From 09397384795f440b5924d9b325988e9cc6eb4d09 Mon Sep 17 00:00:00 2001
From: Raphael Collet <rco@openerp.com>
Date: Tue, 30 Jun 2015 16:23:16 +0200
Subject: [PATCH] [IMP] fields: speedup of `convert_to_cache` for x2many fields
MIME-Version: 1.0
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The algorithm's complexity changed from O(n²) to O(n).
---
 openerp/fields.py     | 33 ++++++++++++++++-----------------
 openerp/tools/misc.py | 13 ++++++++++++-
 2 files changed, 28 insertions(+), 18 deletions(-)

diff --git a/openerp/fields.py b/openerp/fields.py
index 9d3fb496044..e9dbfaa9104 100644
--- a/openerp/fields.py
+++ b/openerp/fields.py
@@ -30,7 +30,7 @@ import logging
 import pytz
 import xmlrpclib
 
-from openerp.tools import float_round, frozendict, html_sanitize, ustr
+from openerp.tools import float_round, frozendict, html_sanitize, ustr, OrderedSet
 from openerp.tools import DEFAULT_SERVER_DATE_FORMAT as DATE_FORMAT
 from openerp.tools import DEFAULT_SERVER_DATETIME_FORMAT as DATETIME_FORMAT
 
@@ -1606,34 +1606,33 @@ class _RelationalMulti(_Relational):
                 return value.with_env(record.env)
         elif isinstance(value, list):
             # value is a list of record ids or commands
-            if not record.id:
-                record = record.browse()        # new record has no value
-            result = record[self.name]
-            # modify result with the commands;
-            # beware to not introduce duplicates in result
+            comodel = record.env[self.comodel_name]
+            ids = OrderedSet(record[self.name].ids)
+            # modify ids with the commands
             for command in value:
                 if isinstance(command, (tuple, list)):
                     if command[0] == 0:
-                        result += result.new(command[2])
+                        ids.add(comodel.new(command[2]).id)
                     elif command[0] == 1:
-                        result.browse(command[1]).update(command[2])
-                        result += result.browse(command[1]) - result
+                        comodel.browse(command[1]).update(command[2])
+                        ids.add(command[1])
                     elif command[0] == 2:
                         # note: the record will be deleted by write()
-                        result -= result.browse(command[1])
+                        ids.discard(command[1])
                     elif command[0] == 3:
-                        result -= result.browse(command[1])
+                        ids.discard(command[1])
                     elif command[0] == 4:
-                        result += result.browse(command[1]) - result
+                        ids.add(command[1])
                     elif command[0] == 5:
-                        result = result.browse()
+                        ids.clear()
                     elif command[0] == 6:
-                        result = result.browse(command[2])
+                        ids = OrderedSet(command[2])
                 elif isinstance(command, dict):
-                    result += result.new(command)
+                    ids.add(comodel.new(command).id)
                 else:
-                    result += result.browse(command) - result
-            return result
+                    ids.add(command)
+            # return result as a recordset
+            return comodel.browse(list(ids))
         elif not value:
             return self.null(record.env)
         raise ValueError("Wrong value for %s: %s" % (self, value))
diff --git a/openerp/tools/misc.py b/openerp/tools/misc.py
index 36b12893bc4..35f570fb7b6 100644
--- a/openerp/tools/misc.py
+++ b/openerp/tools/misc.py
@@ -37,7 +37,7 @@ import threading
 import time
 import werkzeug.utils
 import zipfile
-from collections import defaultdict, Mapping
+from collections import defaultdict, Mapping, OrderedDict
 from datetime import datetime
 from itertools import islice, izip, groupby
 from lxml import etree
@@ -1271,6 +1271,17 @@ class frozendict(dict):
     def update(self, *args, **kwargs):
         raise NotImplementedError("'update' not supported on frozendict")
 
+class OrderedSet(OrderedDict):
+    """ A simple collection that remembers the elements insertion order. """
+    def __init__(self, seq=()):
+        super(OrderedSet, self).__init__([(x, None) for x in seq])
+
+    def add(self, elem):
+        self[elem] = None
+
+    def discard(self, elem):
+        self.pop(elem, None)
+
 @contextmanager
 def ignore(*exc):
     try: