Fix JMXFetch issue when several instances on the same host (#124)

* Remove storage of connections in the connection manager
The connection will now be stored by the instance. No more shared connections

* Change ConnectionManager into ConnectionFactory

src/main/java/org/datadog/jmxfetch/ConnectionFactory.java

@@ -0,0 +1,33 @@
+package org.datadog.jmxfetch;
+
+import java.io.IOException;
+import java.util.LinkedHashMap;
+
+import org.apache.log4j.Logger;
+
+
+/**
+ * Singleton used to create connections to the MBeanServer
+ */
+public class ConnectionFactory {
+    private final static Logger LOGGER = Logger.getLogger(ConnectionFactory.class.getName());
+    public static final String PROCESS_NAME_REGEX = "process_name_regex";
+    private static ConnectionFactory connectionFactory = null;
+
+    public static Connection createConnection(LinkedHashMap<String, Object> connectionParams) throws IOException {
+        if (connectionParams.get(PROCESS_NAME_REGEX) != null) {
+            try {
+                Class.forName( "com.sun.tools.attach.AttachNotSupportedException" );
+            } catch (ClassNotFoundException e) {
+                throw new IOException("Unable to find tools.jar. Are you using a JDK and did you set the pass to tools.jar ?");
+            }
+            LOGGER.info("Connecting using Attach API");
+            return new AttachApiConnection(connectionParams);
+
+        }
+        LOGGER.info("Connecting using JMX Remote");
+        return new RemoteConnection(connectionParams);
+
+    }
+
+}

src/main/java/org/datadog/jmxfetch/Instance.java

@@ -125,9 +125,21 @@ public Instance(LinkedHashMap<String, Object> yamlInstance, LinkedHashMap<String
         configurationList.add(new Configuration((LinkedHashMap<String, Object>) new YamlParser(this.getClass().getResourceAsStream("/jmx-2.yaml")).getParsedYaml()));
     }
 
+    public Connection getConnection(LinkedHashMap<String, Object> connectionParams, boolean forceNewConnection) throws IOException {
+        if (connection == null || !connection.isAlive()) {
+            LOGGER.info("Connection closed or does not exist. Creating a new connection!");
+            return ConnectionFactory.createConnection(connectionParams);
+        } else if (forceNewConnection) {
+                LOGGER.info("Forcing the creation of a new connection");
+                connection.closeConnector();
+                return ConnectionFactory.createConnection(connectionParams);
+        }
+        return connection;
+    }
+
     public void init(boolean forceNewConnection) throws IOException, FailedLoginException, SecurityException {
         LOGGER.info("Trying to connect to JMX Server at " + this.toString());
-        connection = ConnectionManager.getInstance().getConnection(yaml, forceNewConnection);
+        connection = getConnection(yaml, forceNewConnection);
         LOGGER.info("Connected to JMX Server at " + this.toString());
         this.refreshBeansList();
         this.getMatchingAttributes();