internal/cache: add (and move clock to internal/cache/clock)

1 files changed, 0 insertions, 105 deletions

diff --git a/internal/clock/shard_write.go b/internal/clock/shard_write.go
deleted file mode 100644
index 40ddabd0..00000000
--- a/internal/clock/shard_write.go
+++ /dev/null
@@ -1,105 +0,0 @@
-package clock
-
-// add inserts or replaces key, then evicts down to budget.
-//
-// It reports whether the entry was admitted;
-// an entry heavier than the shard budget is rejected
-// and leaves the shard unchanged.
-func (shard *shard[K, V]) add(key K, value V, weight uint64) bool {
-	if weight > shard.maxWeight {
-		return false
-	}
-
-	shard.mu.Lock()
-	defer shard.mu.Unlock()
-
-	if old, ok := shard.items.Load(key); ok {
-		shard.unlink(old)
-		shard.items.Delete(key)
-		shard.weight -= old.weight
-		shard.count--
-	}
-
-	e := &entry[K, V]{ //nolint:exhaustruct
-		key:    key,
-		value:  value,
-		weight: weight,
-	}
-	e.referenced.Store(true)
-
-	shard.linkBeforeHand(e)
-	shard.items.Store(key, e)
-	shard.weight += weight
-	shard.count++
-
-	shard.evict()
-
-	return true
-}
-
-// evict advances the clock hand until the shard is within budget.
-//
-// A referenced entry is spared once, its bit cleared;
-// after a full rotation of spared entries the next is evicted regardless,
-// so a flood of concurrent reads cannot stall progress.
-func (shard *shard[K, V]) evict() {
-	skips := 0
-
-	for shard.weight > shard.maxWeight && shard.hand != nil {
-		victim := shard.hand
-
-		if victim.referenced.Load() && skips < shard.count {
-			victim.referenced.Store(false)
-			shard.hand = victim.next
-			skips++
-
-			continue
-		}
-
-		shard.unlink(victim)
-		shard.items.Delete(victim.key)
-		shard.weight -= victim.weight
-		shard.count--
-		skips = 0
-	}
-}
-
-// linkBeforeHand inserts e just behind the hand,
-// so a full rotation passes before the sweep examines it.
-func (shard *shard[K, V]) linkBeforeHand(e *entry[K, V]) {
-	if shard.hand == nil {
-		e.prev = e
-		e.next = e
-		shard.hand = e
-
-		return
-	}
-
-	tail := shard.hand.prev
-	tail.next = e
-	e.prev = tail
-	e.next = shard.hand
-	shard.hand.prev = e
-}
-
-// unlink removes e from the ring,
-// moving the hand off e when it points at it.
-func (shard *shard[K, V]) unlink(e *entry[K, V]) {
-	if e.next == e {
-		shard.hand = nil
-		e.prev = nil
-		e.next = nil
-
-		return
-	}
-
-	e.prev.next = e.next
-	e.next.prev = e.prev
-
-	if shard.hand == e {
-		shard.hand = e.next
-	}
-
-	e.prev = nil
-	e.next = nil
-}