StefanRRichter commented on a change in pull request #8442: [FLINK-12483] Support (legacy) SourceFunction as special case in the mailbox model for stream tasks URL: https://github.com/apache/flink/pull/8442#discussion_r285894219
########## File path: flink-streaming-java/src/main/java/org/apache/flink/streaming/runtime/tasks/mailbox/MailboxSender.java ########## @@ -0,0 +1,52 @@ +/* + * 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.streaming.runtime.tasks.mailbox; + +import javax.annotation.Nonnull; + +/** + * Producer-facing side of the {@link Mailbox} interface. This is used to enqueue letters. Multiple producers threads + * can put to the same mailbox. + */ +public interface MailboxSender { + + /** + * Enqueues the given letter to the mailbox, if capacity is available. On success, this returns <code>true</code> + * and <code>false</code> if the mailbox was already full. + * + * @param letter the letter to enqueue. + * @return <code>true</code> iff successful. + */ + boolean tryPutMail(@Nonnull Runnable letter); Review comment: Here is my line of thought: user code currently is using the checkpointing lock to execute atomic operations w.r.t. event processing. If we are planning to remove the lock, we should give users a proper substitute for the mechanism. Executing one letter can also be regarded an atomic operation w.r.t. event processing. The exposed interface would then be the `MailboxSender` interface, probably at least through whatever will be the future source contexts, maybe also in other places (sinks come to my mind). It does not take much creativity to think of cases where non-blocking options can help there as well. ---------------------------------------------------------------- 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. For queries about this service, please contact Infrastructure at: us...@infra.apache.org With regards, Apache Git Services
