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/*
* Copyright Camunda Services GmbH and/or licensed to Camunda Services GmbH under
* one or more contributor license agreements. See the NOTICE file distributed
* with this work for additional information regarding copyright ownership.
* Licensed under the Camunda License 1.0. You may not use this file
* except in compliance with the Camunda License 1.0.
*/
package io.camunda.zeebe.journal;
public interface JournalMetaStore {
/**
* Update lastFlushedIndex in metastore. This method can be expensive and blocking as the
* implementations of this may have to write to a database or a file.
*
* @param index last flushed index
*/
void storeLastFlushedIndex(long index);
/**
* Read last flushed index from the metastore. This method might be expensive and blocking as the
* implementations of this may have to read from a database or file. It is recommended for the
* callers of this method to cache lastFlushedIndex and call this method only when necessary.
*
* @return last flushed index
*/
long loadLastFlushedIndex();
/**
* Nulls the last flushed index. After calling this, {@link #hasLastFlushedIndex()} will return
* true.The actual value is implementation specific; to check if it was reset, call {@link
* #hasLastFlushedIndex()}.
*/
void resetLastFlushedIndex();
/** Returns true if there is no known last flushed index. */
boolean hasLastFlushedIndex();
class InMemory implements JournalMetaStore {
private volatile long index = -1L;
@Override
public void storeLastFlushedIndex(final long index) {
this.index = index;
}
@Override
public long loadLastFlushedIndex() {
return index;
}
@Override
public void resetLastFlushedIndex() {
index = -1L;
}
@Override
public boolean hasLastFlushedIndex() {
return index != -1L;
}
}
}