Make-Ec2Region-s-datacenter-name-configurable

patch by Jason Brown; reviewed by Vijay for CASSANDRA-5155

conf/cassandra-rackdc.properties

@@ -14,7 +14,11 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-# This file is specifically for the GossipingPropertyFileSnitch and will
+# These properties are used with GossipingPropertyFileSnitch and will
 # indicate the rack and dc for this node
 dc=DC1
 rack=RAC1
+
+# Add a suffix to a datacenter name. Used by the Ec2Snitch and Ec2MultiRegionSnitch
+# to append a string to the EC2 region name.
+#dc_suffix=

src/java/org/apache/cassandra/locator/Ec2Snitch.java

@@ -60,6 +60,9 @@ public class Ec2Snitch extends AbstractNetworkTopologySnitch
         ec2region = az.substring(0, az.length() - 1);
         if (ec2region.endsWith("1"))
             ec2region = az.substring(0, az.length() - 3);
+
+        String datacenterSuffix = SnitchProperties.get("dc_suffix", "");
+        ec2region = ec2region.concat(datacenterSuffix);
         logger.info("EC2Snitch using region: " + ec2region + ", zone: " + ec2zone + ".");
     }
 

src/java/org/apache/cassandra/locator/GossipingPropertyFileSnitch.java

@@ -36,21 +36,16 @@ public class GossipingPropertyFileSnitch extends AbstractNetworkTopologySnitch
 {
     private static final Logger logger = LoggerFactory.getLogger(GossipingPropertyFileSnitch.class);
 
-    public static final String RACKDC_PROPERTY_FILENAME = "cassandra-rackdc.properties";
     private PropertyFileSnitch psnitch;
     private String myDC;
     private String myRack;
 
     public GossipingPropertyFileSnitch() throws ConfigurationException
     {
-        try
-        {
-            loadConfiguration();
-        }
-        catch (ConfigurationException e)
-        {
-            throw new RuntimeException("Unable to load " + RACKDC_PROPERTY_FILENAME + " : ", e);
-        }
+        myDC = SnitchProperties.get("dc", null);
+        myRack = SnitchProperties.get("rack", null);
+        if (myDC == null || myRack == null)
+            throw new ConfigurationException("DC or rack not found in snitch properties");
         try
         {
             psnitch = new PropertyFileSnitch();
@@ -62,35 +57,6 @@ public class GossipingPropertyFileSnitch extends AbstractNetworkTopologySnitch
         }
     }
 
-    private void loadConfiguration() throws ConfigurationException
-    {
-        InputStream stream = GossipingPropertyFileSnitch.class.getClassLoader().getResourceAsStream(RACKDC_PROPERTY_FILENAME);
-        Properties properties = new Properties();
-        try
-        {
-            properties.load(stream);
-        }
-        catch (Exception e)
-        {
-            throw new ConfigurationException("Unable to read " + RACKDC_PROPERTY_FILENAME, e);
-        }
-        finally
-        {
-            FileUtils.closeQuietly(stream);
-        }
-        for (Map.Entry<Object, Object> entry : properties.entrySet())
-        {
-            String key = (String) entry.getKey();
-            String value = (String) entry.getValue();
-            if (key.equals("dc"))
-                myDC = value;
-            else if (key.equals("rack"))
-                myRack = value;
-        }
-        if (myDC == null || myRack == null)
-            throw new ConfigurationException("DC or rack not found in " + RACKDC_PROPERTY_FILENAME);
-    }
-
     /**
      * Return the data center for which an endpoint resides in
      *

src/java/org/apache/cassandra/locator/SnitchProperties.java

@@ -0,0 +1,54 @@
+/*
+ * 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.cassandra.locator;
+
+import java.io.InputStream;
+import java.util.Properties;
+
+import org.apache.cassandra.io.util.FileUtils;
+
+public class SnitchProperties
+{
+    public static final String RACKDC_PROPERTY_FILENAME = "cassandra-rackdc.properties";
+    private static Properties properties = new Properties();
+
+    static
+    {
+        InputStream stream = SnitchProperties.class.getClassLoader().getResourceAsStream(RACKDC_PROPERTY_FILENAME);
+        try
+        {
+            properties.load(stream);
+        }
+        catch (Exception e)
+        {
+            throw new RuntimeException("Unable to read " + RACKDC_PROPERTY_FILENAME, e);
+        }
+        finally
+        {
+            FileUtils.closeQuietly(stream);
+        }
+    }
+
+    /**
+     * Get a snitch property value or return null if not defined.
+     */
+    public static String get(String propertyName, String defaultValue)
+    {
+        return properties.getProperty(propertyName, defaultValue);
+    }
+}

test/conf/cassandra-rackdc.properties

@@ -0,0 +1,24 @@
+# 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.
+
+# These properties are used with GossipingPropertyFileSnitch and will
+# indicate the rack and dc for this node
+dc=DC1
+rack=RAC1
+
+# Add a suffix to a datacenter name. Used by the Ec2Snitch and Ec2MultiRegionSnitch
+# to append a string to the EC2 region name.
+#dc_suffix=