Dialect.initialize() is not called a second time if an :class:`.Engine`

is recreated, due to a disconnect error.   This fixes a particular
issue in the Oracle 8 dialect, but in general the dialect.initialize()
phase should only be once per dialect.  Also in 0.8.3. [ticket:2776]

3 files changed, 16 insertions, 1 deletions

diff --git a/lib/sqlalchemy/engine/strategies.py b/lib/sqlalchemy/engine/strategies.py
index 3ca91968b..ab9d370a3 100644
--- a/lib/sqlalchemy/engine/strategies.py
+++ b/lib/sqlalchemy/engine/strategies.py
@@ -149,6 +149,7 @@ class DefaultEngineStrategy(EngineStrategy):
                 event.listen(pool, 'first_connect', on_connect)
                 event.listen(pool, 'connect', on_connect)
 
+            @util.only_once
             def first_connect(dbapi_connection, connection_record):
                 c = base.Connection(engine, connection=dbapi_connection,
                             _has_events=False)
diff --git a/lib/sqlalchemy/util/__init__.py b/lib/sqlalchemy/util/__init__.py
index 5d9c4d49e..104566215 100644
--- a/lib/sqlalchemy/util/__init__.py
+++ b/lib/sqlalchemy/util/__init__.py
@@ -31,7 +31,7 @@ from .langhelpers import iterate_attributes, class_hierarchy, \
     classproperty, set_creation_order, warn_exception, warn, NoneType,\
     constructor_copy, methods_equivalent, chop_traceback, asint,\
     generic_repr, counter, PluginLoader, hybridmethod, safe_reraise,\
-    get_callable_argspec
+    get_callable_argspec, only_once
 
 from .deprecations import warn_deprecated, warn_pending_deprecation, \
     deprecated, pending_deprecation, inject_docstring_text
diff --git a/lib/sqlalchemy/util/langhelpers.py b/lib/sqlalchemy/util/langhelpers.py
index c91178a75..d63cc8e2a 100644
--- a/lib/sqlalchemy/util/langhelpers.py
+++ b/lib/sqlalchemy/util/langhelpers.py
@@ -1047,6 +1047,20 @@ _SQLA_RE = re.compile(r'sqlalchemy/([a-z_]+/){0,2}[a-z_]+\.py')
 _UNITTEST_RE = re.compile(r'unit(?:2|test2?/)')
 
 
+def only_once(fn):
+    """Decorate the given function to be a no-op after it is called exactly
+    once."""
+
+    once = [fn]
+    def go(*arg, **kw):
+        if once:
+            once_fn = once.pop()
+            return once_fn(*arg, **kw)
+
+    return update_wrapper(go, fn)
+
+
+
 def chop_traceback(tb, exclude_prefix=_UNITTEST_RE, exclude_suffix=_SQLA_RE):
     """Chop extraneous lines off beginning and end of a traceback.