Add new function GetWithRefresh() (#64)

* Add new function GetWithRefresh()

* Increase test coverage

cache.go

@@ -45,6 +45,11 @@ type Cache[K comparable, V any] interface {
 	// and the return value indicates that the key was not found.
 	Get(key K) (V, bool)
 
+	// GetAndRefresh returns the value associated with the key, setting it as the most
+	// recently used item.
+	// The lifetime of the found cache item is refreshed, even if it was already expired.
+	GetAndRefresh(key K, lifetime time.Duration) (V, bool)
+
 	// Peek looks up a key's value from the cache, without changing its recent-ness.
 	// If the found entry is already expired, the evict function is called.
 	Peek(key K) (V, bool)

lru.go

@@ -324,6 +324,26 @@ func (lru *LRU[K, V]) findKey(hash uint32, key K) (uint32, bool) {
 	}
 }
 
+func (lru *LRU[K, V]) findKeyNoExpire(hash uint32, key K) (uint32, bool) {
+	_, startPos := lru.hashToPos(hash)
+	if startPos == emptyBucket {
+		return emptyBucket, false
+	}
+
+	pos := startPos
+	for {
+		if key == lru.elements[pos].key {
+			return pos, true
+		}
+
+		pos = lru.elements[pos].nextBucket
+		if pos == startPos {
+			// Key not found
+			return emptyBucket, false
+		}
+	}
+}
+
 // Len returns the number of elements stored in the cache.
 func (lru *LRU[K, V]) Len() int {
 	return int(lru.len)
@@ -448,6 +468,28 @@ func (lru *LRU[K, V]) get(hash uint32, key K) (value V, ok bool) {
 	return
 }
 
+// GetAndRefresh returns the value associated with the key, setting it as the most
+// recently used item.
+// The lifetime of the found cache item is refreshed, even if it was already expired.
+func (lru *LRU[K, V]) GetAndRefresh(key K, lifetime time.Duration) (V, bool) {
+	return lru.getAndRefresh(lru.hash(key), key, lifetime)
+}
+
+func (lru *LRU[K, V]) getAndRefresh(hash uint32, key K, lifetime time.Duration) (value V, ok bool) {
+	if pos, ok := lru.findKeyNoExpire(hash, key); ok {
+		if pos != lru.head {
+			lru.unlinkElement(pos)
+			lru.setHead(pos)
+		}
+		lru.metrics.Hits++
+		lru.elements[pos].expire = expire(lifetime)
+		return lru.elements[pos].value, ok
+	}
+
+	lru.metrics.Misses++
+	return
+}
+
 // Peek looks up a key's value from the cache, without changing its recent-ness.
 // If the found entry is already expired, the evict function is called.
 func (lru *LRU[K, V]) Peek(key K) (value V, ok bool) {
@@ -482,7 +524,7 @@ func (lru *LRU[K, V]) Remove(key K) (removed bool) {
 }
 
 func (lru *LRU[K, V]) remove(hash uint32, key K) (removed bool) {
-	if pos, ok := lru.findKey(hash, key); ok {
+	if pos, ok := lru.findKeyNoExpire(hash, key); ok {
 		lru.removeAt(pos)
 		return ok
 	}

lru_test.go

@@ -247,12 +247,33 @@ func TestSyncedLRU_AddWithExpire(t *testing.T) {
 	testCacheAddWithExpire(t, makeSyncedLRU(t, 2, nil))
 }
 
