ext: fix issues in net gc task (#7904)

* don't run on dropping databases
* don't call asyncio.wait([])
* fix wrong logging without decoding JSON

edb/server/net_worker.py

@@ -265,7 +265,11 @@ def _warn(e):
     )
     async for iteration in rloop:
         async with iteration:
-            result = await execute.parse_execute_json(
+            if not db.tenant.is_database_connectable(db.name):
+                # Don't run the net_worker if the database is not
+                # connectable, e.g. being dropped
+                continue
+            result_json = await execute.parse_execute_json(
                 db,
                 """
                 with requests := (
@@ -274,14 +278,15 @@ def _warn(e):
                     and (datetime_of_statement() - .updated_at) >
                     <duration>$expires_in
                 )
-                delete requests;
+                select count((delete requests));
                 """,
                 variables={"expires_in": expires_in.to_backend_str()},
                 cached_globally=True,
                 tx_isolation=defines.TxIsolationLevel.RepeatableRead,
             )
-            if len(result) > 0:
-                logger.info(f"Deleted requests: {result!r}")
+            result: list[int] = json.loads(result_json)
+            if result[0] > 0:
+                logger.info(f"Deleted {result[0]} requests")
             else:
                 logger.info(f"No requests to delete")
 
@@ -311,7 +316,8 @@ async def gc(server: edbserver.BaseServer) -> None:
             if tenant.accept_new_tasks
         ]
         try:
-            await asyncio.wait(tasks)
+            if tasks:
+                await asyncio.wait(tasks)
         except Exception as ex:
             logger.debug(
                 "GC of std::net::http::ScheduledRequest failed", exc_info=ex

edb/server/protocol/auth_ext/pkce.py

@@ -158,23 +158,29 @@ async def delete(db: edbtenant.dbview.Database, id: str) -> None:
     assert len(result_json) == 1
 
 
+async def _delete_challenge(db: edbtenant.dbview.Database) -> None:
+    if not db.tenant.is_database_connectable(db.name):
+        # Don't run gc if the database is not connectable, e.g. being dropped
+        return
+
+    await execute.parse_execute_json(
+        db,
+        """
+        delete ext::auth::PKCEChallenge filter
+            (datetime_of_statement() - .created_at) >
+            <duration>$validity
+        """,
+        variables={"validity": VALIDITY.to_backend_str()},
+        cached_globally=True,
+    )
+
+
 async def _gc(tenant: edbtenant.Tenant) -> None:
     try:
         async with asyncio.TaskGroup() as g:
             for db in tenant.iter_dbs():
                 if "auth" in db.extensions:
-                    g.create_task(
-                        execute.parse_execute_json(
-                            db,
-                            """
-                            delete ext::auth::PKCEChallenge filter
-                                (datetime_of_statement() - .created_at) >
-                                <duration>$validity
-                            """,
-                            variables={"validity": VALIDITY.to_backend_str()},
-                            cached_globally=True,
-                        ),
-                    )
+                    g.create_task(_delete_challenge(db))
     except Exception as ex:
         logger.debug(
             "GC of ext::auth::PKCEChallenge failed (instance: %s)",