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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) 2013-2021 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.reactive;

import org.redisson.ScanResult;
import org.redisson.api.RFuture;
import org.redisson.client.RedisClient;
import reactor.core.publisher.FluxSink;

import java.util.concurrent.atomic.AtomicLong;
import java.util.function.LongConsumer;

/**
 *
 * @author Nikita Koksharov
 *
 */
public abstract class IteratorConsumer implements LongConsumer {

    private final FluxSink emitter;

    private long nextIterPos;
    private RedisClient client;
    private AtomicLong elementsRead = new AtomicLong();

    private boolean finished;
    private volatile boolean completed;
    private AtomicLong readAmount = new AtomicLong();

    public IteratorConsumer(FluxSink emitter) {
        this.emitter = emitter;
    }

    @Override
    public void accept(long value) {
        readAmount.addAndGet(value);
        if (completed || elementsRead.get() == 0) {
            nextValues(emitter);
            completed = false;
        }
    }

    protected void nextValues(FluxSink emitter) {
        scanIterator(client, nextIterPos).whenComplete((res, e) -> {
            if (e != null) {
                emitter.error(e);
                return;
            }

            if (finished) {
                client = null;
                nextIterPos = 0;
                return;
            }

            client = res.getRedisClient();
            nextIterPos = res.getPos();

            for (Object val : res.getValues()) {
                Object v = transformValue(val);
                emitter.next((V) v);
                elementsRead.incrementAndGet();
            }

            if (elementsRead.get() >= readAmount.get()) {
                emitter.complete();
                elementsRead.set(0);
                completed = true;
                return;
            }
            if (res.getPos() == 0 && !tryAgain()) {
                finished = true;
                emitter.complete();
            }

            if (finished || completed) {
                return;
            }
            nextValues(emitter);
        });
    }

    protected Object transformValue(Object value) {
        return value;
    }

    protected abstract boolean tryAgain();

    protected abstract RFuture> scanIterator(RedisClient client, long nextIterPos);

}