| 1 | package cache |
| 2 | |
| 3 | import ( |
| 4 | "context" |
| 5 | "time" |
| 6 | ) |
| 7 | |
| 8 | type janitor[K comparable, V any] struct { |
| 9 | interval time.Duration |
| 10 | cache *cache[K, V] |
| 11 | cancel context.CancelFunc |
| 12 | done chan struct{} |
| 13 | } |
| 14 | |
| 15 | func newJanitor[K comparable, V any](c *cache[K, V], interval time.Duration) *janitor[K, V] { |
| 16 | return &janitor[K, V]{ |
| 17 | interval: interval, |
| 18 | cache: c, |
| 19 | } |
| 20 | } |
| 21 | |
| 22 | // Start begins the background sweep goroutine. It panics if the janitor is |
| 23 | // already running. If the interval is not positive, Start is a no-op. |
| 24 | func (j *janitor[K, V]) Start(ctx context.Context) { |
| 25 | if j.cancel != nil { |
| 26 | panic("cache: janitor already started") |
| 27 | } |
| 28 | if j.interval <= 0 { |
| 29 | return |
| 30 | } |
| 31 | ctx, j.cancel = context.WithCancel(ctx) |
| 32 | j.done = make(chan struct{}) |
| 33 | go j.loop(ctx) |
| 34 | } |
| 35 | |
| 36 | // Stop stops the background sweep goroutine and waits for it to exit. |
| 37 | func (j *janitor[K, V]) Stop() { |
| 38 | if j.cancel == nil { |
| 39 | return |
| 40 | } |
| 41 | j.cancel() |
| 42 | <-j.done |
| 43 | j.cancel = nil |
| 44 | } |
| 45 | |
| 46 | func (j *janitor[K, V]) loop(ctx context.Context) { |
| 47 | defer close(j.done) |
| 48 | ticker := time.NewTicker(j.interval) |
| 49 | defer ticker.Stop() |
| 50 | for { |
| 51 | select { |
| 52 | case <-ticker.C: |
| 53 | j.cache.DeleteExpired() |
| 54 | case <-ctx.Done(): |
| 55 | return |
| 56 | } |
| 57 | } |
| 58 | } |
| 59 | |