GUACAMOLE-102: Initial addition of connection weight to JDBC authentication extension

extensions/guacamole-auth-jdbc/modules/guacamole-auth-jdbc-base/src/main/java/org/apache/guacamole/auth/jdbc/JDBCEnvironment.java

@@ -81,6 +81,17 @@ public abstract class JDBCEnvironment extends LocalEnvironment {
      *     If an error occurs while retrieving the property.
      */
     public abstract int getDefaultMaxConnections() throws GuacamoleException;
+
+    /**
+     * Returns the connection weight for the purpose of WRR calculation
+     *
+     * @return
+     *     The weight of the connection.
+     *
+     * @throws GuacamoleException  
+     *     If an error occurs while retrieving the property.
+     */
+    public abstract int getConnectionWeight() throws GuacamoleException;
     
     /**
      * Returns the default maximum number of concurrent connections to allow to 

extensions/guacamole-auth-jdbc/modules/guacamole-auth-jdbc-base/src/main/java/org/apache/guacamole/auth/jdbc/connection/ConnectionModel.java

@@ -54,6 +54,13 @@ public class ConnectionModel extends ChildObjectModel {
      */
     private Integer maxConnectionsPerUser;
 
+    /**
+     * The weight of the connection for the purposes of calculating
+     * WRR algorithm.  null indicates nothing has been set, -1 indicates
+     * the system is unavailable.
+     */
+    private Integer connectionWeight;
+
     /**
      * The identifiers of all readable sharing profiles associated with this
      * connection.
@@ -164,6 +171,29 @@ public class ConnectionModel extends ChildObjectModel {
         return maxConnectionsPerUser;
     }
 
+    /**
+     * Sets the connection weight.
+     *
+     * @param connectionWeight
+     *     The weight of the connection.  null is acceptable, -1 indicates the
+     *     connection should not be used.
+     */
+    public void setConnectionWeight(Integer connectionWeight) {
+        this.connectionWeight = connectionWeight;
+    }
+
+    /**
+     * Returns the connection weight used in calculating the
+     * WRR algorithm.
+     *
+     * @return
+     *     The connection weight.  Null indicates no weight has been set,
+     *     -1 indicates that the system is unavailable.
+     */
+    public Integer getConnectionWeight() {
+        return connectionWeight;
+    }
+
     /**
      * Sets the maximum number of connections that can be established to this
      * connection concurrently by any one user.

extensions/guacamole-auth-jdbc/modules/guacamole-auth-jdbc-base/src/main/java/org/apache/guacamole/auth/jdbc/connection/ModeledConnection.java

@@ -116,6 +116,11 @@ public class ModeledConnection extends ModeledChildDirectoryObject<ConnectionMod
      */
     public static final String MAX_CONNECTIONS_PER_USER_NAME = "max-connections-per-user";
 
+    /**
+     * The connection weight for the WRR algorithm.
+     */
+    public static final String CONNECTION_WEIGHT = "connection-weight";
+
     /**
      * All attributes related to restricting user accounts, within a logical
      * form.
@@ -265,6 +270,9 @@ public class ModeledConnection extends ModeledChildDirectoryObject<ConnectionMod
             }
         }
 
+        // Set connection weight
+        attributes.put(CONNECTION_WEIGHT, NumericField.format(getModel().getConnectionWeight()));
+
         return attributes;
     }
 
@@ -310,6 +318,13 @@ public class ModeledConnection extends ModeledChildDirectoryObject<ConnectionMod
         else
             getModel().setProxyEncryptionMethod(null);
 
+        // Translate connection weight attribute
+        try { getModel().setConnectionWeight(NumericField.parse(attributes.get(CONNECTION_WEIGHT))); }
+        catch (NumberFormatException e) {
+            logger.warn("Not setting the connection weight: {}", e.getMessage());
+            logger.debug("Unable to parse numeric attribute.", e);
+        }
+
     }
 
     /**
@@ -394,6 +409,25 @@ public class ModeledConnection extends ModeledChildDirectoryObject<ConnectionMod
             encryptionMethod != null ? encryptionMethod : defaultConfig.getEncryptionMethod()
         );
 
