Merge "Add caching to openstack.common.cfg" into stable/essex

1 files changed, 37 insertions, 6 deletions

diff --git a/nova/openstack/common/cfg.py b/nova/openstack/common/cfg.py
index 7adf3b4722..fd1cb83e37 100644
--- a/nova/openstack/common/cfg.py
+++ b/nova/openstack/common/cfg.py
@@ -221,12 +221,13 @@ log files:
 
 import collections
 import copy
+import functools
 import optparse
 import os
 import string
 import sys
 
-import iniparser
+from nova.openstack.common import iniparser
 
 
 class Error(Exception):
@@ -821,6 +822,8 @@ class ConfigOpts(collections.Mapping):
                                               usage=self.usage)
         self._cparser = None
 
+        self.__cache = {}
+
         self.register_cli_opt(
             MultiStrOpt('config-file',
                         default=self.default_config_files,
@@ -830,6 +833,15 @@ class ConfigOpts(collections.Mapping):
                              'files taking precedence. The default files used '
                              'are: %s' % (self.default_config_files, )))
 
+    def __clear_cache(f):
+        @functools.wraps(f)
+        def __inner(self, *args, **kwargs):
+            if kwargs.pop('clear_cache', True):
+                self.__cache.clear()
+            return f(self, *args, **kwargs)
+
+        return __inner
+
     def __call__(self, args=None):
         """Parse command line arguments and config files.
 
@@ -864,7 +876,7 @@ class ConfigOpts(collections.Mapping):
         :returns: the option value (after string subsititution) or a GroupAttr
         :raises: NoSuchOptError,ConfigFileValueError,TemplateSubstitutionError
         """
-        return self._substitute(self._get(name))
+        return self._get(name)
 
     def __getitem__(self, key):
         """Look up an option value and perform string substitution."""
@@ -883,12 +895,14 @@ class ConfigOpts(collections.Mapping):
         """Return the number of options and option groups."""
         return len(self._opts) + len(self._groups)
 
+    @__clear_cache
     def reset(self):
         """Reset the state of the object to before it was called."""
         self._args = None
         self._cli_values = None
         self._cparser = None
 
+    @__clear_cache
     def register_opt(self, opt, group=None):
         """Register an option schema.
 
@@ -911,11 +925,13 @@ class ConfigOpts(collections.Mapping):
 
         return True
 
+    @__clear_cache
     def register_opts(self, opts, group=None):
         """Register multiple option schemas at once."""
         for opt in opts:
-            self.register_opt(opt, group)
+            self.register_opt(opt, group, clear_cache=False)
 
+    @__clear_cache
     def register_cli_opt(self, opt, group=None):
         """Register a CLI option schema.
 
@@ -931,7 +947,7 @@ class ConfigOpts(collections.Mapping):
         if self._args is not None:
             raise ArgsAlreadyParsedError("cannot register CLI option")
 
-        if not self.register_opt(opt, group):
+        if not self.register_opt(opt, group, clear_cache=False):
             return False
 
         if group is not None:
@@ -941,10 +957,11 @@ class ConfigOpts(collections.Mapping):
 
         return True
 
+    @__clear_cache
     def register_cli_opts(self, opts, group=None):
         """Register multiple CLI option schemas at once."""
         for opt in opts:
-            self.register_cli_opt(opt, group)
+            self.register_cli_opt(opt, group, clear_cache=False)
 
     def register_group(self, group):
         """Register an option group.
@@ -959,6 +976,7 @@ class ConfigOpts(collections.Mapping):
 
         self._groups[group.name] = copy.copy(group)
 
+    @__clear_cache
     def set_override(self, name, override, group=None):
         """Override an opt value.
 
@@ -973,6 +991,7 @@ class ConfigOpts(collections.Mapping):
         opt_info = self._get_opt_info(name, group)
         opt_info['override'] = override
 
+    @__clear_cache
     def set_default(self, name, default, group=None):
         """Override an opt's default value.
 
@@ -1056,6 +1075,18 @@ class ConfigOpts(collections.Mapping):
         self._oparser.print_help(file)
 
     def _get(self, name, group=None):
+        if isinstance(group, OptGroup):
+            key = (group.name, name)
+        else:
+            key = (group, name)
+        try:
+            return self.__cache[key]
+        except KeyError:
+            value = self._substitute(self._do_get(name, group))
+            self.__cache[key] = value
+            return value
+
+    def _do_get(self, name, group=None):
         """Look up an option value.
 
         :param name: the opt name (or 'dest', more precisely)
@@ -1196,7 +1227,7 @@ class ConfigOpts(collections.Mapping):
 
         def __getattr__(self, name):
             """Look up an option value and perform template substitution."""
-            return self.conf._substitute(self.conf._get(name, self.group))
+            return self.conf._get(name, self.group)
 
         def __getitem__(self, key):
             """Look up an option value and perform string substitution."""