Android Open Source - interdroid-vdb Avro Provider Registry

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Copyright (c) 2008-2012 Vrije Universiteit, The Netherlands All rights reserved. Redistribution and use in source and binary forms, with or without modification, are permitted provided that the follo...
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Java Source Code

/*
 * Copyright (c) 2008-2012 Vrije Universiteit, The Netherlands All rights
 * reserved.//from w w w  .  java2 s  . c  o  m
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *
 * Redistributions of source code must retain the above copyright notice, this
 * list of conditions and the following disclaimer.
 *
 * Redistributions in binary form must reproduce the above copyright notice,
 * this list of conditions and the following disclaimer in the documentation
 * and/or other materials provided with the distribution.
 *
 * Neither the name of the Vrije Universiteit nor the names of its contributors
 * may be used to endorse or promote products derived from this software without
 * specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS ``AS IS''
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGE.
 */
package interdroid.vdb.content.avro;

import java.io.IOException;
import java.util.ArrayList;
import java.util.List;

import interdroid.vdb.Authority;
import interdroid.vdb.content.EntityUriBuilder;
import interdroid.vdb.content.VdbConfig.RepositoryConf;
import interdroid.vdb.content.VdbProviderRegistry;
import interdroid.vdb.content.metadata.DatabaseFieldType;
import interdroid.vdb.content.orm.DbEntity;
import interdroid.vdb.content.orm.DbField;
import interdroid.vdb.content.orm.ORMGenericContentProvider;
import interdroid.vdb.persistence.api.VdbRepository;
import interdroid.vdb.persistence.api.VdbRepositoryRegistry;

import org.apache.avro.Schema;
import org.eclipse.jgit.lib.Constants;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import android.content.ContentValues;
import android.content.Context;
import android.content.pm.ProviderInfo;
import android.database.Cursor;
import android.net.Uri;

/**
 * This class holds a registry for avro content providers
 * holding the namespace, name and schema for each avro provider.
 *
 * It is a content provider itself, constructed using the ORM
 * system within VDB. Nothing like bootstrapping the system using
 * your own dog food. ;)
 *
 * @author nick &lt;palmer@cs.vu.nl&gt;
 *
 */
public class AvroProviderRegistry extends ORMGenericContentProvider {
  /**
   * Access to logger.
   */
  private static final Logger LOG = LoggerFactory
      .getLogger(AvroProviderRegistry.class);

  /**
   * The registry configuration.
   * @author nick &lt;palmer@cs.vu.nl&gt;
   *
   */
  @DbEntity(name = AvroSchemaRegistrationHandler.NAME,
      itemContentType = "vnd.android.cursor.item/"
          + AvroSchemaRegistrationHandler.FULL_NAME,
          contentType = "vnd.android.cursor.dir/"
              + AvroSchemaRegistrationHandler.FULL_NAME)
  public static final class RegistryConf {
    /**
     * No construction.
     */
    private RegistryConf() { }

    /**
     * The default sort order for this table.
     */
    public static final String DEFAULT_SORT_ORDER = "modified DESC";

    /**
     * The content URI for this type.
     */
    public static final Uri CONTENT_URI =
        Uri.withAppendedPath(EntityUriBuilder.branchUri(
            Authority.VDB, AvroSchemaRegistrationHandler.NAMESPACE,
            "master"), AvroSchemaRegistrationHandler.NAME);

    /**
     * The ID field.
     */
    @DbField(isID = true, dbType = DatabaseFieldType.INTEGER)
    public static final String ID = "_id";

    /**
     * The key field.
     */
    @DbField(dbType = DatabaseFieldType.TEXT)
    public static final String NAME =
    AvroSchemaRegistrationHandler.KEY_NAME;

    /**
     * The namespace field.
     */
    @DbField(dbType = DatabaseFieldType.TEXT)
    public static final String NAMESPACE =
    AvroSchemaRegistrationHandler.KEY_NAMESPACE;

    /**
     * The schema field.
     */
    @DbField(dbType = DatabaseFieldType.TEXT)
    public static final String SCHEMA =
    AvroSchemaRegistrationHandler.KEY_SCHEMA;

  }

  /**
   * The context we are working in.
   */
  private Context mContext;

  /**
   * Construct a provider registry.
   */
  public AvroProviderRegistry() {
    super(AvroSchemaRegistrationHandler.NAMESPACE, RegistryConf.class);
  }

