shopfloor_base: improve lock for update action

Add the skip locked option.

shopfloor_base/actions/lock.py

@@ -1,4 +1,5 @@
 # Copyright 2022 Michael Tietz (MT Software) <mtietz@mt-software.de>
+# Copyright 2023 Camptocamp SA (http://www.camptocamp.com)
 # License LGPL-3.0 or later (http://www.gnu.org/licenses/lgpl.html).
 import hashlib
 import struct
@@ -26,7 +27,23 @@ def advisory(self, name):
         self.env.cr.execute("SELECT pg_advisory_xact_lock(%s);", (int_lock,))
         self.env.cr.fetchone()[0]
 
-    def for_update(self, records, log_exceptions=False):
-        """Lock a table FOR UPDATE"""
-        sql = "SELECT id FROM %s WHERE ID IN %%s FOR UPDATE" % records._table
-        self.env.cr.execute(sql, (tuple(records.ids),), log_exceptions=False)
+    def for_update(self, records, log_exceptions=False, skip_locked=False):
+        """Lock rows for update on a specific table.
+
+        This function will try to obtain a lock on the rows (records parameter) and
+        wait until they are available for update.
+
+        Using the SKIP LOCKED parameter (better used with only one record), it will
+        not wait for the row to be available but return False if the lock could not
+        be obtained.
+
+        """
+        query = "SELECT id FROM %s WHERE ID IN %%s FOR UPDATE"
+        if skip_locked:
+            query += " SKIP LOCKED"
+        sql = query % records._table
+        self.env.cr.execute(sql, (tuple(records.ids),), log_exceptions=log_exceptions)
+        if skip_locked:
+            rows = self.env.cr.fetchall()
+            return len(rows) == len(records)
+        return True

shopfloor_base/tests/__init__.py

@@ -1,4 +1,5 @@
 from . import test_actions_data
+from . import test_actions_lock
 from . import test_menu_service
 from . import test_profile_service
 from . import test_scan_anything_service

shopfloor_base/tests/test_actions_lock.py

@@ -0,0 +1,29 @@
+# Copyright 2023 Camptocamp SA (http://www.camptocamp.com)
+# License LGPL-3.0 or later (http://www.gnu.org/licenses/lgpl.html).
+from contextlib import closing
+
+from .common import CommonCase
+
+
+class ActionsLockCase(CommonCase):
+    @classmethod
+    def setUpClassBaseData(cls):
+        super().setUpClassBaseData()
+        cls.partner = cls.env.ref("base.res_partner_12")
+        with cls.work_on_actions(cls) as work:
+            cls.lock = work.component(usage="lock")
+
+    def test_select_for_update_skip_locked_ok(self):
+        """Check the lock is obtained and True is returned."""
+        result = self.lock.for_update(self.partner, skip_locked=True)
+        self.assertTrue(result)
+
+    def test_select_for_update_skip_locked_not_ok(self):
+        """Check the lock is NOT obtained and False is returned."""
+        with closing(self.registry.cursor()) as cr:
+            # Simulate another user locked a row
+            cr.execute(
+                "SELECT id FROM res_partner WHERE id=%s FOR UPDATE", (self.partner.id,)
+            )
+            result = self.lock.for_update(self.partner, skip_locked=True)
+            self.assertFalse(result)