hbase-common/src/main/java/org/apache/hadoop/hbase/trace/SpanReceiverHost.java

   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.trace;
  19
  20 import java.io.IOException;
  21 import java.util.Collection;
  22 import java.util.HashSet;
  23
  24 import org.apache.hadoop.conf.Configuration;
  25 import org.apache.htrace.core.SpanReceiver;
  26 import org.apache.yetus.audience.InterfaceAudience;
  27 import org.slf4j.Logger;
  28 import org.slf4j.LoggerFactory;
  29
  30 /**
  31  * This class provides functions for reading the names of SpanReceivers from
  32  * hbase-site.xml, adding those SpanReceivers to the Tracer, and closing those
  33  * SpanReceivers when appropriate.
  34  */
  35 @InterfaceAudience.Private
  36 public class SpanReceiverHost {
  37   public static final String SPAN_RECEIVERS_CONF_KEY = "hbase.trace.spanreceiver.classes";
  38   private static final Logger LOG = LoggerFactory.getLogger(SpanReceiverHost.class);
  39   private Collection<SpanReceiver> receivers;
  40   private Configuration conf;
  41   private boolean closed = false;
  42
  43   private enum SingletonHolder {
  44     INSTANCE;
  45     final transient Object lock = new Object();
  46     transient SpanReceiverHost host = null;
  47   }
  48
  49   public static SpanReceiverHost getInstance(Configuration conf) {
  50     synchronized (SingletonHolder.INSTANCE.lock) {
  51       if (SingletonHolder.INSTANCE.host != null) {
  52         return SingletonHolder.INSTANCE.host;
  53       }
  54
  55       SpanReceiverHost host = new SpanReceiverHost(conf);
  56       host.loadSpanReceivers();
  57       SingletonHolder.INSTANCE.host = host;
  58       return SingletonHolder.INSTANCE.host;
  59     }
  60
  61   }
  62
  63   public static Configuration getConfiguration(){
  64     synchronized (SingletonHolder.INSTANCE.lock) {
  65       if (SingletonHolder.INSTANCE.host == null || SingletonHolder.INSTANCE.host.conf == null) {
  66         return null;
  67       }
  68
  69       return SingletonHolder.INSTANCE.host.conf;
  70     }
  71   }
  72
  73   SpanReceiverHost(Configuration conf) {
  74     receivers = new HashSet<>();
  75     this.conf = conf;
  76   }
  77
  78   /**
  79    * Reads the names of classes specified in the {@code hbase.trace.spanreceiver.classes} property
  80    * and instantiates and registers them with the Tracer.
  81    */
  82   public void loadSpanReceivers() {
  83     String[] receiverNames = conf.getStrings(SPAN_RECEIVERS_CONF_KEY);
  84     if (receiverNames == null || receiverNames.length == 0) {
  85       return;
  86     }
  87
  88     SpanReceiver.Builder builder = new SpanReceiver.Builder(new HBaseHTraceConfiguration(conf));
  89     for (String className : receiverNames) {
  90       className = className.trim();
  91
  92       SpanReceiver receiver = builder.className(className).build();
  93       if (receiver != null) {
  94         receivers.add(receiver);
  95         LOG.info("SpanReceiver {} was loaded successfully.", className);
  96       }
  97     }
  98     for (SpanReceiver rcvr : receivers) {
  99       TraceUtil.addReceiver(rcvr);
 100     }
 101   }
 102
 103   /**
 104    * Calls close() on all SpanReceivers created by this SpanReceiverHost.
 105    */
 106   public synchronized void closeReceivers() {
 107     if (closed) {
 108       return;
 109     }
 110
 111     closed = true;
 112     for (SpanReceiver rcvr : receivers) {
 113       try {
 114         rcvr.close();
 115       } catch (IOException e) {
 116         LOG.warn("Unable to close SpanReceiver correctly: " + e.getMessage(), e);
 117       }
 118     }
 119   }
 120 }