Avoid force_reset to make patching thread-safe

setup.py

@@ -24,7 +24,7 @@ def run_tests(self):
         sys.exit(errno)
 
 
-install_requires = ['PyYAML', 'wrapt', 'six>=1.5']
+install_requires = ['PyYAML', 'wrapt', 'six>=1.5', 'byteplay']
 
 
 extras_require = {

vcr/patch.py

@@ -5,12 +5,35 @@
 from .compat import contextlib, mock
 from .stubs import VCRHTTPConnection, VCRHTTPSConnection
 from six.moves import http_client as httplib
+from byteplay import LOAD_GLOBAL, LOAD_ATTR, Code
+
+
+def _patch_name(func, old, new):
+    """Replace references to old with new in func bytecode
+
+    This effectively renames variables and attributes in the code for
+    the function passed.
+    """
+    bytecode = Code.from_code(func.func_code)
+    for i, (opcode, arg) in enumerate(bytecode.code):
+        if opcode in [LOAD_GLOBAL, LOAD_ATTR] and arg == old:
+            bytecode.code[i] = (opcode, new)
+    func.func_code = bytecode.to_code()
 
 
 # Save some of the original types for the purposes of unpatching
 _HTTPConnection = httplib.HTTPConnection
 _HTTPSConnection = httplib.HTTPSConnection
 
+httplib._HTTPConnection = _HTTPConnection
+httplib._HTTPSConnection = _HTTPSConnection
+# Make the original HTTPSConnection class refer to the original
+# HTTPConnection class, always. This means that we don't need to
+# unpatch things when creating HTTPSConnection instances.
+_patch_name(_HTTPSConnection.__init__.im_func,
+            'HTTPConnection', '_HTTPConnection')
+_patch_name(_HTTPSConnection.connect.im_func,
+            'HTTPConnection', '_HTTPConnection')
 
 # Try to save the original types for requests
 try:
@@ -42,6 +65,12 @@
     _HTTPSConnectionWithTimeout = httplib2.HTTPSConnectionWithTimeout
     _SCHEME_TO_CONNECTION = httplib2.SCHEME_TO_CONNECTION
 
+    # Make the original classes refer to the original httplib classes.
+    _patch_name(_HTTPConnectionWithTimeout.__init__.im_func,
+                'HTTPConnection', '_HTTPConnection')
+    _patch_name(_HTTPSConnectionWithTimeout.__init__.im_func,
+                'HTTPSConnection', '_HTTPSConnection')
+
 
 # Try to save the original types for boto
 try:
@@ -50,6 +79,9 @@
     pass
 else:
     _CertValidatingHTTPSConnection = boto.https_connection.CertValidatingHTTPSConnection
+    # Make the original class refer to the original httplib class.
+    _patch_name(_CertValidatingHTTPSConnection.__init__.im_func,
+                'HTTPConnection', '_HTTPConnection')
 
 
 # Try to save the original types for Tornado

vcr/stubs/__init__.py

@@ -244,16 +244,12 @@ def getresponse(self, _=False, **kwargs):
                     self._vcr_request
                 )
             )
-            # This is imported here to avoid circular import.
-            # TODO(@IvanMalison): Refactor to allow normal import.
-            from vcr.patch import force_reset
-            with force_reset():
-                self.real_connection.request(
-                    method=self._vcr_request.method,
-                    url=self._url(self._vcr_request.uri),
-                    body=self._vcr_request.body,
-                    headers=self._vcr_request.headers,
-                )
+            self.real_connection.request(
+                method=self._vcr_request.method,
+                url=self._url(self._vcr_request.uri),
+                body=self._vcr_request.body,
+                headers=self._vcr_request.headers,
+            )
 
             # get the response
             response = self.real_connection.getresponse()
@@ -308,12 +304,7 @@ def __init__(self, *args, **kwargs):
         if six.PY3:
             kwargs.pop('strict', None) # apparently this is gone in py3
 
-        # need to temporarily reset here because the real connection
-        # inherits from the thing that we are mocking out.  Take out
-        # the reset if you want to see what I mean :)
-        from vcr.patch import force_reset
-        with force_reset():
-            self.real_connection = self._baseclass(*args, **kwargs)
+        self.real_connection = self._baseclass(*args, **kwargs)
 
     def __setattr__(self, name, value):
         """