Update cherrpy to 17.4.2

lib/cherrypy/lib/caching.py

@@ -37,9 +37,11 @@ import sys
 import threading
 import time
 
+import six
+
 import cherrypy
 from cherrypy.lib import cptools, httputil
-from cherrypy._cpcompat import copyitems, ntob, set_daemon, sorted, Event
+from cherrypy._cpcompat import Event
 
 
 class Cache(object):
@@ -48,19 +50,19 @@ class Cache(object):
 
     def get(self):
         """Return the current variant if in the cache, else None."""
-        raise NotImplemented
+        raise NotImplementedError
 
     def put(self, obj, size):
         """Store the current variant in the cache."""
-        raise NotImplemented
+        raise NotImplementedError
 
     def delete(self):
         """Remove ALL cached variants of the current resource."""
-        raise NotImplemented
+        raise NotImplementedError
 
     def clear(self):
         """Reset the cache to its initial, empty state."""
-        raise NotImplemented
+        raise NotImplementedError
 
 
 # ------------------------------ Memory Cache ------------------------------- #
@@ -170,7 +172,7 @@ class MemoryCache(Cache):
         # Run self.expire_cache in a separate daemon thread.
         t = threading.Thread(target=self.expire_cache, name='expire_cache')
         self.expiration_thread = t
-        set_daemon(t, True)
+        t.daemon = True
         t.start()
 
     def clear(self):
@@ -197,7 +199,8 @@ class MemoryCache(Cache):
             now = time.time()
             # Must make a copy of expirations so it doesn't change size
             # during iteration
-            for expiration_time, objects in copyitems(self.expirations):
+            items = list(six.iteritems(self.expirations))
+            for expiration_time, objects in items:
                 if expiration_time <= now:
                     for obj_size, uri, sel_header_values in objects:
                         try:
@@ -265,7 +268,7 @@ class MemoryCache(Cache):
         self.store.pop(uri, None)
 
 
-def get(invalid_methods=("POST", "PUT", "DELETE"), debug=False, **kwargs):
+def get(invalid_methods=('POST', 'PUT', 'DELETE'), debug=False, **kwargs):
     """Try to obtain cached output. If fresh enough, raise HTTPError(304).
 
     If POST, PUT, or DELETE:
@@ -291,9 +294,9 @@ def get(invalid_methods=("POST", "PUT", "DELETE"), debug=False, **kwargs):
     request = cherrypy.serving.request
     response = cherrypy.serving.response
 
-    if not hasattr(cherrypy, "_cache"):
+    if not hasattr(cherrypy, '_cache'):
         # Make a process-wide Cache object.
-        cherrypy._cache = kwargs.pop("cache_class", MemoryCache)()
+        cherrypy._cache = kwargs.pop('cache_class', MemoryCache)()
 
         # Take all remaining kwargs and set them on the Cache object.
         for k, v in kwargs.items():
@@ -328,7 +331,7 @@ def get(invalid_methods=("POST", "PUT", "DELETE"), debug=False, **kwargs):
             if directive == 'max-age':
                 if len(atoms) != 1 or not atoms[0].isdigit():
                     raise cherrypy.HTTPError(
-                        400, "Invalid Cache-Control header")
+                        400, 'Invalid Cache-Control header')
                 max_age = int(atoms[0])
                 break
             elif directive == 'no-cache':
@@ -353,13 +356,13 @@ def get(invalid_methods=("POST", "PUT", "DELETE"), debug=False, **kwargs):
             return False
 
         # Copy the response headers. See
-        # https://bitbucket.org/cherrypy/cherrypy/issue/721.
+        # https://github.com/cherrypy/cherrypy/issues/721.
         response.headers = rh = httputil.HeaderMap()
         for k in h:
             dict.__setitem__(rh, k, dict.__getitem__(h, k))
 
         # Add the required Age header
-        response.headers["Age"] = str(age)
+        response.headers['Age'] = str(age)
 
         try:
             # Note that validate_since depends on a Last-Modified header;
@@ -402,10 +405,19 @@ def tee_output():
             output.append(chunk)
             yield chunk
 
-        # save the cache data
-        body = ntob('').join(output)
-        cherrypy._cache.put((response.status, response.headers or {},
-                             body, response.time), len(body))
+        # Save the cache data, but only if the body isn't empty.
+        # e.g. a 304 Not Modified on a static file response will
+        # have an empty body.
+        # If the body is empty, delete the cache because it
+        # contains a stale Threading._Event object that will
+        # stall all consecutive requests until the _Event times
+        # out
+        body = b''.join(output)
+        if not body:
+            cherrypy._cache.delete()
+        else:
+            cherrypy._cache.put((response.status, response.headers or {},
+                                 body, response.time), len(body))
 
     response = cherrypy.serving.response
     response.body = tee(response.body)
@@ -457,14 +469,14 @@ def expires(secs=0, force=False, debug=False):
             secs = (86400 * secs.days) + secs.seconds
 
         if secs == 0:
-            if force or ("Pragma" not in headers):
-                headers["Pragma"] = "no-cache"
+            if force or ('Pragma' not in headers):
+                headers['Pragma'] = 'no-cache'
             if cherrypy.serving.request.protocol >= (1, 1):
-                if force or "Cache-Control" not in headers:
-                    headers["Cache-Control"] = "no-cache, must-revalidate"
+                if force or 'Cache-Control' not in headers:
+                    headers['Cache-Control'] = 'no-cache, must-revalidate'
             # Set an explicit Expires date in the past.
             expiry = httputil.HTTPDate(1169942400.0)
         else:
             expiry = httputil.HTTPDate(response.time + secs)
-        if force or "Expires" not in headers:
-            headers["Expires"] = expiry
+        if force or 'Expires' not in headers:
+            headers['Expires'] = expiry