.golangci.yml

@@ -1,3 +1,6 @@
+# Copyright (c) HashiCorp, Inc.
+# SPDX-License-Identifier: MPL-2.0
+
 linters:
   enable:
     - megacheck

2q.go

@@ -1,7 +1,10 @@
+// Copyright (c) HashiCorp, Inc.
+// SPDX-License-Identifier: MPL-2.0
+
 package lru
 
 import (
-	"fmt"
+	"errors"
 	"sync"
 
 	"github.com/hashicorp/golang-lru/v2/simplelru"
@@ -32,7 +35,7 @@ type TwoQueueCache[K comparable, V any] struct {
 
 	recent      simplelru.LRUCache[K, V]
 	frequent    simplelru.LRUCache[K, V]
-	recentEvict simplelru.LRUCache[K, V]
+	recentEvict simplelru.LRUCache[K, struct{}]
 	lock        sync.RWMutex
 }
 
@@ -46,13 +49,13 @@ func New2Q[K comparable, V any](size int) (*TwoQueueCache[K, V], error) {
 // parameter values.
 func New2QParams[K comparable, V any](size int, recentRatio, ghostRatio float64) (*TwoQueueCache[K, V], error) {
 	if size <= 0 {
-		return nil, fmt.Errorf("invalid size")
+		return nil, errors.New("invalid size")
 	}
 	if recentRatio < 0.0 || recentRatio > 1.0 {
-		return nil, fmt.Errorf("invalid recent ratio")
+		return nil, errors.New("invalid recent ratio")
 	}
 	if ghostRatio < 0.0 || ghostRatio > 1.0 {
-		return nil, fmt.Errorf("invalid ghost ratio")
+		return nil, errors.New("invalid ghost ratio")
 	}
 
 	// Determine the sub-sizes
@@ -68,7 +71,7 @@ func New2QParams[K comparable, V any](size int, recentRatio, ghostRatio float64)
 	if err != nil {
 		return nil, err
 	}
-	recentEvict, err := simplelru.NewLRU[K, V](evictSize, nil)
+	recentEvict, err := simplelru.NewLRU[K, struct{}](evictSize, nil)
 	if err != nil {
 		return nil, err
 	}
@@ -153,8 +156,7 @@ func (c *TwoQueueCache[K, V]) ensureSpace(recentEvict bool) {
 	// the target, evict from there
 	if recentLen > 0 && (recentLen > c.recentSize || (recentLen == c.recentSize && !recentEvict)) {
 		k, _, _ := c.recent.RemoveOldest()
-		var empty V
-		c.recentEvict.Add(k, empty)
+		c.recentEvict.Add(k, struct{}{})
 		return
 	}
 

2q_test.go

@@ -1,3 +1,6 @@
+// Copyright (c) HashiCorp, Inc.
+// SPDX-License-Identifier: MPL-2.0
+
 package lru
 
 import (
@@ -22,8 +25,7 @@ func Benchmark2Q_Rand(b *testing.B) {
 		if i%2 == 0 {
 			l.Add(trace[i], trace[i])
 		} else {
-			_, ok := l.Get(trace[i])
-			if ok {
+			if _, ok := l.Get(trace[i]); ok {
 				hit++
 			} else {
 				miss++
@@ -55,8 +57,7 @@ func Benchmark2Q_Freq(b *testing.B) {
 	}
 	var hit, miss int
 	for i := 0; i < b.N; i++ {
-		_, ok := l.Get(trace[i])
-		if ok {
+		if _, ok := l.Get(trace[i]); ok {
 			hit++
 		} else {
 			miss++
@@ -111,8 +112,7 @@ func Test2Q_Get_RecentToFrequent(t *testing.T) {
 
 	// Get should upgrade to t2
 	for i := 0; i < 128; i++ {
-		_, ok := l.Get(i)
-		if !ok {
+		if _, ok := l.Get(i); !ok {
 			t.Fatalf("missing: %d", i)
 		}
 	}
@@ -125,8 +125,7 @@ func Test2Q_Get_RecentToFrequent(t *testing.T) {
 
