/*
* 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.runtime.query.netty;
import com.google.common.util.concurrent.ThreadFactoryBuilder;
import io.netty.bootstrap.ServerBootstrap;
import io.netty.channel.Channel;
import io.netty.channel.ChannelInitializer;
import io.netty.channel.ChannelOption;
import io.netty.channel.EventLoopGroup;
import io.netty.channel.nio.NioEventLoopGroup;
import io.netty.channel.socket.SocketChannel;
import io.netty.channel.socket.nio.NioServerSocketChannel;
import io.netty.handler.codec.LengthFieldBasedFrameDecoder;
import io.netty.handler.stream.ChunkedWriteHandler;
import org.apache.flink.runtime.io.network.netty.NettyBufferPool;
import org.apache.flink.runtime.query.KvStateRegistry;
import org.apache.flink.runtime.query.KvStateServerAddress;
import org.apache.flink.runtime.query.netty.message.KvStateRequest;
import org.apache.flink.util.Preconditions;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import java.net.InetAddress;
import java.net.InetSocketAddress;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.ThreadFactory;
import java.util.concurrent.TimeUnit;
/**
* Netty-based server answering {@link KvStateRequest} messages.
*
* <p>Requests are handled by asynchronous query tasks (see {@link KvStateServerHandler.AsyncKvStateQueryTask})
* that are executed by a separate query Thread pool. This pool is shared among
* all TCP connections.
*
* <p>The incoming pipeline looks as follows:
* <pre>
* Socket.read() -> LengthFieldBasedFrameDecoder -> KvStateServerHandler
* </pre>
*
* <p>Received binary messages are expected to contain a frame length field. Netty's
* {@link LengthFieldBasedFrameDecoder} is used to fully receive the frame before
* giving it to our {@link KvStateServerHandler}.
*
* <p>Connections are established and closed by the client. The server only
* closes the connection on a fatal failure that cannot be recovered. A
* server-side connection close is considered a failure by the client.
*/
public class KvStateServer {
private static final Logger LOG = LoggerFactory.getLogger(KvStateServer.class);
/** Server config: low water mark */
private static final int LOW_WATER_MARK = 8 * 1024;
/** Server config: high water mark */
private static final int HIGH_WATER_MARK = 32 * 1024;
/** Netty's ServerBootstrap. */
private final ServerBootstrap bootstrap;
/** Query executor thread pool. */
private final ExecutorService queryExecutor;
/** Address of this server. */
private KvStateServerAddress serverAddress;
/**
* Creates the {@link KvStateServer}.
*
* <p>The server needs to be started via {@link #start()} in order to bind
* to the configured bind address.
*
* @param bindAddress Address to bind to
* @param bindPort Port to bind to. Pick random port if 0.
* @param numEventLoopThreads Number of event loop threads
* @param numQueryThreads Number of query threads
* @param kvStateRegistry KvStateRegistry to query for KvState instances
* @param stats Statistics tracker
*/
public KvStateServer(
InetAddress bindAddress,
int bindPort,
int numEventLoopThreads,
int numQueryThreads,
KvStateRegistry kvStateRegistry,
KvStateRequestStats stats) {
Preconditions.checkArgument(bindPort >= 0 && bindPort <= 65536, "Port " + bindPort +
" is out of valid port range (0-65536).");
Preconditions.checkArgument(numEventLoopThreads >= 1, "Non-positive number of event loop threads.");
Preconditions.checkArgument(numQueryThreads >= 1, "Non-positive number of query threads.");
Preconditions.checkNotNull(kvStateRegistry, "KvStateRegistry");
Preconditions.checkNotNull(stats, "KvStateRequestStats");
NettyBufferPool bufferPool = new NettyBufferPool(numEventLoopThreads);
ThreadFactory threadFactory = new ThreadFactoryBuilder()
.setDaemon(true)
.setNameFormat("Flink KvStateServer EventLoop Thread %d")
.build();
NioEventLoopGroup nioGroup = new NioEventLoopGroup(numEventLoopThreads, threadFactory);
queryExecutor = createQueryExecutor(numQueryThreads);
// Shared between all channels
KvStateServerHandler serverHandler = new KvStateServerHandler(
kvStateRegistry,
queryExecutor,
stats);
bootstrap = new ServerBootstrap()
// Bind address and port
.localAddress(bindAddress, bindPort)
// NIO server channels
.group(nioGroup)
.channel(NioServerSocketChannel.class)
// Server channel Options
.option(ChannelOption.ALLOCATOR, bufferPool)
// Child channel options
.childOption(ChannelOption.ALLOCATOR, bufferPool)
.childOption(ChannelOption.WRITE_BUFFER_LOW_WATER_MARK, LOW_WATER_MARK)
.childOption(ChannelOption.WRITE_BUFFER_HIGH_WATER_MARK, HIGH_WATER_MARK)
// See initializer for pipeline details
.childHandler(new KvStateServerChannelInitializer(serverHandler));
}
/**
* Starts the server by binding to the configured bind address (blocking).
*
* @throws InterruptedException If interrupted during the bind operation
*/
public void start() throws InterruptedException {
Channel channel = bootstrap.bind().sync().channel();
InetSocketAddress localAddress = (InetSocketAddress) channel.localAddress();
serverAddress = new KvStateServerAddress(localAddress.getAddress(), localAddress.getPort());
}
/**
* Returns the address of this server.
*
* @return Server address
* @throws IllegalStateException If server has not been started yet
*/
public KvStateServerAddress getAddress() {
if (serverAddress == null) {
throw new IllegalStateException("KvStateServer not started yet.");
}
return serverAddress;
}
/**
* Shuts down the server and all related thread pools.
*/
public void shutDown() {
if (bootstrap != null) {
EventLoopGroup group = bootstrap.group();
if (group != null) {
group.shutdownGracefully(0, 10, TimeUnit.SECONDS);
}
}
if (queryExecutor != null) {
queryExecutor.shutdown();
}
serverAddress = null;
}
/**
* Creates a thread pool for the query execution.
*
* @param numQueryThreads Number of query threads.
* @return Thread pool for query execution
*/
private static ExecutorService createQueryExecutor(int numQueryThreads) {
ThreadFactory threadFactory = new ThreadFactoryBuilder()
.setDaemon(true)
.setNameFormat("Flink KvStateServer Query Thread %d")
.build();
return Executors.newFixedThreadPool(numQueryThreads, threadFactory);
}
/**
* Channel pipeline initializer.
*
* <p>The request handler is shared, whereas the other handlers are created
* per channel.
*/
private static final class KvStateServerChannelInitializer extends ChannelInitializer<SocketChannel> {
/** The shared request handler. */
private final KvStateServerHandler sharedRequestHandler;
/**
* Creates the channel pipeline initializer with the shared request handler.
*
* @param sharedRequestHandler Shared request handler.
*/
public KvStateServerChannelInitializer(KvStateServerHandler sharedRequestHandler) {
this.sharedRequestHandler = Preconditions.checkNotNull(sharedRequestHandler, "Request handler");
}
@Override
protected void initChannel(SocketChannel ch) throws Exception {
ch.pipeline()
.addLast(new ChunkedWriteHandler())
.addLast(new LengthFieldBasedFrameDecoder(Integer.MAX_VALUE, 0, 4, 0, 4))
.addLast(sharedRequestHandler);
}
}
}