[REF] stock: merge quants

In a situation where one transaction is updating a quant via
`_update_available_quantity`and another concurrent one calls
this function with the same argument, we’ll create a new quant
in order for these transactions to not rollback.

This commit adds a method to deduplicate these quants.

addons/stock/models/stock_quant.py

@@ -263,6 +263,34 @@ class StockQuant(models.Model):
                 break
         return reserved_quants
 
+    @api.model
+    def _merge_quants(self):
+        """ In a situation where one transaction is updating a quant via
+        `_update_available_quantity` and another concurrent one calls this function with the same
+        argument, we’ll create a new quant in order for these transactions to not rollback. This
+        method will find and deduplicate these quants.
+        """
+        query = """WITH
+                        dupes AS (
+                            SELECT min(id) as to_update_quant_id,
+                                (array_agg(id ORDER BY id))[2:array_length(array_agg(id), 1)] as to_delete_quant_ids,
+                                SUM(reserved_quantity) as reserved_quantity,
+                                SUM(quantity) as quantity
+                            FROM stock_quant
+                            GROUP BY product_id, company_id, location_id, lot_id, package_id, owner_id, in_date
+                            HAVING count(id) > 1
+                        ),
+                        _up AS (
+                            UPDATE stock_quant q
+                                SET quantity = d.quantity,
+                                    reserved_quantity = d.reserved_quantity
+                            FROM dupes d
+                            WHERE d.to_update_quant_id = q.id
+                        )
+                   DELETE FROM stock_quant WHERE id in (SELECT unnest(to_delete_quant_ids) from dupes)
+        """
+        self.env.cr.execute(query)
+
 
 class QuantPackage(models.Model):
     """ Packages containing quants and/or other packages """

addons/stock/views/stock_quant_views.xml

@@ -139,7 +139,17 @@
         <field name="res_model">stock.quant</field>
     </record>
 
-    <menuitem id="menu_quants" name="Inventory" parent="stock.menu_warehouse_report" sequence="100" action="quantsact"/>
+    <record model="ir.actions.server" id="quant_merge_action"> <!-- Menu + python -->
+      <field name="name">Merge duplicate quants</field>
+      <field name="model_id" ref="stock.model_stock_quant"/>
+      <field name="state">code</field>
+      <field name="code">
+env['stock.quant']._merge_quants()
+action = env.ref('stock.quantsact').read()[0]
+      </field>
+    </record>
+
+    <menuitem id="menu_quants" name="Inventory" parent="stock.menu_warehouse_report" sequence="100" action="stock.quant_merge_action"/>
 
     <record id="quant_package_search_view" model="ir.ui.view">
         <field name="name">stock.quant.package.search</field>