org.apache.flink.runtime.rest.handler.AbstractRestHandler Maven / Gradle / Ivy
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* Licensed to the Apache Software Foundation (ASF) under one
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* 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,
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* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.apache.flink.runtime.rest.handler;
import org.apache.flink.runtime.rest.handler.util.HandlerUtils;
import org.apache.flink.runtime.rest.messages.MessageHeaders;
import org.apache.flink.runtime.rest.messages.MessageParameters;
import org.apache.flink.runtime.rest.messages.RequestBody;
import org.apache.flink.runtime.rest.messages.ResponseBody;
import org.apache.flink.runtime.webmonitor.RestfulGateway;
import org.apache.flink.runtime.webmonitor.retriever.GatewayRetriever;
import org.apache.flink.util.Preconditions;
import org.apache.flink.util.concurrent.FutureUtils;
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.handler.codec.http.HttpRequest;
import org.apache.flink.shaded.netty4.io.netty.handler.codec.http.HttpResponseStatus;
import javax.annotation.Nonnull;
import java.time.Duration;
import java.util.Map;
import java.util.concurrent.CompletableFuture;
/**
* Super class for netty-based handlers that work with {@link RequestBody}s and {@link
* ResponseBody}s.
*
* Subclasses must be thread-safe.
*
* @param type of incoming requests
* @param type of outgoing responses
*/
@ChannelHandler.Sharable
public abstract class AbstractRestHandler<
T extends RestfulGateway,
R extends RequestBody,
P extends ResponseBody,
M extends MessageParameters>
extends AbstractHandler {
private final MessageHeaders messageHeaders;
protected AbstractRestHandler(
GatewayRetriever leaderRetriever,
Duration timeout,
Map responseHeaders,
MessageHeaders messageHeaders) {
super(leaderRetriever, timeout, responseHeaders, messageHeaders);
this.messageHeaders = Preconditions.checkNotNull(messageHeaders);
}
public MessageHeaders getMessageHeaders() {
return messageHeaders;
}
@Override
protected CompletableFuture respondToRequest(
ChannelHandlerContext ctx,
HttpRequest httpRequest,
HandlerRequest handlerRequest,
T gateway) {
CompletableFuture response;
try {
response = handleRequest(handlerRequest, gateway);
} catch (RestHandlerException e) {
response = FutureUtils.completedExceptionally(e);
}
return response.thenAccept(
resp ->
HandlerUtils.sendResponse(
ctx,
httpRequest,
resp,
messageHeaders.getResponseStatusCode(),
responseHeaders));
}
/**
* This method is called for every incoming request and returns a {@link CompletableFuture}
* containing a the response.
*
*
Implementations may decide whether to throw {@link RestHandlerException}s or fail the
* returned {@link CompletableFuture} with a {@link RestHandlerException}.
*
*
Failing the future with another exception type or throwing unchecked exceptions is
* regarded as an implementation error as it does not allow us to provide a meaningful HTTP
* status code. In this case a {@link HttpResponseStatus#INTERNAL_SERVER_ERROR} will be
* returned.
*
* @param request request that should be handled
* @param gateway leader gateway
* @return future containing a handler response
* @throws RestHandlerException if the handling failed
*/
protected abstract CompletableFuture
handleRequest(
@Nonnull HandlerRequest request, @Nonnull T gateway) throws RestHandlerException;
}