pg8000 fix for Windows/Postgresql 13.6 not seen elsewhere.

Author: jamadden

src/relstorage/adapters/postgresql/drivers/pg8000.py

@@ -15,24 +15,19 @@
 """
 pg8000 IDBDriver implementations.
 """
-
-from __future__ import absolute_import
-from __future__ import print_function
-
 from collections import deque
 
 from zope.interface import implementer
 
 from relstorage._compat import number_types
 
+from ...._compat import WIN
 from ...interfaces import IDBDriver
 from ...sql import Compiler
-
 from . import AbstractPostgreSQLDriver
 from . import PostgreSQLDialect
 from ._lobject import LobConnectionMixin
 
-
 __all__ = [
     'PG8000Driver',
 ]
@@ -249,3 +244,17 @@ def connection_may_need_commit(self, conn):
 
     def _get_exception_pgcode(self, exc):
         return exc.args[0]['C']
+
+    if WIN:
+        def exception_is_deadlock(self, exc):
+            is_deadlock = super().exception_is_deadlock(exc)
+            if is_deadlock:
+                return is_deadlock
+            # pg8000 raises pg8000.dbapi.ProgrammingError, which is a DatabaseError.
+            # We've seen both
+            #    40P01 - deadlock_detected (Transaction Rollback)
+            #    55P03 - lock_not_available (Object Not In Prerequisite State)
+            # ERRCODE_DEADLOCK is the first one, checked by super.
+            if isinstance(exc, self.driver_module.DatabaseError):
+                return self._get_exception_pgcode(exc) == '55P03'
+            return None