Ticket #7392: 0001-db-add-the-ability-to-have-a-seperate-write-databas.patch

trac/db/api.py

@@ -49 +49 @@
         """Return the DDL statements necessary to create the specified table,
         including indices."""
 
+class DatabasePair(object):
+    """
+    Holds two database connections, one for reading and one for writing.
+    """
+    def __init__(self, db, dbwr):
+        self.read = db
+        self.write = dbwr
 
 class DatabaseManager(Component):
 
@@ -59 +66 @@
         [wiki:TracEnvironment#DatabaseConnectionStrings string] for this
         project""")
 
+    write_connection_uri = Option('trac', 'database_write', '',
+        """Database write connection
+        [wiki:TracEnvironment#DatabaseConnectionStrings string] for this
+        project""")
+
     timeout = IntOption('trac', 'timeout', '20',
         """Timeout value for database connection, in seconds.
         Use '0' to specify ''no timeout''. ''(Since 0.11)''""")
 
     def __init__(self):
         self._cnx_pool = None
+        self._cnx_pool_write = None
 
     def init_db(self):
-        connector, args = self._get_connector()
+        connector, args = self._get_connector(self.connection_uri)
+        if self.write_connection_uri and self.write_connection_uri != '':
+            connector, args = self._get_connector(self.write_connection_uri)
         connector.init_db(**args)
 
-    def get_connection(self):
+    def _create_pool(self):
         if not self._cnx_pool:
-            connector, args = self._get_connector()
+            connector, args = self._get_connector(self.connection_uri)
             self._cnx_pool = ConnectionPool(5, connector, **args)
-        return self._cnx_pool.get_cnx(self.timeout or None)
+        if self.write_connection_uri and self.write_connection_uri != '' and not self._cnx_pool_write:
+            connector, args = self._get_connector(self.write_connection_uri)
+            ### FIXME: Connection pool does not handle the max number although it might be needed
+            self._cnx_pool_write = ConnectionPool(1, connector, **args)
+
+    def get_connection(self):
+        self._create_pool()
+        conn = self._cnx_pool.get_cnx(self.timeout or None)
+        if not self.write_connection_uri or self.write_connection_uri == '':
+            return DatabasePair(conn, conn);
+        else:
+            return DatabasePair(conn, self._cnx_pool_write.get_cnx(self.timeout or None))
 
     def shutdown(self, tid=None):
         if self._cnx_pool:
             self._cnx_pool.shutdown(tid)
             if not tid:
                 self._cnx_pool = None
+        if self._cnx_pool_write:
+            self._cnx_pool_write.shutdown(tid)
+            if not tid:
+                self._cnx_pool_write = None
 
-    def _get_connector(self): ### FIXME: Make it public?
-        scheme, args = _parse_db_str(self.connection_uri)
+    def _get_connector(self, db_str): ### FIXME: Make it public?
+        scheme, args = _parse_db_str(db_str)
         candidates = {}
         for connector in self.connectors:
             for scheme_, priority in connector.get_supported_schemes():

trac/env.py

@@ -253 +253 @@
             fd.close()
 
     def get_db_cnx(self):
-        """Return a database connection from the connection pool."""
+        """Return a database connection pair from the connection pool."""
         return DatabaseManager(self).get_connection()
 
     def shutdown(self, tid=None):