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/*
 * Copyright (c) 2015 Uber Technologies, Inc.
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
 * THE SOFTWARE.
 */

package com.uber.tchannel.api;

import com.google.common.util.concurrent.AbstractFuture;
import com.google.common.util.concurrent.FutureCallback;
import com.google.common.util.concurrent.Futures;
import com.uber.tchannel.api.handlers.TFutureCallback;
import com.uber.tchannel.errors.ErrorType;
import com.uber.tchannel.headers.ArgScheme;
import com.uber.tchannel.messages.Response;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import java.util.concurrent.ExecutionException;
import java.util.concurrent.Executor;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.atomic.AtomicInteger;

/**
 * Class representing the future response of a TChannel call. It is generic
 * and wraps/contains a payload. You construct instances via the factory
 * {@link #create(ArgScheme)}
 * @param  the type of the payload
 */

public final class TFuture extends AbstractFuture {

    private static final Logger logger = LoggerFactory.getLogger(TFuture.class);

    /**
     * Create future. Example usage: TFuture future = TFuture.create(...);
     * @param 
     * @param argScheme
     * @return 
     */
    public static  TFuture create(ArgScheme argScheme) {
        return new TFuture<>(argScheme);
    }

    private AtomicInteger listenerCount = new AtomicInteger(0);
    private V response = null;
    private ArgScheme argScheme = null;

    private TFuture(ArgScheme argScheme) {
        this.argScheme = argScheme;
    }

    @SuppressWarnings({"unchecked"})
    public void addCallback(final TFutureCallback callback) {
        Futures.addCallback(this, new FutureCallback() {
            @Override
            public void onSuccess(V response) {
                callback.onResponse(response);
            }

            @Override
            public void onFailure(Throwable throwable) {
                callback.onResponse(
                    (V) Response.build(
                        argScheme, 0, ErrorType.UnexpectedError, throwable.getMessage()
                    )
                );
            }
        });
    }

    @Override
    public boolean set(V response) {
        // Error doesn't need to be released
        if (listenerCount.get() == 0 && !response.isError()) {
            logger.warn(
                "No handler is set when response is set. Resource leak may occur.",
                new IllegalStateException() // log the stacktrace
            );
        }

        this.response = response;
        return super.set(response);
    }

    @Override
    public boolean setException(Throwable throwable) {
        return super.setException(throwable);
    }

    @Override
    public void addListener(final Runnable listener, Executor exec) {
        listenerCount.incrementAndGet();
        super.addListener(new Runnable() {
            @Override
            public void run() {
                listener.run();
                if (listenerCount.decrementAndGet() == 0) {
                    response.release();
                }
            }
        }, exec);
    }

    @Override
    public V get() throws InterruptedException, ExecutionException {
        listenerCount.incrementAndGet();
        return super.get();
    }

    @Override
    public V get(long timeout, TimeUnit unit) {
        throw new UnsupportedOperationException("Get timeout is unsupported. Use request timeout instead.");
    }

    @Override
    public boolean cancel(boolean mayInterruptIfRunning) {
        throw new UnsupportedOperationException("Cancel is not supported.");
    }
}