org.apache.kafka.common.cache.Cache 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.common.cache;
/**
* Interface for caches, semi-persistent maps which store key-value mappings until either an eviction criteria is met
* or the entries are manually invalidated. Caches are not required to be thread-safe, but some implementations may be.
*/
public interface Cache {
/**
* Look up a value in the cache.
* @param key the key to
* @return the cached value, or null if it is not present.
*/
V get(K key);
/**
* Insert an entry into the cache.
* @param key the key to insert
* @param value the value to insert
*/
void put(K key, V value);
/**
* Manually invalidate a key, clearing its entry from the cache.
* @param key the key to remove
* @return true if the key existed in the cache and the entry was removed or false if it was not present
*/
boolean remove(K key);
/**
* Get the number of entries in this cache. If this cache is used by multiple threads concurrently, the returned
* value will only be approximate.
* @return the number of entries in the cache
*/
long size();
}