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/*
* 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.ignite.internal.lowwatermark;
import java.util.function.Consumer;
import org.apache.ignite.internal.event.EventProducer;
import org.apache.ignite.internal.hlc.HybridTimestamp;
import org.apache.ignite.internal.lowwatermark.event.LowWatermarkEvent;
import org.apache.ignite.internal.lowwatermark.event.LowWatermarkEventParameters;
import org.jetbrains.annotations.Nullable;
/**
* Low watermark is the node's local time, meaning that data (obsolete versions of table rows, remote indexes, remote tables, etc) that was
* deleted before (less than or equal to) this time will be destroyed on the node, i.e. not available for reading.
*
* <p>Low watermark increases monotonically only after all {@link org.apache.ignite.internal.event.EventListener} have completed processing
* the new value.</p>
*
* @see <a href="https://cwiki.apache.org/confluence/display/IGNITE/IEP-91%3A+Transaction+protocol">IEP-91</a>
*/
public interface LowWatermark extends EventProducer<LowWatermarkEvent, LowWatermarkEventParameters> {
/** Returns the current low watermark, {@code null} means no low watermark has been assigned yet. */
@Nullable HybridTimestamp getLowWatermark();
/**
* Runs the provided {@code consumer} under the {@code lock} preventing concurrent LWM update, {@code null} means no low watermark has
* been assigned yet.
*/
void getLowWatermarkSafe(Consumer<@Nullable HybridTimestamp> consumer);
/**
* Updates the low watermark if it is higher than the current one.
*
* @param newLowWatermark Candidate for update.
*/
void updateLowWatermark(HybridTimestamp newLowWatermark);
}