org.apache.flink.runtime.rpc.FencedRpcEndpoint Maven / Gradle / Ivy
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* 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;
import org.apache.flink.api.common.time.Time;
import org.apache.flink.util.Preconditions;
import javax.annotation.Nonnull;
import javax.annotation.Nullable;
import java.io.Serializable;
import java.util.UUID;
import java.util.concurrent.Callable;
import java.util.concurrent.CompletableFuture;
import java.util.concurrent.Executor;
/**
* Base class for fenced {@link RpcEndpoint}. A fenced rpc endpoint expects all rpc messages
* being enriched with fencing tokens. Furthermore, the rpc endpoint has its own fencing token
* assigned. The rpc is then only executed if the attached fencing token equals the endpoint's own
* token.
*
* @param type of the fencing token
*/
public abstract class FencedRpcEndpoint extends RpcEndpoint {
private final UnfencedMainThreadExecutor unfencedMainThreadExecutor;
private volatile F fencingToken;
private volatile MainThreadExecutor fencedMainThreadExecutor;
protected FencedRpcEndpoint(RpcService rpcService, String endpointId) {
super(rpcService, endpointId);
Preconditions.checkArgument(
rpcServer instanceof FencedMainThreadExecutable,
"The rpcServer must be of type %s.",
FencedMainThreadExecutable.class.getSimpleName());
// no fencing token == no leadership
this.fencingToken = null;
this.unfencedMainThreadExecutor = new UnfencedMainThreadExecutor((FencedMainThreadExecutable) rpcServer);
this.fencedMainThreadExecutor = new MainThreadExecutor(
getRpcService().fenceRpcServer(
rpcServer,
null));
}
protected FencedRpcEndpoint(RpcService rpcService) {
this(rpcService, UUID.randomUUID().toString());
}
public F getFencingToken() {
return fencingToken;
}
protected void setFencingToken(@Nullable F newFencingToken) {
// this method should only be called from within the main thread
validateRunsInMainThread();
this.fencingToken = newFencingToken;
// setting a new fencing token entails that we need a new MainThreadExecutor
// which is bound to the new fencing token
MainThreadExecutable mainThreadExecutable = getRpcService().fenceRpcServer(
rpcServer,
newFencingToken);
this.fencedMainThreadExecutor = new MainThreadExecutor(mainThreadExecutable);
}
/**
* Returns a main thread executor which is bound to the currently valid fencing token.
* This means that runnables which are executed with this executor fail after the fencing
* token has changed. This allows to scope operations by the fencing token.
*
* @return MainThreadExecutor bound to the current fencing token
*/
@Override
protected MainThreadExecutor getMainThreadExecutor() {
return fencedMainThreadExecutor;
}
/**
* Returns a main thread executor which is not bound to the fencing token.
* This means that {@link Runnable} which are executed with this executor will always
* be executed.
*
* @return MainThreadExecutor which is not bound to the fencing token
*/
protected Executor getUnfencedMainThreadExecutor() {
return unfencedMainThreadExecutor;
}
/**
* Run the given runnable in the main thread of the RpcEndpoint without checking the fencing
* token. This allows to run operations outside of the fencing token scope.
*
* @param runnable to execute in the main thread of the rpc endpoint without checking the fencing token.
*/
protected void runAsyncWithoutFencing(Runnable runnable) {
if (rpcServer instanceof FencedMainThreadExecutable) {
((FencedMainThreadExecutable) rpcServer).runAsyncWithoutFencing(runnable);
} else {
throw new RuntimeException("FencedRpcEndpoint has not been started with a FencedMainThreadExecutable RpcServer.");
}
}
/**
* Run the given callable in the main thread of the RpcEndpoint without checking the fencing
* token. This allows to run operations outside of the fencing token scope.
*
* @param callable to run in the main thread of the rpc endpoint without checkint the fencing token.
* @param timeout for the operation.
* @return Future containing the callable result.
*/
protected CompletableFuture callAsyncWithoutFencing(Callable callable, Time timeout) {
if (rpcServer instanceof FencedMainThreadExecutable) {
return ((FencedMainThreadExecutable) rpcServer).callAsyncWithoutFencing(callable, timeout);
} else {
throw new RuntimeException("FencedRpcEndpoint has not been started with a FencedMainThreadExecutable RpcServer.");
}
}
// ------------------------------------------------------------------------
// Utilities
// ------------------------------------------------------------------------
/**
* Executor which executes {@link Runnable} in the main thread context without fencing.
*/
private static class UnfencedMainThreadExecutor implements Executor {
private final FencedMainThreadExecutable gateway;
UnfencedMainThreadExecutor(FencedMainThreadExecutable gateway) {
this.gateway = Preconditions.checkNotNull(gateway);
}
@Override
public void execute(@Nonnull Runnable runnable) {
gateway.runAsyncWithoutFencing(runnable);
}
}
}