Make the DB APi function names clearer

Change-Id: Ieed6cfbaa8dd0930f27b30d0043e400b8bed592c
diff --git a/db/db.py b/db/db.py
index eedaeba..13d3773 100644
--- a/db/db.py
+++ b/db/db.py
@@ -42,7 +42,7 @@
     # Switches must be uniquely named
     def create_switch(self, name):
 
-        switch_id = self.get_switch_id(name)
+        switch_id = self.get_switch_id_by_name(name)
         if switch_id is not None:
             raise InputError("Switch name %s already exists" % name)
 
@@ -72,12 +72,12 @@
     # 3. (Switch/name) must be unique
     def create_port(self, switch_id, name, current_vlan_id, base_vlan_id):
 
-        switch = self.get_switch(switch_id)
+        switch = self.get_switch_by_id(switch_id)
         if switch is None:
             raise InputError("Switch id %s does not exist" % switch_id)
 
         for vlan_id in (current_vlan_id, base_vlan_id):
-            vlan = self.get_vlan(vlan_id)
+            vlan = self.get_vlan_by_id(vlan_id)
             if vlan is None:
                 raise InputError("VLAN id %s does not exist" % vlan_id)
 
@@ -145,7 +145,7 @@
     # 2. The switch may not be referenced by any ports -
     #    delete them first!
     def delete_switch(self, switch_id):
-        switch = self.get_switch(switch_id)
+        switch = self.get_switch_by_id(switch_id)
         if switch is None:
             raise InputError("Switch ID %s does not exist" % switch_id)
         ports = self.get_ports_by_switch(switch_id)
@@ -161,7 +161,7 @@
     # 1. The port must exist
     # 2. The port must not be locked
     def delete_port(self, port_id):
-        port = self.get_port(port_id)
+        port = self.get_port_by_id(port_id)
         if port is None:
             raise InputError("Port ID %s does not exist" % port_id)
         if port.is_locked:
@@ -175,7 +175,7 @@
     # 1. The VLAN
     # 2. The VLAN may not contain any ports - move or delete them first!
     def delete_vlan(self, vlan_id):
-        vlan = self.get_vlan(vlan_id)
+        vlan = self.get_vlan_by_id(vlan_id)
         if vlan is None:
             raise InputError("VLAN ID %s does not exist" % vlan_id)
         ports = self.get_ports_by_current_vlan(vlan_id)
@@ -264,22 +264,22 @@
         else:
             return None
 
-    def get_switch(self, switch_id):
+    def get_switch_by_id(self, switch_id):
         return self._get_row("switch", "switch_id", switch_id)
 
-    def get_switch_id(self, name):
+    def get_switch_id_by_name(self, name):
         return self._get_element("switch_id", "switch", "name", name)
 
-    def get_switch_name(self, switch_id):
+    def get_switch_name_by_id(self, switch_id):
         return self._get_element("name", "switch", "switch_id", switch_id)
 
-    def get_port(self, port_id):
+    def get_port_by_id(self, port_id):
         return self._get_row("port", "port_id", port_id)
 
-    def get_port_id(self, name):
+    def get_port_id_by_name(self, name):
         return self._get_element("port_id", "port", "name", name)
 
-    def get_port_name(self, port_id):
+    def get_port_name_by_id(self, port_id):
         return self._get_element("port_name", "port", "port_id", port_id)
 
     def get_ports_by_switch(self, switch_id):
@@ -294,7 +294,7 @@
     def get_ports_by_base_vlan(self, vlan_id):
         return self._get_multi_elements("port_id", "port", "base_vlan_id", vlan_id)
 
-    def get_vlan(self, vlan_id):
+    def get_vlan_by_id(self, vlan_id):
         return self._get_row("vlan", "vlan_id", vlan_id)
 
     def get_vlan_id_by_name(self, name):
@@ -303,7 +303,7 @@
     def get_vlan_id_by_tag(self, tag):
         return self._get_element("vlan_id", "vlan", "tag", tag)
 
-    def get_vlan_name(self, vlan_id):
+    def get_vlan_name_by_id(self, vlan_id):
         return self._get_element("vlan_name", "vlan", "vlan_id", vlan_id)
 
     def _get_row(self, table, field, value):
@@ -342,14 +342,14 @@
         return port_id        
 
     def set_vlan(self, port_id, vlan_id):
-        port = self.get_port(port_id)
+        port = self.get_port_by_id(port_id)
         if port == None:
             raise("Port %s does not exist" % port_id)
 
         if port["is_trunk"] or port["is_locked"]:
             raise CriticalError("The port is locked")
 
-        vlan = self.get_vlan(vlan_id)
+        vlan = self.get_vlan_by_id(vlan_id)
         if vlan == None:
             raise CriticalError("VLAN %s does not exist" % vlan_id)
 
@@ -362,7 +362,7 @@
             raise
 
     def restore_default_vlan(self, port_id):
-        port = self.get_port(port_id)
+        port = self.get_port_by_id(port_id)
         if port == None:
             raise CriticalError("Port %s does not exist")