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This article mainly introduces the relevant knowledge of "celery asynchronous timing task how to achieve order timing rollback". The editor shows you the operation process through an actual case. The operation method is simple, fast and practical. I hope this "celery asynchronous timing task how to achieve order timing rollback" article can help you solve the problem.

Order rollback

Asynchronously with celery, scheduled tasks. Can be set: if the order is not paid 15 minutes after the order is placed, the order is cancelled. Do the reverse operation

Control execution (how long after execution) from datetime import datetimefrom pro_celery.celery import del_orderdef pay_status (order_id,check_time=5): # 5 seconds later ctime = datetime.now () utc_ctime = datetime.utcfromtimestamp (ctime.timestamp ()) from datetime import timedelta # seconds parameter indicates how many seconds after execution time_delay = timedelta (seconds=check_time) time_task = utc_ctime+ time_delay # submit the task to del_order How long will it take him to execute the res = del_order.apply_async (args = [order_id,], eta= time_task) celery asynchronous timing task?

This task is to cancel the order if it is not paid 5 seconds after the order is placed. Do the reverse operation. Inventory is added to the database again.

Note: considering that a small probability event of zero boundary occurs when the concurrency is more than one, the user immediately pays for which line of code the inventory is added to the database.

The consequence: the user pays, but the inventory is added to the database and the order is gone.

How to avoid: in the transaction to determine the number of affected lines, if the number of affected lines is 1, to prove the success of canceling the order, you can commit.

If the number of rows is not affected, prove that the user paid successfully at this moment, and roll back the data

# be sure to judge pay_status Prevent payment from being completed en route row = models.Order.objects.filter (order_id = order_id Pay_status=0) .update (status= "dead") if row: transaction.savepoint_commit (sid) else: transaction.savepoint_rollback (sid) import celeryimport timebackend = "redis://127.0.0.1:6379/1" broker = "redis://127.0.0.1:6379/2" cel = celery.Celery ("test", backend=backend,broker = broker) import os Sysimport djangoBASE_DIR = os.path.dirname (os.path.dirname (_ _ file__)) # navigate to the root directory of your django sys.path.append (os.path.abspath (BASE_DIR)) os.environ.setdefault ("DJANGO_SETTINGS_MODULE", "shopapi.settings") django.setup () from django.db import transaction@cel.task@transaction.atomicdef del_order (order_id): # check the current order_id order status through the database If there is no payment, we need to operate the inventory and cancel the order from app01 import models # query the order data = models.Order.objects.filter (order_id = order_id,pay_status=0). First () # if the data is not available, it means that the payment is successful and there is no operation. on the contrary, we need to roll back the inventory if data: # which items are rolled back and how much? Where do you know item_data = models.Order_items.objects.filter (order_id = order_id) .values ("product", "nums") # item_data-- > [{'product':1,'nums ": 2}, {product':2) in order_item 'nums ": 1}] all_product_dict = {k [" product "]: K [" nums "] for k in item_data} # {1 nums 2 Mag 2} all_product_id = list (all_product_dict.keys ()) all_product = models.Product.objects.filter (product_id__in = all_product_id) # Open transaction sid = transaction. Savepoint () for product in all_product: for i in range (3): stock = product.stock.quantity new_stock = stock + all_product_ employees [product.product _ id] # uses the optimistic lock res = models.Stock.objects.filter (quantity=stock Stock_id=product.stock.stock_id) .update (quantity=new_stock) if not res: if iTunes 2: transaction.savepoint_rollback (sid) from app01.func import function_tool function_tool.pay_status (order_id 1) return else: continue else: break new_buy_cont = product.buy_count-all_product_ products [product.product _ id] models.Product.objects.filter (product_id = product.product_id) .update (buy_count = new _ buy_cont) # be sure to judge pay_status Prevent payment on the way row = models.Order.objects.filter (order_id = order_id,pay_status=0) .update (status= "dead") if row: transaction.savepoint_commit (sid) else: transaction.savepoint_rollback (sid) about "celery asynchronous timing task how to achieve order timing rollback" is introduced here, thank you for reading. If you want to know more about the industry, you can follow the industry information channel. The editor will update different knowledge points for you every day.

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