Add cleanup to be called when future is garbage collected

.github/workflows/ci.yml

@@ -3,13 +3,11 @@ name: build
 on: push
 jobs:
   tox:
-    runs-on: ubuntu-18.04
+    runs-on: ubuntu-22.04
     strategy:
       fail-fast: false
       matrix:
         python:
-          - py27
-          - py36
           - py37
         httplib:
           - default
@@ -24,7 +22,7 @@ jobs:
       - run: tox -e ${{ matrix.python }}-${{ matrix.httplib }}
 
   misc:
-    runs-on: ubuntu-18.04
+    runs-on: ubuntu-22.04
     strategy:
       fail-fast: false
       matrix:

bravado/http_future.py

@@ -90,6 +90,11 @@ def _raise_connection_error(self, exception):
         # type: (BaseException) -> typing.NoReturn
         self._raise_error(BravadoConnectionError, 'ConnectionError', exception)
 
+    def cleanup(self):
+        # type: () -> None
+        """Perform any cleanup necessary to avoid resource leaks."""
+        pass
+
     def result(self, timeout=None):
         # type: (typing.Optional[float]) -> T
         """
@@ -285,6 +290,10 @@ def cancel(self):
         # type: () -> None
         return self.future.cancel()
 
+    def __del__(self):
+        # type: () -> None
+        self.future.cleanup()
+
     @reraise_errors
     def _get_incoming_response(self, timeout=None):
         # type: (typing.Optional[float]) -> IncomingResponse

setup.py

@@ -26,8 +26,6 @@
         'Topic :: Software Development :: Libraries :: Python Modules',
         'License :: OSI Approved :: BSD License',
         'Operating System :: OS Independent',
-        'Programming Language :: Python :: 2.7',
-        'Programming Language :: Python :: 3.6',
         'Programming Language :: Python :: 3.7',
     ],
     package_data={

tests/http_future/HttpFuture/cleanup_test.py

@@ -0,0 +1,10 @@
+# -*- coding: utf-8 -*-
+import mock
+
+from bravado.http_future import HttpFuture
+
+
+def test_cleanup_on_gc(mock_future_adapter):
+    http_future = HttpFuture(future=mock_future_adapter, response_adapter=mock.Mock())  # type: HttpFuture[None]
+    del http_future
+    assert mock_future_adapter.cleanup.call_count == 1

tox.ini

@@ -1,5 +1,5 @@
 [tox]
-envlist = {py27,py36,py37}-{default,fido}, {py27,py36,py37}-fido-requests2dot17, mypy, pre-commit
+envlist = {py37}-{default,fido}, {py37}-fido-requests2dot17, mypy, pre-commit
 
 [testenv]
 deps =
@@ -37,6 +37,8 @@ deps =
     Twisted<21
     # since we run in py 2.7 compatible mode, swagger-spec-validator>=3.0.0 causes syntax errors
     swagger-spec-validator<3.0.0
+    # so does yelp-bytes > 0.4.0
+    yelp-bytes==0.4.0
     -rrequirements-dev.txt
     .[fido]
     mypy==0.790