maven-resolver-api/src/main/java/org/eclipse/aether/DefaultRepositoryCache.java

/*
 * 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.eclipse.aether;

import java.util.concurrent.ConcurrentHashMap;
import java.util.function.Supplier;

/**
 * A simplistic repository cache backed by a thread-safe map. The simplistic nature of this cache makes it only suitable
 * for use with short-lived repository system sessions where pruning of cache data is not required.
 */
public final class DefaultRepositoryCache implements RepositoryCache {

    private final ConcurrentHashMap<Object, Object> cache = new ConcurrentHashMap<>(256);

    public Object get(RepositorySystemSession session, Object key) {
        return cache.get(key);
    }

    public void put(RepositorySystemSession session, Object key, Object data) {
        if (data != null) {
            cache.put(key, data);
        } else {
            cache.remove(key);
        }
    }

    @Override
    public Object computeIfAbsent(RepositorySystemSession session, Object key, Supplier<Object> supplier) {
        return cache.computeIfAbsent(key, k -> supplier.get());
    }
}