Add an LRU cache to the config.

qutebrowser/config/config.py

@@ -27,6 +27,7 @@ we borrow some methods and classes from there where it makes sense.
 import os
 import os.path
 import textwrap
+import functools
 import configparser
 import collections.abc
 
@@ -277,6 +278,7 @@ class ConfigManager(QObject):
         existed = optname in sectdict
         if existed:
             del sectdict[optname]
+            self.get.cache_clear()
         return existed
 
     @cmdutils.register(name='get', instance='config',
@@ -301,6 +303,7 @@ class ConfigManager(QObject):
             message.info("{} {} = {}".format(sectname, optname, val),
                          immediately=True)
 
+    @functools.lru_cache()
     def get(self, sectname, optname, raw=False, transformed=True):
         """Get the value from a section/option.
 
@@ -411,6 +414,7 @@ class ConfigManager(QObject):
             if sectname in ('colors', 'fonts'):
                 self.style_changed.emit(sectname, optname)
             self.changed.emit(sectname, optname)
+            self.get.cache_clear()
 
     @cmdutils.register(instance='config')
     def save(self):

qutebrowser/utils/debug.py

@@ -29,6 +29,7 @@ from PyQt5.QtCore import pyqtRemoveInputHook, QEvent, QCoreApplication
 
 from qutebrowser.utils import log, utils
 from qutebrowser.commands import cmdutils
+from qutebrowser.config import config
 
 
 @cmdutils.register(debug=True, name='debug-set-trace')
@@ -83,6 +84,11 @@ def debug_all_objects():
     s = QCoreApplication.instance().get_all_objects()
     log.misc.debug(s)
 
+@cmdutils.register(debug=True)
+def debug_cache_stats():
+    """Print config LRU cache stats."""
+    info = config.instance().get.cache_info()
+    log.misc.debug(info)
 
 def log_events(klass):
     """Class decorator to log Qt events."""