com.b2international.snowowl.datastore.version.VersioningManagerBroker.java Source code

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Here is the source code for com.b2international.snowowl.datastore.version.VersioningManagerBroker.java

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/*
 * Copyright 2011-2016 B2i Healthcare Pte Ltd, http://b2i.sg
 * 
 * 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.b2international.snowowl.datastore.version;

import java.util.Collection;
import java.util.Collections;
import java.util.Map;

import org.eclipse.core.runtime.CoreException;
import org.eclipse.core.runtime.IConfigurationElement;
import org.eclipse.core.runtime.Platform;

import com.b2international.commons.ClassUtils;
import com.b2international.commons.Pair;
import com.b2international.snowowl.core.api.SnowowlRuntimeException;
import com.google.common.base.Preconditions;
import com.google.common.base.Supplier;
import com.google.common.base.Suppliers;
import com.google.common.collect.Iterables;
import com.google.common.collect.Maps;
import com.google.common.collect.Sets;

/**
 * Broker for all available terminology specific {@link IVersioningManager versioning manager} instances.
 * <br>Requires a running {@link Platform platform}.
 */
public enum VersioningManagerBroker {

    /**Singleton versioning manager broker.*/
    INSTANCE;

    private static final String VERSIONING_MANAGER_EXTENSION_POINT_ID = "com.b2international.snowowl.datastore.versioningManager";
    private static final String TERMINOLOGY_ID_ATTRIBUTE = "terminologyId";
    private static final String CLASS_ATTRIBUTE = "class";
    private static final String INTERFACE_ATTRIBUTE = "interface";

    /**Cache. Supports mapping between tooling feature IDs (terminology IDs) and {@link IVersioningManager} classes.*/
    private final Supplier<Map<String, Pair<Class<IVersioningManager>, Class<IVersioningManager>>>> cache = Suppliers
            .memoize(new Supplier<Map<String, Pair<Class<IVersioningManager>, Class<IVersioningManager>>>>() {

                @Override
                public Map<String, Pair<Class<IVersioningManager>, Class<IVersioningManager>>> get() {

                    final Map<String, Pair<Class<IVersioningManager>, Class<IVersioningManager>>> $ = Maps
                            .newHashMap();

                    final IConfigurationElement[] elements = Platform.getExtensionRegistry()
                            .getConfigurationElementsFor(VERSIONING_MANAGER_EXTENSION_POINT_ID);
                    for (final IConfigurationElement element : elements) {

                        try {

                            final String toolingId = Preconditions
                                    .checkNotNull(element.getAttribute(TERMINOLOGY_ID_ATTRIBUTE));
                            final IVersioningManager manager = //
                                    ClassUtils.checkAndCast(element.createExecutableExtension(CLASS_ATTRIBUTE),
                                            IVersioningManager.class);

                            final String interfaceName = Preconditions
                                    .checkNotNull(element.getAttribute(INTERFACE_ATTRIBUTE));
                            @SuppressWarnings("unchecked")
                            final Class<IVersioningManager> managerInterface = // 
                                    (Class<IVersioningManager>) manager.getClass().getClassLoader()
                                            .loadClass(interfaceName);

                            @SuppressWarnings("unchecked")
                            final Class<IVersioningManager> managerClass = // 
                                    (Class<IVersioningManager>) manager.getClass();

                            $.put(toolingId, Pair.of(managerInterface, managerClass));

                        } catch (final CoreException e) {
                            throw new SnowowlRuntimeException("Error while instantiating versioning manager.", e);
                        } catch (final ClassNotFoundException e) {
                            throw new SnowowlRuntimeException("Error while instantiating versioning manager.", e);
                        }

                    }

                    return Collections.unmodifiableMap($);

                }

            });

    /**Returns with the component versioning manager for the given tooling feature.*/
    public IVersioningManager createVersioningManager(final String toolingId) {
        try {
            return cache.get().get(toolingId).getB().newInstance();
        } catch (InstantiationException | IllegalAccessException e) {
            throw new SnowowlRuntimeException(e);
        }
    }

    /**Returns with all registered component versioning manager interface-class mappings.*/
    public Iterable<Pair<Class<IVersioningManager>, Class<IVersioningManager>>> getVersioningManagerClasses() {
        final Collection<Pair<Class<IVersioningManager>, Class<IVersioningManager>>> $ = Sets.newHashSet();
        for (final Pair<Class<IVersioningManager>, Class<IVersioningManager>> pair : cache.get().values()) {
            $.add(pair);
        }
        return Iterables.unmodifiableIterable($);
    }

}