CavalliumDBEngine/src/main/java/it/cavallium/dbengine/database/disk/LLLocalReactiveRocksIterator.java
2021-04-03 19:09:06 +02:00

64 lines
1.8 KiB
Java

package it.cavallium.dbengine.database.disk;
import static it.cavallium.dbengine.database.disk.LLLocalDictionary.getRocksIterator;
import it.cavallium.dbengine.database.LLRange;
import org.rocksdb.ColumnFamilyHandle;
import org.rocksdb.ReadOptions;
import org.rocksdb.RocksDB;
import org.rocksdb.RocksMutableObject;
import reactor.core.publisher.Flux;
public abstract class LLLocalReactiveRocksIterator<T> {
private static final byte[] EMPTY = new byte[0];
private final RocksDB db;
private final ColumnFamilyHandle cfh;
private final LLRange range;
private final ReadOptions readOptions;
private final boolean readValues;
public LLLocalReactiveRocksIterator(RocksDB db,
ColumnFamilyHandle cfh,
LLRange range,
ReadOptions readOptions,
boolean readValues) {
this.db = db;
this.cfh = cfh;
this.range = range;
this.readOptions = readOptions;
this.readValues = readValues;
}
public Flux<T> flux() {
return Flux
.generate(() -> {
var readOptions = new ReadOptions(this.readOptions);
if (!range.hasMin() || !range.hasMax()) {
readOptions.setReadaheadSize(2 * 1024 * 1024);
readOptions.setFillCache(false);
}
return getRocksIterator(readOptions, range, db, cfh);
}, (tuple, sink) -> {
var rocksIterator = tuple.getT1();
if (rocksIterator.isValid()) {
byte[] key = rocksIterator.key();
byte[] value = readValues ? rocksIterator.value() : EMPTY;
rocksIterator.next();
sink.next(getEntry(key, value));
} else {
sink.complete();
}
return tuple;
}, tuple -> {
var rocksIterator = tuple.getT1();
rocksIterator.close();
tuple.getT2().ifPresent(RocksMutableObject::close);
tuple.getT3().ifPresent(RocksMutableObject::close);
});
}
public abstract T getEntry(byte[] key, byte[] value);
}