gianm commented on code in PR #15007: URL: https://github.com/apache/druid/pull/15007#discussion_r1341563296
########## processing/src/main/java/org/apache/druid/frame/processor/manager/ProcessorManager.java: ########## @@ -0,0 +1,76 @@ +/* + * 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.druid.frame.processor.manager; + +import com.google.common.util.concurrent.ListenableFuture; +import org.apache.druid.frame.processor.FrameProcessorExecutor; +import org.apache.druid.java.util.common.guava.Sequence; + +import java.io.Closeable; +import java.util.Optional; +import java.util.function.BiFunction; + +/** + * Used by {@link FrameProcessorExecutor#runAllFully} to manage the launching of processors. Processors returned by + * this class may run concurrently with each other. + * + * This interface allows for simple sequences of processors, such as {@link ProcessorManagers#of(Sequence)}. It also + * allows for situations where later processors depend on the results of earlier processors. (The result of earlier + * processors are made available to the manager through {@link ProcessorAndCallback#onComplete(Object)}.) + * + * Implementations do not need to be thread-safe. + */ +public interface ProcessorManager<T, R> extends Closeable +{ + /** + * Returns the next processor that should be run, along with a callback. The callback is called when the processor + * completes successfully, along with the result of the processor. If the processor fails, the callback is not called. + * + * The callback is called in a thread-safe manner: it will never be called concurrently with another callback, or + * concurrently with a call to "next" or {@link #close()}. + * + * Returns an empty Optional if there are no more processors to run. + * + * @throws java.util.NoSuchElementException if a prior call to this method had returned an empty Optional + */ + ListenableFuture<Optional<ProcessorAndCallback<T>>> next(); + + /** + * Called after all procesors are done, prior to {@link #close()}, to retrieve the result of this computation. Review Comment: I updated the docs of `ProcessorManager#result` to call out that behavior is undefined in this case. I don't think it's necessary for the managers to all have code that checks that callers are doing their stuff properly. There's only one caller (`RunAllFullyWidget`) and we have unit tests for that. -- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. To unsubscribe, e-mail: [email protected] For queries about this service, please contact Infrastructure at: [email protected] --------------------------------------------------------------------- To unsubscribe, e-mail: [email protected] For additional commands, e-mail: [email protected]
