[REV] point_of_sale,pos_sale: remove usage of lru_cache

Since b6242264ea9f9f9f42cca4427e30071219ae6a70 a new caching strategy
for reducing the database queries when computing frequently the currency
conversions or rate was implemented. Therefor it isn't needed to use a
local `lru_cache` anymore. The new cache is implemented via
a `depends_context` which each have their own ORM cache lasting for the
current transaction.

Part-of: odoo/odoo#148825

addons/point_of_sale/models/pos_order.py

@@ -3,7 +3,7 @@
 import logging
 from datetime import datetime
 from markupsafe import Markup
-from functools import partial, lru_cache
+from functools import partial
 from itertools import groupby
 from collections import defaultdict
 
@@ -380,18 +380,8 @@ class PosOrder(models.Model):
 
     @api.depends('date_order', 'company_id', 'currency_id', 'company_id.currency_id')
     def _compute_currency_rate(self):
-        @lru_cache
-        def get_rate(from_currency, to_currency, company, date):
-            return self.env['res.currency']._get_conversion_rate(
-                from_currency=from_currency,
-                to_currency=to_currency,
-                company=company,
-                date=date,
-            )
         for order in self:
-            # date_order is a datetime, but the rates are looked up on a date basis,
-            # therefor converting the date_order to a date helps with sharing entries in the lru_cache
-            order.currency_rate = get_rate(order.company_id.currency_id, order.currency_id, order.company_id, order.date_order.date())
+            order.currency_rate = self.env['res.currency']._get_conversion_rate(order.company_id.currency_id, order.currency_id, order.company_id, order.date_order)
 
     @api.depends('lines.is_total_cost_computed')
     def _compute_is_total_cost_computed(self):

addons/pos_sale/models/pos_order.py

@@ -1,6 +1,5 @@
 # -*- coding: utf-8 -*-
 # Part of Odoo. See LICENSE file for full copyright and licensing details.
-from functools import lru_cache
 
 from odoo import api, fields, models, _
 from odoo.tools import float_compare, float_is_zero
@@ -25,19 +24,9 @@ class PosOrder(models.Model):
 
     @api.depends('date_order', 'company_id')
     def _compute_currency_rate(self):
-        @lru_cache
-        def get_rate(from_currency, to_currency, company, date):
-            return self.env['res.currency']._get_conversion_rate(
-                from_currency=from_currency,
-                to_currency=to_currency,
-                company=company,
-                date=date,
-            )
         for order in self:
             date_order = order.date_order or fields.Datetime.now()
-            # date_order is a datetime, but the rates are looked up on a date basis,
-            # therefor converting the date_order to a date helps with sharing entries in the lru_cache
-            order.currency_rate = get_rate(order.company_id.currency_id, order.currency_id, order.company_id, date_order.date())
+            order.currency_rate = self.env['res.currency']._get_conversion_rate(order.company_id.currency_id, order.currency_id, order.company_id, date_order)
 
     def _prepare_invoice_vals(self):
         invoice_vals = super(PosOrder, self)._prepare_invoice_vals()