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.coprocessor;
019
020import java.util.Optional;
021import org.apache.hadoop.hbase.CoprocessorEnvironment;
022import org.apache.hadoop.hbase.ipc.RpcServer;
023import org.apache.hadoop.hbase.security.User;
024import org.apache.yetus.audience.InterfaceAudience;
025
026/**
027 * This is the only implementation of {@link ObserverContext}, which serves as the interface for
028 * third-party Coprocessor developers.
029 */
030@InterfaceAudience.Private
031public class ObserverContextImpl<E extends CoprocessorEnvironment> implements ObserverContext<E> {
032  private E env;
033  private boolean bypass;
034  /**
035   * Is this operation bypassable?
036   */
037  private final boolean bypassable;
038  private final User caller;
039
040  public ObserverContextImpl(User caller) {
041    this(caller, false);
042  }
043
044  public ObserverContextImpl(User caller, boolean bypassable) {
045    this.caller = caller;
046    this.bypassable = bypassable;
047  }
048
049  @Override
050  public E getEnvironment() {
051    return env;
052  }
053
054  public void prepare(E env) {
055    this.env = env;
056  }
057
058  public boolean isBypassable() {
059    return this.bypassable;
060  };
061
062  @Override
063  public void bypass() {
064    if (!this.bypassable) {
065      throw new UnsupportedOperationException("This method does not support 'bypass'.");
066    }
067    bypass = true;
068  }
069
070  /**
071   * @return {@code true}, if {@link ObserverContext#bypass()} was called by one of the loaded
072   *         coprocessors, {@code false} otherwise.
073   */
074  public boolean shouldBypass() {
075    if (!isBypassable()) {
076      return false;
077    }
078    if (bypass) {
079      bypass = false;
080      return true;
081    }
082    return false;
083  }
084
085  @Override
086  public Optional<User> getCaller() {
087    return Optional.ofNullable(caller);
088  }
089
090  /**
091   * Instantiates a new ObserverContext instance if the passed reference is <code>null</code> and
092   * sets the environment in the new or existing instance. This allows deferring the instantiation
093   * of a ObserverContext until it is actually needed.
094   * @param <E> The environment type for the context
095   * @param env The coprocessor environment to set
096   * @return An instance of <code>ObserverContext</code> with the environment set
097   */
098  @Deprecated
099  // TODO: Remove this method, ObserverContext should not depend on RpcServer
100  public static <E extends CoprocessorEnvironment> ObserverContext<E> createAndPrepare(E env) {
101    ObserverContextImpl<E> ctx = new ObserverContextImpl<>(RpcServer.getRequestUser().orElse(null));
102    ctx.prepare(env);
103    return ctx;
104  }
105}