Banktransfer: Add retry in import task

src/pretix/plugins/banktransfer/tasks.py

@@ -3,6 +3,7 @@ import logging
 import re
 from decimal import Decimal
 
+from celery.exceptions import MaxRetriesExceededError
 from django.conf import settings
 from django.db import transaction
 from django.utils.translation import ugettext_noop
@@ -10,6 +11,7 @@ from django.utils.translation import ugettext_noop
 from pretix.base.i18n import language
 from pretix.base.models import Event, Order, Quota
 from pretix.base.services.async import TransactionAwareTask
+from pretix.base.services.locking import LockTimeoutException
 from pretix.base.services.mail import SendMailException
 from pretix.base.services.orders import mark_order_paid
 from pretix.celery import app
@@ -96,8 +98,8 @@ def _get_unknown_transactions(event: Event, job: BankImportJob, data: list):
     return transactions
 
 
-@app.task(base=TransactionAwareTask)
-def process_banktransfers(event: int, job: int, data: list) -> None:
+@app.task(base=TransactionAwareTask, bind=True, max_retries=5, default_retry_delay=1)
+def process_banktransfers(self, event: int, job: int, data: list) -> None:
     with language("en"):  # We'll translate error messages at display time
         event = Event.objects.get(pk=event)
         job = BankImportJob.objects.get(pk=job)
@@ -123,6 +125,13 @@ def process_banktransfers(event: int, job: int, data: list) -> None:
                 else:
                     trans.state = BankTransaction.STATE_NOMATCH
                     trans.save()
+        except LockTimeoutException:
+            try:
+                self.retry()
+            except MaxRetriesExceededError:
+                logger.exception('Maximum number of retries exceeded for task.')
+                job.state = BankImportJob.STATE_ERROR
+                job.save()
         except Exception as e:
             job.state = BankImportJob.STATE_ERROR
             job.save()