org.apache.kafka.connect.util.SharedTopicAdmin Maven / Gradle / Ivy
/*
* 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.kafka.connect.util;
import org.apache.kafka.clients.admin.AdminClientConfig;
import org.apache.kafka.connect.errors.ConnectException;
import java.time.Duration;
import java.util.Map;
import java.util.Objects;
import java.util.concurrent.atomic.AtomicBoolean;
import java.util.concurrent.atomic.AtomicReference;
import java.util.function.Function;
import java.util.function.Supplier;
import java.util.function.UnaryOperator;
/**
* A holder of a {@link TopicAdmin} object that is lazily and atomically created when needed by multiple callers.
* As soon as one of the getters is called, all getters will return the same shared {@link TopicAdmin}
* instance until this SharedAdmin is closed via {@link #close()} or {@link #close(Duration)}.
*
* The owner of this object is responsible for ensuring that either {@link #close()} or {@link #close(Duration)}
* is called when the {@link TopicAdmin} instance is no longer needed. Consequently, once this
* {@link SharedTopicAdmin} instance has been closed, the {@link #get()} and {@link #topicAdmin()} methods,
* nor any previously returned {@link TopicAdmin} instances may be used.
*
*
This class is thread-safe. It also appears as immutable to callers that obtain the {@link TopicAdmin} object,
* until this object is closed, at which point it cannot be used anymore
*/
public class SharedTopicAdmin implements AutoCloseable, Supplier {
// Visible for testing
static final Duration DEFAULT_CLOSE_DURATION = Duration.ofMillis(Long.MAX_VALUE);
private final Map adminProps;
private final AtomicReference admin = new AtomicReference<>();
private final AtomicBoolean closed = new AtomicBoolean(false);
private final Function, TopicAdmin> factory;
public SharedTopicAdmin(Map adminProps) {
this(adminProps, TopicAdmin::new);
}
// Visible for testing
SharedTopicAdmin(Map adminProps, Function, TopicAdmin> factory) {
this.adminProps = Objects.requireNonNull(adminProps);
this.factory = Objects.requireNonNull(factory);
}
/**
* Get the shared {@link TopicAdmin} instance.
*
* @return the shared instance; never null
* @throws ConnectException if this object has already been closed
*/
@Override
public TopicAdmin get() {
return topicAdmin();
}
/**
* Get the shared {@link TopicAdmin} instance.
*
* @return the shared instance; never null
* @throws ConnectException if this object has already been closed
*/
public TopicAdmin topicAdmin() {
return admin.updateAndGet(this::createAdmin);
}
/**
* Get the string containing the list of bootstrap server addresses to the Kafka broker(s) to which
* the admin client connects.
*
* @return the bootstrap servers as a string; never null
*/
public String bootstrapServers() {
return adminProps.getOrDefault(AdminClientConfig.BOOTSTRAP_SERVERS_CONFIG, "").toString();
}
/**
* Close the underlying {@link TopicAdmin} instance, if one has been created, and prevent new ones from being created.
*
* Once this method is called, the {@link #get()} and {@link #topicAdmin()} methods,
* nor any previously returned {@link TopicAdmin} instances may be used.
*/
@Override
public void close() {
close(DEFAULT_CLOSE_DURATION);
}
/**
* Close the underlying {@link TopicAdmin} instance, if one has been created, and prevent new ones from being created.
*
*
Once this method is called, the {@link #get()} and {@link #topicAdmin()} methods,
* nor any previously returned {@link TopicAdmin} instances may be used.
*
* @param timeout the maximum time to wait while the underlying admin client is closed; may not be null
*/
public void close(Duration timeout) {
Objects.requireNonNull(timeout);
if (this.closed.compareAndSet(false, true)) {
TopicAdmin admin = this.admin.getAndSet(null);
if (admin != null) {
admin.close(timeout);
}
}
}
@Override
public String toString() {
return "admin client for brokers at " + bootstrapServers();
}
/**
* Method used to create a {@link TopicAdmin} instance. This method must be side-effect free, since it is called from within
* the {@link AtomicReference#updateAndGet(UnaryOperator)}.
*
* @param existing the existing instance; may be null
* @return the
*/
protected TopicAdmin createAdmin(TopicAdmin existing) {
if (closed.get()) {
throw new ConnectException("The " + this + " has already been closed and cannot be used.");
}
if (existing != null) {
return existing;
}
return factory.apply(adminProps);
}
}