 	// Get be from t2
 	for i := 0; i < 128; i++ {
-		_, ok := l.Get(i)
-		if !ok {
+		if _, ok := l.Get(i); !ok {
 			t.Fatalf("missing: %d", i)
 		}
 	}
@@ -238,21 +237,18 @@ func Test2Q(t *testing.T) {
 		}
 	}
 	for i := 0; i < 128; i++ {
-		_, ok := l.Get(i)
-		if ok {
+		if _, ok := l.Get(i); ok {
 			t.Fatalf("should be evicted")
 		}
 	}
 	for i := 128; i < 256; i++ {
-		_, ok := l.Get(i)
-		if !ok {
+		if _, ok := l.Get(i); !ok {
 			t.Fatalf("should not be evicted")
 		}
 	}
 	for i := 128; i < 192; i++ {
 		l.Remove(i)
-		_, ok := l.Get(i)
-		if ok {
+		if _, ok := l.Get(i); ok {
 			t.Fatalf("should be deleted")
 		}
 	}

README.md

@@ -15,7 +15,7 @@ Example
 Using the LRU is very simple:
 
 ```go
-l, _ := New(128)
+l, _ := New[int, interface{}](128)
 for i := 0; i < 256; i++ {
     l.Add(i, nil)
 }

arc.go

@@ -1,3 +1,6 @@
+// Copyright (c) HashiCorp, Inc.
+// SPDX-License-Identifier: MPL-2.0
+
 package lru
 
 import (
@@ -18,23 +21,23 @@ type ARCCache[K comparable, V any] struct {
 	size int // Size is the total capacity of the cache
 	p    int // P is the dynamic preference towards T1 or T2
 
-	t1 simplelru.LRUCache[K, V] // T1 is the LRU for recently accessed items
-	b1 simplelru.LRUCache[K, V] // B1 is the LRU for evictions from t1
+	t1 simplelru.LRUCache[K, V]        // T1 is the LRU for recently accessed items
+	b1 simplelru.LRUCache[K, struct{}] // B1 is the LRU for evictions from t1
 
-	t2 simplelru.LRUCache[K, V] // T2 is the LRU for frequently accessed items
-	b2 simplelru.LRUCache[K, V] // B2 is the LRU for evictions from t2
+	t2 simplelru.LRUCache[K, V]        // T2 is the LRU for frequently accessed items
+	b2 simplelru.LRUCache[K, struct{}] // B2 is the LRU for evictions from t2
 
 	lock sync.RWMutex
 }
 
 // NewARC creates an ARC of the given size
 func NewARC[K comparable, V any](size int) (*ARCCache[K, V], error) {
 	// Create the sub LRUs
-	b1, err := simplelru.NewLRU[K, V](size, nil)
+	b1, err := simplelru.NewLRU[K, struct{}](size, nil)
 	if err != nil {
 		return nil, err
 	}
-	b2, err := simplelru.NewLRU[K, V](size, nil)
+	b2, err := simplelru.NewLRU[K, struct{}](size, nil)
 	if err != nil {
 		return nil, err
 	}
@@ -182,14 +185,12 @@ func (c *ARCCache[K, V]) replace(b2ContainsKey bool) {
 	if t1Len > 0 && (t1Len > c.p || (t1Len == c.p && b2ContainsKey)) {
 		k, _, ok := c.t1.RemoveOldest()
 		if ok {
-			var empty V
-			c.b1.Add(k, empty)
+			c.b1.Add(k, struct{}{})
 		}
 	} else {
 		k, _, ok := c.t2.RemoveOldest()
 		if ok {
-			var empty V
-			c.b2.Add(k, empty)
+			c.b2.Add(k, struct{}{})
 		}
 	}
 }

arc_test.go

@@ -1,3 +1,6 @@
+// Copyright (c) HashiCorp, Inc.
+// SPDX-License-Identifier: MPL-2.0
+
 package lru
 
 import (
@@ -28,8 +31,7 @@ func BenchmarkARC_Rand(b *testing.B) {
