From aded39f68c29e44a50c85be1ddb370d3d1affe9d Mon Sep 17 00:00:00 2001
From: Mike Bayer <mike_mp@zzzcomputing.com>
Date: Tue, 21 Apr 2020 12:51:13 -0400
Subject: Propose Result as immediate replacement for ResultProxy

As progress is made on the _future.Result, including breaking
it out such that DBAPI behaviors are local to specific
implementations, it becomes apparent that the Result object
is a functional superset of ResultProxy and that basic
operations like fetchone(), fetchall(), and fetchmany()
behave pretty much exactly the same way on the new object.
Reorganize things so that ResultProxy is now referred to
as LegacyCursorResult, which subclasses CursorResult
that represents the DBAPI-cursor version of Result,
making use of a multiple inheritance pattern so that
the functionality of Result is also available in non-DBAPI
contexts, as will be necessary for some ORM
patterns.

Additionally propose the composition system for Result
that will form the basis for ORM-alternative result
systems such as horizontal sharding and dogpile cache.
As ORM results will soon be coming directly from
instances of Result, these extensions will instead
build their own ResultFetchStrategies that perform
the special steps to create composed or cached
result sets.

Also considering at the moment not emitting deprecation
warnings for fetchXYZ() methods; the immediate issue
is Keystone tests are calling upon it, but as the
implementations here are proving to be not in any
kind of conflict with how Result works, there's
not too much issue leaving them around and deprecating
at some later point.

References: #5087
References: #4395
Fixes: #4959
Change-Id: I8091919d45421e3f53029b8660427f844fee0228
---
 lib/sqlalchemy/dialects/mssql/base.py       |  4 ++--
 lib/sqlalchemy/dialects/oracle/cx_oracle.py | 31 ++++++++---------------------
 2 files changed, 10 insertions(+), 25 deletions(-)

(limited to 'lib/sqlalchemy/dialects')

diff --git a/lib/sqlalchemy/dialects/mssql/base.py b/lib/sqlalchemy/dialects/mssql/base.py
index dda445743..5618a67f9 100644
--- a/lib/sqlalchemy/dialects/mssql/base.py
+++ b/lib/sqlalchemy/dialects/mssql/base.py
@@ -704,9 +704,9 @@ from ... import schema as sa_schema
 from ... import sql
 from ... import types as sqltypes
 from ... import util
+from ...engine import cursor as _cursor
 from ...engine import default
 from ...engine import reflection
-from ...engine import result as _result
 from ...sql import compiler
 from ...sql import elements
 from ...sql import expression
@@ -1525,7 +1525,7 @@ class MSExecutionContext(default.DefaultExecutionContext):
         elif (
             self.isinsert or self.isupdate or self.isdelete
         ) and self.compiled.returning:
-            fbcr = _result.FullyBufferedCursorFetchStrategy
+            fbcr = _cursor.FullyBufferedCursorFetchStrategy
             self._result_strategy = fbcr.create_from_buffer(
                 self.cursor, self.cursor.description, self.cursor.fetchall()
             )
diff --git a/lib/sqlalchemy/dialects/oracle/cx_oracle.py b/lib/sqlalchemy/dialects/oracle/cx_oracle.py
index b555c4555..9e10679c6 100644
--- a/lib/sqlalchemy/dialects/oracle/cx_oracle.py
+++ b/lib/sqlalchemy/dialects/oracle/cx_oracle.py
@@ -299,7 +299,6 @@ SQLAlchemy type (or a subclass of such).
 
 from __future__ import absolute_import
 
-import collections
 import decimal
 import random
 import re
@@ -312,7 +311,7 @@ from ... import exc
 from ... import processors
 from ... import types as sqltypes
 from ... import util
-from ...engine import result as _result
+from ...engine import cursor as _cursor
 from ...util import compat
 
 
@@ -680,8 +679,13 @@ class OracleExecutionContext_cx_oracle(OracleExecutionContext):
                 for i in range(len(self.out_parameters))
             ]
 
-            return ReturningResultStrategy(
-                result, result.cursor, returning_params
+            return _cursor.FullyBufferedCursorFetchStrategy(
+                result.cursor,
+                [
+                    (getattr(col, "name", col.anon_label), None)
+                    for col in result.context.compiled.returning
+                ],
+                initial_buffer=[tuple(returning_params)],
             )
         else:
             return super(
@@ -689,25 +693,6 @@ class OracleExecutionContext_cx_oracle(OracleExecutionContext):
             ).get_result_cursor_strategy(result)
 
 
-class ReturningResultStrategy(_result.FullyBufferedCursorFetchStrategy):
-    __slots__ = ("_returning_params",)
-
-    def __init__(self, result, dbapi_cursor, returning_params):
-        self._returning_params = returning_params
-
-        returning = result.context.compiled.returning
-        cursor_description = [
-            (getattr(col, "name", col.anon_label), None) for col in returning
-        ]
-
-        super(ReturningResultStrategy, self).__init__(
-            dbapi_cursor, cursor_description
-        )
-
-    def _buffer_rows(self):
-        return collections.deque([tuple(self._returning_params)])
-
-
 class OracleDialect_cx_oracle(OracleDialect):
     execution_ctx_cls = OracleExecutionContext_cx_oracle
     statement_compiler = OracleCompiler_cx_oracle
-- 
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