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Graph Engine for QWAZR
There is a newer version: 1.4.0
/**
 * Copyright 2015-2017 Emmanuel Keller / QWAZR
 * 
 * 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.qwazr.graph;

import com.qwazr.database.store.Table;
import com.qwazr.database.store.Tables;
import com.qwazr.graph.model.GraphDefinition;
import com.qwazr.server.ApplicationBuilder;
import com.qwazr.server.GenericServer;
import com.qwazr.server.ServerException;
import com.qwazr.utils.FileUtils;
import com.qwazr.utils.LockUtils;
import com.qwazr.utils.json.DirectoryJsonManager;

import javax.ws.rs.core.Response.Status;
import java.io.File;
import java.io.IOException;
import java.nio.file.Files;
import java.nio.file.Path;
import java.util.HashMap;
import java.util.Map;
import java.util.Set;

public class GraphManager extends DirectoryJsonManager {

	private final LockUtils.ReadWriteLock rwl = new LockUtils.ReadWriteLock();

	private final GraphServiceInterface service;

	private final Map graphMap;

	public GraphManager(final Path graphesDirectory) throws ServerException, IOException {
		super(graphesDirectory.toFile(), GraphDefinition.class);
		graphMap = new HashMap<>();
		for (String name : nameSet())
			addNewInstance(name, get(name));
		service = new GraphServiceImpl(this);
	}

	public GraphManager registerContextAttribute(final GenericServer.Builder builder) {
		builder.contextAttribute(this);
		return this;
	}

	public GraphManager registerWebService(final ApplicationBuilder builder) {
		builder.singletons(service);
		return this;
	}

	public static Path checkGraphesDirectory(final Path dataDirectory) throws IOException {
		final Path tablesDirectory = dataDirectory.resolve(GraphServiceInterface.SERVICE_NAME);
		if (!Files.exists(tablesDirectory))
			Files.createDirectory(tablesDirectory);
		return tablesDirectory;
	}

	public GraphServiceInterface getService() {
		return service;
	}

	private GraphInstance addNewInstance(final String graphName, final GraphDefinition graphDef)
			throws IOException, ServerException {
		final File dbDirectory = new File(directory, graphName);
		if (!dbDirectory.exists())
			dbDirectory.mkdir();
		final Table table = Tables.getInstance(dbDirectory, graphDef.implementation);
		GraphInstance graphInstance = new GraphInstance(graphName, table, graphDef);
		graphInstance.checkFields();
		graphMap.put(graphName, graphInstance);
		return graphInstance;
	}

	public GraphInstance getGraphInstance(final String graphName) throws ServerException {
		return rwl.readEx(() -> {
			GraphInstance graphInstance = graphMap.get(graphName);
			if (graphInstance == null)
				throw new ServerException(Status.NOT_FOUND, "Graph instance not found");
			return graphInstance;
		});
	}

	@Override
	public Set nameSet() {
		return super.nameSet();
	}

	@Override
	public GraphDefinition get(final String name) throws IOException {
		return super.get(name);
	}

	public void createUpdateGraph(final String graphName, final GraphDefinition graphDef)
			throws IOException, ServerException {
		rwl.writeEx(() -> {
			super.set(graphName, graphDef);
			graphMap.remove(graphName);
			addNewInstance(graphName, graphDef);
		});
	}

	@Override
	public GraphDefinition delete(String graphName) throws ServerException, IOException {
		return rwl.writeEx(() -> {
			GraphDefinition graphDef = super.delete(graphName);
			File dbDirectory = new File(directory, graphName);
			Tables.delete(dbDirectory);
			FileUtils.deleteDirectory(dbDirectory);
			graphMap.remove(graphName);
			return graphDef;
		});
	}

}