Zakelly commented on code in PR #25996: URL: https://github.com/apache/flink/pull/25996#discussion_r1920944894
########## flink-runtime/src/main/java/org/apache/flink/runtime/asyncprocessing/operators/windowing/triggers/AsyncTrigger.java: ########## @@ -0,0 +1,195 @@ +/* + * 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.asyncprocessing.operators.windowing.triggers; + +import org.apache.flink.annotation.Experimental; +import org.apache.flink.api.common.functions.RuntimeContext; +import org.apache.flink.api.common.state.v2.State; +import org.apache.flink.api.common.state.v2.StateDescriptor; +import org.apache.flink.api.common.state.v2.StateFuture; +import org.apache.flink.metrics.MetricGroup; +import org.apache.flink.streaming.api.windowing.triggers.TriggerResult; +import org.apache.flink.streaming.api.windowing.windows.Window; + +import java.io.Serializable; + +/** + * A {@code Trigger} determines when a pane of a window should be evaluated to emit the results for + * that part of the window. This trigger is for the async window operator, i.e., {@link + * org.apache.flink.runtime.asyncprocessing.operators.windowing.AsyncWindowOperator}. + * + * <p>All State APIs in the async trigger are from State V2. + * + * <p>A pane is the bucket of elements that have the same key (assigned by the {@link + * org.apache.flink.api.java.functions.KeySelector}) and same {@link Window}. An element can be in + * multiple panes if it was assigned to multiple windows by the {@link + * org.apache.flink.streaming.api.windowing.assigners.WindowAssigner}. These panes all have their + * own instance of the {@code Trigger}. + * + * <p>Triggers must not maintain state internally since they can be re-created or reused for + * different keys. All necessary state should be persisted using the state abstraction available on + * the {@link TriggerContext}. + * + * <p>When used with a {@link + * org.apache.flink.streaming.api.windowing.assigners.MergingWindowAssigner} the {@code Trigger} + * must return {@code true} from {@link #canMerge()} and {@link #onMerge(Window, OnMergeContext)} + * most be properly implemented. + * + * @param <T> The type of elements on which this {@code Trigger} works. + * @param <W> The type of {@link Window Windows} on which this {@code Trigger} can operate. + */ +@Experimental Review Comment: We'd better mark all the async triggers as `@Internal` since they are not exposed to users. -- 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: issues-unsubscr...@flink.apache.org For queries about this service, please contact Infrastructure at: us...@infra.apache.org
