Split the development into daemon and wsgi_server.

Implemented basic infrastructure for daemon (Prolog), and partial support for services in wsgi_server.

1 files changed, 14 insertions, 6 deletions

diff --git a/db/__init__.py b/db/__init__.py
index e02a1fe..def4bb8 100644
--- a/db/__init__.py
+++ b/db/__init__.py
@@ -1,11 +1,13 @@
 # coding=utf-8
 
 import os
-
+import threading
 import psycopg2
 
 __all__ = ['get_connection', 'return_connection', 'setup', 'models']
 
+_module_access_lock = threading.Lock()
+
 _host = None  # the database hostname/IP
 _port = None  # the database port number
 _database = None  # the name of the database
@@ -44,16 +46,22 @@ _connection_pool = []
 
 def get_connection():
     """Retrieves a database connection from the connection pool."""
-    if _host is None:
-        setup()  # lazy init
-    if len(_connection_pool) > 0:
-        return _connection_pool.pop()
+    with _module_access_lock:
+        if _host is None:
+            setup()  # lazy init
+        if len(_connection_pool) > 0:
+            return _connection_pool.pop()
     return psycopg2.connect(host=_host, port=_port, database=_database, user=_username, password=_password)
 
 
 def return_connection(connection):
     """Returns the given database connection to the pool."""
-    _connection_pool.append(connection)
+    try:
+        connection.rollback()  # sanity check
+    except:
+        return
+    with _module_access_lock:
+        _connection_pool.append(connection)
 
 
 if __name__ == '__main__':