  /**
   * Returns all repositories registered with the system.
   * @return the list of repository configurations.
   */
  public final List<RepositoryConf> getAllRepositories() {
    Cursor c = null;
    ArrayList<RepositoryConf> result = new ArrayList<RepositoryConf>();
    try {
      c = query(AvroSchemaRegistrationHandler.URI,
          new String[]{AvroSchemaRegistrationHandler.KEY_NAMESPACE,
          AvroSchemaRegistrationHandler.KEY_SCHEMA},
          null, null, null);
      if (c != null) {
        while (c.moveToNext()) {
          result.add(new RepositoryConf(
              c.getString(0),
              c.getString(1)));
        }
      }
    } finally {
      if (c != null) {
        try {
          c.close();
        } catch (Exception e) {
          LOG.warn("Exception while closing cursor: ", e);
        }
      }
    }

    return result;
  }

  @Override
  public final void onAttach(final Context context, final ProviderInfo info) {
    super.attachInfo(context, info);
    mContext = context;
  }

  @Override
  public final void onPostUpdate(final Uri uri, final ContentValues values,
      final String where, final String[] whereArgs) {
    // TODO: Finish implementation of schema migration.
//    try {
//      LOG.debug("Migrating DB: {} {}", values, whereArgs);
////            migrateDb(
////                    whereArgs[0],
////                    values.getAsString(AvroSchemaRegistrationHandler.KEY_SCHEMA));
//    } catch (IOException e) {
//      throw new RuntimeException("Error updating database.");
//    }
  }

  @Override
  public final void onPostInsert(final Uri uri,
      final ContentValues userValues) {
    LOG.debug("On post insert: {}", userValues);
    String name = userValues.getAsString(
        AvroSchemaRegistrationHandler.KEY_NAMESPACE);
    String schema = userValues.getAsString(
        AvroSchemaRegistrationHandler.KEY_SCHEMA);
    LOG.debug("Registering: {} {}", name, schema);
    registerRepository(name, schema);
  }

  @Override
  public final void onPostDelete(final Uri uri,
      final String where, final String[] whereArgs) {
    LOG.debug("Deleted avro repo: {}", whereArgs[0]);
    VdbRepositoryRegistry.getInstance().deleteRepository(getContext(),
        whereArgs[0]);
    try {
      new VdbProviderRegistry(getContext()).unregister(whereArgs[0]);
    } catch (IOException e) {
      // TODO: Auto-generated catch block
      e.printStackTrace();
    }
  }


  private void registerRepository(final String namespace, final String schema) {
    VdbProviderRegistry registry;
    try {
      LOG.debug("Registering avro repo: {} {}", namespace, schema);
      registry = new VdbProviderRegistry(mContext);
      registry.registerRepository(
          new RepositoryConf(namespace, schema));
    } catch (IOException e) {
      throw new RuntimeException("Unable to build registry: ", e);
    }
  }

  /**
   * Migrates a database from one schema to the new schema.
   * @param namespace the namespace for the repository
   * @param schemaString the new schema as a string.
   * @throws IOException
   */
  private void migrateDb(final String namespace, final String schemaString)
      throws IOException {
    // Make sure the repo is registered.
    registerRepository(namespace, schemaString);

    // Parse the schema
    Schema newSchema = Schema.parse(schemaString);

    VdbRepository repo = VdbRepositoryRegistry.getInstance()
        .getRepository(getContext(), namespace);

    repo.updateDatabase(Constants.MASTER, newSchema);
  }

  /**
   * Queries for the schema for the given URI.
   *
   * @param context the context to query in
   * @param uri the uri to retrieve the schema for
   * @return the schema for the given uri
   */
  public static Schema getSchema(final Context context, final Uri uri) {
    Cursor c = null;
    Schema schema = null;
    Uri dbUri = uri;
    try {
      // We expect to deal with internal paths
      if (!Authority.VDB.equals(uri.getAuthority())) {
        LOG.debug("Mapping to native: {}", uri);
        dbUri = EntityUriBuilder.toInternal(uri);
      }
      LOG.debug("Querying for schema for: {} {}", dbUri,
          dbUri.getPathSegments().get(0));
      c = context.getContentResolver().query(
          AvroSchemaRegistrationHandler.URI,
          new String[]{AvroSchemaRegistrationHandler.KEY_SCHEMA},
          AvroSchemaRegistrationHandler.KEY_NAMESPACE + "=?",
          new String[] {dbUri.getPathSegments().get(0)}, null);
      if (c != null && c.moveToFirst()) {
        String schemaString = c.getString(0);
        LOG.debug("Got schema: {}", schemaString);
        schema = Schema.parse(schemaString);
      } else {
        LOG.error("Schema not found.");
      }
    } finally {
      if (c != null) {
        try {
          c.close();
        } catch (Exception e) {
          LOG.warn("Exception while closing cursor: ", e);
        }
      }
    }
    return schema;
  }
}
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