Fixes#71758.
A platform adapter that dies on a transient upstream failure (marked
retryable=True, e.g. photon's sidecar exiting when its upstream
gRPC/CDN returns errors) is correctly queued into _failed_platforms
for background reconnection. But the reconnect watcher task itself
was spawned via a bare asyncio.create_task -- if an exception ever
escaped its OUTER while-loop (not just the per-platform inner
try/except), the watcher died silently: no log, no restart.
_ensure_reconnect_watcher_running() already existed to respawn a dead
watcher, but it's only called from _handle_adapter_fatal_error_impl()
when a NEW platform's fatal error arrives. If the watcher dies while a
platform is already sitting in the queue and no OTHER platform ever
fails afterward, nothing ever notices the watcher is dead -- exactly
matching the reported symptom: photon queued for reconnect, the
gateway itself healthy (other platforms kept working, so nothing
re-triggered the ensure-alive check), and the platform stayed dead for
17.5h until a manual restart, well after the transient upstream outage
had recovered.
Fix: spawn the reconnect watcher via the existing _spawn_supervised()
task-level supervisor (already used for kanban_dispatcher_watcher,
handoff_watcher, etc.) instead of a bare asyncio.create_task, at both
the initial startup spawn and the manual-respawn path in
_ensure_reconnect_watcher_running(). _spawn_supervised already
provides exactly what's missing here: catches and logs any exception
escaping the task, and auto-restarts with capped exponential backoff
(healthy-run counter resets so a daemon that crashes occasionally over
days is never permanently abandoned) -- self-healing independent of
any new fatal-error event.
Also hardened a related race: the watcher's per-platform loop looked
up self._failed_platforms[platform] via direct indexing after
snapshotting the keys with list(...). A platform removed concurrently
between the snapshot and the lookup (e.g. a manual /platform resume,
or a reconnect that succeeded via a different path) would raise an
uncaught KeyError -- exactly the class of bug this fix's supervision
now catches, but avoiding the crash-and-restart cycle entirely is
better than relying on it. Changed to .get() with a skip-if-missing
guard.
6 new tests pass (initial spawn uses _spawn_supervised, manual respawn
uses _spawn_supervised, the core regression -- watcher self-heals
after an uncaught exception with no new fatal-error event -- and the
race-guard scenario); 52/52 in the full
tests/gateway/test_platform_reconnect.py file (including the 4
pre-existing _ensure_reconnect_watcher_running tests, confirming no
regression to that respawn-when-dead-or-missing behavior).
ygd58
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