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1   /**
2    * Licensed to the Apache Software Foundation (ASF) under one
3    * or more contributor license agreements.  See the NOTICE file
4    * distributed with this work for additional information
5    * regarding copyright ownership.  The ASF licenses this file
6    * to you under the Apache License, Version 2.0 (the
7    * "License"); you may not use this file except in compliance
8    * with the License.  You may obtain a copy of the License at
9    *
10   *   http://www.apache.org/licenses/LICENSE-2.0
11   *
12   * Unless required by applicable law or agreed to in writing, software
13   * distributed under the License is distributed on an "AS IS" BASIS,
14   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
15   * See the License for the specific language governing permissions and
16   * limitations under the License.
17   */
18  
19  package org.apache.hadoop.hbase.rest;
20  
21  import java.io.IOException;
22  
23  import org.apache.hadoop.classification.InterfaceAudience;
24  import org.apache.hadoop.conf.Configuration;
25  import org.apache.hadoop.hbase.client.HBaseAdmin;
26  import org.apache.hadoop.hbase.client.HTableInterface;
27  import org.apache.hadoop.hbase.security.UserProvider;
28  import org.apache.hadoop.hbase.util.ConnectionCache;
29  import org.apache.hadoop.security.UserGroupInformation;
30  
31  /**
32   * Singleton class encapsulating global REST servlet state and functions.
33   */
34  @InterfaceAudience.Private
35  public class RESTServlet implements Constants {
36    private static RESTServlet INSTANCE;
37    private final Configuration conf;
38    private final MetricsREST metrics = new MetricsREST();
39    private final ConnectionCache connectionCache;
40    private final UserGroupInformation realUser;
41  
42    static final String CLEANUP_INTERVAL = "hbase.rest.connection.cleanup-interval";
43    static final String MAX_IDLETIME = "hbase.rest.connection.max-idletime";
44  
45    UserGroupInformation getRealUser() {
46      return realUser;
47    }
48  
49    /**
50     * @return the RESTServlet singleton instance
51     */
52    public synchronized static RESTServlet getInstance() {
53      assert(INSTANCE != null);
54      return INSTANCE;
55    }
56  
57    /**
58     * @param conf Existing configuration to use in rest servlet
59     * @param userProvider the login user provider
60     * @return the RESTServlet singleton instance
61     * @throws IOException
62     */
63    public synchronized static RESTServlet getInstance(Configuration conf,
64        UserProvider userProvider) throws IOException {
65      if (INSTANCE == null) {
66        INSTANCE = new RESTServlet(conf, userProvider);
67      }
68      return INSTANCE;
69    }
70  
71    public synchronized static void stop() {
72      if (INSTANCE != null)  INSTANCE = null;
73    }
74  
75    /**
76     * Constructor with existing configuration
77     * @param conf existing configuration
78     * @param userProvider the login user provider
79     * @throws IOException
80     */
81    RESTServlet(final Configuration conf,
82        final UserProvider userProvider) throws IOException {
83      this.realUser = userProvider.getCurrent().getUGI();
84      this.conf = conf;
85  
86      int cleanInterval = conf.getInt(CLEANUP_INTERVAL, 10 * 1000);
87      int maxIdleTime = conf.getInt(MAX_IDLETIME, 10 * 60 * 1000);
88      connectionCache = new ConnectionCache(
89        conf, userProvider, cleanInterval, maxIdleTime);
90    }
91  
92    HBaseAdmin getAdmin() throws IOException {
93      return connectionCache.getAdmin();
94    }
95  
96    /**
97     * Caller closes the table afterwards.
98     */
99    HTableInterface getTable(String tableName) throws IOException {
100     return connectionCache.getTable(tableName);
101   }
102 
103   Configuration getConfiguration() {
104     return conf;
105   }
106 
107   MetricsREST getMetrics() {
108     return metrics;
109   }
110 
111   /**
112    * Helper method to determine if server should
113    * only respond to GET HTTP method requests.
114    * @return boolean for server read-only state
115    */
116   boolean isReadOnly() {
117     return getConfiguration().getBoolean("hbase.rest.readonly", false);
118   }
119 
120   void setEffectiveUser(String effectiveUser) {
121     connectionCache.setEffectiveUser(effectiveUser);
122   }
123 }