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Easy Redis Java client and Real-Time Data Platform. Valkey compatible. Sync/Async/RxJava3/Reactive API. Client side caching. Over 50 Redis based Java objects and services: JCache API, Apache Tomcat, Hibernate, Spring, Set, Multimap, SortedSet, Map, List, Queue, Deque, Semaphore, Lock, AtomicLong, Map Reduce, Bloom filter, Scheduler, RPC

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/**
 * Copyright (c) 2013-2024 Nikita Koksharov
 *
 * 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 org.redisson;

import org.redisson.api.RFuture;
import org.redisson.api.RQueue;
import org.redisson.api.RedissonClient;
import org.redisson.client.codec.Codec;
import org.redisson.client.protocol.RedisCommands;
import org.redisson.command.CommandAsyncExecutor;

import java.util.Collections;
import java.util.List;
import java.util.NoSuchElementException;

/**
 * Distributed and concurrent implementation of {@link java.util.Queue}
 *
 * @author Nikita Koksharov
 *
 * @param  the type of elements held in this collection
 */
public class RedissonQueue extends BaseRedissonList implements RQueue {

    public RedissonQueue(CommandAsyncExecutor commandExecutor, String name, RedissonClient redisson) {
        super(commandExecutor, name, redisson);
    }

    public RedissonQueue(Codec codec, CommandAsyncExecutor commandExecutor, String name, RedissonClient redisson) {
        super(codec, commandExecutor, name, redisson);
    }

    @Override
    public boolean offer(V e) {
        return get(offerAsync(e));
    }

    @Override
    public RFuture offerAsync(V e) {
        return addAsync(e);
    }

    public V getFirst() {
        V value = getValue(0);
        if (value == null) {
            throw new NoSuchElementException();
        }
        return value;
    }

    public V removeFirst() {
        V value = poll();
        if (value == null) {
            throw new NoSuchElementException();
        }
        return value;
    }
    
    @Override
    public V remove() {
        return removeFirst();
    }

    @Override
    public RFuture pollAsync() {
        return commandExecutor.writeAsync(getRawName(), codec, RedisCommands.LPOP, getRawName());
    }

    @Override
    public List poll(int limit) {
        return get(pollAsync(limit));
    }

    @Override
    public RFuture> pollAsync(int limit) {
        return commandExecutor.evalWriteNoRetryAsync(getRawName(), codec, RedisCommands.EVAL_LIST,
                   "local result = {};"
                 + "for i = 1, ARGV[1], 1 do " +
                       "local value = redis.call('lpop', KEYS[1]);" +
                       "if value ~= false then " +
                           "table.insert(result, value);" +
                       "else " +
                           "return result;" +
                       "end;" +
                   "end; " +
                   "return result;",
                Collections.singletonList(getRawName()), limit);
    }

    @Override
    public V poll() {
        return get(pollAsync());
    }

    @Override
    public V element() {
        return getFirst();
    }

    @Override
    public RFuture peekAsync() {
        return getAsync(0);
    }

    @Override
    public V peek() {
        return getValue(0);
    }

    @Override
    public V pollLastAndOfferFirstTo(String queueName) {
        return get(pollLastAndOfferFirstToAsync(queueName));
    }

    @Override
    public RFuture pollLastAndOfferFirstToAsync(String queueName) {
        return commandExecutor.writeAsync(getRawName(), codec, RedisCommands.RPOPLPUSH, getRawName(), queueName);
    }

}