maven-core/src/main/java/org/apache/maven/project/DefaultProjectRealmCache.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.apache.maven.project;

import javax.inject.Named;
import javax.inject.Singleton;

import java.util.Collections;
import java.util.List;
import java.util.Map;
import java.util.Objects;
import java.util.concurrent.ConcurrentHashMap;

import org.codehaus.plexus.classworlds.realm.ClassRealm;
import org.codehaus.plexus.classworlds.realm.NoSuchRealmException;
import org.codehaus.plexus.personality.plexus.lifecycle.phase.Disposable;
import org.eclipse.aether.graph.DependencyFilter;

/**
 * Default project realm cache implementation. Assumes cached data does not change.
 */
@Named
@Singleton
public class DefaultProjectRealmCache implements ProjectRealmCache, Disposable {
    /**
     * CacheKey
     */
    protected static class CacheKey implements Key {

        private final List<? extends ClassRealm> extensionRealms;

        private final int hashCode;

        public CacheKey(List<? extends ClassRealm> extensionRealms) {
            this.extensionRealms =
                    (extensionRealms != null) ? Collections.unmodifiableList(extensionRealms) : Collections.emptyList();

            this.hashCode = this.extensionRealms.hashCode();
        }

        @Override
        public int hashCode() {
            return hashCode;
        }

        @Override
        public boolean equals(Object o) {
            if (o == this) {
                return true;
            }

            if (!(o instanceof CacheKey)) {
                return false;
            }

            CacheKey other = (CacheKey) o;

            return extensionRealms.equals(other.extensionRealms);
        }

        @Override
        public String toString() {
            return extensionRealms.toString();
        }
    }

    protected final Map<Key, CacheRecord> cache = new ConcurrentHashMap<>();

    @Override
    public Key createKey(List<? extends ClassRealm> extensionRealms) {
        return new CacheKey(extensionRealms);
    }

    public CacheRecord get(Key key) {
        return cache.get(key);
    }

    public CacheRecord put(Key key, ClassRealm projectRealm, DependencyFilter extensionArtifactFilter) {
        Objects.requireNonNull(projectRealm, "projectRealm cannot be null");

        if (cache.containsKey(key)) {
            throw new IllegalStateException("Duplicate project realm for extensions " + key);
        }

        CacheRecord record = new CacheRecord(projectRealm, extensionArtifactFilter);

        cache.put(key, record);

        return record;
    }

    public void flush() {
        for (CacheRecord record : cache.values()) {
            ClassRealm realm = record.getRealm();
            try {
                realm.getWorld().disposeRealm(realm.getId());
            } catch (NoSuchRealmException e) {
                // ignore
            }
        }
        cache.clear();
    }

    public void register(MavenProject project, Key key, CacheRecord record) {
        // default cache does not track record usage
    }

    @Override
    public void dispose() {
        flush();
    }
}