001/**
002 * Licensed to the Apache Software Foundation (ASF) under one
003 * or more contributor license agreements.  See the NOTICE file
004 * distributed with this work for additional information
005 * regarding copyright ownership.  The ASF licenses this file
006 * to you under the Apache License, Version 2.0 (the
007 * "License"); you may not use this file except in compliance
008 * with the License.  You may obtain a copy of the License at
009 *
010 *     http://www.apache.org/licenses/LICENSE-2.0
011 *
012 * Unless required by applicable law or agreed to in writing, software
013 * distributed under the License is distributed on an "AS IS" BASIS,
014 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
015 * See the License for the specific language governing permissions and
016 * limitations under the License.
017 */
018package org.apache.hadoop.hbase.constraint;
019
020import java.io.IOException;
021import java.util.ArrayList;
022import java.util.List;
023import java.util.Optional;
024
025import org.apache.yetus.audience.InterfaceAudience;
026import org.slf4j.Logger;
027import org.slf4j.LoggerFactory;
028import org.apache.hadoop.hbase.Cell;
029import org.apache.hadoop.hbase.CoprocessorEnvironment;
030import org.apache.hadoop.hbase.client.Put;
031import org.apache.hadoop.hbase.client.Durability;
032import org.apache.hadoop.hbase.client.TableDescriptor;
033import org.apache.hadoop.hbase.coprocessor.ObserverContext;
034import org.apache.hadoop.hbase.coprocessor.RegionCoprocessor;
035import org.apache.hadoop.hbase.coprocessor.RegionCoprocessorEnvironment;
036import org.apache.hadoop.hbase.coprocessor.RegionObserver;
037import org.apache.hadoop.hbase.regionserver.InternalScanner;
038import org.apache.hadoop.hbase.wal.WALEdit;
039
040/***
041 * Processes multiple {@link Constraint Constraints} on a given table.
042 * <p>
043 * This is an ease of use mechanism - all the functionality here could be
044 * implemented on any given system by a coprocessor.
045 */
046@InterfaceAudience.Private
047public class ConstraintProcessor implements RegionCoprocessor, RegionObserver {
048
049  private static final Logger LOG = LoggerFactory.getLogger(ConstraintProcessor.class);
050
051  private final ClassLoader classloader;
052
053  private List<? extends Constraint> constraints = new ArrayList<>();
054
055  @Override
056  public Optional<RegionObserver> getRegionObserver() {
057    return Optional.of(this);
058  }
059
060  /**
061   * Create the constraint processor.
062   * <p>
063   * Stores the current classloader.
064   */
065  public ConstraintProcessor() {
066    classloader = this.getClass().getClassLoader();
067  }
068
069  @Override
070  public void start(CoprocessorEnvironment environment) {
071    // make sure we are on a region server
072    if (!(environment instanceof RegionCoprocessorEnvironment)) {
073      throw new IllegalArgumentException(
074          "Constraints only act on regions - started in an environment that was not a region");
075    }
076    RegionCoprocessorEnvironment env = (RegionCoprocessorEnvironment) environment;
077    TableDescriptor desc = env.getRegion().getTableDescriptor();
078    // load all the constraints from the HTD
079    try {
080      this.constraints = Constraints.getConstraints(desc, classloader);
081    } catch (IOException e) {
082      throw new IllegalArgumentException(e);
083    }
084
085    if (LOG.isInfoEnabled()) {
086      LOG.info("Finished loading " + constraints.size()
087          + " user Constraints on table: " + desc.getTableName());
088    }
089
090  }
091
092  @Override
093  public void prePut(ObserverContext<RegionCoprocessorEnvironment> e, Put put,
094      WALEdit edit, Durability durability) throws IOException {
095    // check the put against the stored constraints
096    for (Constraint c : constraints) {
097      c.check(put);
098    }
099    // if we made it here, then the Put is valid
100  }
101
102  @Override
103  public boolean postScannerFilterRow(final ObserverContext<RegionCoprocessorEnvironment> e,
104      final InternalScanner s, final Cell curRowCell, final boolean hasMore) throws IOException {
105    // 'default' in RegionObserver might do unnecessary copy for Off heap backed Cells.
106    return hasMore;
107  }
108}