Do away with pool._refs

This collection was added only for the benefit of unit tests
and is unnecessary for the pool to function.  As SQLAlchemy 2.0
will be removing the automatic handling of connections that are
garbage collection, remove this collection so that we ultimately
don't need a weakref handler to do anything within the pool.
The handler will do nothing other than emit a warning that
a connection was dereferenced without being explicitly returned
to the pool, invalidated, or detached.

Change-Id: I4ca196270d5714efbac44dbf6f034e8c7f0af58a

2 files changed, 8 insertions, 50 deletions

diff --git a/lib/sqlalchemy/testing/assertions.py b/lib/sqlalchemy/testing/assertions.py
index a465bedd4..c74259bdf 100644
--- a/lib/sqlalchemy/testing/assertions.py
+++ b/lib/sqlalchemy/testing/assertions.py
@@ -13,13 +13,12 @@ import warnings
 
 from . import assertsql
 from . import config
+from . import engines
 from . import mock
-from . import util as testutil
 from .exclusions import db_spec
 from .util import fail
 from .. import exc as sa_exc
 from .. import orm
-from .. import pool
 from .. import schema
 from .. import types as sqltypes
 from .. import util
@@ -183,49 +182,8 @@ def global_cleanup_assertions():
     _assert_no_stray_pool_connections()
 
 
-_STRAY_CONNECTION_FAILURES = 0
-
-
 def _assert_no_stray_pool_connections():
-    global _STRAY_CONNECTION_FAILURES
-
-    # lazy gc on cPython means "do nothing."  pool connections
-    # shouldn't be in cycles, should go away.
-    testutil.lazy_gc()
-
-    # however, once in awhile, on an EC2 machine usually,
-    # there's a ref in there.  usually just one.
-    if pool._refs:
-
-        # OK, let's be somewhat forgiving.
-        _STRAY_CONNECTION_FAILURES += 1
-
-        print(
-            "Encountered a stray connection in test cleanup: %s"
-            % str(pool._refs)
-        )
-        # then do a real GC sweep.   We shouldn't even be here
-        # so a single sweep should really be doing it, otherwise
-        # there's probably a real unreachable cycle somewhere.
-        testutil.gc_collect()
-
-    # if we've already had two of these occurrences, or
-    # after a hard gc sweep we still have pool._refs?!
-    # now we have to raise.
-    if pool._refs:
-        err = str(pool._refs)
-
-        # but clean out the pool refs collection directly,
-        # reset the counter,
-        # so the error doesn't at least keep happening.
-        pool._refs.clear()
-        _STRAY_CONNECTION_FAILURES = 0
-        warnings.warn(
-            "Stray connection refused to leave " "after gc.collect(): %s" % err
-        )
-    elif _STRAY_CONNECTION_FAILURES > 10:
-        assert False, "Encountered more than 10 stray connections"
-        _STRAY_CONNECTION_FAILURES = 0
+    engines.testing_reaper.assert_all_closed()
 
 
 def eq_regex(a, b, msg=None):
diff --git a/lib/sqlalchemy/testing/engines.py b/lib/sqlalchemy/testing/engines.py
index ff4f89606..4f413915a 100644
--- a/lib/sqlalchemy/testing/engines.py
+++ b/lib/sqlalchemy/testing/engines.py
@@ -12,7 +12,6 @@ import warnings
 import weakref
 
 from . import config
-from . import uses_deprecated
 from .util import decorator
 from .. import event
 from .. import pool
@@ -24,7 +23,13 @@ class ConnectionKiller(object):
         self.testing_engines = weakref.WeakKeyDictionary()
         self.conns = set()
 
+    def add_pool(self, pool):
+        event.listen(pool, "connect", self.connect)
+        event.listen(pool, "checkout", self.checkout)
+        event.listen(pool, "invalidate", self.invalidate)
+
     def add_engine(self, engine):
+        self.add_pool(engine.pool)
         self.testing_engines[engine] = True
 
     def connect(self, dbapi_conn, con_record):
@@ -75,7 +80,6 @@ class ConnectionKiller(object):
         else:
             self._stop_test_ctx_aggressive()
 
-    @uses_deprecated()
     def _stop_test_ctx_minimal(self):
         self.close_all()
 
@@ -85,7 +89,6 @@ class ConnectionKiller(object):
             if rec is not config.db:
                 rec.dispose()
 
-    @uses_deprecated()
     def _stop_test_ctx_aggressive(self):
         self.close_all()
         for conn, rec in list(self.conns):
@@ -265,9 +268,6 @@ def testing_engine(url=None, options=None):
         engine.pool._timeout = 0
         engine.pool._max_overflow = 0
     if use_reaper:
-        event.listen(engine.pool, "connect", testing_reaper.connect)
-        event.listen(engine.pool, "checkout", testing_reaper.checkout)
-        event.listen(engine.pool, "invalidate", testing_reaper.invalidate)
         testing_reaper.add_engine(engine)
 
     return engine