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/*
 * 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.flink.runtime.concurrent.akka;

import org.apache.flink.util.TemporaryClassLoaderContext;
import org.apache.flink.util.concurrent.FutureUtils;
import org.apache.flink.util.function.SupplierWithException;
import org.apache.flink.util.function.ThrowingRunnable;

import java.util.concurrent.CompletableFuture;
import java.util.concurrent.Executor;

/** Classloading utilities. */
public class ClassLoadingUtils {

    /**
     * Wraps the given runnable in a {@link TemporaryClassLoaderContext} to prevent the plugin class
     * loader from leaking into Flink.
     *
     * @param runnable runnable to wrap
     * @param contextClassLoader class loader that should be set as the context class loader
     * @return wrapped runnable
     */
    public static Runnable withContextClassLoader(
            Runnable runnable, ClassLoader contextClassLoader) {
        return () -> runWithContextClassLoader(runnable::run, contextClassLoader);
    }

    /**
     * Wraps the given executor such that all submitted are runnables are run in a {@link
     * TemporaryClassLoaderContext} based on the given classloader.
     *
     * @param executor executor to wrap
     * @param contextClassLoader class loader that should be set as the context class loader
     * @return wrapped executor
     */
    public static Executor withContextClassLoader(
            Executor executor, ClassLoader contextClassLoader) {
        return new ContextClassLoaderSettingExecutor(executor, contextClassLoader);
    }

    /**
     * Runs the given runnable in a {@link TemporaryClassLoaderContext} to prevent the plugin class
     * loader from leaking into Flink.
     *
     * @param runnable runnable to run
     * @param contextClassLoader class loader that should be set as the context class loader
     */
    public static  void runWithContextClassLoader(
            ThrowingRunnable runnable, ClassLoader contextClassLoader) throws T {
        try (TemporaryClassLoaderContext ignored =
                TemporaryClassLoaderContext.of(contextClassLoader)) {
            runnable.run();
        }
    }

    /**
     * Runs the given supplier in a {@link TemporaryClassLoaderContext} based on the given
     * classloader.
     *
     * @param supplier supplier to run
     * @param contextClassLoader class loader that should be set as the context class loader
     */
    public static  T runWithContextClassLoader(
            SupplierWithException supplier, ClassLoader contextClassLoader) throws E {
        try (TemporaryClassLoaderContext ignored =
                TemporaryClassLoaderContext.of(contextClassLoader)) {
            return supplier.get();
        }
    }

    public static  CompletableFuture guardCompletionWithContextClassLoader(
            CompletableFuture future, ClassLoader contextClassLoader) {
        final CompletableFuture guardedFuture = new CompletableFuture<>();
        future.whenComplete(
                (value, throwable) ->
                        runWithContextClassLoader(
                                () -> FutureUtils.doForward(value, throwable, guardedFuture),
                                contextClassLoader));
        return guardedFuture;
    }

    /**
     * An {@link Executor} wrapper that temporarily resets the ContextClassLoader to the given
     * ClassLoader.
     */
    private static class ContextClassLoaderSettingExecutor implements Executor {

        private final Executor backingExecutor;
        private final ClassLoader contextClassLoader;

        public ContextClassLoaderSettingExecutor(
                Executor backingExecutor, ClassLoader contextClassLoader) {
            this.backingExecutor = backingExecutor;
            this.contextClassLoader = contextClassLoader;
        }

        @Override
        public void execute(Runnable command) {
            backingExecutor.execute(
                    ClassLoadingUtils.withContextClassLoader(command, contextClassLoader));
        }
    }
}