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A common base library for Apache Accumulo servers.
There is a newer version: 3.0.0
/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You 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 org.apache.accumulo.server.master.state;

import java.io.IOException;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collection;
import java.util.Collections;
import java.util.Iterator;
import java.util.List;
import java.util.Map.Entry;
import java.util.SortedMap;

import org.apache.accumulo.core.client.BatchScanner;
import org.apache.accumulo.core.client.Connector;
import org.apache.accumulo.core.client.IteratorSetting;
import org.apache.accumulo.core.client.ScannerBase;
import org.apache.accumulo.core.client.impl.ClientContext;
import org.apache.accumulo.core.data.Key;
import org.apache.accumulo.core.data.Range;
import org.apache.accumulo.core.data.Value;
import org.apache.accumulo.core.data.impl.KeyExtent;
import org.apache.accumulo.core.iterators.user.WholeRowIterator;
import org.apache.accumulo.core.metadata.MetadataTable;
import org.apache.accumulo.core.metadata.schema.MetadataSchema.TabletsSection;
import org.apache.accumulo.core.metadata.schema.MetadataSchema.TabletsSection.ChoppedColumnFamily;
import org.apache.accumulo.core.metadata.schema.MetadataSchema.TabletsSection.LogColumnFamily;
import org.apache.accumulo.core.security.Authorizations;
import org.apache.accumulo.server.master.state.TabletLocationState.BadLocationStateException;
import org.apache.hadoop.io.Text;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

public class MetaDataTableScanner implements ClosableIterator {
  private static final Logger log = LoggerFactory.getLogger(MetaDataTableScanner.class);

  BatchScanner mdScanner = null;
  Iterator> iter = null;

  public MetaDataTableScanner(ClientContext context, Range range, CurrentState state) {
    this(context, range, state, MetadataTable.NAME);
  }

  MetaDataTableScanner(ClientContext context, Range range, CurrentState state, String tableName) {
    // scan over metadata table, looking for tablets in the wrong state based on the live servers and online tables
    try {
      Connector connector = context.getConnector();
      mdScanner = connector.createBatchScanner(tableName, Authorizations.EMPTY, 8);
      configureScanner(mdScanner, state);
      mdScanner.setRanges(Collections.singletonList(range));
      iter = mdScanner.iterator();
    } catch (Exception ex) {
      if (mdScanner != null)
        mdScanner.close();
      iter = null;
      mdScanner = null;
      throw new RuntimeException(ex);
    }
  }

  static public void configureScanner(ScannerBase scanner, CurrentState state) {
    TabletsSection.TabletColumnFamily.PREV_ROW_COLUMN.fetch(scanner);
    scanner.fetchColumnFamily(TabletsSection.CurrentLocationColumnFamily.NAME);
    scanner.fetchColumnFamily(TabletsSection.FutureLocationColumnFamily.NAME);
    scanner.fetchColumnFamily(TabletsSection.LastLocationColumnFamily.NAME);
    scanner.fetchColumnFamily(LogColumnFamily.NAME);
    scanner.fetchColumnFamily(ChoppedColumnFamily.NAME);
    scanner.addScanIterator(new IteratorSetting(1000, "wholeRows", WholeRowIterator.class));
    IteratorSetting tabletChange = new IteratorSetting(1001, "tabletChange", TabletStateChangeIterator.class);
    if (state != null) {
      TabletStateChangeIterator.setCurrentServers(tabletChange, state.onlineTabletServers());
      TabletStateChangeIterator.setOnlineTables(tabletChange, state.onlineTables());
      TabletStateChangeIterator.setMerges(tabletChange, state.merges());
      TabletStateChangeIterator.setMigrations(tabletChange, state.migrationsSnapshot());
      TabletStateChangeIterator.setMasterState(tabletChange, state.getMasterState());
      TabletStateChangeIterator.setShuttingDown(tabletChange, state.shutdownServers());
    }
    scanner.addScanIterator(tabletChange);
  }

  public MetaDataTableScanner(ClientContext context, Range range) {
    this(context, range, MetadataTable.NAME);
  }

  public MetaDataTableScanner(ClientContext context, Range range, String tableName) {
    this(context, range, null, tableName);
  }

  @Override
  public void close() {
    if (iter != null) {
      mdScanner.close();
      iter = null;
    }
  }

  @Override
  protected void finalize() {
    close();
  }

  @Override
  public boolean hasNext() {
    if (iter == null)
      return false;
    boolean result = iter.hasNext();
    if (!result) {
      close();
    }
    return result;
  }

  @Override
  public TabletLocationState next() {
    return fetch();
  }

  public static TabletLocationState createTabletLocationState(Key k, Value v) throws IOException, BadLocationStateException {
    final SortedMap decodedRow = WholeRowIterator.decodeRow(k, v);
    KeyExtent extent = null;
    TServerInstance future = null;
    TServerInstance current = null;
    TServerInstance last = null;
    long lastTimestamp = 0;
    List> walogs = new ArrayList>();
    boolean chopped = false;

    for (Entry entry : decodedRow.entrySet()) {
      Key key = entry.getKey();
      Text row = key.getRow();
      Text cf = key.getColumnFamily();
      Text cq = key.getColumnQualifier();

      if (cf.compareTo(TabletsSection.FutureLocationColumnFamily.NAME) == 0) {
        TServerInstance location = new TServerInstance(entry.getValue(), cq);
        if (future != null) {
          throw new BadLocationStateException("found two assignments for the same extent " + key.getRow() + ": " + future + " and " + location, entry.getKey()
              .getRow());
        }
        future = location;
      } else if (cf.compareTo(TabletsSection.CurrentLocationColumnFamily.NAME) == 0) {
        TServerInstance location = new TServerInstance(entry.getValue(), cq);
        if (current != null) {
          throw new BadLocationStateException("found two locations for the same extent " + key.getRow() + ": " + current + " and " + location, entry.getKey()
              .getRow());
        }
        current = location;
      } else if (cf.compareTo(LogColumnFamily.NAME) == 0) {
        String[] split = entry.getValue().toString().split("\\|")[0].split(";");
        walogs.add(Arrays.asList(split));
      } else if (cf.compareTo(TabletsSection.LastLocationColumnFamily.NAME) == 0) {
        if (lastTimestamp < entry.getKey().getTimestamp())
          last = new TServerInstance(entry.getValue(), cq);
      } else if (cf.compareTo(ChoppedColumnFamily.NAME) == 0) {
        chopped = true;
      } else if (TabletsSection.TabletColumnFamily.PREV_ROW_COLUMN.equals(cf, cq)) {
        extent = new KeyExtent(row, entry.getValue());
      }
    }
    if (extent == null) {
      log.warn("No prev-row for key extent: " + decodedRow);
      return null;
    }
    return new TabletLocationState(extent, future, current, last, walogs, chopped);
  }

  private TabletLocationState fetch() {
    try {
      Entry e = iter.next();
      return createTabletLocationState(e.getKey(), e.getValue());
    } catch (IOException ex) {
      throw new RuntimeException(ex);
    } catch (BadLocationStateException ex) {
      throw new RuntimeException(ex);
    }
  }

  @Override
  public void remove() {
    throw new RuntimeException("Unimplemented");
  }
}