org.apache.kafka.streams.state.ReadOnlyWindowStore Maven / Gradle / Ivy
/*
* 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;
import org.apache.kafka.streams.errors.InvalidStateStoreException;
import org.apache.kafka.streams.kstream.Windowed;
/**
* A window store that only supports read operations
* Implementations should be thread-safe as concurrent reads and writes
* are expected.
* @param Type of keys
* @param Type of values
*/
public interface ReadOnlyWindowStore {
/**
* Get all the key-value pairs with the given key and the time range from all
* the existing windows.
*
* The time range is inclusive and applies to the starting timestamp of the window.
* For example, if we have the following windows:
*
*
* +-------------------------------+
* | key | start time | end time |
* +-------+------------+----------+
* | A | 10 | 20 |
* +-------+------------+----------+
* | A | 15 | 25 |
* +-------+------------+----------+
* | A | 20 | 30 |
* +-------+------------+----------+
* | A | 25 | 35 |
* +--------------------------------
*
* And we call {@code store.fetch("A", 10, 20)} then the results will contain the first
* three windows from the table above, i.e., all those where 10 <= start time <= 20.
*
* For each key, the iterator guarantees ordering of windows, starting from the oldest/earliest
* available window to the newest/latest window.
*
* @return an iterator over key-value pairs {@code }
* @throws InvalidStateStoreException if the store is not initialized
*/
WindowStoreIterator fetch(K key, long timeFrom, long timeTo);
/**
* Get all the key-value pairs in the given key range and time range from all
* the existing windows.
*
* @param from the first key in the range
* @param to the last key in the range
* @param timeFrom time range start (inclusive)
* @param timeTo time range end (inclusive)
* @return an iterator over windowed key-value pairs {@code , value>}
* @throws InvalidStateStoreException if the store is not initialized
*/
KeyValueIterator, V> fetch(K from, K to, long timeFrom, long timeTo);
}