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The Adobe Experience Manager SDK
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/*
 * Copyright (C) 2009 The Guava 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
 *
 * 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 com.google.common.util.concurrent;

import static com.google.common.base.Preconditions.checkNotNull;
import com.google.common.base.Supplier;
import java.util.concurrent.Callable;
import javax.annotation.Nullable;

/**
 *  Static utility methods pertaining to the {@link Callable} interface.
 *
 *  @author Isaac Shum
 *  @since 1.0
 *
 * @deprecated The Google Guava Core Libraries are deprecated and will not be part of the AEM SDK after April 2023
 */
@Deprecated(since = "2022-12-01")
public final class Callables {

    private Callables() {
    }

    /**
     * Creates a {@code Callable} which immediately returns a preset value each
     * time it is called.
     */
    public static  Callable returning(@Nullable final T value) {
        return new Callable() {

            @Override
            public T call() {
                return value;
            }
        };
    }

    /**
     * Wraps the given callable such that for the duration of {@link Callable#call} the thread that is
     * running will have the given name.
     *
     * @param callable The callable to wrap
     * @param nameSupplier The supplier of thread names, {@link Supplier#get get} will be called once
     *     for each invocation of the wrapped callable.
     */
    static  Callable threadRenaming(final Callable callable, final Supplier nameSupplier) {
        checkNotNull(nameSupplier);
        checkNotNull(callable);
        return new Callable() {

            @Override
            public T call() throws Exception {
                Thread currentThread = Thread.currentThread();
                String oldName = currentThread.getName();
                boolean restoreName = trySetName(nameSupplier.get(), currentThread);
                try {
                    return callable.call();
                } finally {
                    if (restoreName) {
                        trySetName(oldName, currentThread);
                    }
                }
            }
        };
    }

    /**
     * Wraps the given runnable such that for the duration of {@link Runnable#run} the thread that is
     * running with have the given name.
     *
     * @param task The Runnable to wrap
     * @param nameSupplier The supplier of thread names, {@link Supplier#get get} will be called once
     *     for each invocation of the wrapped callable.
     */
    static Runnable threadRenaming(final Runnable task, final Supplier nameSupplier) {
        checkNotNull(nameSupplier);
        checkNotNull(task);
        return new Runnable() {

            @Override
            public void run() {
                Thread currentThread = Thread.currentThread();
                String oldName = currentThread.getName();
                boolean restoreName = trySetName(nameSupplier.get(), currentThread);
                try {
                    task.run();
                } finally {
                    if (restoreName) {
                        trySetName(oldName, currentThread);
                    }
                }
            }
        };
    }

    /**
     * Tries to set name of the given {@link Thread}, returns true if successful.
     */
    private static boolean trySetName(final String threadName, Thread currentThread) {
        // In AppEngine this will always fail, should we test for that explicitly using
        // MoreExecutors.isAppEngine.  More generally, is there a way to see if we have the modifyThread
        // permission without catching an exception?
        try {
            currentThread.setName(threadName);
            return true;
        } catch (SecurityException e) {
            return false;
        }
    }
}