org.apache.flink.queryablestate.server.KvStateServerHandler 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.flink.queryablestate.server;
import org.apache.flink.annotation.Internal;
import org.apache.flink.queryablestate.exceptions.UnknownKeyOrNamespaceException;
import org.apache.flink.queryablestate.exceptions.UnknownKvStateIdException;
import org.apache.flink.queryablestate.messages.KvStateInternalRequest;
import org.apache.flink.queryablestate.messages.KvStateResponse;
import org.apache.flink.queryablestate.network.AbstractServerHandler;
import org.apache.flink.queryablestate.network.messages.MessageSerializer;
import org.apache.flink.queryablestate.network.stats.KvStateRequestStats;
import org.apache.flink.runtime.query.KvStateEntry;
import org.apache.flink.runtime.query.KvStateInfo;
import org.apache.flink.runtime.query.KvStateRegistry;
import org.apache.flink.runtime.state.internal.InternalKvState;
import org.apache.flink.util.ExceptionUtils;
import org.apache.flink.util.LambdaUtil;
import org.apache.flink.util.Preconditions;
import org.apache.flink.shaded.netty4.io.netty.channel.ChannelHandler;
import java.util.concurrent.CompletableFuture;
/**
* This handler dispatches asynchronous tasks, which query {@link InternalKvState} instances and
* write the result to the channel.
*
* The network threads receive the message, deserialize it and dispatch the query task. The
* actual query is handled in a separate thread as it might otherwise block the network threads
* (file I/O etc.).
*/
@Internal
@ChannelHandler.Sharable
public class KvStateServerHandler
extends AbstractServerHandler {
/** KvState registry holding references to the KvState instances. */
private final KvStateRegistry registry;
/**
* Create the handler used by the {@link KvStateServerImpl}.
*
* @param server the {@link KvStateServerImpl} using the handler.
* @param kvStateRegistry registry to query.
* @param serializer the {@link MessageSerializer} used to (de-) serialize the different
* messages.
* @param stats server statistics collector.
*/
public KvStateServerHandler(
final KvStateServerImpl server,
final KvStateRegistry kvStateRegistry,
final MessageSerializer serializer,
final KvStateRequestStats stats) {
super(server, serializer, stats);
this.registry = Preconditions.checkNotNull(kvStateRegistry);
}
@Override
public CompletableFuture handleRequest(
final long requestId, final KvStateInternalRequest request) {
final CompletableFuture responseFuture = new CompletableFuture<>();
try {
final KvStateEntry kvState = registry.getKvState(request.getKvStateId());
if (kvState == null) {
responseFuture.completeExceptionally(
new UnknownKvStateIdException(getServerName(), request.getKvStateId()));
} else {
byte[] serializedKeyAndNamespace = request.getSerializedKeyAndNamespace();
byte[] serializedResult = getSerializedValue(kvState, serializedKeyAndNamespace);
if (serializedResult != null) {
responseFuture.complete(new KvStateResponse(serializedResult));
} else {
responseFuture.completeExceptionally(
new UnknownKeyOrNamespaceException(getServerName()));
}
}
return responseFuture;
} catch (Throwable t) {
String errMsg =
"Error while processing request with ID "
+ requestId
+ ". Caused by: "
+ ExceptionUtils.stringifyException(t);
responseFuture.completeExceptionally(new RuntimeException(errMsg));
return responseFuture;
}
}
private static byte[] getSerializedValue(
final KvStateEntry entry, final byte[] serializedKeyAndNamespace)
throws Exception {
return LambdaUtil.withContextClassLoader(
entry.getUserClassLoader(),
() -> {
final InternalKvState state = entry.getState();
final KvStateInfo infoForCurrentThread =
entry.getInfoForCurrentThread();
return state.getSerializedValue(
serializedKeyAndNamespace,
infoForCurrentThread.getKeySerializer(),
infoForCurrentThread.getNamespaceSerializer(),
infoForCurrentThread.getStateValueSerializer());
});
}
@Override
public CompletableFuture shutdown() {
return CompletableFuture.completedFuture(null);
}
}