com.lambdaworks.redis.protocol.AsyncCommand Maven / Gradle / Ivy

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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 2011-2016 the original author or 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.lambdaworks.redis.protocol;

import java.util.concurrent.CompletableFuture;
import java.util.concurrent.CountDownLatch;
import java.util.concurrent.TimeUnit;
import java.util.function.Consumer;

import com.lambdaworks.redis.RedisCommandExecutionException;
import com.lambdaworks.redis.RedisCommandInterruptedException;
import com.lambdaworks.redis.RedisFuture;
import com.lambdaworks.redis.internal.LettuceAssert;
import com.lambdaworks.redis.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 {

    protected CountDownLatch latch = new CountDownLatch(1);
    protected RedisCommand command;

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

    /**
     * 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 {
            return latch.await(timeout, unit);
        } catch (InterruptedException e) {
            Thread.currentThread().interrupt();
            throw new RedisCommandInterruptedException(e);
        }
    }

    /**
     * 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 (latch.getCount() == 1) {
            completeResult();
            command.complete();
        }
        latch.countDown();
    }

    protected void completeResult() {
        if (command.getOutput() == null) {
            complete(null);
        } else if (command.getOutput().hasError()) {
            completeExceptionally(new RedisCommandExecutionException(command.getOutput().getError()));
        } else {
            complete(command.getOutput().get());
        }
    }

    @Override
    public boolean completeExceptionally(Throwable ex) {
        boolean result = false;
        if (latch.getCount() == 1) {
            command.completeExceptionally(ex);
            result = super.completeExceptionally(ex);
        }
        latch.countDown();
        return result;
    }

    @Override
    public boolean cancel(boolean mayInterruptIfRunning) {
        try {
            command.cancel();
            return super.cancel(mayInterruptIfRunning);
        } finally {
            latch.countDown();
        }
    }

    @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 RedisCommand getDelegate() {
		return command;
	}
	
}