GUACAMOLE-102: Merge support for weighted least-connections (WLC) balancing algorithm.

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

@@ -81,7 +81,7 @@ public abstract class JDBCEnvironment extends LocalEnvironment {
      *     If an error occurs while retrieving the property.
      */
     public abstract int getDefaultMaxConnections() throws GuacamoleException;
-    
+
     /**
      * Returns the default maximum number of concurrent connections to allow to 
      * any one connection group, unless specified differently on an individual 

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
+     * WLC algorithm.  null indicates nothing has been set, and anything less
+     * than 1 eliminates the system from being used for connections.
+     */
+    private Integer connectionWeight;
+
     /**
      * The identifiers of all readable sharing profiles associated with this
      * connection.
@@ -164,6 +171,31 @@ public class ConnectionModel extends ChildObjectModel {
         return maxConnectionsPerUser;
     }
 
+    /**
+     * Sets the connection weight for load balancing.
+     *
+     * @param connectionWeight
+     *     The weight of the connection used in load balancing. 
+     *     The value is not required for the connection (null), and
+     *     values less than 1 will prevent the connection from being
+     *     used.
+     */
+    public void setConnectionWeight(Integer connectionWeight) {
+        this.connectionWeight = connectionWeight;
+    }
+
+    /**
+     * Returns the connection weight used in applying weighted
+     * load balancing algorithms.
+     *
+     * @return
+     *     The connection weight used in applying weighted
+     *     load balancing aglorithms.
+     */
+    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 attribute used for weighted load balancing algorithms.
+     */
+    public static final String CONNECTION_WEIGHT = "weight";
+
     /**
      * All attributes related to restricting user accounts, within a logical
      * form.
@@ -125,12 +130,20 @@ public class ModeledConnection extends ModeledChildDirectoryObject<ConnectionMod
         new NumericField(MAX_CONNECTIONS_PER_USER_NAME)
     ));
 
+    /**
+     * All attributes related to load balancing in a logical form.
+     */
+    public static final Form LOAD_BALANCING = new Form("load-balancing", Arrays.<Field>asList(
+        new NumericField(CONNECTION_WEIGHT)
+    ));
+
     /**
      * All possible attributes of connection objects organized as individual,
      * logical forms.
      */
     public static final Collection<Form> ATTRIBUTES = Collections.unmodifiableCollection(Arrays.asList(
         CONCURRENCY_LIMITS,
+        LOAD_BALANCING,
         GUACD_PARAMETERS
     ));
 
@@ -265,6 +278,9 @@ public class ModeledConnection extends ModeledChildDirectoryObject<ConnectionMod
             }
         }
 
+        // Set connection weight
+        attributes.put(CONNECTION_WEIGHT, NumericField.format(getModel().getConnectionWeight()));
+
         return attributes;
     }
 
@@ -310,6 +326,13 @@ 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);
+        }
+
     }
 
     /**
@@ -393,6 +416,23 @@ public class ModeledConnection extends ModeledChildDirectoryObject<ConnectionMod
             port             != null ? port             : defaultConfig.getPort(),
             encryptionMethod != null ? encryptionMethod : defaultConfig.getEncryptionMethod()
         );
+    }
+
+    /** 
+     * Returns the weight of the connection used in applying weighted
+     * load balancing algorithms, or a default of 1 if the 
+     * attribute is undefined.
+     *  
+     * @return
+     *     The weight of the connection used in applying weighted
+     *     load balancing algorithms.
+     */
+    public int getConnectionWeight() {
+
+        Integer connectionWeight = getModel().getConnectionWeight();
+        if (connectionWeight == null)
+            return 1;
+        return connectionWeight;
 
     }
 

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.
      */
@@ -180,8 +187,24 @@ public class RestrictedGuacamoleTunnelService
             @Override
             public int compare(ModeledConnection a, ModeledConnection b) {
 
