- merged the patch from #516 + fixes

- improves the framework for auto-invalidation of connections that have
lost their underlying database - the error catching/invalidate
step is totally moved to the connection pool.
- added better condition checking for do_rollback() and do_commit() including
SQLError excepetion wrapping

3 files changed, 40 insertions, 14 deletions

diff --git a/lib/sqlalchemy/databases/mssql.py b/lib/sqlalchemy/databases/mssql.py
index 6d2ff66cd..013e78c6a 100644
--- a/lib/sqlalchemy/databases/mssql.py
+++ b/lib/sqlalchemy/databases/mssql.py
@@ -553,6 +553,7 @@ class MSSQLDialect_pymssql(MSSQLDialect):
 
     def do_rollback(self, connection):
         # pymssql throws an error on repeated rollbacks. Ignore it.
+        # TODO: this is normal behavior for most DBs.  are we sure we want to ignore it ?
         try:
             connection.rollback()
         except:
@@ -571,6 +572,11 @@ class MSSQLDialect_pymssql(MSSQLDialect):
             del keys['port']
         return [[], keys]
 
+    def get_disconnect_checker(self):
+        def disconnect_checker(e):
+            return isinstance(e, self.dbapi.DatabaseError) and "Error 10054" in str(e)
+        return disconnect_checker
+
 
 ##    This code is leftover from the initial implementation, for reference
 ##    def do_begin(self, connection):
@@ -630,6 +636,11 @@ class MSSQLDialect_pyodbc(MSSQLDialect):
             connectors.append ("TrustedConnection=Yes")
         return [[";".join (connectors)], {}]
 
+    def get_disconnect_checker(self):
+        def disconnect_checker(e):
+            return isinstance(e, self.dbapi.Error) and '[08S01]' in e.args[1]
+        return disconnect_checker
+
 
 class MSSQLDialect_adodbapi(MSSQLDialect):
     def import_dbapi(cls):
@@ -660,6 +671,11 @@ class MSSQLDialect_adodbapi(MSSQLDialect):
             connectors.append("Integrated Security=SSPI")
         return [[";".join (connectors)], {}]
 
+    def get_disconnect_checker(self):
+        def disconnect_checker(e):
+            return isinstance(e, self.dbapi.adodbapi.DatabaseError) and "'connection failure'" in str(e)
+        return disconnect_checker
+
 dialect_mapping = {
     'pymssql':  MSSQLDialect_pymssql,
     'pyodbc':   MSSQLDialect_pyodbc,
diff --git a/lib/sqlalchemy/databases/mysql.py b/lib/sqlalchemy/databases/mysql.py
index 65ccb6af1..7ea98e92f 100644
--- a/lib/sqlalchemy/databases/mysql.py
+++ b/lib/sqlalchemy/databases/mysql.py
@@ -328,21 +328,12 @@ class MySQLDialect(ansisql.ANSIDialect):
         return MySQLIdentifierPreparer(self)
 
     def do_executemany(self, cursor, statement, parameters, context=None, **kwargs):
-        try:
-            rowcount = cursor.executemany(statement, parameters)
-            if context is not None:
-                context._rowcount = rowcount
-        except self.dbapi.OperationalError, o:
-            if o.args[0] == 2006 or o.args[0] == 2014:
-                cursor.invalidate()
-            raise o
+        rowcount = cursor.executemany(statement, parameters)
+        if context is not None:
+            context._rowcount = rowcount
+            
     def do_execute(self, cursor, statement, parameters, **kwargs):
-        try:
-            cursor.execute(statement, parameters)
-        except self.dbapi.OperationalError, o:
-            if o.args[0] == 2006 or o.args[0] == 2014:
-                cursor.invalidate()
-            raise o
+        cursor.execute(statement, parameters)
 
     def do_rollback(self, connection):
         # MySQL without InnoDB doesnt support rollback()
@@ -351,6 +342,12 @@ class MySQLDialect(ansisql.ANSIDialect):
         except:
             pass
 
+    def get_disconnect_checker(self):
+        def disconnect_checker(e):
+            return isinstance(e, self.dbapi.OperationalError) and e.args[0] in (2006, 2014)
+        return disconnect_checker            
+
+
     def get_default_schema_name(self):
         if not hasattr(self, '_default_schema_name'):
             self._default_schema_name = text("select database()", self).scalar()
diff --git a/lib/sqlalchemy/databases/postgres.py b/lib/sqlalchemy/databases/postgres.py
index 2943d163e..a26ef76b6 100644
--- a/lib/sqlalchemy/databases/postgres.py
+++ b/lib/sqlalchemy/databases/postgres.py
@@ -338,6 +338,19 @@ class PGDialect(ansisql.ANSIDialect):
         cursor = connection.execute('''SELECT relname FROM pg_class WHERE relkind = 'S' AND relnamespace IN ( SELECT oid FROM pg_namespace WHERE nspname NOT LIKE 'pg_%%' AND nspname != 'information_schema' AND relname = %(seqname)s);''', {'seqname': sequence_name})
         return bool(not not cursor.rowcount)
 
+    def get_disconnect_checker(self):
+        def disconnect_checker(e):
+            if isinstance(e, self.dbapi.OperationalError):
+                return 'closed the connection' in str(e) or 'connection not open' in str(e)
+            elif isinstance(e, self.dbapi.InterfaceError):
+                return 'connection already closed' in str(e)
+            elif isinstance(e, self.dbapi.ProgrammingError):
+                # yes, it really says "losed", not "closed"
+                return "losed the connection unexpectedly" in str(e)
+            else:
+                return False
+        return disconnect_checker
+
     def reflecttable(self, connection, table):
         if self.version == 2:
             ischema_names = pg2_ischema_names