From: Daniele Varrazzo <daniele.varrazzo@gmail.com>
Date: Mon, 2 May 2022 00:45:21 +0000 (+0200)
Subject: fix: allow to use cancel() on a closed connection
X-Git-Tag: 3.1~123
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=b0796add5ebda8df2693fb2f387bbc181a10c84b;p=thirdparty%2Fpsycopg.git

fix: allow to use cancel() on a closed connection
---

diff --git a/docs/news.rst b/docs/news.rst
index 1ed40085d..08ad5151f 100644
--- a/docs/news.rst
+++ b/docs/news.rst
@@ -29,6 +29,8 @@ Psycopg 3.0.13 (unreleased)
 ^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
 - Fix `Cursor.stream()` slowness (:ticket:`#286`).
+- Make `Connection.cancel()` on a closed connection a no-op instead of an
+  error.
 
 
 Current release
diff --git a/psycopg/psycopg/connection.py b/psycopg/psycopg/connection.py
index 2efd7c4b6..65bc2f658 100644
--- a/psycopg/psycopg/connection.py
+++ b/psycopg/psycopg/connection.py
@@ -283,6 +283,12 @@ class BaseConnection(Generic[Row]):
 
     def cancel(self) -> None:
         """Cancel the current operation on the connection."""
+        # No-op if the connection is closed
+        # this allows to use the method as callback handler without caring
+        # about its life.
+        if self.closed:
+            return
+
         if self._tpc and self._tpc[1]:
             raise e.ProgrammingError(
                 "cancel() cannot be used with a prepared two-phase transaction"
diff --git a/tests/test_connection.py b/tests/test_connection.py
index 4013a16a0..800c5a11a 100644
--- a/tests/test_connection.py
+++ b/tests/test_connection.py
@@ -737,3 +737,8 @@ def test_connect_context_copy(dsn, conn):
     cur = conn2.execute("select %b", ["hello"])
     assert cur.fetchone()[0] == "hellob"  # type: ignore[index]
     conn2.close()
+
+
+def test_cancel_closed(conn):
+    conn.close()
+    conn.cancel()
diff --git a/tests/test_connection_async.py b/tests/test_connection_async.py
index 804c7bcd2..dd10ed6fc 100644
--- a/tests/test_connection_async.py
+++ b/tests/test_connection_async.py
@@ -686,3 +686,8 @@ async def test_connect_context_copy(dsn, aconn):
     cur = await aconn2.execute("select %b", ["hello"])
     assert (await cur.fetchone())[0] == "hellob"  # type: ignore[index]
     await aconn2.close()
+
+
+async def test_cancel_closed(aconn):
+    await aconn.close()
+    aconn.cancel()