org.apache.kafka.streams.state.ReadOnlyWindowStore Maven / Gradle / Ivy
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* 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;
import java.time.Instant;
/**
* A window store that only supports read operations.
* Implementations should be thread-safe as concurrent reads and writes are expected.
*
* Note: The current implementation of either forward or backward fetches on range-key-range-time does not
* obey the ordering when there are multiple local stores hosted on that instance. For example,
* if there are two stores from two tasks hosting keys {1,3} and {2,4}, then a range query of key [1,4]
* would return in the order of [1,3,2,4] but not [1,2,3,4] since it is just looping over the stores only.
*
* @param Type of keys
* @param Type of values
*/
public interface ReadOnlyWindowStore {
/**
* Get the value of key from a window.
*
* @param key the key to fetch
* @param time start timestamp (inclusive) of the window
* @return The value or {@code null} if no value is found in the window
* @throws InvalidStateStoreException if the store is not initialized
* @throws NullPointerException if {@code null} is used for any key.
*/
V fetch(K key, long time);
/**
* Get all the key-value pairs with the given key and the time range from all the existing windows.
*
* This iterator must be closed after use.
*
* 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", Instant.ofEpochMilli(10), Instant.ofEpochMilli(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.
*
* @param key the key to fetch
* @param timeFrom time range start (inclusive), where iteration starts.
* @param timeTo time range end (inclusive), where iteration ends.
* @return an iterator over key-value pairs {@code }, from beginning to end of time.
* @throws InvalidStateStoreException if the store is not initialized
* @throws NullPointerException if {@code null} is used for key.
* @throws IllegalArgumentException if duration is negative or can't be represented as {@code long milliseconds}
*/
WindowStoreIterator fetch(K key, Instant timeFrom, Instant timeTo) throws IllegalArgumentException;
/**
* Get all the key-value pairs with the given key and the time range from all the existing windows
* in backward order with respect to time (from end to beginning of time).
*
* This iterator must be closed after use.
*
* 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.backwardFetch("A", Instant.ofEpochMilli(10), Instant.ofEpochMilli(20))} then the
* results will contain the first three windows from the table above in backward order,
* i.e., all those where 10 <= start time <= 20.
*
* For each key, the iterator guarantees ordering of windows, starting from the newest/latest
* available window to the oldest/earliest window.
*
* @param key the key to fetch
* @param timeFrom time range start (inclusive), where iteration ends.
* @param timeTo time range end (inclusive), where iteration starts.
* @return an iterator over key-value pairs {@code }, from end to beginning of time.
* @throws InvalidStateStoreException if the store is not initialized
* @throws NullPointerException if {@code null} is used for key.
* @throws IllegalArgumentException if duration is negative or can't be represented as {@code long milliseconds}
*/
default WindowStoreIterator backwardFetch(K key, Instant timeFrom, Instant timeTo) throws IllegalArgumentException {
throw new UnsupportedOperationException();
}
/**
* Get all the key-value pairs in the given key range and time range from all the existing windows.
*
* This iterator must be closed after use.
*
* @param keyFrom the first key in the range
* A null value indicates a starting position from the first element in the store.
* @param keyTo the last key in the range
* A null value indicates that the range ends with the last element in the store.
* @param timeFrom time range start (inclusive), where iteration starts.
* @param timeTo time range end (inclusive), where iteration ends.
* @return an iterator over windowed key-value pairs {@code , value>}, from beginning to end of time.
* @throws InvalidStateStoreException if the store is not initialized
* @throws IllegalArgumentException if duration is negative or can't be represented as {@code long milliseconds}
*/
KeyValueIterator, V> fetch(K keyFrom, K keyTo, Instant timeFrom, Instant timeTo)
throws IllegalArgumentException;
/**
* Get all the key-value pairs in the given key range and time range from all the existing windows
* in backward order with respect to time (from end to beginning of time).
*
* This iterator must be closed after use.
*
* @param keyFrom the first key in the range
* A null value indicates a starting position from the first element in the store.
* @param keyTo the last key in the range
* A null value indicates that the range ends with the last element in the store.
* @param timeFrom time range start (inclusive), where iteration ends.
* @param timeTo time range end (inclusive), where iteration starts.
* @return an iterator over windowed key-value pairs {@code , value>}, from end to beginning of time.
* @throws InvalidStateStoreException if the store is not initialized
* @throws IllegalArgumentException if duration is negative or can't be represented as {@code long milliseconds}
*/
default KeyValueIterator, V> backwardFetch(K keyFrom, K keyTo, Instant timeFrom, Instant timeTo)
throws IllegalArgumentException {
throw new UnsupportedOperationException();
}
/**
* Gets all the key-value pairs in the existing windows.
*
* @return an iterator over windowed key-value pairs {@code , value>}, from beginning to end of time.
* @throws InvalidStateStoreException if the store is not initialized
*/
KeyValueIterator, V> all();
/**
* Gets all the key-value pairs in the existing windows in backward order
* with respect to time (from end to beginning of time).
*
* @return an backward iterator over windowed key-value pairs {@code , value>}, from the end to beginning of time.
* @throws InvalidStateStoreException if the store is not initialized
*/
default KeyValueIterator, V> backwardAll() {
throw new UnsupportedOperationException();
}
/**
* Gets all the key-value pairs that belong to the windows within in the given time range.
*
* @param timeFrom the beginning of the time slot from which to search (inclusive), where iteration starts.
* @param timeTo the end of the time slot from which to search (inclusive), where iteration ends.
* @return an iterator over windowed key-value pairs {@code , value>}, from beginning to end of time.
* @throws InvalidStateStoreException if the store is not initialized
* @throws NullPointerException if {@code null} is used for any key
* @throws IllegalArgumentException if duration is negative or can't be represented as {@code long milliseconds}
*/
KeyValueIterator, V> fetchAll(Instant timeFrom, Instant timeTo) throws IllegalArgumentException;
/**
* Gets all the key-value pairs that belong to the windows within in the given time range in backward order
* with respect to time (from end to beginning of time).
*
* @param timeFrom the beginning of the time slot from which to search (inclusive), where iteration ends.
* @param timeTo the end of the time slot from which to search (inclusive), where iteration starts.
* @return an backward iterator over windowed key-value pairs {@code , value>}, from end to beginning of time.
* @throws InvalidStateStoreException if the store is not initialized
* @throws NullPointerException if {@code null} is used for any key
* @throws IllegalArgumentException if duration is negative or can't be represented as {@code long milliseconds}
*/
default KeyValueIterator, V> backwardFetchAll(Instant timeFrom, Instant timeTo) throws IllegalArgumentException {
throw new UnsupportedOperationException();
}
}