-                return getActiveConnections(a).size()
+                // Active connections
-                     - getActiveConnections(b).size();
+                int connA = getActiveConnections(a).size();
+                int connB = getActiveConnections(b).size();
+
+                // Assigned weight
+                int weightA = a.getConnectionWeight();
+                int weightB = b.getConnectionWeight();
+
+                // Calculated weight of connections
+                int calcWeightA = connA * weightB;
+                int calcWeightB = connB * weightA;
+
+                // If calculated weights are equal, return difference in assigned weight
+                if (calcWeightA == calcWeightB)
+                    return (weightA - weightB);
+
+                // Return different in calculated weights
+                return (calcWeightA - calcWeightB);
 
             }
 
@@ -193,6 +216,12 @@ public class RestrictedGuacamoleTunnelService
         // Return the first unreserved connection
         for (ModeledConnection connection : sortedConnections) {
 
+            // If connection weight is less than 1 this host is disabled and should not be used.
+            if (connection.getConnectionWeight() < 1) {
+                logger.debug("Weight for {} is < 1, connection will be skipped.", connection.getName());
+                continue;
+            }
+
             // Attempt to aquire connection according to per-user limits
             Seat seat = new Seat(username, connection.getIdentifier());
             if (tryAdd(activeSeats, seat,

extensions/guacamole-auth-jdbc/modules/guacamole-auth-jdbc-base/src/main/resources/translations/en.json

@@ -20,6 +20,8 @@
         "FIELD_HEADER_MAX_CONNECTIONS"          : "Maximum number of connections:",
         "FIELD_HEADER_MAX_CONNECTIONS_PER_USER" : "Maximum number of connections per user:",
 
+        "FIELD_HEADER_WEIGHT"                   : "Connection weight:",
+
         "FIELD_HEADER_GUACD_HOSTNAME"   : "Hostname:",
         "FIELD_HEADER_GUACD_ENCRYPTION" : "Encryption:",
         "FIELD_HEADER_GUACD_PORT"       : "Port:",
@@ -28,8 +30,9 @@
         "FIELD_OPTION_GUACD_ENCRYPTION_NONE"  : "None (unencrypted)",
         "FIELD_OPTION_GUACD_ENCRYPTION_SSL"   : "SSL / TLS",
 
-        "SECTION_HEADER_CONCURRENCY" : "Concurrency Limits",
+        "SECTION_HEADER_CONCURRENCY"    : "Concurrency Limits",
-        "SECTION_HEADER_GUACD"       : "Guacamole Proxy Parameters (guacd)"
+        "SECTION_HEADER_LOAD_BALANCING" : "Load Balancing",
+        "SECTION_HEADER_GUACD"          : "Guacamole Proxy Parameters (guacd)"
 
     },
 

extensions/guacamole-auth-jdbc/modules/guacamole-auth-jdbc-mysql/schema/001-create-schema.sql

@@ -34,7 +34,6 @@ CREATE TABLE `guacamole_connection_group` (
   `max_connections_per_user` int(11),
   `enable_session_affinity`  boolean NOT NULL DEFAULT 0,
 
-
   PRIMARY KEY (`connection_group_id`),
   UNIQUE KEY `connection_group_name_parent` (`connection_group_name`, `parent_id`),
 
@@ -65,6 +64,10 @@ CREATE TABLE `guacamole_connection` (
   -- Concurrency limits
   `max_connections`          int(11),
   `max_connections_per_user` int(11),
+  
+  -- Connection weight
+  `connection_weight`        int(11),
+
 
   PRIMARY KEY (`connection_id`),
   UNIQUE KEY `connection_name_parent` (`connection_name`, `parent_id`),

extensions/guacamole-auth-jdbc/modules/guacamole-auth-jdbc-mysql/schema/upgrade/upgrade-pre-0.9.14.sql

