Github user tillrohrmann commented on a diff in the pull request:
https://github.com/apache/flink/pull/4569#discussion_r134459093
--- Diff:
flink-runtime/src/main/java/org/apache/flink/runtime/rest/RestClientEndpoint.java
---
@@ -0,0 +1,263 @@
+/*
+ * 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.rest;
+
+import org.apache.flink.configuration.ConfigConstants;
+import org.apache.flink.runtime.concurrent.Executors;
+import org.apache.flink.runtime.concurrent.FutureUtils;
+import org.apache.flink.runtime.rest.handler.PipelineErrorHandler;
+import org.apache.flink.runtime.rest.messages.ErrorResponseBody;
+import org.apache.flink.runtime.rest.messages.MessageHeaders;
+import org.apache.flink.runtime.rest.messages.ParameterMapper;
+import org.apache.flink.runtime.rest.messages.RequestBody;
+import org.apache.flink.runtime.rest.messages.ResponseBody;
+import org.apache.flink.runtime.rest.util.RestMapperUtils;
+import org.apache.flink.util.Preconditions;
+
+import org.apache.flink.shaded.netty4.io.netty.bootstrap.Bootstrap;
+import org.apache.flink.shaded.netty4.io.netty.buffer.ByteBuf;
+import org.apache.flink.shaded.netty4.io.netty.buffer.ByteBufInputStream;
+import org.apache.flink.shaded.netty4.io.netty.buffer.Unpooled;
+import org.apache.flink.shaded.netty4.io.netty.channel.Channel;
+import org.apache.flink.shaded.netty4.io.netty.channel.ChannelHandler;
+import
org.apache.flink.shaded.netty4.io.netty.channel.ChannelHandlerContext;
+import org.apache.flink.shaded.netty4.io.netty.channel.ChannelInitializer;
+import
org.apache.flink.shaded.netty4.io.netty.channel.SimpleChannelInboundHandler;
+import
org.apache.flink.shaded.netty4.io.netty.channel.nio.NioEventLoopGroup;
+import
org.apache.flink.shaded.netty4.io.netty.channel.socket.SocketChannel;
+import
org.apache.flink.shaded.netty4.io.netty.channel.socket.nio.NioSocketChannel;
+import
org.apache.flink.shaded.netty4.io.netty.handler.codec.http.DefaultFullHttpRequest;
+import
org.apache.flink.shaded.netty4.io.netty.handler.codec.http.FullHttpRequest;
+import
org.apache.flink.shaded.netty4.io.netty.handler.codec.http.FullHttpResponse;
+import
org.apache.flink.shaded.netty4.io.netty.handler.codec.http.HttpClientCodec;
+import
org.apache.flink.shaded.netty4.io.netty.handler.codec.http.HttpHeaders;
+import
org.apache.flink.shaded.netty4.io.netty.handler.codec.http.HttpObjectAggregator;
+import
org.apache.flink.shaded.netty4.io.netty.handler.codec.http.HttpVersion;
+import org.apache.flink.shaded.netty4.io.netty.handler.ssl.SslHandler;
+
+import com.fasterxml.jackson.core.JsonParseException;
+import com.fasterxml.jackson.core.JsonProcessingException;
+import com.fasterxml.jackson.databind.JsonMappingException;
+import com.fasterxml.jackson.databind.JsonNode;
+import com.fasterxml.jackson.databind.ObjectMapper;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+import javax.net.ssl.SSLEngine;
+
+import java.io.IOException;
+import java.io.InputStream;
+import java.io.StringWriter;
+import java.util.concurrent.CompletableFuture;
+import java.util.concurrent.Executor;
+
+/**
+ * This client is the counter-part to the {@link RestServerEndpoint}.
