DefaultTableMetadataManager.java

/**
 * diqube: Distributed Query Base.
 *
 * Copyright (C) 2015 Bastian Gloeckle
 *
 * This file is part of diqube.
 *
 * diqube is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Affero General Public License as
 * published by the Free Software Foundation, either version 3 of the
 * License, or (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU Affero General Public License for more details.
 *
 * You should have received a copy of the GNU Affero General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */
package org.diqube.metadata;

import java.lang.Thread.UncaughtExceptionHandler;
import java.util.List;
import java.util.concurrent.ExecutorService;
import java.util.function.Function;

import javax.annotation.PostConstruct;
import javax.annotation.PreDestroy;
import javax.inject.Inject;

import org.diqube.consensus.ConsensusClient;
import org.diqube.consensus.ConsensusClient.ClosableProvider;
import org.diqube.consensus.ConsensusClient.ConsensusClusterUnavailableException;
import org.diqube.consensus.internal.DiqubeCatalystSerializer;
import org.diqube.context.AutoInstatiate;
import org.diqube.context.InjectOptional;
import org.diqube.metadata.consensus.TableMetadataStateMachine;
import org.diqube.metadata.consensus.TableMetadataStateMachine.CompareAndSetTableMetadata;
import org.diqube.metadata.consensus.TableMetadataStateMachine.GetTableMetadata;
import org.diqube.metadata.consensus.TableMetadataStateMachine.RecomputeTableMetadata;
import org.diqube.metadata.consensus.TableMetadataStateMachineImplementation;
import org.diqube.metadata.create.TableMetadataRecomputeRequestListener;
import org.diqube.metadata.util.CurrentFlattenedTableNameUtil;
import org.diqube.metadata.util.CurrentFlattenedTableNameUtil.FlattenIdentificationImpossibleException;
import org.diqube.name.FlattenedTableNameUtil;
import org.diqube.threads.ExecutorManager;
import org.diqube.thrift.base.thrift.AuthorizationException;
import org.diqube.thrift.base.thrift.TableMetadata;
import org.diqube.util.Pair;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

/**
 * Manages table metadata across the cluster using an internal consensus state machine.
 *
 * <p>
 * This class manages calling the {@link TableMetadataRecomputeRequestListener}s in a separate thread pool.
 *
 * @author Bastian Gloeckle
 */
@AutoInstatiate
public class DefaultTableMetadataManager implements TableMetadataManager {
  private static final Logger logger = LoggerFactory.getLogger(DefaultTableMetadataManager.class);

  @Inject
  private ConsensusClient consensusClient;

  @Inject
  private TableMetadataStateMachineImplementation tableMetadataStateMachineImplementation;

  @InjectOptional
  private List<TableMetadataRecomputeRequestListener> recomputeListeners;

  @InjectOptional
  private ExecutorManager executorManager;

  @Inject
  private DiqubeCatalystSerializer diqubeCatalystSerializer;

  @Inject
  private CurrentFlattenedTableNameUtil currentFlattenedTableNameUtil;

  @Inject
  private FlattenedTableNameUtil flattenedTableNameUtil;

  private ExecutorService recomputeExecutor;

  @PostConstruct
  public void initialize() {
    tableMetadataStateMachineImplementation.setRecomputeConsumer(tableName -> requestLocalRecomputation(tableName));

    recomputeExecutor =
        executorManager.newCachedThreadPoolWithMax("table-metadata-recompute-%d", new UncaughtExceptionHandler() {
          @Override
          public void uncaughtException(Thread t, Throwable e) {
            logger.error("Uncaught exception while recomputing table metadata. This node should be restarted.", e);
          }
        }, 1);
  }

  @PreDestroy
  public void cleanup() {
    if (recomputeExecutor != null)
      recomputeExecutor.shutdownNow();
  }

  @Override
  public TableMetadata getCurrentTableMetadata(String tableName) throws AuthorizationException {
    if (flattenedTableNameUtil.isFlattenedTableName(tableName)
        && !flattenedTableNameUtil.isFullFlattenedTableName(tableName)) {
      try {
        tableName = currentFlattenedTableNameUtil.enhanceIncompleteFlattenedTableNameWithNewestFlattenId(tableName);
      } catch (FlattenIdentificationImpossibleException e) {
        logger.warn("Cannot get newest flatten ID for table '{}' of which metadata should've been loaded", tableName,
            e);
        // cannot identify any metadata.
        return null;
      }
    }

    Pair<TableMetadata, Long> current = null;
    try (ClosableProvider<TableMetadataStateMachine> p =
        consensusClient.getStateMachineClient(TableMetadataStateMachine.class)) {
      current = p.getClient().getTableMetadata(GetTableMetadata.local(tableName));
    } catch (ConsensusClusterUnavailableException e) {
      return null;
    }

    return (current != null) ? current.getLeft() : null;
  }

  @Override
  public void adjustTableMetadata(String tableName, Function<TableMetadata, TableMetadata> adjustFunction) {
    try (ClosableProvider<TableMetadataStateMachine> p =
        consensusClient.getStateMachineClient(TableMetadataStateMachine.class)) {

      boolean success = false;
      while (!success) {
        Pair<TableMetadata, Long> currentMetadataPair =
            p.getClient().getTableMetadata(GetTableMetadata.local(tableName));

        TableMetadata newMetadata;
        long previousVersion;
        if (currentMetadataPair == null) {
          newMetadata = adjustFunction.apply(null);
          previousVersion = Long.MIN_VALUE;
        } else {
          newMetadata = adjustFunction.apply(currentMetadataPair.getLeft());
          previousVersion = currentMetadataPair.getRight();
        }

        try {
          diqubeCatalystSerializer.validateSerializationObject(newMetadata);
        } catch (IllegalArgumentException e) {
          logger.warn("Cannot publish metadata for table {} because metadata cannot be accepted by consensus cluster.",
              tableName, e);
          return;
        }

        success =
            p.getClient().compareAndSetTableMetadata(CompareAndSetTableMetadata.local(previousVersion, newMetadata));
      }

      logger.debug("Sent the current metadata of the local '{}' table to the cluster.", tableName);
    } catch (ConsensusClusterUnavailableException e) {
      logger.warn("Could not publish metadata becuase consensus cluster is not available", e);
    }
  }

  @Override
  public void startRecomputingTableMetadata(String tableName) {
    try (ClosableProvider<TableMetadataStateMachine> p =
        consensusClient.getStateMachineClient(TableMetadataStateMachine.class)) {
      p.getClient().recomputeTableMetadata(RecomputeTableMetadata.local(tableName));
      logger.debug("Informing cluster that metadata for table '{}' needs to be recomputed.", tableName);
    } catch (ConsensusClusterUnavailableException e) {
      throw new IllegalStateException("Consensus cluster not available", e);
    }
  }

  /**
   * A request to recompute metadata has arrived us from another cluster node (perhaps even we ourselves started that!).
   */
  private void requestLocalRecomputation(String tableName) {
    if (recomputeListeners != null) {
      // execute listeners on different thread, because this method is effectively called by the state machine thread of
      // the consensus implementation - we must not block it. In addition, we expect the listeners to recompute and send
      // the results again -> another interaction with consensus, and this cannot happen while still working on applying
      // a commit to the local state machine.
      for (TableMetadataRecomputeRequestListener listener : recomputeListeners) {
        recomputeExecutor.execute(() -> listener.tableMetadataRecomputeRequestReceived(tableName));
      }
    }
  }

}