github.com/onflow/flow-go@v0.35.7-crescendo-preview.23-atree-inlining/module/mempool/herocache/backdata/tracer.go

package herocache

import "github.com/onflow/flow-go/model/flow"

type CacheOpt func(*Cache)

// Tracer is a generic interface that is used to report specific events that happen during
// lifetime of Cache and are potentially interesting for external consumer.
type Tracer interface {
	// EntityEjectionDueToEmergency reports ejected entity whenever a bucket is found full and all of its keys are valid, i.e.,
	// each key belongs to an existing (key, entity) pair.
	// Hence, adding a new key to that bucket will replace the oldest valid key inside that bucket.
	// This ejection happens with very low, but still cryptographically non-negligible probability.
	EntityEjectionDueToEmergency(ejectedEntity flow.Entity)
	// EntityEjectionDueToFullCapacity reports ejected entity whenever adding a new (key, entity) to the cache results in ejection of another (key', entity') pair.
	// This normally happens -- and is expected -- when the cache is full.
	EntityEjectionDueToFullCapacity(ejectedEntity flow.Entity)
}

// WithTracer injects tracer into the cache
func WithTracer(t Tracer) CacheOpt {
	return func(c *Cache) {
		c.tracer = t
	}
}