+func testCacheAddWithRefresh(t *testing.T, cache Cache[uint64, uint64]) {
+	cache.AddWithLifetime(1, 2, 100*time.Millisecond)
+	cache.AddWithLifetime(2, 3, 100*time.Millisecond)
+	_, ok := cache.Get(1)
+	FatalIf(t, !ok, "Failed to get")
+
+	time.Sleep(101 * time.Millisecond)
+	_, ok = cache.GetAndRefresh(1, 0)
+	FatalIf(t, !ok, "Unexpected expiration")
+	_, ok = cache.GetAndRefresh(2, 0)
+	FatalIf(t, !ok, "Unexpected expiration")
+}
+
+func TestLRU_AddWithRefresh(t *testing.T) {
+	testCacheAddWithRefresh(t, makeCache(t, 2, nil))
+}
+
+func TestSyncedLRU_AddWithRefresh(t *testing.T) {
+	testCacheAddWithRefresh(t, makeSyncedLRU(t, 2, nil))
+}
+
 func TestLRUMatch(t *testing.T) {
 	testCacheMatch(t, makeCache(t, 2, nil), 128)
 }
 
 func TestSyncedLRUMatch(t *testing.T) {
-	testCacheMatch(t, makeCache(t, 2, nil), 128)
+	testCacheMatch(t, makeSyncedLRU(t, 2, nil), 128)
 }
 
 // Test that Go map and the Cache stay in sync when adding

shardedlru.go

@@ -165,6 +165,20 @@ func (lru *ShardedLRU[K, V]) Get(key K) (value V, ok bool) {
 	return
 }
 
+// GetAndRefresh returns the value associated with the key, setting it as the most
+// recently used item.
+// The lifetime of the found cache item is refreshed, even if it was already expired.
+func (lru *ShardedLRU[K, V]) GetAndRefresh(key K, lifetime time.Duration) (value V, ok bool) {
+	hash := lru.hash(key)
+	shard := (hash >> 16) & lru.mask
+
+	lru.mus[shard].Lock()
+	value, ok = lru.lrus[shard].getAndRefresh(hash, key, lifetime)
+	lru.mus[shard].Unlock()
+
+	return
+}
+
 // Peek looks up a key's value from the cache, without changing its recent-ness.
 // If the found entry is already expired, the evict function is called.
 func (lru *ShardedLRU[K, V]) Peek(key K) (value V, ok bool) {

shardedlru_test.go

@@ -35,6 +35,7 @@ func TestShardedRaceCondition(t *testing.T) {
 	call(func() { _ = lru.AddWithLifetime(1, 1, 0) })
 	call(func() { _ = lru.Add(1, 1) })
 	call(func() { _, _ = lru.Get(1) })
+	call(func() { _, _ = lru.GetAndRefresh(1, 0) })
 	call(func() { _, _ = lru.Peek(1) })
 	call(func() { _ = lru.Contains(1) })
 	call(func() { _ = lru.Remove(1) })

syncedlru.go

@@ -90,6 +90,19 @@ func (lru *SyncedLRU[K, V]) Get(key K) (value V, ok bool) {
 	return
 }
 
+// GetAndRefresh returns the value associated with the key, setting it as the most
+// recently used item.
+// The lifetime of the found cache item is refreshed, even if it was already expired.
+func (lru *SyncedLRU[K, V]) GetAndRefresh(key K, lifetime time.Duration) (value V, ok bool) {
+	hash := lru.lru.hash(key)
+
+	lru.mu.Lock()
+	value, ok = lru.lru.getAndRefresh(hash, key, lifetime)
+	lru.mu.Unlock()
+
+	return
+}
+
 // Peek looks up a key's value from the cache, without changing its recent-ness.
 // If the found entry is already expired, the evict function is called.
 func (lru *SyncedLRU[K, V]) Peek(key K) (value V, ok bool) {

syncedlru_test.go

@@ -32,6 +32,7 @@ func TestSyncedRaceCondition(t *testing.T) {
 	call(func() { _ = lru.AddWithLifetime(1, 1, 0) })
 	call(func() { _ = lru.Add(1, 1) })
 	call(func() { _, _ = lru.Get(1) })
+	call(func() { _, _ = lru.GetAndRefresh(1, 0) })
 	call(func() { _, _ = lru.Peek(1) })
 	call(func() { _ = lru.Contains(1) })
 	call(func() { _ = lru.Remove(1) })