org.apache.pulsar.client.api.Reader Maven / Gradle / Ivy
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* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you 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.apache.pulsar.client.api;
import java.io.Closeable;
import java.util.concurrent.CompletableFuture;
import java.util.concurrent.TimeUnit;
/**
* A Reader can be used to scan through all the messages currently available in a topic.
*
*/
public interface Reader extends Closeable {
/**
* @return the topic from which this reader is reading from
*/
String getTopic();
/**
* Read the next message in the topic.
*
* @return the next message
* @throws PulsarClientException
*/
Message readNext() throws PulsarClientException;
/**
* Read the next message in the topic waiting for a maximum of timeout
* time units. Returns null if no message is received in that time.
*
* @return the next message(Could be null if none received in time)
* @throws PulsarClientException
*/
Message readNext(int timeout, TimeUnit unit) throws PulsarClientException;
CompletableFuture> readNextAsync();
/**
* Asynchronously close the reader and stop the broker to push more messages.
*
* @return a future that can be used to track the completion of the operation
*/
CompletableFuture closeAsync();
/**
* Return true if the topic was terminated and this reader has reached the end of the topic.
*/
boolean hasReachedEndOfTopic();
/**
* Check if there is any message available to read from the current position.
*/
boolean hasMessageAvailable() throws PulsarClientException;
/**
* Asynchronously Check if there is message that has been published successfully to the broker in the topic.
*/
CompletableFuture hasMessageAvailableAsync();
/**
* @return Whether the reader is connected to the broker
*/
boolean isConnected();
}