# HG changeset patch
# User Adrien Di Mascio <Adrien.DiMascio@logilab.fr>
# Date 1304087671 -7200
# Node ID 39437617f3f0e44ac1c9fa46b81de344e6880895
# Parent  a474cb98954662d560c454b630bcac30f18bc709
[optim] cache rset column structures

When iterating over large resultsets (lot of colcumns, lot of lines)
to build entities, caching column structure (which attribute or relation
is stored in each column) can improve performance noticeably.

diff -r a474cb989546 -r 39437617f3f0 rset.py
--- a/rset.py	Fri Apr 29 12:34:53 2011 +0200
+++ b/rset.py	Fri Apr 29 16:34:31 2011 +0200
@@ -475,43 +475,57 @@
         entity.eid = eid
         # cache entity
         req.set_entity_cache(entity)
-        eschema = entity.e_schema
         # try to complete the entity if there are some additional columns
         if len(rowvalues) > 1:
-            rqlst = self.syntax_tree()
-            if rqlst.TYPE == 'select':
-                # UNION query, find the subquery from which this entity has been
-                # found
-                select, col = rqlst.locate_subquery(col, etype, self.args)
+            eschema = entity.e_schema
+            eid_col, attr_cols, rel_cols = self._rset_structure(eschema, col)
+            entity.eid = rowvalues[eid_col]
+            for attr, col_idx in attr_cols.items():
+                entity.cw_attr_cache[attr] = rowvalues[col_idx]
+            for (rtype, role), col_idx in rel_cols.items():
+                value = rowvalues[col_idx]
+                if value is None:
+                    if role == 'subject':
+                        rql = 'Any Y WHERE X %s Y, X eid %s'
+                    else:
+                        rql = 'Any Y WHERE Y %s X, X eid %s'
+                    rrset = ResultSet([], rql % (rtype, entity.eid))
+                    rrset.req = req
+                else:
+                    rrset = self._build_entity(row, col_idx).as_rset()
+                entity.cw_set_relation_cache(rtype, role, rrset)
+        return entity
+
+    @cached
+    def _rset_structure(self, eschema, entity_col):
+        eid_col = col = entity_col
+        rqlst = self.syntax_tree()
+        attr_cols = {}
+        rel_cols = {}
+        if rqlst.TYPE == 'select':
+            # UNION query, find the subquery from which this entity has been
+            # found
+            select, col = rqlst.locate_subquery(entity_col, eschema.type, self.args)
+        else:
+            select = rqlst
+        # take care, due to outer join support, we may find None
+        # values for non final relation
+        for i, attr, role in attr_desc_iterator(select, col, entity_col):
+            if role == 'subject':
+                rschema = eschema.subjrels[attr]
             else:
-                select = rqlst
-            # take care, due to outer join support, we may find None
-            # values for non final relation
-            for i, attr, role in attr_desc_iterator(select, col, entity.cw_col):
-                if role == 'subject':
-                    rschema = eschema.subjrels[attr]
-                    if rschema.final:
-                        if attr == 'eid':
-                            entity.eid = rowvalues[i]
-                        else:
-                            entity.cw_attr_cache[attr] = rowvalues[i]
-                        continue
+                rschema = eschema.objrels[attr]
+            if rschema.final:
+                if attr == 'eid':
+                    eid_col = i
                 else:
-                    rschema = eschema.objrels[attr]
+                    attr_cols[attr] = i
+            else:
                 rdef = eschema.rdef(attr, role)
                 # only keep value if it can't be multivalued
                 if rdef.role_cardinality(role) in '1?':
-                    if rowvalues[i] is None:
-                        if role == 'subject':
-                            rql = 'Any Y WHERE X %s Y, X eid %s'
-                        else:
-                            rql = 'Any Y WHERE Y %s X, X eid %s'
-                        rrset = ResultSet([], rql % (attr, entity.eid))
-                        rrset.req = req
-                    else:
-                        rrset = self._build_entity(row, i).as_rset()
-                    entity.cw_set_relation_cache(attr, role, rrset)
-        return entity
+                    rel_cols[(attr, role)] = i
+        return eid_col, attr_cols, rel_cols
 
     @cached
     def syntax_tree(self):