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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  package org.apache.hadoop.hbase.regionserver;
19  
20  import java.lang.reflect.Method;
21  import java.util.HashMap;
22  import java.util.Map;
23  
24  import org.apache.commons.logging.Log;
25  import org.apache.commons.logging.LogFactory;
26  import org.apache.hadoop.hbase.classification.InterfaceAudience;
27  import org.apache.hadoop.hbase.HConstants;
28  import org.apache.hadoop.hbase.NotServingRegionException;
29  import org.apache.hadoop.hbase.ipc.PriorityFunction;
30  import org.apache.hadoop.hbase.protobuf.generated.AdminProtos.CloseRegionRequest;
31  import org.apache.hadoop.hbase.protobuf.generated.AdminProtos.CompactRegionRequest;
32  import org.apache.hadoop.hbase.protobuf.generated.AdminProtos.FlushRegionRequest;
33  import org.apache.hadoop.hbase.protobuf.generated.AdminProtos.GetRegionInfoRequest;
34  import org.apache.hadoop.hbase.protobuf.generated.AdminProtos.GetStoreFileRequest;
35  import org.apache.hadoop.hbase.protobuf.generated.AdminProtos.SplitRegionRequest;
36  import org.apache.hadoop.hbase.protobuf.generated.ClientProtos.GetRequest;
37  import org.apache.hadoop.hbase.protobuf.generated.ClientProtos.MultiRequest;
38  import org.apache.hadoop.hbase.protobuf.generated.ClientProtos.MutateRequest;
39  import org.apache.hadoop.hbase.protobuf.generated.ClientProtos.ScanRequest;
40  import org.apache.hadoop.hbase.protobuf.generated.HBaseProtos.RegionSpecifier;
41  import org.apache.hadoop.hbase.protobuf.generated.RPCProtos.RequestHeader;
42  import org.apache.hadoop.hbase.regionserver.HRegionServer.QosPriority;
43  
44  import com.google.common.annotations.VisibleForTesting;
45  import com.google.protobuf.Message;
46  import com.google.protobuf.TextFormat;
47  
48  
49  /**
50   * Reads special method annotations and table names to figure a priority for use by QoS facility in
51   * ipc; e.g: rpcs to hbase:meta get priority.
52   */
53  // TODO: Remove.  This is doing way too much work just to figure a priority.  Do as Elliott
54  // suggests and just have the client specify a priority.
55  
56  //The logic for figuring out high priority RPCs is as follows:
57  //1. if the method is annotated with a QosPriority of QOS_HIGH,
58  //   that is honored
59  //2. parse out the protobuf message and see if the request is for meta
60  //   region, and if so, treat it as a high priority RPC
61  //Some optimizations for (2) are done here -
62  //Clients send the argument classname as part of making the RPC. The server
63  //decides whether to deserialize the proto argument message based on the
64  //pre-established set of argument classes (knownArgumentClasses below).
65  //This prevents the server from having to deserialize all proto argument
66  //messages prematurely.
67  //All the argument classes declare a 'getRegion' method that returns a
68  //RegionSpecifier object. Methods can be invoked on the returned object
69  //to figure out whether it is a meta region or not.
70  @InterfaceAudience.Private
71  class AnnotationReadingPriorityFunction implements PriorityFunction {
72    public static final Log LOG =
73      LogFactory.getLog(AnnotationReadingPriorityFunction.class.getName());
74    private final Map<String, Integer> annotatedQos;
75    //We need to mock the regionserver instance for some unit tests (set via
76    //setRegionServer method.
77    private HRegionServer hRegionServer;
78    @SuppressWarnings("unchecked")
79    private final Class<? extends Message>[] knownArgumentClasses = new Class[]{
80        GetRegionInfoRequest.class,
81        GetStoreFileRequest.class,
82        CloseRegionRequest.class,
83        FlushRegionRequest.class,
84        SplitRegionRequest.class,
85        CompactRegionRequest.class,
86        GetRequest.class,
87        MutateRequest.class,
88        ScanRequest.class
89    };
90  
91    // Some caches for helping performance
92    private final Map<String, Class<? extends Message>> argumentToClassMap =
93      new HashMap<String, Class<? extends Message>>();
94    private final Map<String, Map<Class<? extends Message>, Method>> methodMap =
95      new HashMap<String, Map<Class<? extends Message>, Method>>();
96  
97    AnnotationReadingPriorityFunction(final HRegionServer hrs) {
98      this.hRegionServer = hrs;
99      Map<String, Integer> qosMap = new HashMap<String, Integer>();
100     for (Method m : HRegionServer.class.getMethods()) {
101       QosPriority p = m.getAnnotation(QosPriority.class);
102       if (p != null) {
103         // Since we protobuf'd, and then subsequently, when we went with pb style, method names
104         // are capitalized.  This meant that this brittle compare of method names gotten by
105         // reflection no longer matched the method names coming in over pb.  TODO: Get rid of this
106         // check.  For now, workaround is to capitalize the names we got from reflection so they
107         // have chance of matching the pb ones.
