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package clock
import (
"sync"
"sync/atomic"
lsync "lindenii.org/go/lgo/sync"
)
// entry is one cached key/value with CLOCK.
type entry[K comparable, V any] struct {
key K
value V
weight uint64
prev, next *entry[K, V]
// referenced is set on access and cleared by the eviction sweep;
// prev and next link the entry into its shard's ring.
referenced atomic.Bool
}
// shard is an independently locked CLOCK cache.
type shard[K comparable, V any] struct {
items lsync.Map[K, *entry[K, V]]
hand *entry[K, V]
weight uint64
count int
maxWeight uint64
// mu protects the ring, hand, totals, and writes.
mu sync.Mutex
}
// newShard returns an empty shard with the given weight budget.
func newShard[K comparable, V any](maxWeight uint64) *shard[K, V] {
return &shard[K, V]{ //nolint:exhaustruct
maxWeight: maxWeight,
}
}
// len returns the shard's entry count.
func (shard *shard[K, V]) len() int {
shard.mu.Lock()
defer shard.mu.Unlock()
return shard.count
}
// loadWeight returns the shard's current total weight.
func (shard *shard[K, V]) loadWeight() uint64 {
shard.mu.Lock()
defer shard.mu.Unlock()
return shard.weight
}
// clear removes every entry.
func (shard *shard[K, V]) clear() {
shard.mu.Lock()
defer shard.mu.Unlock()
shard.items.Clear()
shard.hand = nil
shard.weight = 0
shard.count = 0
}
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