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;
024import org.apache.hadoop.hbase.CoprocessorEnvironment;
025import org.apache.hadoop.hbase.client.Durability;
026import org.apache.hadoop.hbase.client.Put;
027import org.apache.hadoop.hbase.client.TableDescriptor;
028import org.apache.hadoop.hbase.coprocessor.ObserverContext;
029import org.apache.hadoop.hbase.coprocessor.RegionCoprocessor;
030import org.apache.hadoop.hbase.coprocessor.RegionCoprocessorEnvironment;
031import org.apache.hadoop.hbase.coprocessor.RegionObserver;
032import org.apache.hadoop.hbase.wal.WALEdit;
033import org.apache.yetus.audience.InterfaceAudience;
034import org.slf4j.Logger;
035import org.slf4j.LoggerFactory;
036
037/***
038 * Processes multiple {@link Constraint Constraints} on a given table.
039 * <p>
040 * This is an ease of use mechanism - all the functionality here could be implemented on any given
041 * system by a coprocessor.
042 */
043@InterfaceAudience.Private
044public class ConstraintProcessor implements RegionCoprocessor, RegionObserver {
045
046  private static final Logger LOG = LoggerFactory.getLogger(ConstraintProcessor.class);
047
048  private final ClassLoader classloader;
049
050  private List<? extends Constraint> constraints = new ArrayList<>();
051
052  @Override
053  public Optional<RegionObserver> getRegionObserver() {
054    return Optional.of(this);
055  }
056
057  /**
058   * Create the constraint processor.
059   * <p>
060   * Stores the current classloader.
061   */
062  public ConstraintProcessor() {
063    classloader = this.getClass().getClassLoader();
064  }
065
066  @Override
067  public void start(CoprocessorEnvironment environment) {
068    // make sure we are on a region server
069    if (!(environment instanceof RegionCoprocessorEnvironment)) {
070      throw new IllegalArgumentException(
071        "Constraints only act on regions - started in an environment that was not a region");
072    }
073    RegionCoprocessorEnvironment env = (RegionCoprocessorEnvironment) environment;
074    TableDescriptor desc = env.getRegion().getTableDescriptor();
075    // load all the constraints from the HTD
076    try {
077      this.constraints = Constraints.getConstraints(desc, classloader);
078    } catch (IOException e) {
079      throw new IllegalArgumentException(e);
080    }
081
082    if (LOG.isInfoEnabled()) {
083      LOG.info("Finished loading " + constraints.size() + " user Constraints on table: "
084        + desc.getTableName());
085    }
086
087  }
088
089  @Override
090  public void prePut(ObserverContext<? extends RegionCoprocessorEnvironment> e, Put put,
091    WALEdit edit, Durability durability) throws IOException {
092    // check the put against the stored constraints
093    for (Constraint c : constraints) {
094      c.check(put);
095    }
096    // if we made it here, then the Put is valid
097  }
098}