+ */
+public class RestClientEndpoint {
+ private static final Logger LOG =
LoggerFactory.getLogger(RestClientEndpoint.class);
+
+ private static final ObjectMapper objectMapper =
RestMapperUtils.getStrictObjectMapper();
+
+ private final String configuredTargetAddress;
+ private final int configuredTargetPort;
+ private final SSLEngine sslEngine;
+
+ private Bootstrap bootstrap;
+
+ private final ClientHandler handler = new ClientHandler();
+
+ private CompletableFuture<?> lastFuture =
CompletableFuture.completedFuture(null);
+
+ private final Executor directExecutor = Executors.directExecutor();
+
+ public RestClientEndpoint(RestClientEndpointConfiguration
configuration) {
+ this.configuredTargetAddress =
configuration.getTargetRestEndpointAddress();
+ this.configuredTargetPort =
configuration.getTargetRestEndpointPort();
+ this.sslEngine = configuration.getSslEngine();
+ }
+
+ public void start() {
+ ChannelInitializer<SocketChannel> initializer = new
ChannelInitializer<SocketChannel>() {
+
+ @Override
+ protected void initChannel(SocketChannel ch) {
+
+ // SSL should be the first handler in the
pipeline
+ if (sslEngine != null) {
+ ch.pipeline().addLast("ssl", new
SslHandler(sslEngine));
+ }
+
+ ch.pipeline()
+ .addLast(new HttpClientCodec())
+ .addLast(new HttpObjectAggregator(1024
* 1024))
+ .addLast(handler)
+ .addLast(new PipelineErrorHandler(LOG));
+ }
+ };
+
+ NioEventLoopGroup group = new NioEventLoopGroup(1);
+
+ bootstrap = new Bootstrap();
+ bootstrap
+ .group(group)
+ .channel(NioSocketChannel.class)
+ .handler(initializer);
+
+ LOG.info("Rest client endpoint started.");
+ }
+
+ public void shutdown() {
+ if (bootstrap != null) {
+ if (bootstrap.group() != null) {
+ bootstrap.group().shutdownGracefully();
+ }
+ }
+ }
+
+ public <M extends MessageHeaders<R, P, U>, U extends ParameterMapper, R
extends RequestBody, P extends ResponseBody> CompletableFuture<P> sendRequest(M
messageHeaders, U urlResolver, R request) throws IOException {
+ Preconditions.checkNotNull(messageHeaders);
+ Preconditions.checkNotNull(request);
+
+ String targetUrl = ParameterMapper.resolveUrl(
+ messageHeaders.getTargetRestEndpointURL(),
+
urlResolver.mapPathParameters(messageHeaders.getPathParameters()),
+
urlResolver.mapQueryParameters(messageHeaders.getQueryParameters())
+ );
+
+ LOG.debug("Sending request of class {} to {}",
request.getClass(), targetUrl);
+ // serialize payload
+ StringWriter sw = new StringWriter();
+ objectMapper.writeValue(sw, request);
+ ByteBuf payload =
Unpooled.wrappedBuffer(sw.toString().getBytes(ConfigConstants.DEFAULT_CHARSET));
+
+ // create request and set headers
+ FullHttpRequest httpRequest = new
DefaultFullHttpRequest(HttpVersion.HTTP_1_1,
messageHeaders.getHttpMethod().getNettyHttpMethod(), targetUrl, payload);
+ httpRequest.headers()
+ .add(HttpHeaders.Names.CONTENT_LENGTH,
payload.capacity())
+ .add(HttpHeaders.Names.CONTENT_TYPE, "application/json;
charset=" + ConfigConstants.DEFAULT_CHARSET.name())
+ .set(HttpHeaders.Names.HOST, configuredTargetAddress +
":" + configuredTargetPort)
+ .set(HttpHeaders.Names.CONNECTION,
HttpHeaders.Values.CLOSE);
+
+ synchronized (this) {
+ // This ensures strict sequential processing of
requests.
+ // If we send new requests immediately we can no longer
make assumptions about the order in which responses
+ // arrive, due to which the handler cannot know which
future he should complete (not to mention what response
+ // type to read).
+ CompletableFuture<P> nextFuture = lastFuture
+ .handleAsync((f, e) ->
submitRequest(httpRequest, messageHeaders), directExecutor)
+ .thenCompose((future) -> future);
+
+ lastFuture = nextFuture;
+ return nextFuture;
+ }
+ }
+
+ private <M extends MessageHeaders<R, P, U>, U extends ParameterMapper,
R extends RequestBody, P extends ResponseBody> CompletableFuture<P>
submitRequest(FullHttpRequest httpRequest, M messageHeaders) {
+ CompletableFuture<P> responseFuture =
handler.expectResponse(messageHeaders.getResponseClass());
+
+ try {
+ // write request
+ Channel channel =
bootstrap.connect(configuredTargetAddress,
configuredTargetPort).sync().channel();
+ channel.writeAndFlush(httpRequest);
+ channel.closeFuture();
+ } catch (InterruptedException e) {
+ return FutureUtils.completedExceptionally(e);
+ }
+ return responseFuture;
+ }
+
+ @ChannelHandler.Sharable
+ private static class ClientHandler extends
SimpleChannelInboundHandler<Object> {
+
+ private volatile ExpectedResponse<? extends ResponseBody>
expectedResponse = null;
+
+ @Override
+ protected void channelRead0(ChannelHandlerContext ctx, Object
msg) throws Exception {
+ if (msg instanceof FullHttpResponse) {
+ completeFuture((FullHttpResponse) msg);
+ } else {
+ LOG.error("Implementation error: Received a
response that wasn't a FullHttpResponse.");
--- End diff --
Shouldn't this fail the associated future?
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