Improve resource ownership semantics of _solve_conn_curs()

A new cursor is always creates so always close it once finished.

lib/_json.py

@@ -180,8 +180,7 @@ def _get_json_oids(conn_or_curs, name='json'):
     from psycopg2.extensions import STATUS_IN_TRANSACTION
     from psycopg2.extras import _solve_conn_curs
 
-    conn, curs = _solve_conn_curs(conn_or_curs)
-
+    with _solve_conn_curs(conn_or_curs) as (conn, curs):
         # Store the transaction status of the connection to revert it after use
         conn_status = conn.status
 

lib/_range.py

@@ -351,8 +351,7 @@ class RangeCaster(object):
         """
         from psycopg2.extensions import STATUS_IN_TRANSACTION
         from psycopg2.extras import _solve_conn_curs
-        conn, curs = _solve_conn_curs(conn_or_curs)
-
+        with _solve_conn_curs(conn_or_curs) as (conn, curs):
             if conn.info.server_version < 90200:
                 raise ProgrammingError("range types not available in version %s"
                     % conn.info.server_version)

lib/extras.py

@@ -26,6 +26,7 @@ and classes until a better place in the distribution is found.
 # FITNESS FOR A PARTICULAR PURPOSE.  See the GNU Lesser General Public
 # License for more details.
 
+import contextlib
 import os as _os
 import time as _time
 import re as _re
@@ -781,6 +782,7 @@ def wait_select(conn):
             continue
 
 
+@contextlib.contextmanager
 def _solve_conn_curs(conn_or_curs):
     """Return the connection and a DBAPI cursor from a connection or cursor."""
     if conn_or_curs is None:
@@ -793,7 +795,8 @@ def _solve_conn_curs(conn_or_curs):
         conn = conn_or_curs
         curs = conn.cursor(cursor_factory=_cursor)
 
-    return conn, curs
+    with curs:
+        yield conn, curs
 
 
 class HstoreAdapter(object):
@@ -904,8 +907,7 @@ class HstoreAdapter(object):
     def get_oids(self, conn_or_curs):
         """Return the lists of OID of the hstore and hstore[] types.
         """
-        conn, curs = _solve_conn_curs(conn_or_curs)
-
+        with _solve_conn_curs(conn_or_curs) as (conn, curs):
             # Store the transaction status of the connection to revert it after use
             conn_status = conn.status
 
@@ -1083,8 +1085,7 @@ class CompositeCaster(object):
 
         Raise `ProgrammingError` if the type is not found.
         """
-        conn, curs = _solve_conn_curs(conn_or_curs)
-
+        with _solve_conn_curs(conn_or_curs) as (conn, curs):
             # Store the transaction status of the connection to revert it after use
             conn_status = conn.status
 

tests/test_types_extras.py

@@ -36,7 +36,7 @@ from psycopg2._json import _get_json_oids
 from psycopg2.extras import (
     CompositeCaster, DateRange, DateTimeRange, DateTimeTZRange, HstoreAdapter,
     Inet, Json, NumericRange, Range, RealDictConnection,
-    register_composite, register_hstore, register_range,
+    register_composite, register_hstore, register_range, _solve_conn_curs
 )
 from psycopg2.tz import FixedOffsetTimezone
 
@@ -1624,6 +1624,32 @@ class RangeCasterTestCase(ConnectingTestCase):
         cur.execute("rollback to savepoint x;")
 
 
+class TestSolveConnCurs(ConnectingTestCase):
+    def test_pass_connection(self):
+        with _solve_conn_curs(self.conn) as (conn, curs):
+            self.assertIsInstance(conn, psycopg2.extensions.connection)
+            self.assertIsInstance(curs, psycopg2.extensions.cursor)
+            self.assertIs(conn, self.conn)
+            self.assertFalse(conn.closed)
+            self.assertFalse(curs.closed)
+        self.assertFalse(conn.closed)
+        self.assertTrue(curs.closed)
+
+    def test_pass_cursor(self):
+        with self.conn.cursor() as cursor:
+            with _solve_conn_curs(cursor) as (conn, curs):
+                self.assertIsInstance(conn, psycopg2.extensions.connection)
+                self.assertIsInstance(curs, psycopg2.extensions.cursor)
+                self.assertIs(conn, self.conn)
+                self.assertIsNot(curs, cursor)
+                self.assertFalse(conn.closed)
+                self.assertFalse(curs.closed)
+            self.assertFalse(conn.closed)
+            self.assertTrue(curs.closed)
+        self.assertFalse(conn.closed)
+        self.assertTrue(curs.closed)
+
+
 def test_suite():
     return unittest.TestLoader().loadTestsFromName(__name__)