[pypy-svn] r39870 - pypy/dist/pypy/doc/discussion

[hpk at codespeak.net]

Author: hpk
Date: Sun Mar  4 12:52:03 2007
New Revision: 39870

Modified:
   pypy/dist/pypy/doc/discussion/chained_getattr.txt
Log:
(Anto, hpk) updates, rather use a dict at module global level,
and tweak the current code consideations a bit  


Modified: pypy/dist/pypy/doc/discussion/chained_getattr.txt
==============================================================================
--- pypy/dist/pypy/doc/discussion/chained_getattr.txt	(original)
+++ pypy/dist/pypy/doc/discussion/chained_getattr.txt	Sun Mar  4 12:52:03 2007
@@ -26,31 +26,41 @@
     now for the LOAD_CHAINED_GLOBAL bytecode implementation:
 
         Module dicts have a special implemnetation, providing: 
-        - an extra "fastlookup" rpython-list serving as a cache for
-          LOAD_CHAINED_GLOBAL places within the modules
-        - LOAD_CHAINED_GLOBAL has an index pointing into the
-          rpython-list 
-        - the fastlookup list contains e.g. tuple entries:
-          ([obj1, obj2, obj3], [verglobals, ver1, ver2])
-          "verglobals" refers to the version of the module globals 
-          at which the initial 'os' global lookup was done. 
+        - an extra "fastlookup" rpython-dict serving as a cache for
+          LOAD_CHAINED_GLOBAL places within the modules: 
+          - keys are e.g. ('os', 'path', 'normpath')
+          - values are tuples of the form: 
+            ([obj1, obj2, obj3], [ver1, ver2])
           "ver1" refer to the version of the globals of "os"
           "ver2" refer to the version of the globals of "os.path"
           "obj3" is the resulting "normpath" function 
 
+        - upon changes to the global dict, "fastlookup.clear()" is called
+
         - after the fastlookup entry is filled for a given
           LOAD_CHAINED_GLOBAL index, the following checks need
           to be performed in the bytecode implementation: 
     
-          objects, versions = f_globals.fastlookup[chained_global_index]
-          if getver(f_globals) != versions[0]:
-             return do_full_lookup()
-          i = 0
-          while i < len(objects) - 1:
-              curobj = objects[i]
-              lastversion = versions[i+1]
-              currentversion = getver(curobj)
-              if currentversion != lastversion:
-                 return do_full_lookup() # can be more clever 
-              i += 1
+          value = f_globals.fastlookup.get(key, None)
+          if value is None:
+             # fill entry 
+          else:
+             # check that our cached lookups are still valid 
+              assert isinstance(value, tuple) 
+              objects, versions = value
+              i = 0
+              while i < len(versions): 
+                  lastversion = versions[i]
+                  ver = getver_for_obj(objects[i])
+                  if ver == -1 or ver != lastversion:
+                     name = key[i]
+                     objects[i] = space.getattr(curobj, name)
+                     versions[i] = ver
+                  curobj = objects[i]
+                  i += 1
           return objects[i]
+
+        def getver_for_obj(obj):
+            if "obj is not Module":
+                return -1
+            return obj.w_dict.version