Ilia Denisov
118 lines
3.6 KiB
Go
118 lines
3.6 KiB
Go
// Package gamelease implements the Redis-backed adapter for
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// `ports.GameLeaseStore`.
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//
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// The lease guards every lifecycle operation Runtime Manager runs
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// against one game (start, stop, restart, patch, cleanup, plus the
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// reconciler's drift mutations). Acquisition uses `SET NX PX <ttl>`
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// with a random caller token; release runs a Lua compare-and-delete
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// so a holder that lost the lease through TTL expiry cannot wipe
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// another caller's claim.
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package gamelease
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import (
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"context"
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"errors"
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"fmt"
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"strings"
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"time"
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"galaxy/rtmanager/internal/adapters/redisstate"
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"galaxy/rtmanager/internal/ports"
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"github.com/redis/go-redis/v9"
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)
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// releaseScript removes the per-game lease only when the supplied token
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// still owns it. Compare-and-delete prevents a TTL-expired holder from
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// clearing another caller's claim.
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var releaseScript = redis.NewScript(`
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if redis.call("GET", KEYS[1]) == ARGV[1] then
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return redis.call("DEL", KEYS[1])
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end
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return 0
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`)
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// Config configures one Redis-backed game lease store instance. The
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// store does not own the redis client lifecycle; the caller (typically
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// the service runtime) opens and closes it.
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type Config struct {
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// Client stores the Redis client the store uses for every command.
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Client *redis.Client
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}
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// Store persists the per-game lifecycle lease in Redis.
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type Store struct {
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client *redis.Client
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keys redisstate.Keyspace
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}
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// New constructs one Redis-backed game lease store from cfg.
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func New(cfg Config) (*Store, error) {
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if cfg.Client == nil {
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return nil, errors.New("new rtmanager game lease store: nil redis client")
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}
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return &Store{
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client: cfg.Client,
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keys: redisstate.Keyspace{},
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}, nil
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}
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// TryAcquire attempts to acquire the per-game lease for gameID owned by
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// token for ttl. The acquired return is true on a successful claim and
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// false when another caller still owns the lease. A non-nil error
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// reports a transport failure and must not be confused with a missed
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// lease.
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func (store *Store) TryAcquire(ctx context.Context, gameID, token string, ttl time.Duration) (bool, error) {
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if store == nil || store.client == nil {
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return false, errors.New("try acquire game lease: nil store")
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}
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if ctx == nil {
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return false, errors.New("try acquire game lease: nil context")
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}
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if strings.TrimSpace(gameID) == "" {
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return false, errors.New("try acquire game lease: game id must not be empty")
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}
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if strings.TrimSpace(token) == "" {
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return false, errors.New("try acquire game lease: token must not be empty")
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}
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if ttl <= 0 {
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return false, errors.New("try acquire game lease: ttl must be positive")
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}
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acquired, err := store.client.SetNX(ctx, store.keys.GameLease(gameID), token, ttl).Result()
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if err != nil {
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return false, fmt.Errorf("try acquire game lease: %w", err)
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}
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return acquired, nil
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}
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// Release removes the per-game lease for gameID only when token still
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// matches the stored owner value. A token mismatch is a silent no-op.
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func (store *Store) Release(ctx context.Context, gameID, token string) error {
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if store == nil || store.client == nil {
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return errors.New("release game lease: nil store")
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}
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if ctx == nil {
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return errors.New("release game lease: nil context")
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}
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if strings.TrimSpace(gameID) == "" {
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return errors.New("release game lease: game id must not be empty")
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}
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if strings.TrimSpace(token) == "" {
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return errors.New("release game lease: token must not be empty")
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}
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if err := releaseScript.Run(
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ctx,
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store.client,
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[]string{store.keys.GameLease(gameID)},
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token,
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).Err(); err != nil {
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return fmt.Errorf("release game lease: %w", err)
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}
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return nil
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}
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// Compile-time assertion: Store implements ports.GameLeaseStore.
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var _ ports.GameLeaseStore = (*Store)(nil)
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