@@ -0,0 +1,25 @@
+--
+-- 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.
+--
+
+--
+-- Add per-connection weight
+--
+
+ALTER TABLE guacamole_connection
+    ADD COLUMN connection_weight int(11);

extensions/guacamole-auth-jdbc/modules/guacamole-auth-jdbc-mysql/src/main/resources/org/apache/guacamole/auth/jdbc/connection/ConnectionMapper.xml

@@ -37,6 +37,7 @@
         <result column="proxy_port"               property="proxyPort"             jdbcType="INTEGER"/>
         <result column="proxy_encryption_method"  property="proxyEncryptionMethod" jdbcType="VARCHAR"
                 javaType="org.apache.guacamole.net.auth.GuacamoleProxyConfiguration$EncryptionMethod"/>
+        <result column="connection_weight"        property="connectionWeight"      jdbcType="INTEGER"/>
 
         <!-- Associated sharing profiles -->
         <collection property="sharingProfileIdentifiers" resultSet="sharingProfiles" ofType="java.lang.String"
@@ -95,7 +96,8 @@
             max_connections_per_user,
             proxy_hostname,
             proxy_port,
-            proxy_encryption_method
+            proxy_encryption_method,
+            connection_weight
         FROM guacamole_connection
         WHERE connection_id IN
             <foreach collection="identifiers" item="identifier"
@@ -126,7 +128,8 @@
             max_connections_per_user,
             proxy_hostname,
             proxy_port,
-            proxy_encryption_method
+            proxy_encryption_method,
+            connection_weight
         FROM guacamole_connection
         JOIN guacamole_connection_permission ON guacamole_connection_permission.connection_id = guacamole_connection.connection_id
         WHERE guacamole_connection.connection_id IN
@@ -162,7 +165,8 @@
             max_connections_per_user,
             proxy_hostname,
             proxy_port,
-            proxy_encryption_method
+            proxy_encryption_method,
+            connection_weight
         FROM guacamole_connection
         WHERE 
             <if test="parentIdentifier != null">parent_id = #{parentIdentifier,jdbcType=VARCHAR}</if>
@@ -189,7 +193,8 @@
             max_connections_per_user,
             proxy_hostname,
             proxy_port,
-            proxy_encryption_method
+            proxy_encryption_method,
+            connection_weight
         )
         VALUES (
             #{object.name,jdbcType=VARCHAR},
@@ -199,7 +204,8 @@
             #{object.maxConnectionsPerUser,jdbcType=INTEGER},
             #{object.proxyHostname,jdbcType=VARCHAR},
             #{object.proxyPort,jdbcType=INTEGER},
-            #{object.proxyEncryptionMethod,jdbcType=VARCHAR}
+            #{object.proxyEncryptionMethod,jdbcType=VARCHAR},
+            #{object.connectionWeight,jdbcType=INTEGER}
         )
 
     </insert>
@@ -214,7 +220,8 @@
             max_connections_per_user = #{object.maxConnectionsPerUser,jdbcType=INTEGER},
             proxy_hostname           = #{object.proxyHostname,jdbcType=VARCHAR},
             proxy_port               = #{object.proxyPort,jdbcType=INTEGER},
-            proxy_encryption_method  = #{object.proxyEncryptionMethod,jdbcType=VARCHAR}
+            proxy_encryption_method  = #{object.proxyEncryptionMethod,jdbcType=VARCHAR},
+            connection_weight        = #{object.connectionWeight,jdbcType=INTEGER}
         WHERE connection_id = #{object.objectID,jdbcType=INTEGER}
     </update>
 

extensions/guacamole-auth-jdbc/modules/guacamole-auth-jdbc-postgresql/schema/001-create-schema.sql

@@ -106,6 +106,9 @@ CREATE TABLE guacamole_connection (
   max_connections          integer,
   max_connections_per_user integer,
 
+  -- Connection Weight
+  connection_weight        integer,
+
   -- Guacamole proxy (guacd) overrides
   proxy_port              integer,
   proxy_hostname          varchar(512),

extensions/guacamole-auth-jdbc/modules/guacamole-auth-jdbc-postgresql/schema/upgrade/upgrade-pre-0.9.14.sql

