Improve performance

* Compute the 'zone' fields in the same method
* Remove the dependency on 'zone_location_id', which seems to take
  a lot of time if not an infinite loop

stock_location_zone/models/stock_location.py

@@ -17,7 +17,7 @@ class StockLocation(models.Model):
     zone_location_id = fields.Many2one(
         'stock.location',
         string='Location zone',
-        compute='_compute_zone_location_id',
+        compute='_compute_location_zone',
         store=True,
         index=True,
     )
@@ -31,7 +31,7 @@ class StockLocation(models.Model):
             ('other', 'Other'),
         ],
         string='Location Kind',
-        compute='_compute_location_kind',
+        compute='_compute_location_zone',
         help='Group location according to their kinds:'
              '* Zone: locations that are flagged as being zones'
              '* Area: locations with children that are part of a zone'
@@ -40,13 +40,27 @@ class StockLocation(models.Model):
              '* Other: any other location',
     )
 
-    @api.depends('is_zone', 'usage', 'location_id.usage', 'zone_location_id',
-                 'child_ids')
-    def _compute_location_kind(self):
+    @api.depends('is_zone', 'usage', 'location_id.usage', 'child_ids',
+                 'location_id.is_zone')
+    def _compute_location_zone(self):
         for location in self:
             if location.is_zone:
                 location.location_kind = 'zone'
+                location.zone_location_id = location
                 continue
+
+            # Get the zone from the parents
+            parent = location.location_id
+            while parent:
+                if parent.is_zone:
+                    zone_location = parent
+                    break
+                parent = parent.location_id
+            else:
+                zone_location = self.browse()
+
+            location.zone_location_id = zone_location
+
             # Internal locations whose parent is view are main stocks
             if (
                 location.usage == 'internal'
@@ -57,7 +71,7 @@ class StockLocation(models.Model):
             # Internal locations having a zone and no children are bins
             if (
                 location.usage == 'internal'
-                and location.zone_location_id
+                and zone_location
                 and not location.child_ids
             ):
                 location.location_kind = 'bin'
@@ -65,7 +79,7 @@ class StockLocation(models.Model):
             # Internal locations having a zone and children are areas
             if (
                 location.usage == 'internal'
-                and location.zone_location_id
+                and zone_location
                 and location.child_ids
             ):
                 location.location_kind = 'area'
@@ -73,15 +87,6 @@ class StockLocation(models.Model):
             # All the rest are other locations
             location.location_kind = 'other'
 
-    @api.depends('is_zone', 'location_id.zone_location_id')
-    def _compute_zone_location_id(self):
-        for location in self:
-            if location.is_zone:
-                location.zone_location_id = location
-            else:
-                location.zone_location_id = \
-                    location.location_id.zone_location_id
-
     @api.multi
     @api.returns('self', lambda value: value.id)
     def copy(self, default=None):