[commands/cache] make pip cache purge remove everything from http +…

… wheels caches; make `pip cache remove` prune empty directories.

src/pip/_internal/commands/cache.py

@@ -179,24 +179,34 @@ def remove_cache_items(self, options, args):
 
         files = self._find_wheels(options, args[0])
 
-        # Only fetch http files if no specific pattern given
-        if args[0] == '*':
-            files += self._find_http_files(options)
-
         if not files:
             raise CommandError('No matching packages')
 
         for filename in files:
             os.unlink(filename)
             logger.debug('Removed %s', filename)
+
+        dirs = filesystem.list_empty_subdirs(self._cache_dir(options, 'http')) + \
+               filesystem.list_empty_subdirs(self._cache_dir(options, 'wheels'))
+        for dirname in dirs:
+            os.rmdir(dirname)
+
         logger.info('Files removed: %s', len(files))
+        logger.info('Empty directories removed: %s', len(dirs))
 
     def purge_cache(self, options, args):
         # type: (Values, List[Any]) -> None
         if args:
             raise CommandError('Too many arguments')
 
-        return self.remove_cache_items(options, ['*'])
+        # Remove everything in the "http" and "wheels" cache directories.
+        filesystem.remove_subdirs(self._cache_dir(options, 'http'))
+        filesystem.remove_subdirs(self._cache_dir(options, 'wheels'))
+
+        # selfcheck.json is no longer used by pip.
+        selfcheck_json = self._cache_dir(options, 'selfcheck.json')
+        if os.path.isfile(selfcheck_json):
+            os.remove(selfcheck_json)
 
     def _cache_dir(self, options, subdir):
         # type: (Values, str) -> str

src/pip/_internal/utils/filesystem.py

@@ -198,3 +198,21 @@ def directory_size(path):
 def format_directory_size(path):
     # type: (str) -> str
     return format_size(directory_size(path))
+
+
+def list_empty_subdirs(path):
+    # type: (str) -> List[str]
+    """Returns a list of absolute paths of empty directories beneath path.
+    """
+    result = []  # type: List[str]
+    for root, dirs, _files in os.walk(path, topdown=False):
+        result.extend(os.path.join(root, d) for d in dirs)
+    return result
+
+
+def remove_subdirs(path):
+    # type: (str)  -> None
+    """Removes all subdirectories under path."""
+    for entry in os.scandir(path):
+        if entry.is_dir():
+            shutil.rmtree(entry.path)