Mailing-List: contact issues-help@flink.apache.org; run by ezmlm
Precedence: bulk
Reply-To: dev@flink.apache.org
From: StephanEwen <git@git.apache.org>
To: issues@flink.incubator.apache.org
Reply-To: issues@flink.incubator.apache.org
References: <git-pr-2357-flink@git.apache.org>
In-Reply-To: <git-pr-2357-flink@git.apache.org>
Subject: [GitHub] flink pull request #2357: [FLINK-4362] [rpc] Auto generate rpc gateways via ...
Content-Type: text/plain
Message-Id: <20160811150237.2CD31E0019@git1-us-west.apache.org>
Date: Thu, 11 Aug 2016 15:02:37 +0000 (UTC)
archived-at: Thu, 11 Aug 2016 15:02:42 -0000

Github user StephanEwen commented on a diff in the pull request:

    https://github.com/apache/flink/pull/2357#discussion_r74439096
  
    --- Diff: flink-runtime/src/main/java/org/apache/flink/runtime/rpc/akka/AkkaRpcActor.java ---
    @@ -0,0 +1,176 @@
    +/*
    + * 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.rpc.akka;
    +
    +import akka.actor.Status;
    +import akka.actor.UntypedActor;
    +import akka.pattern.Patterns;
    +import org.apache.flink.runtime.rpc.RpcEndpoint;
    +import org.apache.flink.runtime.rpc.RpcGateway;
    +import org.apache.flink.runtime.rpc.akka.messages.CallAsync;
    +import org.apache.flink.runtime.rpc.akka.messages.RpcInvocation;
    +import org.apache.flink.runtime.rpc.akka.messages.RunAsync;
    +import org.apache.flink.util.Preconditions;
    +import org.slf4j.Logger;
    +import org.slf4j.LoggerFactory;
    +import scala.concurrent.Future;
    +
    +import java.lang.reflect.Method;
    +import java.util.concurrent.Callable;
    +
    +/**
    + * Akka rpc actor which receives {@link RpcInvocation}, {@link RunAsync} and {@link CallAsync}
    + * messages.
    + * <p>
    + * The {@link RpcInvocation} designates a rpc and is dispatched to the given {@link RpcEndpoint}
    + * instance.
    + * <p>
    + * The {@link RunAsync} and {@link CallAsync} messages contain executable code which is executed
    + * in the context of the actor thread.
    + *
    + * @param <C> Type of the {@link RpcGateway} associated with the {@link RpcEndpoint}
    + * @param <T> Type of the {@link RpcEndpoint}
    + */
    +class AkkaRpcActor<C extends RpcGateway, T extends RpcEndpoint<C>> extends UntypedActor {
    +	private static final Logger LOG = LoggerFactory.getLogger(AkkaRpcActor.class);
    +
    +	private final T rpcEndpoint;
    +
    +	AkkaRpcActor(final T rpcEndpoint) {
    +		this.rpcEndpoint = Preconditions.checkNotNull(rpcEndpoint, "rpc endpoint");
    +	}
    +
    +	@Override
    +	public void onReceive(final Object message)  {
    +		if (message instanceof RunAsync) {
    +			handleRunAsync((RunAsync) message);
    +		} else if (message instanceof CallAsync) {
    +			handleCallAsync((CallAsync) message);
    +		} else if (message instanceof RpcInvocation) {
    +			handleRpcInvocation((RpcInvocation) message);
    +		} else {
    +			throw new RuntimeException("Encountered unknown message type " + message.getClass() +
    +				" with value " + message + '.');
    +		}
    +	}
    +
    +	/**
    +	 * Handle rpc invocations by looking up the rpc method on the rpc endpoint and calling this
    +	 * method with the provided method arguments. If the method has a return value, it is returned
    +	 * to the sender of the call.
    +	 *
    +	 * @param rpcInvocation Rpc invocation message
    +	 */
    +	private void handleRpcInvocation(RpcInvocation rpcInvocation) {
    +		Method rpcMethod = null;
    +
    +		try {
    +			rpcMethod = lookupRpcMethod(rpcInvocation.getMethodName(), rpcInvocation.getParameterTypes());
    +		} catch (final NoSuchMethodException e) {
    +			LOG.error("Could not find rpc method for rpc invocation: {}.", rpcInvocation, e);
    +		}
    +
    +		if (rpcMethod != null) {
    +			if (rpcMethod.getReturnType().equals(Void.TYPE)) {
    +				// No return value to send back
    +				try {
    +					rpcMethod.invoke(rpcEndpoint, rpcInvocation.getArgs());
    +				} catch (Throwable e) {
    +					LOG.error("Error while executing remote procedure call {}.", rpcMethod, e);
    +				}
    +			} else {
    +				try {
    +					Object result = rpcMethod.invoke(rpcEndpoint, rpcInvocation.getArgs());
    +
    +					if (result instanceof Future) {
    +						// pipe result to sender
    +						Patterns.pipe((Future<?>) result, getContext().dispatcher()).to(getSender());
    +					} else {
    +						// tell the sender the result of the computation
    +						getSender().tell(new Status.Success(result), getSelf());
    +					}
    +				} catch (Throwable e) {
    +					// tell the sender about the failure
    +					getSender().tell(new Status.Failure(e), getSelf());
    +				}
    +			}
    +		}
    +	}
    +
    +	/**
    +	 * Handle asynchronous {@link Callable}. This method simply executes the given {@link Callable}
    +	 * in the context of the actor thread.
    +	 *
    +	 * @param callAsync Call async message
    +	 */
    +	private void handleCallAsync(CallAsync callAsync) {
    +		if (callAsync.getCallable() == null) {
    +			final String result = "Received a " + callAsync.getClass().getName() + " message with an empty " +
    --- End diff --
    
    This should in practice never occur, because the `runAsync` method is not on any gateway, but only on the hidden self gateway type, correct?


---
If your project is set up for it, you can reply to this email and have your
reply appear on GitHub as well. If your project does not have this feature
enabled and wishes so, or if the feature is enabled but not working, please
contact infrastructure at infrastructure@apache.org or file a JIRA ticket
with INFRA.
---