1 files changed, 39 insertions, 3 deletions
diff --git a/exam/xmlrpc_clients.py b/exam/xmlrpc_clients.py
index 5dc51c6..115ee6e 100644
--- a/exam/xmlrpc_clients.py
+++ b/exam/xmlrpc_clients.py
@@ -1,5 +1,41 @@
 from xmlrpclib import ServerProxy
-from settings import SERVER_PORT
+from settings import SERVER_PORTS
+import random
+import socket
 
-# Connect to the python server.
-python_server = ServerProxy('http://localhost:%d'%(SERVER_PORT))
+
+class PythonServer(object):
+    """A class that manages accesing the farm of Python servers and making
+    calls to them such that no one XMLRPC server is overloaded.
+    """
+    def __init__(self):
+        servers = [ServerProxy('http://localhost:%d'%(x)) for x in SERVER_PORTS]
+        self.servers = servers
+        self.indices = range(len(SERVER_PORTS))
+    
+    def run_code(self, answer, test_code, user_dir):
+        """See the documentation of the method of the same name in 
+        python_server.py.
+        """
+        done = False
+        result = [False, 'Unable to connect to any Python servers!']
+        # Try to connect a few times if not, quit.
+        count = 5
+        while (not done) and (count > 0):
+            try:
+                server = self._get_server()
+                result = server.run_code(answer, test_code, user_dir)
+            except socket.error:
+                count -= 1
+            else:
+                done = True
+        return result
+
+    def _get_server(self):
+        # pick a suitable server at random from our pool of servers.
+        index = random.choice(self.indices)
+        return self.servers[index]
+
+# views.py calls this Python server which forwards the request to one
+# of the running servers.
+python_server = PythonServer()