semaphore-for-db-write-lock: sqlite only

See #117

bugsink/transaction.py

@@ -7,6 +7,7 @@ import threading
 
 from django.db import transaction as django_db_transaction
 from django.db import DEFAULT_DB_ALIAS
+from django.conf import settings
 
 from snappea.settings import get_settings as get_snappea_settings
 
@@ -218,6 +219,17 @@ def immediate_atomic(using=None, savepoint=True, durable=True):
         # case.
         with immediate_atomic:
             yield
+
+    elif "sqlite" not in settings.DATABASES[using]["ENGINE"]:
+        # The SemaphoreContext was added specifically to address the WAL growth issue in sqlite; better not to use it
+        # for other database backends; in particular, if such databases have longer default timeouts, then the error
+        # message may be confusing (semaphore timeout after 10s throws an error... while the thread that hogs the DB
+        # is _not_ (yet) timed out)
+        #
+        # in-string matching matches both our 'timed' backend and the django default.
+        with immediate_atomic:
+            yield
+
     else:
         # https://stackoverflow.com/a/45681273/339144 provides some context on nesting context managers; and how to
         # proceed if you want to do this with an arbitrary number of context managers.