+    /** 
+     * Returns the weight of the connection, or the default.
+     *  
+     * @return
+     *     The weight of the connection.
+     *  
+     * @throws GuacamoleException
+     *     If an error occurs while parsing the concurrency limit properties
+     *     specified within guacamole.properties.
+     */
+    public int getConnectionWeight() throws GuacamoleException {
+
+        // Pull default from environment if weight is unset
+        Integer value = getModel().getConnectionWeight();
+        if (value == null)
+            return environment.getDefaultConnectionWeight();
+
+        // Otherwise use defined value
+        return value;
     }
 
 }

extensions/guacamole-auth-jdbc/modules/guacamole-auth-jdbc-base/src/main/java/org/apache/guacamole/auth/jdbc/tunnel/RestrictedGuacamoleTunnelService.java

@@ -33,6 +33,8 @@ import org.apache.guacamole.GuacamoleResourceConflictException;
 import org.apache.guacamole.auth.jdbc.JDBCEnvironment;
 import org.apache.guacamole.auth.jdbc.connectiongroup.ModeledConnectionGroup;
 import org.apache.guacamole.auth.jdbc.user.RemoteAuthenticatedUser;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
 
 
 /**
@@ -44,6 +46,11 @@ import org.apache.guacamole.auth.jdbc.user.RemoteAuthenticatedUser;
 public class RestrictedGuacamoleTunnelService
     extends AbstractGuacamoleTunnelService {
 
+    /**
+     * Logger for this class.
+     */
+    private static final Logger logger = LoggerFactory.getLogger(RestrictedGuacamoleTunnelService.class);
+
     /**
      * The environment of the Guacamole server.
      */
@@ -166,20 +173,24 @@ public class RestrictedGuacamoleTunnelService
     protected ModeledConnection acquire(RemoteAuthenticatedUser user,
             List<ModeledConnection> connections) throws GuacamoleException {
 
+        logger.trace("Attempting to acquire a connection...");
         // Do not acquire connection unless within overall limits
         if (!tryIncrement(totalActiveConnections, environment.getAbsoluteMaxConnections()))
             throw new GuacamoleResourceConflictException("Cannot connect. Overall maximum connections reached.");
 
         // Get username
         String username = user.getIdentifier();
+        logger.trace("Username is: {}", username);
 
+        logger.trace("Sorting {} connections.", connections.size());
         // Sort connections in ascending order of usage
         ModeledConnection[] sortedConnections = connections.toArray(new ModeledConnection[connections.size()]);
         Arrays.sort(sortedConnections, new Comparator<ModeledConnection>() {
 
             @Override
             public int compare(ModeledConnection a, ModeledConnection b) {
-
+                
+                logger.trace("Comparing {} to {}.", a.getName(), b.getName());
                 return getActiveConnections(a).size()
                      - getActiveConnections(b).size();
 
@@ -194,15 +205,18 @@ public class RestrictedGuacamoleTunnelService
         for (ModeledConnection connection : sortedConnections) {
 
             // Attempt to aquire connection according to per-user limits
+            logger.trace("Trying to grab a seat on this train: {}", connection.getName());
             Seat seat = new Seat(username, connection.getIdentifier());
             if (tryAdd(activeSeats, seat,
                     connection.getMaxConnectionsPerUser())) {
 
+                logger.trace("Got a seat, trying to get the connection...");
                 // Attempt to aquire connection according to overall limits
                 if (tryAdd(activeConnections, connection.getIdentifier(),
                         connection.getMaxConnections()))
                     return connection;
 
+                logger.trace("Uh-oh, failed to get the connection...");
                 // Acquire failed - retry with next connection
                 activeSeats.remove(seat);
 
@@ -213,6 +227,7 @@ public class RestrictedGuacamoleTunnelService
 
         }
 
+        logger.trace("Well, we failed to get a seat at all...");
         // Acquire failed
         totalActiveConnections.decrementAndGet();