HADOOP-4675 Current Ganglia metrics implementation is incompatible with Ganglia 3.1

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/trunk@810710 13f79535-47bb-0310-9956-ffa450edef68

src/java/org/apache/hadoop/metrics/ganglia/GangliaContext31.java

@@ -0,0 +1,144 @@
+/*
+ * GangliaContext.java
+ *
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.apache.hadoop.metrics.ganglia;
+
+import java.io.IOException;
+import java.net.DatagramPacket;
+import java.net.SocketAddress;
+import java.net.UnknownHostException;
+
+import org.apache.commons.logging.Log;
+import org.apache.commons.logging.LogFactory;
+import org.apache.hadoop.conf.Configuration;
+import org.apache.hadoop.metrics.ContextFactory;
+import org.apache.hadoop.net.DNS;
+
+/**
+ * Context for sending metrics to Ganglia version 3.1.x.
+ * 
+ * 3.1.1 has a slightly different wire portal compared to 3.0.x.
+ */
+public class GangliaContext31 extends GangliaContext {
+
+  String hostName = "UNKNOWN.example.com";
+
+  private static final Log LOG = 
+    LogFactory.getLog("org.apache.hadoop.util.GangliaContext31");
+
+  public void init(String contextName, ContextFactory factory) {
+    super.init(contextName, factory);
+
+    LOG.debug("Initializing the GangliaContext31 for Ganglia 3.1 metrics.");
+
+    // Take the hostname from the DNS class.
+
+    Configuration conf = new Configuration();
+
+    if (conf.get("slave.host.name") != null) {
+      hostName = conf.get("slave.host.name");
+    } else {
+      try {
+        hostName = DNS.getDefaultHost(
+          conf.get("dfs.datanode.dns.interface","default"),
+          conf.get("dfs.datanode.dns.nameserver","default"));
+      } catch (UnknownHostException uhe) {
+        LOG.error(uhe);
+    	hostName = "UNKNOWN.example.com";
+      }
+    }
+  }
+
+  protected void emitMetric(String name, String type,  String value) 
+    throws IOException
+  {
+    if (name == null) {
+      LOG.warn("Metric was emitted with no name.");
+      return;
+    } else if (value == null) {
+      LOG.warn("Metric name " + name +" was emitted with a null value.");
+      return;
+    } else if (type == null) {
+      LOG.warn("Metric name " + name + ", value " + value + " has no type.");
+      return;
+    }
+
+    LOG.debug("Emitting metric " + name + ", type " + type + ", value " + 
+      value + " from hostname" + hostName);
+
+    String units = getUnits(name);
+    if (units == null) {
+      LOG.warn("Metric name " + name + ", value " + value
+        + " had 'null' units");
+      units = "";
+    }
+    int slope = getSlope(name);
+    int tmax = getTmax(name);
+    int dmax = getDmax(name);
+    offset = 0;
+    String groupName = name.substring(0,name.lastIndexOf("."));
+
+    // The following XDR recipe was done through a careful reading of
+    // gm_protocol.x in Ganglia 3.1 and carefully examining the output of
+    // the gmetric utility with strace.
+
+    // First we send out a metadata message
+    xdr_int(128);         // metric_id = metadata_msg
+    xdr_string(hostName); // hostname
+    xdr_string(name);     // metric name
+    xdr_int(0);           // spoof = False
+    xdr_string(type);     // metric type
+    xdr_string(name);     // metric name
+    xdr_string(units);    // units
+    xdr_int(slope);       // slope
+    xdr_int(tmax);        // tmax, the maximum time between metrics
+    xdr_int(dmax);        // dmax, the maximum data value
+
+    xdr_int(1);             /*Num of the entries in extra_value field for 
+                              Ganglia 3.1.x*/
+    xdr_string("GROUP");    /*Group attribute*/
+    xdr_string(groupName);  /*Group value*/
+
+    for (SocketAddress socketAddress : metricsServers) {
+      DatagramPacket packet =
+        new DatagramPacket(buffer, offset, socketAddress);
+      datagramSocket.send(packet);
+    }
+
+    // Now we send out a message with the actual value.
+    // Technically, we only need to send out the metadata message once for
+    // each metric, but I don't want to have to record which metrics we did and
+    // did not send.
+    offset = 0;
+    xdr_int(133);         // we are sending a string value
+    xdr_string(hostName); // hostName
+    xdr_string(name);     // metric name
+    xdr_int(0);           // spoof = False
+    xdr_string("%s");     // format field
+    xdr_string(value);    // metric value
+        
+    for (SocketAddress socketAddress : metricsServers) {
+      DatagramPacket packet = 
+        new DatagramPacket(buffer, offset, socketAddress);
+      datagramSocket.send(packet);
+    }
+  }
+
+}