nolt 7671fe2d94 Serialize player context mutations against the periodic save ...

A player's progress is persisted from two unrelated flows: action
handlers triggered by incoming packets (sequential per connection) and
the periodic save, which runs on an independent timer. Action handlers
mutate tracked entities with plain field and collection writes - for
example crafting toggles item.ItemOptions, and item stacking and NPC
selling delete item rows - which bypass the persistence context's own
lock. When such a mutation runs while SaveChangesAsync enumerates the
change tracker, the save throws (collection-modified, or a
DbUpdateConcurrency "affected 0 rows" since the context has no
concurrency tokens). SaveChanges is atomic, so every following save
fails too and the whole session never persists: on relog the player
rolls back, losing progress and items.

Add a per-player re-entrant persistence lock and acquire it around both
the packet-handling funnel and SaveProgressAsync, so a player's
mutations and saves can never overlap. The lock is re-entrant per
asynchronous flow (an instance AsyncLocal), so an inline save inside an
already-serialized handler does not deadlock; and it is per player, so a
trade still acquires the trading partner's lock separately.

Add regression tests covering mutual exclusion and re-entrancy of the
lock.

2026-08-13 08:45:38 +03:00

4.6 KiB

Raw Blame History

View Raw