LuciferYang commented on code in PR #7759: URL: https://github.com/apache/hadoop/pull/7759#discussion_r2163285206
########## hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/util/SignalUtil.java: ########## @@ -0,0 +1,161 @@ +/* + * 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.hadoop.util; + +import org.apache.hadoop.classification.InterfaceAudience; + +import org.apache.hadoop.util.dynamic.BindingUtils; +import org.apache.hadoop.util.dynamic.DynConstructors; +import org.apache.hadoop.util.dynamic.DynMethods; + +import java.lang.reflect.Proxy; + +@InterfaceAudience.Private +public class SignalUtil { + + static final Class<?> jdkSignalClazz = + BindingUtils.loadClassSafely("sun.misc.Signal"); + static final Class<?> jdkSignalHandlerClazz = + BindingUtils.loadClassSafely("sun.misc.SignalHandler"); + + static DynConstructors.Ctor<?> jdkSignalCtor = + new DynConstructors.Builder() + .impl(jdkSignalClazz, String.class) + .build(); + + static DynMethods.StaticMethod jdkSignalHandleStaticMethod = + new DynMethods.Builder("handle") + .impl(jdkSignalClazz, jdkSignalClazz, jdkSignalHandlerClazz) + .buildStatic(); + + static DynMethods.StaticMethod jdkSignalRaiseStaticMethod = + new DynMethods.Builder("raise") + .impl(jdkSignalClazz, jdkSignalClazz) + .buildStatic(); + + static DynMethods.UnboundMethod jdkSignalHandlerHandleUnboundMethod = + new DynMethods.Builder("handle") + .impl(jdkSignalHandlerClazz, jdkSignalClazz) + .build(); + + @InterfaceAudience.Private + public static class Signal { + private final DynMethods.UnboundMethod getNumberUnboundMethod = + new DynMethods.Builder("getNumber").impl(jdkSignalClazz).build(); + + private final DynMethods.UnboundMethod getNameUnboundMethod = + new DynMethods.Builder("getName").impl(jdkSignalClazz).build(); + + private final Object delegate; + private final DynMethods.BoundMethod getNumberMethod; + private final DynMethods.BoundMethod getNameMethod; + + public Signal(String name) { + Preconditions.checkNotNull(name); + this.delegate = jdkSignalCtor.newInstance(name); + this.getNumberMethod = getNumberUnboundMethod.bind(delegate); + this.getNameMethod = getNameUnboundMethod.bind(delegate); + } + + public Signal(Object delegate) { + Preconditions.checkArgument(jdkSignalClazz.isInstance(delegate), + String.format("Expected class is '%s', but actual class is '%s'", + jdkSignalClazz.getName(), delegate.getClass().getName())); + this.delegate = delegate; + this.getNumberMethod = getNumberUnboundMethod.bind(delegate); + this.getNameMethod = getNameUnboundMethod.bind(delegate); + } + + public int getNumber() { + return getNumberMethod.invoke(); + } + + public String getName() { + return getNameMethod.invoke(); + } + + public boolean equals(Object obj) { + if (this == obj) { + return true; + } + if (obj instanceof Signal) { + return delegate.equals(((Signal)obj).delegate); + } + return false; + } + + public int hashCode() { + return delegate.hashCode(); + } + + public String toString() { + return delegate.toString(); + } + } + + @InterfaceAudience.Private + public interface Handler { + void handle(Signal sig); + } + + static class JdkSignalHandlerImpl implements Handler { + + private final Object delegate; + private final DynMethods.BoundMethod jdkSignalHandlerHandleMethod; + + JdkSignalHandlerImpl(Handler handler) { + this.delegate = Proxy.newProxyInstance( + getClass().getClassLoader(), + new Class<?>[] { jdkSignalHandlerClazz }, + (proxyObj, method, args) -> { + if ("handle".equals(method.getName()) && args.length == 1 && jdkSignalClazz.isInstance(args[0])) { + handler.handle(new Signal(args[0])); + return null; + } else { + return method.invoke(proxyObj, args); Review Comment: Perhaps there's still an issue here... If someone invokes methods like `toString()`, `equals()`, `hashCode()`, etc., on the proxy object, and these invocations don't match the "handle" condition, they will enter the `else` branch and execute `method.invoke(proxyObj, args)`. However, since `proxyObj` is the proxy object itself, this will again trigger the `InvocationHandler`, potentially leading to an infinite recursive call? Is my understanding correct? -- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. To unsubscribe, e-mail: common-issues-unsubscr...@hadoop.apache.org For queries about this service, please contact Infrastructure at: us...@infra.apache.org --------------------------------------------------------------------- To unsubscribe, e-mail: common-issues-unsubscr...@hadoop.apache.org For additional commands, e-mail: common-issues-h...@hadoop.apache.org
