ReaderImpl.java

/**
 * Copyright 2016 Yahoo Inc.
 *
 * 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.yahoo.pulsar.client.impl;

import java.io.IOException;
import java.util.UUID;
import java.util.concurrent.CompletableFuture;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.TimeUnit;

import org.apache.commons.codec.digest.DigestUtils;

import com.yahoo.pulsar.client.api.Consumer;
import com.yahoo.pulsar.client.api.ConsumerConfiguration;
import com.yahoo.pulsar.client.api.Message;
import com.yahoo.pulsar.client.api.MessageId;
import com.yahoo.pulsar.client.api.PulsarClientException;
import com.yahoo.pulsar.client.api.Reader;
import com.yahoo.pulsar.client.api.ReaderConfiguration;
import com.yahoo.pulsar.client.api.ReaderListener;
import com.yahoo.pulsar.client.api.SubscriptionType;
import com.yahoo.pulsar.client.impl.ConsumerImpl.SubscriptionMode;

public class ReaderImpl implements Reader {

    private final ConsumerImpl consumer;

    public ReaderImpl(PulsarClientImpl client, String topic, MessageId startMessageId,
            ReaderConfiguration readerConfiguration, ExecutorService listenerExecutor,
            CompletableFuture<Consumer> consumerFuture) {

        String subscription = "reader-" + DigestUtils.sha1Hex(UUID.randomUUID().toString()).substring(0, 10);

        ConsumerConfiguration consumerConfiguration = new ConsumerConfiguration();
        consumerConfiguration.setSubscriptionType(SubscriptionType.Exclusive);
        consumerConfiguration.setReceiverQueueSize(readerConfiguration.getReceiverQueueSize());
        if (readerConfiguration.getReaderName() != null) {
            consumerConfiguration.setConsumerName(readerConfiguration.getReaderName());
        }

        if (readerConfiguration.getReaderListener() != null) {
            ReaderListener readerListener = readerConfiguration.getReaderListener();
            consumerConfiguration.setMessageListener((consumer, msg) -> {
                readerListener.received(this, msg);
                consumer.acknowledgeCumulativeAsync(msg);
            });
        }

        consumer = new ConsumerImpl(client, topic, subscription, consumerConfiguration, listenerExecutor, -1,
                consumerFuture, SubscriptionMode.NonDurable, startMessageId);
    }

    @Override
    public String getTopic() {
        return consumer.getTopic();
    }

    ConsumerImpl getConsumer() {
        return consumer;
    }

    @Override
    public Message readNext() throws PulsarClientException {
        Message msg = consumer.receive();

        // Acknowledge message immediately because the reader is based on non-durable subscription. When it reconnects,
        // it will specify the subscription position anyway
        consumer.acknowledgeCumulativeAsync(msg);
        return msg;
    }

    @Override
    public Message readNext(int timeout, TimeUnit unit) throws PulsarClientException {
        Message msg  = consumer.receive(timeout, unit);

        if (msg != null) {
            consumer.acknowledgeCumulativeAsync(msg);
        }
        return msg;
    }

    @Override
    public CompletableFuture<Message> readNextAsync() {
        return consumer.receiveAsync().thenApply(msg -> {
           consumer.acknowledgeCumulativeAsync(msg);
           return msg;
        });
    }

    @Override
    public void close() throws IOException {
        consumer.close();
    }

    @Override
    public CompletableFuture<Void> closeAsync() {
        return consumer.closeAsync();
    }

}