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/**
* Copyright (c) Microsoft Corporation. All rights reserved.
* Licensed under the MIT License. See License.txt in the project root for
* license information.
*/
package com.microsoft.azure.functions.cache;
import java.util.function.Supplier;
/**
* A concurrency-safe object cache that uses a top-level namespace (Class)
* plus a typed key (K extends CacheKey) to store values (V).
*
* By default, only {@link #computeIfAbsent} is abstract and must be implemented.
* The {@link #get} and {@link #remove} methods are default methods that throw
* {@link UnsupportedOperationException} unless overridden.
*
* @param Type of the cache key, which must implement {@link CacheKey}.
* @param Type of the stored objects/values.
*/
public interface ObjectCache {
/**
* Retrieves or creates a value for (namespace, key).
* If already cached, returns the existing value.
* Otherwise, calls {@code creator}, stores that result, and returns it.
*
* @param namespace A "namespace" class (often the middleware's class).
* @param key A {@link CacheKey} object (must define equals/hashCode).
* @param creator A supplier that builds the value if absent.
* @return The existing or newly created object.
*/
V computeIfAbsent(Class namespace, K key, Supplier creator);
/**
* Retrieves the cached value for (namespace, key) if present,
* or null if not found.
*
* By default, throws {@code UnsupportedOperationException}.
* Override if your implementation supports direct get.
*
* @param namespace The "namespace" class.
* @param key The cache key.
* @return The cached value or null.
*/
default V get(Class namespace, K key) {
throw new UnsupportedOperationException("get(...) not implemented by default.");
}
/**
* Removes the cached value for (namespace, key) if present.
*
* By default, throws {@code UnsupportedOperationException}.
* Override if your implementation supports removal.
*
* @param namespace The "namespace" class.
* @param key The cache key.
* @return The removed value, or null if it was not in the cache.
*/
default V remove(Class namespace, K key) {
throw new UnsupportedOperationException("remove(...) not implemented by default.");
}
}