/pull/4858#discussion_r439905059
########## File path: apm-sniffer/apm-agent-core/src/main/java/org/apache/skywalking/apm/agent/core/plugin/bytebuddy/CacheableTransformerDecorator.java ########## @@ -0,0 +1,195 @@ +/* + * Licensed to the Apache Software Foundation (ASF) under one or more + * contributor license agreements. See the NOTICE file distributed with + * this work for additional information regarding copyright ownership. + * The ASF licenses this file to You 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 + * + * http://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.apache.skywalking.apm.agent.core.plugin.bytebuddy; + +import net.bytebuddy.agent.builder.AgentBuilder; +import net.bytebuddy.agent.builder.ResettableClassFileTransformer; +import net.bytebuddy.utility.RandomString; +import org.apache.skywalking.apm.agent.core.logging.api.ILog; +import org.apache.skywalking.apm.agent.core.logging.api.LogManager; +import org.apache.skywalking.apm.agent.core.util.FileUtils; +import org.apache.skywalking.apm.agent.core.util.IOUtils; + +import java.io.ByteArrayInputStream; +import java.io.File; +import java.io.FileInputStream; +import java.io.FileOutputStream; +import java.io.IOException; +import java.lang.instrument.IllegalClassFormatException; +import java.nio.file.Files; +import java.security.ProtectionDomain; +import java.util.Map; +import java.util.concurrent.ConcurrentHashMap; + +/** + * Wrapper classFileTransformer of ByteBuddy, save the enhanced bytecode to memory cache or file cache, + * and automatically load the previously generated bytecode during the second retransform, + * to solve the problem that ByteBuddy generates auxiliary classes with different random names every time. + * Allow other javaagent to enhance those classes that enhanced by SkyWalking agent. + */ +public class CacheableTransformerDecorator implements AgentBuilder.TransformerDecorator { + + private static final ILog logger = LogManager.getLogger(CacheableTransformerDecorator.class); + + private String cacheDirBase; + private final ClassCacheMode cacheMode; + private ClassCacheResolver cacheResolver; + + public CacheableTransformerDecorator(ClassCacheMode cacheMode) throws IOException { + this.cacheMode = cacheMode; + initClassCache(); + } + + public CacheableTransformerDecorator(ClassCacheMode cacheMode, String cacheDirBase) throws IOException { + this.cacheDirBase = cacheDirBase; + this.cacheMode = cacheMode; + initClassCache(); + } + + private void initClassCache() throws IOException { + if (this.cacheMode.equals(ClassCacheMode.FILE)) { + File cacheDir; + if (this.cacheDirBase == null) { + cacheDir = Files.createTempDirectory("class-cache").toFile(); + } else { + cacheDir = new File(this.cacheDirBase + "/class-cache-" + RandomString.make()); + } + cacheResolver = new FileCacheResolver(cacheDir); + } else { + cacheResolver = new MemoryCacheResolver(); + } + } + + @Override + public ResettableClassFileTransformer decorate(ResettableClassFileTransformer classFileTransformer) { + return new ResettableClassFileTransformer.WithDelegation(classFileTransformer) { + + @Override + public byte[] transform(ClassLoader loader, String className, Class<?> classBeingRedefined, ProtectionDomain protectionDomain, byte[] classfileBuffer) throws IllegalClassFormatException { + // load from cache + byte[] classCache = cacheResolver.getClassCache(loader, className); + if (classCache != null) { + return classCache; + } + + //transform class + classfileBuffer = classFileTransformer.transform(loader, className, classBeingRedefined, protectionDomain, classfileBuffer); + + // save to cache + if (classfileBuffer != null) { + cacheResolver.putClassCache(loader, className, classfileBuffer); + } + + return classfileBuffer; + } + }; + } + + private static String getClassLoaderHash(ClassLoader loader) { + String classloader; + if (loader != null) { + classloader = Integer.toHexString(loader.hashCode()); + } else { + //classloader is null for BootstrapClassLoader + classloader = "00000000"; + } + return classloader; + } + + interface ClassCacheResolver { + + byte[] getClassCache(ClassLoader loader, String className); + + void putClassCache(ClassLoader loader, String className, byte[] classfileBuffer); + } + + static class MemoryCacheResolver implements ClassCacheResolver { + // classloaderHashcode@className -> class bytes + private Map<String, byte[]> classCacheMap = new ConcurrentHashMap<String, byte[]>(); + + @Override + public byte[] getClassCache(ClassLoader loader, String className) { + String cacheKey = getCacheKey(loader, className); + return classCacheMap.get(cacheKey); + } + + @Override + public void putClassCache(ClassLoader loader, String className, byte[] classfileBuffer) { + String cacheKey = getCacheKey(loader, className); + classCacheMap.put(cacheKey, classfileBuffer); + } + + private String getCacheKey(ClassLoader loader, String className) { + return getClassLoaderHash(loader) + "@" + className; + } + } + + static class FileCacheResolver implements ClassCacheResolver { Review comment: class cache dir is a randomly generated random directory, different agents will isolate their respective class cache. `cacheDir = new File(this.cacheDirBase + "/class-cache-" + RandomString.make());` ---------------------------------------------------------------- This is an automated message from the Apache Git Service. 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