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.quotas;
019
020import java.util.Collections;
021import java.util.HashMap;
022import java.util.Map;
023import java.util.Objects;
024import org.apache.hadoop.hbase.TableName;
025import org.apache.hadoop.hbase.regionserver.Region;
026import org.apache.hadoop.hbase.regionserver.RegionServerServices;
027import org.apache.yetus.audience.InterfaceAudience;
028import org.apache.yetus.audience.InterfaceStability;
029
030/**
031 * A class to ease dealing with tables that have and do not have violation policies being enforced.
032 * This class is immutable, expect for {@code locallyCachedPolicies}. The
033 * {@code locallyCachedPolicies} are mutable given the current {@code activePolicies} and
034 * {@code snapshots}. It is expected that when a new instance of this class is instantiated, we also
035 * want to invalidate those previously cached policies (as they may now be invalidate if we received
036 * new quota usage information).
037 */
038@InterfaceAudience.Private
039@InterfaceStability.Evolving
040public class ActivePolicyEnforcement {
041  private final Map<TableName, SpaceViolationPolicyEnforcement> activePolicies;
042  private final Map<TableName, SpaceQuotaSnapshot> snapshots;
043  private final RegionServerServices rss;
044  private final SpaceViolationPolicyEnforcementFactory factory;
045  private final Map<TableName, SpaceViolationPolicyEnforcement> locallyCachedPolicies;
046
047  public ActivePolicyEnforcement(Map<TableName, SpaceViolationPolicyEnforcement> activePolicies,
048    Map<TableName, SpaceQuotaSnapshot> snapshots, RegionServerServices rss) {
049    this(activePolicies, snapshots, rss, SpaceViolationPolicyEnforcementFactory.getInstance());
050  }
051
052  public ActivePolicyEnforcement(Map<TableName, SpaceViolationPolicyEnforcement> activePolicies,
053    Map<TableName, SpaceQuotaSnapshot> snapshots, RegionServerServices rss,
054    SpaceViolationPolicyEnforcementFactory factory) {
055    this.activePolicies = activePolicies;
056    this.snapshots = snapshots;
057    this.rss = rss;
058    this.factory = factory;
059    // Mutable!
060    this.locallyCachedPolicies = new HashMap<>();
061  }
062
063  /**
064   * Returns the proper {@link SpaceViolationPolicyEnforcement} implementation for the given table.
065   * If the given table does not have a violation policy enforced, a "no-op" policy will be returned
066   * which always allows an action.
067   * @see #getPolicyEnforcement(TableName)
068   */
069  public SpaceViolationPolicyEnforcement getPolicyEnforcement(Region r) {
070    return getPolicyEnforcement(Objects.requireNonNull(r).getTableDescriptor().getTableName());
071  }
072
073  /**
074   * Returns the proper {@link SpaceViolationPolicyEnforcement} implementation for the given table.
075   * If the given table does not have a violation policy enforced, a "no-op" policy will be returned
076   * which always allows an action.
077   * @param tableName The table to fetch the policy for.
078   * @return A non-null {@link SpaceViolationPolicyEnforcement} instance.
079   */
080  public SpaceViolationPolicyEnforcement getPolicyEnforcement(TableName tableName) {
081    SpaceViolationPolicyEnforcement policy = activePolicies.get(Objects.requireNonNull(tableName));
082    if (policy == null) {
083      synchronized (locallyCachedPolicies) {
084        // When we don't have an policy enforcement for the table, there could be one of two cases:
085        // 1) The table has no quota defined
086        // 2) The table is not in violation of its quota
087        // In both of these cases, we want to make sure that access remains fast and we minimize
088        // object creation. We can accomplish this by locally caching policies instead of creating
089        // a new instance of the policy each time.
090        policy = locallyCachedPolicies.get(tableName);
091        // We have already created/cached the enforcement, use it again. `activePolicies` and
092        // `snapshots` are immutable, thus this policy is valid for the lifetime of `this`.
093        if (policy != null) {
094          return policy;
095        }
096        // Create a PolicyEnforcement for this table and snapshot. The snapshot may be null
097        // which is OK.
098        policy = factory.createWithoutViolation(rss, tableName, snapshots.get(tableName));
099        // Cache the policy we created
100        locallyCachedPolicies.put(tableName, policy);
101      }
102    }
103    return policy;
104  }
105
106  /**
107   * Returns an unmodifiable version of the active {@link SpaceViolationPolicyEnforcement}s.
108   */
109  public Map<TableName, SpaceViolationPolicyEnforcement> getPolicies() {
110    return Collections.unmodifiableMap(activePolicies);
111  }
112
113  /**
114   * Returns an unmodifiable version of the policy enforcements that were cached because they are
115   * not in violation of their quota.
116   */
117  Map<TableName, SpaceViolationPolicyEnforcement> getLocallyCachedPolicies() {
118    return Collections.unmodifiableMap(locallyCachedPolicies);
119  }
120
121  @Override
122  public String toString() {
123    return getClass().getSimpleName() + ": " + activePolicies;
124  }
125}