fix(tracing): fix error when using sqlite3 backup method (backport #4246) (#4250)

* fix(tracing): fix error when using sqlite3 backup method (#4246)

## Description
SQlite3 does an explicit type check on the `target` of `backup()` if the target is also a patched connection we need to unwrap it before calling the original `backup` method.

Note: this does not add a span/tracing to `backup`

## Checklist
- [ ] Title must conform to [conventional commit](https://github.com/conventional-changelog/commitlint/tree/master/%40commitlint/config-conventional).
- [ ] Add additional sections for `feat` and `fix` pull requests.
- [ ] Ensure tests are passing for affected code.
- [ ] [Library documentation](https://github.com/DataDog/dd-trace-py/tree/1.x/docs) and/or [Datadog's documentation site](https://github.com/DataDog/documentation/) is updated. Link to doc PR in description.

## Relevant issue(s)

Fixes #4241

## Testing strategy

Added a test case/call to `backup` to ensure when the target is also a traced connection that there is no error.

## Reviewer Checklist
- [x] Title is accurate.
- [x] Description motivates each change.
- [x] No unnecessary changes were introduced in this PR.
- [x] PR cannot be broken up into smaller PRs.
- [x] Avoid breaking [API](https://ddtrace.readthedocs.io/en/stable/versioning.html#interfaces) changes unless absolutely necessary.
- [x] Tests provided or description of manual testing performed is included in the code or PR.
- [x] Release note has been added for fixes and features, or else `changelog/no-changelog` label added.
- [x] All relevant GitHub issues are correctly linked.
- [x] Backports are identified and tagged with Mergifyio.
- [ ] Add to milestone.

(cherry picked from commit 82b1521)

# Conflicts:
#	tests/contrib/sqlite3/test_sqlite3.py

* Update tests/contrib/sqlite3/test_sqlite3.py

* Update tests/contrib/sqlite3/test_sqlite3.py

Co-authored-by: Brett Langdon <[email protected]>
Co-authored-by: mergify[bot] <37929162+mergify[bot]@users.noreply.github.com>
Co-authored-by: Munir Abdinur <[email protected]>

Author: 3 people

ddtrace/contrib/sqlite3/patch.py

@@ -1,6 +1,7 @@
 import os
 import sqlite3
 import sqlite3.dbapi2
+import sys
 
 from ddtrace import config
 from ddtrace.vendor import wrapt
@@ -75,3 +76,13 @@ def __init__(self, conn, pin=None, cursor_cls=None):
     def execute(self, *args, **kwargs):
         # sqlite has a few extra sugar functions
         return self.cursor().execute(*args, **kwargs)
+
+    # backup was added in Python 3.7
+    if sys.version_info >= (3, 7, 0):
+
+        def backup(self, target, *args, **kwargs):
+            # sqlite3 checks the type of `target`, it cannot be a wrapped connection
+            # https://github.com/python/cpython/blob/4652093e1b816b78e9a585d671a807ce66427417/Modules/_sqlite/connection.c#L1897-L1899
+            if isinstance(target, TracedConnection):
+                target = target.__wrapped__
+            return self.__wrapped__.backup(target, *args, **kwargs)

releasenotes/notes/fix-sqlite3-backup-bf92c698567237b9.yaml

@@ -0,0 +1,4 @@
+---
+fixes:
+  - |
+    sqlite3: fix error when using ``connection.backup`` method.

tests/contrib/sqlite3/test_sqlite3.py

@@ -1,4 +1,5 @@
 import sqlite3
+import sys
 import time
 from typing import TYPE_CHECKING
 
@@ -371,3 +372,12 @@ def test_iterator_usage(patched_conn):
     """Ensure sqlite3 patched cursors can be used as iterators."""
     rows = next(patched_conn.execute("select 1"))
     assert len(rows) == 1
+
+
+@pytest.mark.skipif(sys.version_info < (3, 7), reason="Connection.backup was added in Python 3.7")
+def test_backup(patched_conn):
+    """Ensure sqlite3 patched connections backup function can be used"""
+    destination = sqlite3.connect(":memory:")
+
+    with destination:
+        patched_conn.backup(destination, pages=1)