@@ -0,0 +1,25 @@
+--
+-- 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.
+--
+
+--
+-- Add per-connection weight
+--
+
+ALTER TABLE guacamole_connection
+    ADD COLUMN connection_weight int;

extensions/guacamole-auth-jdbc/modules/guacamole-auth-jdbc-postgresql/src/main/resources/org/apache/guacamole/auth/jdbc/connection/ConnectionMapper.xml

@@ -37,6 +37,7 @@
         <result column="proxy_port"               property="proxyPort"             jdbcType="INTEGER"/>
         <result column="proxy_encryption_method"  property="proxyEncryptionMethod" jdbcType="VARCHAR"
                 javaType="org.apache.guacamole.net.auth.GuacamoleProxyConfiguration$EncryptionMethod"/>
+        <result column="connection_weight"        property="connectionWeight"      jdbcType="INTEGER"/>
 
         <!-- Associated sharing profiles -->
         <collection property="sharingProfileIdentifiers" resultSet="sharingProfiles" ofType="java.lang.String"
@@ -95,7 +96,8 @@
             max_connections_per_user,
             proxy_hostname,
             proxy_port,
-            proxy_encryption_method
+            proxy_encryption_method,
+            connection_weight
         FROM guacamole_connection
         WHERE connection_id IN
             <foreach collection="identifiers" item="identifier"
@@ -126,7 +128,8 @@
             max_connections_per_user,
             proxy_hostname,
             proxy_port,
-            proxy_encryption_method
+            proxy_encryption_method,
+            connection_weight
         FROM guacamole_connection
         JOIN guacamole_connection_permission ON guacamole_connection_permission.connection_id = guacamole_connection.connection_id
         WHERE guacamole_connection.connection_id IN
@@ -162,7 +165,8 @@
             max_connections_per_user,
             proxy_hostname,
             proxy_port,
-            proxy_encryption_method
+            proxy_encryption_method,
+            connection_weight
         FROM guacamole_connection
         WHERE 
             <if test="parentIdentifier != null">parent_id = #{parentIdentifier,jdbcType=INTEGER}::integer</if>
@@ -189,7 +193,8 @@
             max_connections_per_user,
             proxy_hostname,
             proxy_port,
-            proxy_encryption_method
+            proxy_encryption_method,
+            connection_weight
         )
         VALUES (
             #{object.name,jdbcType=VARCHAR},
@@ -199,7 +204,8 @@
             #{object.maxConnectionsPerUser,jdbcType=INTEGER},
             #{object.proxyHostname,jdbcType=VARCHAR},
             #{object.proxyPort,jdbcType=INTEGER},
-            #{object.proxyEncryptionMethod,jdbcType=VARCHAR}::guacamole_proxy_encryption_method
+            #{object.proxyEncryptionMethod,jdbcType=VARCHAR}::guacamole_proxy_encryption_method,
+            #{object.connectionWeight,jdbcType=INTEGER}
         )
 
     </insert>
@@ -214,7 +220,8 @@
             max_connections_per_user = #{object.maxConnectionsPerUser,jdbcType=INTEGER},
             proxy_hostname           = #{object.proxyHostname,jdbcType=VARCHAR},
             proxy_port               = #{object.proxyPort,jdbcType=INTEGER},
-            proxy_encryption_method  = #{object.proxyEncryptionMethod,jdbcType=VARCHAR}::guacamole_proxy_encryption_method
+            proxy_encryption_method  = #{object.proxyEncryptionMethod,jdbcType=VARCHAR}::guacamole_proxy_encryption_method,
+            connection_weight        = #{object.connectionWeight,jdbcType=INTEGER}
         WHERE connection_id = #{object.objectID,jdbcType=INTEGER}::integer
     </update>