CavalliumDBEngine/src/main/java/it/cavallium/dbengine/database/collections/SubStageGetterSingle.java
2021-02-03 14:37:02 +01:00

48 lines
1.2 KiB
Java

package it.cavallium.dbengine.database.collections;
import it.cavallium.dbengine.client.CompositeSnapshot;
import it.cavallium.dbengine.database.LLDictionary;
import it.cavallium.dbengine.database.serialization.Serializer;
import java.util.Arrays;
import org.jetbrains.annotations.Nullable;
import reactor.core.publisher.Flux;
import reactor.core.publisher.Mono;
public class SubStageGetterSingle<T> implements SubStageGetter<T, DatabaseStageEntry<T>> {
private final Serializer<T, byte[]> serializer;
public SubStageGetterSingle(Serializer<T, byte[]> serializer) {
this.serializer = serializer;
}
@Override
public Mono<DatabaseStageEntry<T>> subStage(LLDictionary dictionary,
@Nullable CompositeSnapshot snapshot,
byte[] keyPrefix,
Flux<byte[]> keyFlux) {
return keyFlux
.singleOrEmpty()
.flatMap(key -> Mono
.<DatabaseStageEntry<T>>fromCallable(() -> {
if (!Arrays.equals(keyPrefix, key)) {
throw new IndexOutOfBoundsException("Found more than one element!");
}
return null;
})
)
.then(Mono.fromSupplier(() -> {
return new DatabaseSingle<>(dictionary,
keyPrefix,
serializer
);
}));
}
@Override
public boolean needsKeyFlux() {
return true;
}
}