001/*
002 * Licensed to the Apache Software Foundation (ASF) under one or more
003 * contributor license agreements.  See the NOTICE file distributed with
004 * this work for additional information regarding copyright ownership.
005 * The ASF licenses this file to you under the Apache License, Version 2.0
006 * (the "License"); you may not use this file except in compliance with
007 * the License.  You may obtain a copy of the License at
008 *
009 * http://www.apache.org/licenses/LICENSE-2.0
010 *
011 * Unless required by applicable law or agreed to in writing, software
012 * distributed under the License is distributed on an "AS IS" BASIS,
013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
014 * See the License for the specific language governing permissions and
015 * limitations under the License.
016 */
017package org.apache.hadoop.hbase.quotas;
018
019import java.util.Collections;
020import java.util.HashMap;
021import java.util.Map;
022import java.util.Objects;
023
024import org.apache.hadoop.hbase.TableName;
025import org.apache.yetus.audience.InterfaceAudience;
026import org.apache.yetus.audience.InterfaceStability;
027import org.apache.hadoop.hbase.regionserver.Region;
028import org.apache.hadoop.hbase.regionserver.RegionServerServices;
029
030/**
031 * A class to ease dealing with tables that have and do not have violation policies
032 * being enforced. This class is immutable, expect for {@code locallyCachedPolicies}.
033 *
034 * The {@code locallyCachedPolicies} are mutable given the current {@code activePolicies}
035 * and {@code snapshots}. It is expected that when a new instance of this class is
036 * instantiated, we also want to invalidate those previously cached policies (as they
037 * may now be invalidate if we received new quota usage information).
038 */
039@InterfaceAudience.Private
040@InterfaceStability.Evolving
041public class ActivePolicyEnforcement {
042  private final Map<TableName,SpaceViolationPolicyEnforcement> activePolicies;
043  private final Map<TableName,SpaceQuotaSnapshot> snapshots;
044  private final RegionServerServices rss;
045  private final SpaceViolationPolicyEnforcementFactory factory;
046  private final Map<TableName,SpaceViolationPolicyEnforcement> locallyCachedPolicies;
047
048  public ActivePolicyEnforcement(Map<TableName,SpaceViolationPolicyEnforcement> activePolicies,
049      Map<TableName,SpaceQuotaSnapshot> snapshots, RegionServerServices rss) {
050    this(activePolicies, snapshots, rss, SpaceViolationPolicyEnforcementFactory.getInstance());
051  }
052
053  public ActivePolicyEnforcement(Map<TableName,SpaceViolationPolicyEnforcement> activePolicies,
054      Map<TableName,SpaceQuotaSnapshot> snapshots, RegionServerServices rss,
055      SpaceViolationPolicyEnforcementFactory factory) {
056    this.activePolicies = activePolicies;
057    this.snapshots = snapshots;
058    this.rss = rss;
059    this.factory = factory;
060    // Mutable!
061    this.locallyCachedPolicies = new HashMap<>();
062  }
063
064  /**
065   * Returns the proper {@link SpaceViolationPolicyEnforcement} implementation for the given table.
066   * If the given table does not have a violation policy enforced, a "no-op" policy will
067   * be returned which always allows an action.
068   *
069   * @see #getPolicyEnforcement(TableName)
070   */
071  public SpaceViolationPolicyEnforcement getPolicyEnforcement(Region r) {
072    return getPolicyEnforcement(Objects.requireNonNull(r).getTableDescriptor().getTableName());
073  }
074
075  /**
076   * Returns the proper {@link SpaceViolationPolicyEnforcement} implementation for the given table.
077   * If the given table does not have a violation policy enforced, a "no-op" policy will
078   * be returned which always allows an action.
079   *
080   * @param tableName The table to fetch the policy for.
081   * @return A non-null {@link SpaceViolationPolicyEnforcement} instance.
082   */
083  public SpaceViolationPolicyEnforcement getPolicyEnforcement(TableName tableName) {
084    SpaceViolationPolicyEnforcement policy = activePolicies.get(Objects.requireNonNull(tableName));
085    if (policy == null) {
086      synchronized (locallyCachedPolicies) {
087        // When we don't have an policy enforcement for the table, there could be one of two cases:
088        //  1) The table has no quota defined
089        //  2) The table is not in violation of its quota
090        // In both of these cases, we want to make sure that access remains fast and we minimize
091        // object creation. We can accomplish this by locally caching policies instead of creating
092        // a new instance of the policy each time.
093        policy = locallyCachedPolicies.get(tableName);
094        // We have already created/cached the enforcement, use it again. `activePolicies` and
095        // `snapshots` are immutable, thus this policy is valid for the lifetime of `this`.
096        if (policy != null) {
097          return policy;
098        }
099        // Create a PolicyEnforcement for this table and snapshot. The snapshot may be null
100        // which is OK.
101        policy = factory.createWithoutViolation(rss, tableName, snapshots.get(tableName));
102        // Cache the policy we created
103        locallyCachedPolicies.put(tableName, policy);
104      }
105    }
106    return policy;
107  }
108
109  /**
110   * Returns an unmodifiable version of the active {@link SpaceViolationPolicyEnforcement}s.
111   */
112  public Map<TableName,SpaceViolationPolicyEnforcement> getPolicies() {
113    return Collections.unmodifiableMap(activePolicies);
114  }
115
116  /**
117   * Returns an unmodifiable version of the policy enforcements that were cached because they are
118   * not in violation of their quota.
119   */
120  Map<TableName,SpaceViolationPolicyEnforcement> getLocallyCachedPolicies() {
121    return Collections.unmodifiableMap(locallyCachedPolicies);
122  }
123
124  @Override
125  public String toString() {
126    return getClass().getSimpleName() + ": " + activePolicies;
127  }
128}