108         String capitalizedMethodName = capitalize(m.getName());
109         qosMap.put(capitalizedMethodName, p.priority());
110       }
111     }
112     this.annotatedQos = qosMap;
113     if (methodMap.get("getRegion") == null) {
114       methodMap.put("hasRegion", new HashMap<Class<? extends Message>, Method>());
115       methodMap.put("getRegion", new HashMap<Class<? extends Message>, Method>());
116     }
117     for (Class<? extends Message> cls : knownArgumentClasses) {
118       argumentToClassMap.put(cls.getName(), cls);
119       try {
120         methodMap.get("hasRegion").put(cls, cls.getDeclaredMethod("hasRegion"));
121         methodMap.get("getRegion").put(cls, cls.getDeclaredMethod("getRegion"));
122       } catch (Exception e) {
123         throw new RuntimeException(e);
124       }
125     }
126   }
127 
128   private String capitalize(final String s) {
129     StringBuilder strBuilder = new StringBuilder(s);
130     strBuilder.setCharAt(0, Character.toUpperCase(strBuilder.charAt(0)));
131     return strBuilder.toString();
132   }
133 
134   public boolean isMetaRegion(byte[] regionName) {
135     HRegion region;
136     try {
137       region = hRegionServer.getRegion(regionName);
138     } catch (NotServingRegionException ignored) {
139       return false;
140     }
141     return region.getRegionInfo().isMetaTable();
142   }
143 
144   @Override
145   public int getPriority(RequestHeader header, Message param) {
146     String methodName = header.getMethodName();
147     Integer priorityByAnnotation = annotatedQos.get(methodName);
148     if (priorityByAnnotation != null) {
149       return priorityByAnnotation;
150     }
151     if (param == null) {
152       return HConstants.NORMAL_QOS;
153     }
154     if (methodName.equalsIgnoreCase("multi") && param instanceof MultiRequest) {
155       // The multi call has its priority set in the header.  All calls should work this way but
156       // only this one has been converted so far.  No priority == NORMAL_QOS.
157       return header.hasPriority()? header.getPriority(): HConstants.NORMAL_QOS;
158     }
159     String cls = param.getClass().getName();
160     Class<? extends Message> rpcArgClass = argumentToClassMap.get(cls);
161     RegionSpecifier regionSpecifier = null;
162     //check whether the request has reference to meta region or now.
163     try {
164       // Check if the param has a region specifier; the pb methods are hasRegion and getRegion if
165       // hasRegion returns true.  Not all listed methods have region specifier each time.  For
166       // example, the ScanRequest has it on setup but thereafter relies on the scannerid rather than
167       // send the region over every time.
168       Method hasRegion = methodMap.get("hasRegion").get(rpcArgClass);
169       if (hasRegion != null && (Boolean)hasRegion.invoke(param, (Object[])null)) {
170         Method getRegion = methodMap.get("getRegion").get(rpcArgClass);
171         regionSpecifier = (RegionSpecifier)getRegion.invoke(param, (Object[])null);
172         HRegion region = hRegionServer.getRegion(regionSpecifier);
173         if (region.getRegionInfo().isMetaTable()) {
174           if (LOG.isTraceEnabled()) {
175             LOG.trace("High priority because region=" + region.getRegionNameAsString());
176           }
177           return HConstants.HIGH_QOS;
178         }
179       }
180     } catch (Exception ex) {
181       // Not good throwing an exception out of here, a runtime anyways.  Let the query go into the
182       // server and have it throw the exception if still an issue.  Just mark it normal priority.
183       if (LOG.isTraceEnabled()) LOG.trace("Marking normal priority after getting exception=" + ex);
184       return HConstants.NORMAL_QOS;
185     }
186 
187     if (methodName.equalsIgnoreCase("scan")) { // scanner methods...
188       ScanRequest request = (ScanRequest)param;
189       if (!request.hasScannerId()) {
190         return HConstants.NORMAL_QOS;
191       }
192       RegionScanner scanner = hRegionServer.getScanner(request.getScannerId());
193       if (scanner != null && scanner.getRegionInfo().isMetaRegion()) {
194         if (LOG.isTraceEnabled()) {
195           // Scanner requests are small in size so TextFormat version should not overwhelm log.
196           LOG.trace("High priority scanner request " + TextFormat.shortDebugString(request));
197         }
198         return HConstants.HIGH_QOS;
199       }
200     }
201     return HConstants.NORMAL_QOS;
202   }
203 
204   @VisibleForTesting
205   void setRegionServer(final HRegionServer hrs) {
206     this.hRegionServer = hrs;
207   }
208 }