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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) 2013-2020 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.mapreduce;

import java.lang.reflect.Modifier;
import java.util.Map;
import java.util.UUID;
import java.util.concurrent.Callable;

import org.redisson.api.RBatch;
import org.redisson.api.RExecutorService;
import org.redisson.api.RFuture;
import org.redisson.api.RMapAsync;
import org.redisson.api.RObject;
import org.redisson.api.RedissonClient;
import org.redisson.api.mapreduce.RCollator;
import org.redisson.api.mapreduce.RMapReduceExecutor;
import org.redisson.api.mapreduce.RReducer;
import org.redisson.client.codec.Codec;
import org.redisson.connection.ConnectionManager;
import org.redisson.misc.RPromise;
import org.redisson.misc.RedissonPromise;
import org.redisson.misc.TransferListener;

/**
 * 
 * @author Nikita Koksharov
 *
 * @param  mapper type
 * @param  input value type
 * @param  output key type
 * @param  output value type
 */
abstract class MapReduceExecutor implements RMapReduceExecutor {

    private final RedissonClient redisson;
    private final RExecutorService executorService;
    final String resultMapName;
    
    final Codec objectCodec;
    final String objectName;
    final Class objectClass;
    

    private ConnectionManager connectionManager;
    RReducer reducer;
    M mapper;
    long timeout;
    
    MapReduceExecutor(RObject object, RedissonClient redisson, ConnectionManager connectionManager) {
        this.objectName = object.getName();
        this.objectCodec = object.getCodec();
        this.objectClass = object.getClass();

        this.redisson = redisson;
        UUID id = UUID.randomUUID();
        this.resultMapName = object.getName() + ":result:" + id;
        this.executorService = redisson.getExecutorService(RExecutorService.MAPREDUCE_NAME);
        this.connectionManager = connectionManager;
    }

    protected void check(Object task) {
        if (task == null) {
            throw new NullPointerException("Task is not defined");
        }
        if (task.getClass().isAnonymousClass()) {
            throw new IllegalArgumentException("Task can't be created using anonymous class");
        }
        if (task.getClass().isMemberClass()
                && !Modifier.isStatic(task.getClass().getModifiers())) {
            throw new IllegalArgumentException("Task class is an inner class and it should be static");
        }
    }
    
    @Override
    public Map execute() {
        return connectionManager.getCommandExecutor().get(executeAsync());
    }
    
    @Override
    public RFuture> executeAsync() {
        final RPromise> promise = new RedissonPromise>();
        final RFuture future = executeMapperAsync(resultMapName, null);
        addCancelHandling(promise, future);
        future.onComplete((res, e) -> {
            if (e != null) {
                promise.tryFailure(e);
                return;
            }
            
            RBatch batch = redisson.createBatch();
            RMapAsync resultMap = batch.getMap(resultMapName, objectCodec);
            resultMap.readAllMapAsync().onComplete(new TransferListener>(promise));
            resultMap.deleteAsync();
            batch.executeAsync();
        });        
        return promise;
    }

    private  void addCancelHandling(RPromise promise, RFuture future) {
        promise.onComplete((res, e) -> {
            if (promise.isCancelled()) {
                future.cancel(true);
            }
        });
    }
    
    @Override
    public void execute(String resultMapName) {
        connectionManager.getCommandExecutor().get(executeAsync(resultMapName));
    }
    
    @Override
    public RFuture executeAsync(String resultMapName) {
        return executeMapperAsync(resultMapName, null);
    }


    private  RFuture executeMapperAsync(String resultMapName, RCollator collator) {
        if (mapper == null) {
            throw new NullPointerException("Mapper is not defined");
        }
        if (reducer == null) {
            throw new NullPointerException("Reducer is not defined");
        }
        
        Callable task = createTask(resultMapName, (RCollator) collator);
        return (RFuture) executorService.submit(task);
    }

    protected abstract Callable createTask(String resultMapName, RCollator collator);
    
    @Override
    public  R execute(RCollator collator) {
        return connectionManager.getCommandExecutor().get(executeAsync(collator));
    }
    
    @Override
    public  RFuture executeAsync(final RCollator collator) {
        check(collator);
        
        return executeMapperAsync(resultMapName, collator);
    }
    
}