EndPointSnitch example (using a property file)

Patch by Sammy Yu; reviewed by eevans for CASSANDRA-422

git-svn-id: https://svn.apache.org/repos/asf/incubator/cassandra/trunk@812676 13f79535-47bb-0310-9956-ffa450edef68

contrib/endpointsnitch_example/CustomEndPointSnitch.java

@@ -0,0 +1,162 @@
+package org.apache.cassandra.locator;
+
+import java.io.FileNotFoundException;
+import java.io.FileReader;
+import java.io.IOException;
+import java.lang.management.ManagementFactory;
+import java.net.UnknownHostException;
+import java.util.Properties;
+import java.util.StringTokenizer;
+
+import javax.management.MBeanServer;
+import javax.management.ObjectName;
+
+import org.apache.cassandra.locator.EndPointSnitch;
+import org.apache.cassandra.net.EndPoint;
+import org.apache.cassandra.utils.LogUtil;
+import org.apache.log4j.Logger;
+
+/**
+ * CustomEndPointSnitch
+ * 
+ * CustomEndPointSnitch is used by Digg to determine if two IP's are in the same datacenter
+ * or on the same rack.
+ * 
+ * @author Sammy Yu <syu@sammyyu.net>
+ * 
+ */
+public class CustomEndPointSnitch extends EndPointSnitch implements CustomEndPointSnitchMBean {
+    /**
+     * A list of properties with keys being host:port and values being datacenter:rack
+     */
+    private Properties hostProperties = new Properties();
+    
+    /**
+     * The default rack property file to be read.
+     */
+    private static String DEFAULT_RACK_PROPERTY_FILE = "/etc/cassandra/rack.properties"; 
+
+    /**
+     * Whether to use the parent for detection of same node
+     */
+    private boolean runInBaseMode = false;
+    
+    /**
+     * Reference to the logger.
+     */
+    private static Logger logger_ = Logger.getLogger(CustomEndPointSnitch.class);     
+
+    public CustomEndPointSnitch() throws IOException {
+        reloadConfiguration();
+        try
+        {
+            MBeanServer mbs = ManagementFactory.getPlatformMBeanServer();
+            mbs.registerMBean(this, new ObjectName(MBEAN_OBJECT_NAME));
+        }
+        catch (Exception e)
+        {
+            logger_.error(LogUtil.throwableToString(e));
+        }
+    }
+
+    /**
+     * Get the raw information about an end point
+     * 
+     * @param endPoint endPoint to process
+     * 
+     * @return a array of string with the first index being the data center and the second being the rack
+     */
+    public String[] getEndPointInfo(EndPoint endPoint) {
+        String key = endPoint.toString();
+        String value = hostProperties.getProperty(key);
+        if (value == null)
+        {
+            logger_.error("Could not find end point information for " + key + ", will use default.");
+            value = hostProperties.getProperty("default");
+        }
+        StringTokenizer st = new StringTokenizer(value, ":");
+        if (st.countTokens() < 2)
+        {
+            logger_.error("Value for " + key + " is invalid: " + value);
+            return new String [] {"default", "default"};
+        }
+        return new String[] {st.nextToken(), st.nextToken()};
+    }
+
+    /**
+     * Return the data center for which an endpoint resides in
+     *  
+     * @param endPoint the endPoint to process
+     * @return string of data center
+     */
+    public String getDataCenterForEndPoint(EndPoint endPoint) {
+        return getEndPointInfo(endPoint)[0];
+    }
+
+    /**
+     * Return the rack for which an endpoint resides in
+     *  
+     * @param endPoint the endPoint to process
+     * 
+     * @return string of rack
+     */
+    public String getRackForEndPoint(EndPoint endPoint) {
+        return getEndPointInfo(endPoint)[1];
+    }
+
+    @Override
+    public boolean isInSameDataCenter(EndPoint host, EndPoint host2)
+            throws UnknownHostException {
+        if (runInBaseMode) 
+        {
+            return super.isInSameDataCenter(host, host2);
+        }
+        return getDataCenterForEndPoint(host).equals(getDataCenterForEndPoint(host2));
+    }
+
+    @Override
+    public boolean isOnSameRack(EndPoint host, EndPoint host2)
+            throws UnknownHostException {
+        if (runInBaseMode) 
+        {
+            return super.isOnSameRack(host, host2);
+        }
+        if (!isInSameDataCenter(host, host2)) 
+        {
+            return false;
+        }
+        return getRackForEndPoint(host).equals(getRackForEndPoint(host2)); 
+    }
+
+    @Override
+    public String displayConfiguration() {
+        StringBuffer configurationString = new StringBuffer("Current rack configuration\n=================\n");
+        for (Object key: hostProperties.keySet()) {
+            String endpoint = (String) key;
+            String value = hostProperties.getProperty(endpoint);
+            configurationString.append(endpoint + "=" + value + "\n");
+        }
+        return configurationString.toString();
+    }
+    
+    @Override
+    public void reloadConfiguration() throws IOException {        
+        String rackPropertyFilename = System.getProperty("rackFile", DEFAULT_RACK_PROPERTY_FILE);
+        try 
+        {
+            Properties localHostProperties = new Properties();
+            localHostProperties.load(new FileReader(rackPropertyFilename));
+            hostProperties = localHostProperties;
+            runInBaseMode = false;
+        }
+        catch (FileNotFoundException fnfe) {
+            logger_.error("Could not find " + rackPropertyFilename + ", using default EndPointSnitch", fnfe);
+            runInBaseMode = true;
+        }
+        catch (IOException ioe) {
+            logger_.error("Could not process " + rackPropertyFilename, ioe);
+            throw ioe;
+        }
+    }
+
+}

contrib/endpointsnitch_example/CustomEndPointSnitchMBean.java

@@ -0,0 +1,29 @@
+package org.apache.cassandra.locator;
+
+import java.io.IOException;
+
+/**
+ * CustomEndPointSnitchMBean
+ * 
+ * CustomEndPointSnitchMBean is the management interface for Digg's EndpointSnitch MBean
+ * 
+ * @author Sammy Yu <syu@sammyyu.net>
+ * 
+ */
+public interface CustomEndPointSnitchMBean {
+    /**
+     * The object name of the mbean.
+     */
+    public static String MBEAN_OBJECT_NAME = "org.apache.cassandra.locator:type=EndPointSnitch";
+    
+    /**
+     * Reload the rack configuration
+     */
+    public void reloadConfiguration() throws IOException;
+    
+    /**
+     * Display the current configuration
+     */
+    public String displayConfiguration();
+
+}