From: Mike Bayer <mike_mp@zzzcomputing.com>
Date: Thu, 11 Jul 2013 19:15:09 +0000 (-0400)
Subject: Dialect.initialize() is not called a second time if an :class:`.Engine`
X-Git-Tag: rel_0_8_3~101
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=9a95a39b49a2fadb3e1674d083d7c3da2fd886a8;p=thirdparty%2Fsqlalchemy%2Fsqlalchemy.git

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.  [ticket:2776]
---

diff --git a/doc/build/changelog/changelog_08.rst b/doc/build/changelog/changelog_08.rst
index d6a0b69621..145eb14971 100644
--- a/doc/build/changelog/changelog_08.rst
+++ b/doc/build/changelog/changelog_08.rst
@@ -6,6 +6,13 @@
 .. changelog::
     :version: 0.8.3
 
+        :tickets: 2776
+
+        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.
+
     .. change::
         :tags: feature, sql
         :tickets: 722
diff --git a/lib/sqlalchemy/engine/strategies.py b/lib/sqlalchemy/engine/strategies.py
index 4c81df8f06..8f30f1a2c7 100644
--- a/lib/sqlalchemy/engine/strategies.py
+++ b/lib/sqlalchemy/engine/strategies.py
@@ -155,6 +155,7 @@ 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)
 
diff --git a/lib/sqlalchemy/util/__init__.py b/lib/sqlalchemy/util/__init__.py
index c2c5bddb85..8e36ea611d 100644
--- a/lib/sqlalchemy/util/__init__.py
+++ b/lib/sqlalchemy/util/__init__.py
@@ -28,7 +28,8 @@ from .langhelpers import iterate_attributes, class_hierarchy, \
     duck_type_collection, assert_arg_type, symbol, dictlike_iteritems,\
     classproperty, set_creation_order, warn_exception, warn, NoneType,\
     constructor_copy, methods_equivalent, chop_traceback, asint,\
-    generic_repr, counter, PluginLoader, hybridmethod, safe_reraise
+    generic_repr, counter, PluginLoader, hybridmethod, safe_reraise,\
+    only_once
 
 from .deprecations import warn_deprecated, warn_pending_deprecation, \
     deprecated, pending_deprecation
diff --git a/lib/sqlalchemy/util/langhelpers.py b/lib/sqlalchemy/util/langhelpers.py
index d82aefdeae..82822b086b 100644
--- a/lib/sqlalchemy/util/langhelpers.py
+++ b/lib/sqlalchemy/util/langhelpers.py
@@ -1042,6 +1042,20 @@ _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.
 
diff --git a/test/engine/test_reconnect.py b/test/engine/test_reconnect.py
index dee2fd2169..1936cec081 100644
--- a/test/engine/test_reconnect.py
+++ b/test/engine/test_reconnect.py
@@ -348,6 +348,28 @@ class MockReconnectTest(fixtures.TestBase):
             list, result
         )
 
+    def test_dialect_initialize_once(self):
+        from sqlalchemy.engine.base import Engine
+        from sqlalchemy.engine.url import URL
+        from sqlalchemy.engine.default import DefaultDialect
+        from sqlalchemy.pool import QueuePool
+        dbapi = self.dbapi
+
+        mock_dialect = Mock()
+        class MyURL(URL):
+            def get_dialect(self):
+                return Dialect
+        class Dialect(DefaultDialect):
+            initialize = Mock()
+
+        engine = create_engine(MyURL("foo://"), module=dbapi)
+        c1 = engine.connect()
+        engine.dispose()
+        c2 = engine.connect()
+        eq_(Dialect.initialize.call_count, 1)
+
+
+
 class CursorErrTest(fixtures.TestBase):
 
     def setup(self):
@@ -493,9 +515,15 @@ class RealReconnectTest(fixtures.TestBase):
         # raises a DBAPIError, not an AttributeError
         assert_raises(exc.DBAPIError, engine.connect)
 
-        # dispose connections so we get a new one on
-        # next go
-        engine.dispose()
+    @testing.skip_if(
+        [lambda: util.py3k, "oracle+cx_oracle"],
+        "Crashes on py3k+cx_oracle")
+    def test_explode_in_initializer_disconnect(self):
+        engine = engines.testing_engine()
+        def broken_initialize(connection):
+            connection.execute("select fake_stuff from _fake_table")
+
+        engine.dialect.initialize = broken_initialize
 
         p1 = engine.pool