/*
* 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.kafka.streams.state.internals;
import org.apache.kafka.streams.errors.InvalidStateStoreException;
import org.apache.kafka.streams.processor.StateStore;
import org.apache.kafka.streams.state.QueryableStoreType;
import java.util.ArrayList;
import java.util.Collections;
import java.util.List;
/**
* A wrapper over all of the {@link StateStoreProvider}s in a Topology
*/
public class QueryableStoreProvider {
private final List<StateStoreProvider> storeProviders;
private final GlobalStateStoreProvider globalStoreProvider;
public QueryableStoreProvider(final List<StateStoreProvider> storeProviders,
final GlobalStateStoreProvider globalStateStoreProvider) {
this.storeProviders = new ArrayList<>(storeProviders);
this.globalStoreProvider = globalStateStoreProvider;
}
/**
* Get a composite object wrapping the instances of the {@link StateStore} with the provided
* storeName and {@link QueryableStoreType}
*
* @param storeName name of the store
* @param queryableStoreType accept stores passing {@link QueryableStoreType#accepts(StateStore)}
* @param <T> The expected type of the returned store
* @return A composite object that wraps the store instances.
*/
public <T> T getStore(final String storeName, final QueryableStoreType<T> queryableStoreType) {
final List<T> globalStore = globalStoreProvider.stores(storeName, queryableStoreType);
if (!globalStore.isEmpty()) {
return queryableStoreType.create(new WrappingStoreProvider(Collections.<StateStoreProvider>singletonList(globalStoreProvider)), storeName);
}
final List<T> allStores = new ArrayList<>();
for (StateStoreProvider storeProvider : storeProviders) {
allStores.addAll(storeProvider.stores(storeName, queryableStoreType));
}
if (allStores.isEmpty()) {
throw new InvalidStateStoreException("the state store, " + storeName + ", may have migrated to another instance.");
}
return queryableStoreType.create(
new WrappingStoreProvider(storeProviders),
storeName);
}
}