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a simple lib for transmitting ThreadLocal value between thread even using thread pool.
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package com.alibaba.ttl;

import java.util.ArrayList;
import java.util.Collection;
import java.util.List;
import java.util.Map;
import java.util.concurrent.Callable;
import java.util.concurrent.atomic.AtomicReference;
import java.util.Collections;

/**
 * {@link TtlCallable} decorate {@link Callable}, so as to get {@link TransmittableThreadLocal}
 * and transmit it to the time of {@link Callable} execution, needed when use {@link Callable} to thread pool.
 * 
 * Use factory method {@link #get(Callable)} to get decorated instance.
 *
 * @author Jerry Lee (oldratlee at gmail dot com)
 * @see java.util.concurrent.Executor
 * @see java.util.concurrent.ExecutorService
 * @see java.util.concurrent.ThreadPoolExecutor
 * @see java.util.concurrent.ScheduledThreadPoolExecutor
 * @see java.util.concurrent.Executors
 * @see java.util.concurrent.CompletionService
 * @see java.util.concurrent.ExecutorCompletionService
 * @since 0.9.0
 */
public final class TtlCallable implements Callable {
    private final AtomicReference, Object>> copiedRef;
    private final Callable callable;
    private final boolean releaseTtlValueReferenceAfterCall;


    private TtlCallable(Callable callable, boolean releaseTtlValueReferenceAfterCall) {
        this.copiedRef = new AtomicReference, Object>>(TransmittableThreadLocal.copy());
        this.callable = callable;
        this.releaseTtlValueReferenceAfterCall = releaseTtlValueReferenceAfterCall;
    }

    /**
     * wrap method {@link Callable#call()}.
     */
    @Override
    public V call() throws Exception {
        Map, Object> copied = copiedRef.get();
        if (copied == null || releaseTtlValueReferenceAfterCall && !copiedRef.compareAndSet(copied, null)) {
            throw new IllegalStateException("TTL value reference is released after call!");
        }

        Map, Object> backup = TransmittableThreadLocal.backupAndSetToCopied(copied);
        try {
            return callable.call();
        } finally {
            TransmittableThreadLocal.restoreBackup(backup);
        }
    }

    public Callable getCallable() {
        return callable;
    }

    /**
     * Factory method, wrapper input {@link Callable} to {@link TtlCallable}.
     * 

     * This method is idempotent.
     *
     * @param callable input {@link Callable}
     * @return Wrapped {@link Callable}
     */
    public static  TtlCallable get(Callable callable) {
        return get(callable, false);
    }


    /**
     * Factory method, wrapper input {@link Callable} to {@link TtlCallable}.
     * 

     * This method is idempotent.
     *
     * @param callable                          input {@link Callable}
     * @param releaseTtlValueReferenceAfterCall release TTL value reference after run, avoid memory leak even if {@link TtlRunnable} is referred.
     * @return Wrapped {@link Callable}
     */
    public static  TtlCallable get(Callable callable, boolean releaseTtlValueReferenceAfterCall) {
        return get(callable, releaseTtlValueReferenceAfterCall, false);
    }

    /**
     * Factory method, wrapper input {@link Callable} to {@link TtlCallable}.
     * 
     * This method is idempotent.
     *
     * @param callable                          input {@link Callable}
     * @param releaseTtlValueReferenceAfterCall release TTL value reference after run, avoid memory leak even if {@link TtlRunnable} is referred.
     * @param idempotent                        is idempotent or not. {@code true} will cover up bugs! DO NOT set, only when you know why.
     * @return Wrapped {@link Callable}
     */
    public static  TtlCallable get(Callable callable, boolean releaseTtlValueReferenceAfterCall, boolean idempotent) {
        if (null == callable) {
            return null;
        }

        if (callable instanceof TtlCallable) {
            if (idempotent) {
                // avoid redundant decoration, and ensure idempotency
                return (TtlCallable) callable;
            } else {
                throw new IllegalStateException("Already TtlCallable!");
            }
        }
        return new TtlCallable(callable, releaseTtlValueReferenceAfterCall);
    }

    /**
     * wrapper input {@link Callable} Collection to {@link TtlCallable} Collection.
     *
     * @param tasks task to be wrapped
     * @return Wrapped {@link Callable}
     */
    public static  List> gets(Collection> tasks) {
        return gets(tasks, false, false);
    }

    /**
     * wrapper input {@link Callable} Collection to {@link TtlCallable} Collection.
     *
     * @param tasks                             task to be wrapped
     * @param releaseTtlValueReferenceAfterCall release TTL value reference after run, avoid memory leak even if {@link TtlRunnable} is referred.
     * @return Wrapped {@link Callable}
     */
    public static  List> gets(Collection> tasks, boolean releaseTtlValueReferenceAfterCall) {
        return gets(tasks, releaseTtlValueReferenceAfterCall, false);
    }

    /**
     * wrapper input {@link Callable} Collection to {@link TtlCallable} Collection.
     *
     * @param tasks                             task to be wrapped
     * @param releaseTtlValueReferenceAfterCall release TTL value reference after run, avoid memory leak even if {@link TtlRunnable} is referred.
     * @param idempotent                        is idempotent or not. {@code true} will cover up bugs! DO NOT set, only when you know why.
     * @return Wrapped {@link Callable}
     */
    public static  List> gets(Collection> tasks, boolean releaseTtlValueReferenceAfterCall, boolean idempotent) {
        if (null == tasks) {
            return Collections.emptyList();
        }
        List> copy = new ArrayList>();
        for (Callable task : tasks) {
            copy.add(TtlCallable.get(task, releaseTtlValueReferenceAfterCall, idempotent));
        }
        return copy;
    }
}