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Advanced and thread-safe Java Redis client for synchronous, asynchronous, and reactive usage. Supports Cluster, Sentinel, Pipelining, Auto-Reconnect, Codecs and much more.
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/*
 * Copyright 2011-Present, Redis Ltd. and Contributors
 * All rights reserved.
 *
 * Licensed under the MIT License.
 *
 * This file contains contributions from third-party contributors
 * 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
 *
 *      https://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 io.lettuce.core.protocol;

import java.util.concurrent.CompletableFuture;
import java.util.concurrent.ExecutionException;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.TimeoutException;
import java.util.concurrent.atomic.AtomicIntegerFieldUpdater;
import java.util.function.BiConsumer;
import java.util.function.Consumer;

import io.lettuce.core.internal.ExceptionFactory;
import io.lettuce.core.RedisCommandInterruptedException;
import io.lettuce.core.RedisFuture;
import io.lettuce.core.internal.LettuceAssert;
import io.lettuce.core.output.CommandOutput;
import io.netty.buffer.ByteBuf;

/**
 * An asynchronous redis command and its result. All successfully executed commands will eventually return a
 * {@link CommandOutput} object.
 *
 * @param  Key type.
 * @param  Value type.
 * @param  Command output type.
 *
 * @author Mark Paluch
 */
public class AsyncCommand extends CompletableFuture
        implements RedisCommand, RedisFuture, CompleteableCommand, DecoratedCommand {

    @SuppressWarnings("rawtypes")
    private static final AtomicIntegerFieldUpdater COUNT_UPDATER = AtomicIntegerFieldUpdater
            .newUpdater(AsyncCommand.class, "count");

    private final RedisCommand command;

    // access via COUNT_UPDATER
    @SuppressWarnings({ "unused" })
    private volatile int count = 1;

    /**
     * @param command the command, must not be {@code null}.
     */
    public AsyncCommand(RedisCommand command) {
        this(command, 1);
    }

    /**
     * @param command the command, must not be {@code null}.
     */
    protected AsyncCommand(RedisCommand command, int count) {
        LettuceAssert.notNull(command, "RedisCommand must not be null");
        this.command = command;
        this.count = count;
    }

    /**
     * Wait up to the specified time for the command output to become available.
     *
     * @param timeout Maximum time to wait for a result.
     * @param unit Unit of time for the timeout.
     *
     * @return true if the output became available.
     */
    @Override
    public boolean await(long timeout, TimeUnit unit) {
        try {
            get(timeout, unit);
            return true;
        } catch (InterruptedException e) {
            Thread.currentThread().interrupt();
            throw new RedisCommandInterruptedException(e);
        } catch (ExecutionException e) {
            return true;
        } catch (TimeoutException e) {
            return false;
        }
    }

    /**
     * Get the object that holds this command's output.
     *
     * @return The command output object.
     */
    @Override
    public CommandOutput getOutput() {
        return command.getOutput();
    }

    /**
     * Mark this command complete and notify all waiting threads.
     */
    @Override
    public void complete() {
        if (COUNT_UPDATER.decrementAndGet(this) == 0) {
            completeResult();
            command.complete();
        }
    }

    protected void completeResult() {
        if (command.getOutput() == null) {
            complete(null);
        } else if (command.getOutput().hasError()) {
            doCompleteExceptionally(ExceptionFactory.createExecutionException(command.getOutput().getError()));
        } else {
            complete(command.getOutput().get());
        }
    }

    @Override
    public boolean completeExceptionally(Throwable ex) {
        boolean result = false;

        int ref = COUNT_UPDATER.get(this);
        if (ref > 0 && COUNT_UPDATER.compareAndSet(this, ref, 0)) {
            result = doCompleteExceptionally(ex);
        }
        return result;
    }

    private boolean doCompleteExceptionally(Throwable ex) {
        command.completeExceptionally(ex);
        return super.completeExceptionally(ex);
    }

    @Override
    public boolean cancel(boolean mayInterruptIfRunning) {
        try {
            command.cancel();
            return super.cancel(mayInterruptIfRunning);
        } finally {
            COUNT_UPDATER.set(this, 0);
        }
    }

    @Override
    public String getError() {
        return command.getOutput().getError();
    }

    @Override
    public CommandArgs getArgs() {
        return command.getArgs();
    }

    @Override
    public String toString() {
        final StringBuilder sb = new StringBuilder();
        sb.append(getClass().getSimpleName());
        sb.append(" [type=").append(getType());
        sb.append(", output=").append(getOutput());
        sb.append(", commandType=").append(command.getClass().getName());
        sb.append(']');
        return sb.toString();
    }

    @Override
    public ProtocolKeyword getType() {
        return command.getType();
    }

    @Override
    public void cancel() {
        cancel(true);
    }

    @Override
    public void encode(ByteBuf buf) {
        command.encode(buf);
    }

    @Override
    public void setOutput(CommandOutput output) {
        command.setOutput(output);
    }

    @Override
    public void onComplete(Consumer action) {
        thenAccept(action);
    }

    @Override
    public void onComplete(BiConsumer action) {
        whenComplete(action);
    }

    @Override
    public RedisCommand getDelegate() {
        return command;
    }

    @Override
    public boolean equals(Object o) {

        if (this == o)
            return true;
        if (!(o instanceof RedisCommand)) {
            return false;
        }

        RedisCommand left = CommandWrapper.unwrap(command);
        RedisCommand right = CommandWrapper.unwrap((RedisCommand) o);

        return left == right;
    }

    @Override
    public int hashCode() {

        RedisCommand toHash = CommandWrapper.unwrap(command);

        return toHash != null ? toHash.hashCode() : 0;
    }

}