org.apache.flink.streaming.runtime.io.CheckpointBarrierHandler Maven / Gradle / Ivy
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* Licensed to the Apache Software Foundation (ASF) under one
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* 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,
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* See the License for the specific language governing permissions and
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*/
package org.apache.flink.streaming.runtime.io;
import org.apache.flink.annotation.Internal;
import org.apache.flink.runtime.io.network.partition.consumer.BufferOrEvent;
import org.apache.flink.runtime.jobgraph.tasks.AbstractInvokable;
import java.io.IOException;
/**
* The CheckpointBarrierHandler reacts to checkpoint barrier arriving from the input channels.
* Different implementations may either simply track barriers, or block certain inputs on
* barriers.
*/
@Internal
public interface CheckpointBarrierHandler {
/**
* Returns the next {@link BufferOrEvent} that the operator may consume.
* This call blocks until the next BufferOrEvent is available, or until the stream
* has been determined to be finished.
*
* @return The next BufferOrEvent, or {@code null}, if the stream is finished.
*
* @throws IOException Thrown if the network or local disk I/O fails.
*
* @throws InterruptedException Thrown if the thread is interrupted while blocking during
* waiting for the next BufferOrEvent to become available.
* @throws Exception Thrown in case that a checkpoint fails that is started as the result of receiving
* the last checkpoint barrier
*/
BufferOrEvent getNextNonBlocked() throws Exception;
/**
* Registers the task be notified once all checkpoint barriers have been received for a checkpoint.
*
* @param task The task to notify
*/
void registerCheckpointEventHandler(AbstractInvokable task);
/**
* Cleans up all internally held resources.
*
* @throws IOException Thrown if the cleanup of I/O resources failed.
*/
void cleanup() throws IOException;
/**
* Checks if the barrier handler has buffered any data internally.
* @return {@code True}, if no data is buffered internally, {@code false} otherwise.
*/
boolean isEmpty();
/**
* Gets the time that the latest alignment took, in nanoseconds.
* If there is currently an alignment in progress, it will return the time spent in the
* current alignment so far.
*
* @return The duration in nanoseconds
*/
long getAlignmentDurationNanos();
}