org.apache.flink.runtime.io.network.api.CheckpointBarrier Maven / Gradle / Ivy
/*
* 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.io.network.api;
import org.apache.flink.core.memory.DataInputView;
import org.apache.flink.core.memory.DataOutputView;
import org.apache.flink.runtime.checkpoint.CheckpointOptions;
import org.apache.flink.runtime.event.RuntimeEvent;
import java.io.IOException;
import static org.apache.flink.util.Preconditions.checkNotNull;
/**
* Checkpoint barriers are used to align checkpoints throughout the streaming topology. The
* barriers are emitted by the sources when instructed to do so by the JobManager. When
* operators receive a CheckpointBarrier on one of its inputs, it knows that this is the point
* between the pre-checkpoint and post-checkpoint data.
*
* Once an operator has received a checkpoint barrier from all its input channels, it
* knows that a certain checkpoint is complete. It can trigger the operator specific checkpoint
* behavior and broadcast the barrier to downstream operators.
*
*
Depending on the semantic guarantees, may hold off post-checkpoint data until the checkpoint
* is complete (exactly once).
*
*
The checkpoint barrier IDs are strictly monotonous increasing.
*/
public class CheckpointBarrier extends RuntimeEvent {
private final long id;
private final long timestamp;
private final CheckpointOptions checkpointOptions;
public CheckpointBarrier(long id, long timestamp, CheckpointOptions checkpointOptions) {
this.id = id;
this.timestamp = timestamp;
this.checkpointOptions = checkNotNull(checkpointOptions);
}
public long getId() {
return id;
}
public long getTimestamp() {
return timestamp;
}
public CheckpointOptions getCheckpointOptions() {
return checkpointOptions;
}
// ------------------------------------------------------------------------
// Serialization
// ------------------------------------------------------------------------
//
// These methods are inherited form the generic serialization of AbstractEvent
// but would require the CheckpointBarrier to be mutable. Since all serialization
// for events goes through the EventSerializer class, which has special serialization
// for the CheckpointBarrier, we don't need these methods
//
@Override
public void write(DataOutputView out) throws IOException {
throw new UnsupportedOperationException("This method should never be called");
}
@Override
public void read(DataInputView in) throws IOException {
throw new UnsupportedOperationException("This method should never be called");
}
// ------------------------------------------------------------------------
@Override
public int hashCode() {
return (int) (id ^ (id >>> 32) ^ timestamp ^ (timestamp >>> 32));
}
@Override
public boolean equals(Object other) {
if (other == this) {
return true;
}
else if (other == null || other.getClass() != CheckpointBarrier.class) {
return false;
}
else {
CheckpointBarrier that = (CheckpointBarrier) other;
return that.id == this.id && that.timestamp == this.timestamp &&
this.checkpointOptions.equals(that.checkpointOptions);
}
}
@Override
public String toString() {
return String.format("CheckpointBarrier %d @ %d Options: %s", id, timestamp, checkpointOptions);
}
}