Global cache lock, more strict error handling

parso/_compatibility.py

@@ -49,7 +49,7 @@ def u(string):
     FileNotFoundError = FileNotFoundError
 except NameError:
     # Python 2.7 (both IOError + OSError)
-    FileNotFoundError = EnvironmentError
+    FileNotFoundError = (IOError, OSError)
 
 
 def utf8_repr(func):

parso/cache.py

@@ -100,8 +100,7 @@ def _get_cache_clear_lock(cache_path = None):
     collection once a day (can be configured in _CACHE_CLEAR_THRESHOLD).
     """
     cache_path = cache_path or _get_default_cache_path()
-
-    return FileIO(os.path.join(cache_path, "{}-cache-lock".format(_VERSION_TAG)))
+    return FileIO(os.path.join(cache_path, "PARSO-CACHE-LOCK"))
 
 
 parser_cache = {}
@@ -226,7 +225,10 @@ def clear_inactive_cache(
                 file.stat().st_atime + _CACHED_FILE_MAXIMUM_SURVIVAL
                 <= time.time()
             ):
-                os.remove(file.path)
+                try:
+                    os.remove(file.path)
+                except OSError: # silently ignore all failures
+                    continue
     else:
         return True
 
@@ -238,8 +240,13 @@ def _remove_cache_and_update_lock(cache_path = None):
         clear_lock_time is None # first time
         or clear_lock_time + _CACHE_CLEAR_THRESHOLD <= time.time()
     ):
-        if clear_inactive_cache(cache_path = cache_path):
-            lock._touch()
+        if not lock._touch():
+            # First make sure that as few as possible other cleanup jobs also
+            # get started. There is still a race condition but it's probably
+            # not a big problem.
+            return False
+
+        clear_inactive_cache(cache_path = cache_path)
 
 def _get_hashed_path(hashed_grammar, path, cache_path=None):
     directory = _get_cache_directory_path(cache_path=cache_path)

parso/file_io.py

@@ -27,8 +27,12 @@ def _touch(self):
         try:
             os.utime(self.path, None)
         except FileNotFoundError:
-            file = open(self.path, 'a')
-            file.close()
+            try:
+                file = open(self.path, 'a')
+                file.close()
+            except OSError:  # TODO Maybe log this?
+                return False
+        return True
 
     def __repr__(self):
         return '%s(%s)' % (self.__class__.__name__, self.path)