[FIX] fields.py: improve computation time of records having a different value in cache

Instead of using a filtered with `cache.get`,
use a dedicated method in the Cache class to get
the records having a different value in cache then asked.

This is mainly to avoid the creation of intermediate
`browse` of 1 record, when doing `for rec in self`
in `filtered`.

Creating browses is costly, and avoiding it leads
to performance gains.

The dedicated method `get_records_different_from`
loops on the record ids, instead of on browse records

2 files changed, 22 insertions, 8 deletions

diff --git a/odoo/api.py b/odoo/api.py
index 1bba63b4400..65ae87f2b92 100644
--- a/odoo/api.py
+++ b/odoo/api.py
@@ -766,6 +766,24 @@ class Cache(object):
             except KeyError:
                 pass
 
+    def get_records_different_from(self, records, field, value):
+        """ Return the subset of ``records`` that has not ``value`` for ``field``. """
+        field_cache = self._data[field]
+        key = self._get_context_key(records.env, field) if field.depends_context else None
+        ids = []
+        for record_id in records._ids:
+            try:
+                if key:
+                    val = field_cache[record_id][key]
+                else:
+                    val = field_cache[record_id]
+            except KeyError:
+                ids.append(record_id)
+            else:
+                if val != value:
+                    ids.append(record_id)
+        return records.browse(ids)
+
     def get_fields(self, record):
         """ Return the fields with a value for ``record``. """
         for name, field in record._fields.items():
diff --git a/odoo/fields.py b/odoo/fields.py
index 9e285517674..e82bc06ee98 100644
--- a/odoo/fields.py
+++ b/odoo/fields.py
@@ -967,9 +967,8 @@ class Field(MetaField('DummyField', (object,), {})):
 
         # update the cache, and discard the records that are not modified
         cache = records.env.cache
-        NOTHING = object()
         cache_value = self.convert_to_cache(value, records)
-        records = records.filtered(lambda record: cache.get(record, self, NOTHING) != cache_value)
+        records = cache.get_records_different_from(records, self, cache_value)
         if not records:
             return records
         cache.update(records, self, [cache_value] * len(records))
@@ -1386,9 +1385,8 @@ class _String(Field):
 
         # update the cache, and discard the records that are not modified
         cache = records.env.cache
-        NOTHING = object()
         cache_value = self.convert_to_cache(value, records)
-        records = records.filtered(lambda record: cache.get(record, self, NOTHING) != cache_value)
+        records = cache.get_records_different_from(records, self, cache_value)
         if not records:
             return records
         cache.update(records, self, [cache_value] * len(records))
@@ -1912,9 +1910,8 @@ class Binary(Field):
 
         # update the cache, and discard the records that are not modified
         cache = records.env.cache
-        NOTHING = object()
         cache_value = self.convert_to_cache(value, records)
-        records = records.filtered(lambda record: cache.get(record, self, NOTHING) != cache_value)
+        records = cache.get_records_different_from(records, self, cache_value)
         if not records:
             return records
         cache.update(records, self, [cache_value] * len(records))
@@ -2396,9 +2393,8 @@ class Many2one(_Relational):
 
         # discard the records that are not modified
         cache = records.env.cache
-        NOTHING = object()
         cache_value = self.convert_to_cache(value, records)
-        records = records.filtered(lambda record: cache.get(record, self, NOTHING) != cache_value)
+        records = cache.get_records_different_from(records, self, cache_value)
         if not records:
             return records