add minimumCacheSize

cache/lru_cache.go

@@ -10,6 +10,10 @@ import (
 	"github.com/ava-labs/gecko/ids"
 )
 
+const (
+	minCacheSize = 32
+)
+
 type entry struct {
 	Key   ids.ID
 	Value interface{}
@@ -59,7 +63,7 @@ func (c *LRU) Flush() {
 
 func (c *LRU) init() {
 	if c.entryMap == nil {
-		c.entryMap = make(map[[32]byte]*list.Element)
+		c.entryMap = make(map[[32]byte]*list.Element, minCacheSize)
 	}
 	if c.entryList == nil {
 		c.entryList = list.New()
@@ -134,6 +138,6 @@ func (c *LRU) evict(key ids.ID) {
 func (c *LRU) flush() {
 	c.init()
 
-	c.entryMap = make(map[[32]byte]*list.Element)
+	c.entryMap = make(map[[32]byte]*list.Element, minCacheSize)
 	c.entryList = list.New()
 }

cache/lru_cache_benchmark_test.go

@@ -0,0 +1,53 @@
+package cache
+
+import (
+	"crypto/rand"
+	"testing"
+
+	"github.com/ava-labs/gecko/ids"
+)
+
+func BenchmarkLRUCachePutSmall(b *testing.B) {
+	smallLen := 5
+	cache := &LRU{Size: smallLen}
+	for n := 0; n < b.N; n++ {
+		for i := 0; i < smallLen; i++ {
+			var idBytes [32]byte
+			rand.Read(idBytes[:])
+			cache.Put(ids.NewID(idBytes), n)
+		}
+		b.StopTimer()
+		cache.Flush()
+		b.StartTimer()
+	}
+}
+
+func BenchmarkLRUCachePutMedium(b *testing.B) {
+	mediumLen := 250
+	cache := &LRU{Size: mediumLen}
+	for n := 0; n < b.N; n++ {
+		for i := 0; i < mediumLen; i++ {
+			var idBytes [32]byte
+			rand.Read(idBytes[:])
+			cache.Put(ids.NewID(idBytes), n)
+		}
+		b.StopTimer()
+		cache.Flush()
+		b.StartTimer()
+	}
+}
+
+func BenchmarkLRUCachePutLarge(b *testing.B) {
+	largeLen := 10000
+	cache := &LRU{Size: largeLen}
+	for n := 0; n < b.N; n++ {
+		for i := 0; i < largeLen; i++ {
+			var idBytes [32]byte
+			rand.Read(idBytes[:])
+			cache.Put(ids.NewID(idBytes), n)
+		}
+		b.StopTimer()
+		cache.Flush()
+		b.StartTimer()
+	}
+}