/*
* 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.spark.network.client;
import java.io.Closeable;
import java.io.IOException;
import java.util.UUID;
import java.util.concurrent.ExecutionException;
import java.util.concurrent.TimeUnit;
import com.google.common.base.Objects;
import com.google.common.base.Preconditions;
import com.google.common.base.Throwables;
import com.google.common.util.concurrent.SettableFuture;
import io.netty.channel.Channel;
import io.netty.channel.ChannelFuture;
import io.netty.channel.ChannelFutureListener;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.apache.spark.network.protocol.ChunkFetchRequest;
import org.apache.spark.network.protocol.RpcRequest;
import org.apache.spark.network.protocol.StreamChunkId;
import org.apache.spark.network.util.NettyUtils;
/**
* Client for fetching consecutive chunks of a pre-negotiated stream. This API is intended to allow
* efficient transfer of a large amount of data, broken up into chunks with size ranging from
* hundreds of KB to a few MB.
*
* Note that while this client deals with the fetching of chunks from a stream (i.e., data plane),
* the actual setup of the streams is done outside the scope of the transport layer. The convenience
* method "sendRPC" is provided to enable control plane communication between the client and server
* to perform this setup.
*
* For example, a typical workflow might be:
* client.sendRPC(new OpenFile("/foo")) --> returns StreamId = 100
* client.fetchChunk(streamId = 100, chunkIndex = 0, callback)
* client.fetchChunk(streamId = 100, chunkIndex = 1, callback)
* ...
* client.sendRPC(new CloseStream(100))
*
* Construct an instance of TransportClient using {@link TransportClientFactory}. A single
* TransportClient may be used for multiple streams, but any given stream must be restricted to a
* single client, in order to avoid out-of-order responses.
*
* NB: This class is used to make requests to the server, while {@link TransportResponseHandler} is
* responsible for handling responses from the server.
*
* Concurrency: thread safe and can be called from multiple threads.
*/
public class TransportClient implements Closeable {
private final Logger logger = LoggerFactory.getLogger(TransportClient.class);
private final Channel channel;
private final TransportResponseHandler handler;
public TransportClient(Channel channel, TransportResponseHandler handler) {
this.channel = Preconditions.checkNotNull(channel);
this.handler = Preconditions.checkNotNull(handler);
}
public boolean isActive() {
return channel.isOpen() || channel.isActive();
}
/**
* Requests a single chunk from the remote side, from the pre-negotiated streamId.
*
* Chunk indices go from 0 onwards. It is valid to request the same chunk multiple times, though
* some streams may not support this.
*
* Multiple fetchChunk requests may be outstanding simultaneously, and the chunks are guaranteed
* to be returned in the same order that they were requested, assuming only a single
* TransportClient is used to fetch the chunks.
*
* @param streamId Identifier that refers to a stream in the remote StreamManager. This should
* be agreed upon by client and server beforehand.
* @param chunkIndex 0-based index of the chunk to fetch
* @param callback Callback invoked upon successful receipt of chunk, or upon any failure.
*/
public void fetchChunk(
long streamId,
final int chunkIndex,
final ChunkReceivedCallback callback) {
final String serverAddr = NettyUtils.getRemoteAddress(channel);
final long startTime = System.currentTimeMillis();
logger.debug("Sending fetch chunk request {} to {}", chunkIndex, serverAddr);
final StreamChunkId streamChunkId = new StreamChunkId(streamId, chunkIndex);
handler.addFetchRequest(streamChunkId, callback);
channel.writeAndFlush(new ChunkFetchRequest(streamChunkId)).addListener(
new ChannelFutureListener() {
@Override
public void operationComplete(ChannelFuture future) throws Exception {
if (future.isSuccess()) {
long timeTaken = System.currentTimeMillis() - startTime;
logger.trace("Sending request {} to {} took {} ms", streamChunkId, serverAddr,
timeTaken);
} else {
String errorMsg = String.format("Failed to send request %s to %s: %s", streamChunkId,
serverAddr, future.cause());
logger.error(errorMsg, future.cause());
handler.removeFetchRequest(streamChunkId);
channel.close();
try {
callback.onFailure(chunkIndex, new IOException(errorMsg, future.cause()));
} catch (Exception e) {
logger.error("Uncaught exception in RPC response callback handler!", e);
}
}
}
});
}
/**
* Sends an opaque message to the RpcHandler on the server-side. The callback will be invoked
* with the server's response or upon any failure.
*/
public void sendRpc(byte[] message, final RpcResponseCallback callback) {
final String serverAddr = NettyUtils.getRemoteAddress(channel);
final long startTime = System.currentTimeMillis();
logger.trace("Sending RPC to {}", serverAddr);
final long requestId = Math.abs(UUID.randomUUID().getLeastSignificantBits());
handler.addRpcRequest(requestId, callback);
channel.writeAndFlush(new RpcRequest(requestId, message)).addListener(
new ChannelFutureListener() {
@Override
public void operationComplete(ChannelFuture future) throws Exception {
if (future.isSuccess()) {
long timeTaken = System.currentTimeMillis() - startTime;
logger.trace("Sending request {} to {} took {} ms", requestId, serverAddr, timeTaken);
} else {
String errorMsg = String.format("Failed to send RPC %s to %s: %s", requestId,
serverAddr, future.cause());
logger.error(errorMsg, future.cause());
handler.removeRpcRequest(requestId);
channel.close();
try {
callback.onFailure(new IOException(errorMsg, future.cause()));
} catch (Exception e) {
logger.error("Uncaught exception in RPC response callback handler!", e);
}
}
}
});
}
/**
* Synchronously sends an opaque message to the RpcHandler on the server-side, waiting for up to
* a specified timeout for a response.
*/
public byte[] sendRpcSync(byte[] message, long timeoutMs) {
final SettableFuture<byte[]> result = SettableFuture.create();
sendRpc(message, new RpcResponseCallback() {
@Override
public void onSuccess(byte[] response) {
result.set(response);
}
@Override
public void onFailure(Throwable e) {
result.setException(e);
}
});
try {
return result.get(timeoutMs, TimeUnit.MILLISECONDS);
} catch (ExecutionException e) {
throw Throwables.propagate(e.getCause());
} catch (Exception e) {
throw Throwables.propagate(e);
}
}
@Override
public void close() {
// close is a local operation and should finish with milliseconds; timeout just to be safe
channel.close().awaitUninterruptibly(10, TimeUnit.SECONDS);
}
@Override
public String toString() {
return Objects.toStringHelper(this)
.add("remoteAdress", channel.remoteAddress())
.add("isActive", isActive())
.toString();
}
}