Files
scrabble-game/backend/internal/game/cache.go
T
Ilia Denisov 751e74b14f
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Stage 3: game domain (lifecycle, journal+cache, hint, word-check, GCG, stats)
internal/game drives the engine over a single match and owns everything the
engine does not: event-sourced persistence (a games row + an append-only decoded
move journal, with the live engine.Game kept warm in a cache and rebuilt by
replay on a miss), the play/pass/exchange/resign transitions with
validate-at-submit scoring, an unlimited score/legality preview, the hint
(per-game allowance + profile wallet), the word-check tool with complaint
capture, per-player game state, history and GCG export (Poslfit dialect), and a
background turn-timeout sweeper that auto-resigns overdue turns honouring each
player's daily away window. Like Stages 1-2 it is a service/store layer with no
HTTP; the gateway surface lands in Stage 6.

Engine: additive decoded domain API (Direction, SubmitPlay/SubmitExchange/
EvaluatePlay/HintView/Hand, MoveRecord.{Dir,MainRow,MainCol}, Registry.Lookup,
ParseVariant) so internal/game never imports scrabble-solver; and a Resign fix
so the resigner keeps their score yet never wins (the other player wins a
two-player game). Timeout reuses Resign.

Persistence: migration 00002 adds games, game_players, game_moves, complaints,
account_stats and extends accounts with away_start/away_end/hint_balance; go-jet
regenerated. account gained SpendHint. Config adds BACKEND_DICT_DIR (required),
BACKEND_DICT_VERSION, BACKEND_GAME_TIMEOUT_SWEEP_INTERVAL, BACKEND_GAME_CACHE_TTL;
main loads the registry at boot (hard dependency) and starts the sweeper.

Tests: engine resign + decoded-API tests; game unit tests (GCG, away-window
boundaries, hint budget, cache, keyed mutex, payload); inttest integration
(lifecycle, replay equivalence, timeout sweep with away grace, resign stats,
hint policy, word-check/complaint, per-game-lock). Docs (PLAN, ARCHITECTURE,
FUNCTIONAL +_ru, TESTING, README) updated.
2026-06-02 17:33:49 +02:00

122 lines
2.7 KiB
Go

package game
import (
"sync"
"time"
"github.com/google/uuid"
"scrabble/backend/internal/engine"
)
// keyedMutex hands out one mutex per game id, serialising every operation on a
// single game (engine.Game is not safe for concurrent use) while letting
// different games proceed in parallel. Locks are reference-counted and removed
// once no caller holds or awaits them.
type keyedMutex struct {
mu sync.Mutex
locks map[uuid.UUID]*lockRef
}
type lockRef struct {
mu sync.Mutex
refs int
}
func newKeyedMutex() *keyedMutex {
return &keyedMutex{locks: make(map[uuid.UUID]*lockRef)}
}
// lock acquires the mutex for id and returns its release function.
func (k *keyedMutex) lock(id uuid.UUID) func() {
k.mu.Lock()
ref := k.locks[id]
if ref == nil {
ref = &lockRef{}
k.locks[id] = ref
}
ref.refs++
k.mu.Unlock()
ref.mu.Lock()
return func() {
ref.mu.Unlock()
k.mu.Lock()
ref.refs--
if ref.refs == 0 {
delete(k.locks, id)
}
k.mu.Unlock()
}
}
// gameCache holds live engine.Game values keyed by game id and evicts an entry
// once it has been idle for ttl. An evicted game is transparently rebuilt from
// the journal on next access, so eviction never affects correctness. It is safe
// for concurrent use.
type gameCache struct {
mu sync.Mutex
entries map[uuid.UUID]*cachedGame
ttl time.Duration
now func() time.Time
}
type cachedGame struct {
game *engine.Game
lastAccess time.Time
}
func newGameCache(ttl time.Duration, now func() time.Time) *gameCache {
return &gameCache{entries: make(map[uuid.UUID]*cachedGame), ttl: ttl, now: now}
}
// get returns the live game for id and refreshes its idle timer, or (nil, false).
func (c *gameCache) get(id uuid.UUID) (*engine.Game, bool) {
c.mu.Lock()
defer c.mu.Unlock()
e, ok := c.entries[id]
if !ok {
return nil, false
}
e.lastAccess = c.now()
return e.game, true
}
// put stores g as the live game for id.
func (c *gameCache) put(id uuid.UUID, g *engine.Game) {
c.mu.Lock()
defer c.mu.Unlock()
c.entries[id] = &cachedGame{game: g, lastAccess: c.now()}
}
// remove drops id from the cache (used on a finished game and after a failed
// persist, so the next access rebuilds from the journal).
func (c *gameCache) remove(id uuid.UUID) {
c.mu.Lock()
defer c.mu.Unlock()
delete(c.entries, id)
}
// sweep evicts every entry idle longer than ttl and returns how many were
// dropped.
func (c *gameCache) sweep() int {
c.mu.Lock()
defer c.mu.Unlock()
cutoff := c.now().Add(-c.ttl)
var n int
for id, e := range c.entries {
if e.lastAccess.Before(cutoff) {
delete(c.entries, id)
n++
}
}
return n
}
// size reports the number of resident games (for diagnostics and tests).
func (c *gameCache) size() int {
c.mu.Lock()
defer c.mu.Unlock()
return len(c.entries)
}