org.apache.kafka.clients.MetadataUpdater 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.clients;
import org.apache.kafka.common.Node;
import org.apache.kafka.common.requests.MetadataResponse;
import org.apache.kafka.common.requests.RequestHeader;
import java.util.List;
/**
* The interface used by `NetworkClient` to request cluster metadata info to be updated and to retrieve the cluster nodes
* from such metadata. This is an internal class.
*
* This class is not thread-safe!
*/
interface MetadataUpdater {
/**
* Gets the current cluster info without blocking.
*/
List fetchNodes();
/**
* Returns true if an update to the cluster metadata info is due.
*/
boolean isUpdateDue(long now);
/**
* Starts a cluster metadata update if needed and possible. Returns the time until the metadata update (which would
* be 0 if an update has been started as a result of this call).
*
* If the implementation relies on `NetworkClient` to send requests, `handleCompletedMetadataResponse` will be
* invoked after the metadata response is received.
*
* The semantics of `needed` and `possible` are implementation-dependent and may take into account a number of
* factors like node availability, how long since the last metadata update, etc.
*/
long maybeUpdate(long now);
/**
* If `request` is a metadata request, handles it and return `true`. Otherwise, returns `false`.
*
* This provides a mechanism for the `MetadataUpdater` implementation to use the NetworkClient instance for its own
* requests with special handling for disconnections of such requests.
* @param destination
*/
void handleDisconnection(String destination);
/**
* If `request` is a metadata request, handles it and returns `true`. Otherwise, returns `false`.
*
* This provides a mechanism for the `MetadataUpdater` implementation to use the NetworkClient instance for its own
* requests with special handling for completed receives of such requests.
*/
void handleCompletedMetadataResponse(RequestHeader requestHeader, long now, MetadataResponse metadataResponse);
/**
* Schedules an update of the current cluster metadata info. A subsequent call to `maybeUpdate` would trigger the
* start of the update if possible (see `maybeUpdate` for more information).
*/
void requestUpdate();
}