1 files changed, 82 insertions, 0 deletions
diff --git a/db/__init__.py b/db/__init__.py
new file mode 100644
index 0000000..783df6c
--- /dev/null
+++ b/db/__init__.py
@@ -0,0 +1,82 @@
+# CodeQ: an online programming tutor.
+# Copyright (C) 2015 UL FRI
+#
+# This program is free software: you can redistribute it and/or modify it under
+# the terms of the GNU Affero General Public License as published by the Free
+# Software Foundation, either version 3 of the License, or (at your option) any
+# later version.
+#
+# This program is distributed in the hope that it will be useful, but WITHOUT
+# ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
+# FOR A PARTICULAR PURPOSE. See the GNU Affero General Public License for more
+# details.
+#
+# You should have received a copy of the GNU Affero General Public License
+# along with this program. If not, see <http://www.gnu.org/licenses/>.
+
+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
+_username = None  # the username to access the database
+_password = None  # the password to access the database
+
+
+# database parameters setup
+
+def _get_port():
+    try:
+        return int(os.environ.get('CODEQ_DB_PORT'))
+    except:
+        return 5432
+
+
+def setup(
+        host=os.environ.get('CODEQ_DB_HOST') or 'localhost',
+        port=_get_port(),
+        database=os.environ.get('CODEQ_DB_DATABASE') or 'codeq',
+        username=os.environ.get('CODEQ_DB_USER') or 'codeq',
+        password=os.environ.get('CODEQ_DB_PASS') or 'c0d3q'
+):
+    """Sets the database location and authentication parameters."""
+    global _host, _port, _database, _username, _password
+    _host = host
+    _port = port
+    _database = database
+    _username = username
+    _password = password
+
+# connection pooling
+
+_connection_pool = []
+
+
+def get_connection():
+    """Retrieves a database connection from the connection pool."""
+    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."""
+    try:
+        connection.rollback()  # sanity check
+    except:
+        return
+    with _module_access_lock:
+        _connection_pool.append(connection)
+
+
+if __name__ == '__main__':
+    setup()