From f4f0d7ee3f99fa363b8a4b478f8820f7cf926dc3 Mon Sep 17 00:00:00 2001
From: Wang Xiaoqing <wx7i@outlook.com>
Date: Mon, 14 Oct 2024 19:12:10 +0800
Subject: [PATCH] Remove the policy interface (#393)

Remove the policy interface, as only one policy is being maintained.
---
 cache.go  |  2 +-
 policy.go | 33 +--------------------------------
 store.go  |  4 ++--
 ttl.go    |  2 +-
 4 files changed, 5 insertions(+), 36 deletions(-)

diff --git a/cache.go b/cache.go
index 7a40b0e7..86ef5813 100644
--- a/cache.go
+++ b/cache.go
@@ -52,7 +52,7 @@ type Cache[K Key, V any] struct {
 	// storedItems is the central concurrent hashmap where key-value items are stored.
 	storedItems store[V]
 	// cachePolicy determines what gets let in to the cache and what gets kicked out.
-	cachePolicy policy[V]
+	cachePolicy *defaultPolicy[V]
 	// getBuf is a custom ring buffer implementation that gets pushed to when
 	// keys are read.
 	getBuf *ringBuffer
diff --git a/policy.go b/policy.go
index 290488d8..08963b1e 100644
--- a/policy.go
+++ b/policy.go
@@ -30,38 +30,7 @@ const (
 	lfuSample = 5
 )
 
-// policy is the interface encapsulating eviction/admission behavior.
-// TODO: remove this interface and just rename defaultPolicy to policy, as we
-// are probably only going to use/implement/maintain one policy.
-type policy[V any] interface {
-	ringConsumer
-	// Add attempts to Add the key-cost pair to the Policy. It returns a slice
-	// of evicted keys and a bool denoting whether or not the key-cost pair
-	// was added. If it returns true, the key should be stored in cache.
-	Add(uint64, int64) ([]*Item[V], bool)
-	// Has returns true if the key exists in the Policy.
-	Has(uint64) bool
-	// Del deletes the key from the Policy.
-	Del(uint64)
-	// Cap returns the available capacity.
-	Cap() int64
-	// Close stops all goroutines and closes all channels.
-	Close()
-	// Update updates the cost value for the key.
-	Update(uint64, int64)
-	// Cost returns the cost value of a key or -1 if missing.
-	Cost(uint64) int64
-	// Optionally, set stats object to track how policy is performing.
-	CollectMetrics(*Metrics)
-	// Clear zeroes out all counters and clears hashmaps.
-	Clear()
-	// MaxCost returns the current max cost of the cache policy.
-	MaxCost() int64
-	// UpdateMaxCost updates the max cost of the cache policy.
-	UpdateMaxCost(int64)
-}
-
-func newPolicy[V any](numCounters, maxCost int64) policy[V] {
+func newPolicy[V any](numCounters, maxCost int64) *defaultPolicy[V] {
 	return newDefaultPolicy[V](numCounters, maxCost)
 }
 
diff --git a/store.go b/store.go
index e2ca800c..dfcfaa8d 100644
--- a/store.go
+++ b/store.go
@@ -50,7 +50,7 @@ type store[V any] interface {
 	// successful.
 	Update(*Item[V]) (V, bool)
 	// Cleanup removes items that have an expired TTL.
-	Cleanup(policy policy[V], onEvict func(item *Item[V]))
+	Cleanup(policy *defaultPolicy[V], onEvict func(item *Item[V]))
 	// Clear clears all contents of the store.
 	Clear(onEvict func(item *Item[V]))
 }
@@ -103,7 +103,7 @@ func (sm *shardedMap[V]) Update(newItem *Item[V]) (V, bool) {
 	return sm.shards[newItem.Key%numShards].Update(newItem)
 }
 
-func (sm *shardedMap[V]) Cleanup(policy policy[V], onEvict func(item *Item[V])) {
+func (sm *shardedMap[V]) Cleanup(policy *defaultPolicy[V], onEvict func(item *Item[V])) {
 	sm.expiryMap.cleanup(sm, policy, onEvict)
 }
 
diff --git a/ttl.go b/ttl.go
index 08e77c16..ccb0d7cb 100644
--- a/ttl.go
+++ b/ttl.go
@@ -121,7 +121,7 @@ func (m *expirationMap[_]) del(key uint64, expiration time.Time) {
 // cleanup removes all the items in the bucket that was just completed. It deletes
 // those items from the store, and calls the onEvict function on those items.
 // This function is meant to be called periodically.
-func (m *expirationMap[V]) cleanup(store store[V], policy policy[V], onEvict func(item *Item[V])) {
+func (m *expirationMap[V]) cleanup(store store[V], policy *defaultPolicy[V], onEvict func(item *Item[V])) {
 	if m == nil {
 		return
 	}