P2RepositoriesFactory.java

/*
 * Copyright (C) 2012 The Android Open Source Project
 *
 * Licensed 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 com.motorola.studio.android.installer.utilities;

import java.net.URI;
import java.util.HashMap;
import java.util.Map;

import org.eclipse.core.runtime.IProgressMonitor;
import org.eclipse.equinox.p2.repository.artifact.IArtifactRepository;
import org.eclipse.equinox.p2.repository.metadata.IMetadataRepository;

import com.motorola.studio.android.installer.InstallerException;

/**
 * Factory for {@link IMetadataRepository} and {@link IArtifactRepository}.
 * Will retrieve P2 repositories based on it's URI, keeping a cached version of the repositories in order to increase speed.
 * Note: This class is a singleton, use the getInstance() method. 
 */
class P2RepositoriesFactory
{

    private static P2RepositoriesFactory instance;

    private final Map<URI, IMetadataRepository> metadataRepositories;

    private final Map<URI, IArtifactRepository> artifactRepositories;

    /*
     * This class is a singleton.
     */
    private P2RepositoriesFactory()
    {
        metadataRepositories = new HashMap<URI, IMetadataRepository>();
        artifactRepositories = new HashMap<URI, IArtifactRepository>();
    }

    public static P2RepositoriesFactory getInstance()
    {
        if (instance == null)
        {
            instance = new P2RepositoriesFactory();
        }

        return instance;
    }

    /**
     * Retrieves a {@link IMetadataRepository} from a given URI.
     * If the repository is found on the internal cache then the cached version is retrieved,
     * otherwise the repository is loaded and added to the cache.
     * The behavior can be overridden by setting the force flag to true. When this happens
     * the repository will be loaded again and a new version will be put on cache. 
     * @param uri repository URI
     * @param force force loading the repository from the P2 mechanism.
     * @param monitor
     * @return {@link IMetadataRepository} from the given URI, if none is found null is returned.
     * @throws InstallerException
     */
    public IMetadataRepository getMetadataRepository(URI uri, boolean force,
            IProgressMonitor monitor) throws InstallerException
    {
        IMetadataRepository repository = null;

        repository = metadataRepositories.get(uri);

        if ((repository == null) || force)
        {
            repository = P2Utilities.getMetadataRepository(uri, monitor);
            metadataRepositories.put(uri, repository);
        }
        else
        {
            monitor.done();
        }
        return repository;
    }

    /**
     * Retrieves a {@link IArtifactRepository} from a given URI.
     * If the repository is found on the internal cache then the cached version is retrieved,
     * otherwise the repository is loaded and added to the cache.
     * The behavior can be overridden by setting the force flag to true. When this happens
     * the repository will be loaded again and a new version will be put on cache. 
     * @param uri repository URI
     * @param force force loading the repository from the P2 mechanism.
     * @param monitor
     * @return {@link IArtifactRepository} from the given URI, if none is found null is returned.
     * @throws InstallerException
     */
    public IArtifactRepository getArtifactRepository(URI uri, boolean force,
            IProgressMonitor monitor) throws InstallerException
    {
        IArtifactRepository repository = null;

        repository = artifactRepositories.get(uri);

        if ((repository == null) || force)
        {
            repository = P2Utilities.getArtifactRepository(uri, monitor);
            artifactRepositories.put(uri, repository);
        }
        else
        {
            monitor.done();
        }
        return repository;
    }

}