 		if i%2 == 0 {
 			l.Add(trace[i], trace[i])
 		} else {
-			_, ok := l.Get(trace[i])
-			if ok {
+			if _, ok := l.Get(trace[i]); ok {
 				hit++
 			} else {
 				miss++
@@ -61,8 +63,7 @@ func BenchmarkARC_Freq(b *testing.B) {
 	}
 	var hit, miss int
 	for i := 0; i < b.N; i++ {
-		_, ok := l.Get(trace[i])
-		if ok {
+		if _, ok := l.Get(trace[i]); ok {
 			hit++
 		} else {
 			miss++
@@ -121,8 +122,7 @@ func TestARC_Get_RecentToFrequent(t *testing.T) {
 
 	// Get should upgrade to t2
 	for i := 0; i < 128; i++ {
-		_, ok := l.Get(i)
-		if !ok {
+		if _, ok := l.Get(i); !ok {
 			t.Fatalf("missing: %d", i)
 		}
 	}
@@ -135,8 +135,7 @@ func TestARC_Get_RecentToFrequent(t *testing.T) {
 
 	// Get be from t2
 	for i := 0; i < 128; i++ {
-		_, ok := l.Get(i)
-		if !ok {
+		if _, ok := l.Get(i); !ok {
 			t.Fatalf("missing: %d", i)
 		}
 	}
@@ -310,21 +309,18 @@ func TestARC(t *testing.T) {
 		}
 	}
 	for i := 0; i < 128; i++ {
-		_, ok := l.Get(i)
-		if ok {
+		if _, ok := l.Get(i); ok {
 			t.Fatalf("should be evicted")
 		}
 	}
 	for i := 128; i < 256; i++ {
-		_, ok := l.Get(i)
-		if !ok {
+		if _, ok := l.Get(i); !ok {
 			t.Fatalf("should not be evicted")
 		}
 	}
 	for i := 128; i < 192; i++ {
 		l.Remove(i)
-		_, ok := l.Get(i)
-		if ok {
+		if _, ok := l.Get(i); ok {
 			t.Fatalf("should be deleted")
 		}
 	}

doc.go

@@ -1,3 +1,6 @@
+// Copyright (c) HashiCorp, Inc.
+// SPDX-License-Identifier: MPL-2.0
+
 // Package lru provides three different LRU caches of varying sophistication.
 //
 // Cache is a simple LRU cache. It is based on the

lru.go

@@ -1,3 +1,6 @@
+// Copyright (c) HashiCorp, Inc.
+// SPDX-License-Identifier: MPL-2.0
+
 package lru
 
 import (

lru_test.go

@@ -1,3 +1,6 @@
+// Copyright (c) HashiCorp, Inc.
+// SPDX-License-Identifier: MPL-2.0
+
 package lru
 
 import (
@@ -22,8 +25,7 @@ func BenchmarkLRU_Rand(b *testing.B) {
 		if i%2 == 0 {
 			l.Add(trace[i], trace[i])
 		} else {
-			_, ok := l.Get(trace[i])
-			if ok {
+			if _, ok := l.Get(trace[i]); ok {
 				hit++
 			} else {
 				miss++
@@ -55,8 +57,7 @@ func BenchmarkLRU_Freq(b *testing.B) {
 	}
 	var hit, miss int
 	for i := 0; i < b.N; i++ {
-		_, ok := l.Get(trace[i])
-		if ok {
+		if _, ok := l.Get(trace[i]); ok {
 			hit++
 		} else {
 			miss++
@@ -95,21 +96,18 @@ func TestLRU(t *testing.T) {
 		}
 	}
 	for i := 0; i < 128; i++ {
-		_, ok := l.Get(i)
-		if ok {
+		if _, ok := l.Get(i); ok {
 			t.Fatalf("should be evicted")
 		}
 	}
 	for i := 128; i < 256; i++ {
-		_, ok := l.Get(i)
-		if !ok {
+		if _, ok := l.Get(i); !ok {
 			t.Fatalf("should not be evicted")
 		}
 	}
 	for i := 128; i < 192; i++ {
 		l.Remove(i)
-		_, ok := l.Get(i)
-		if ok {
+		if _, ok := l.Get(i); ok {
 			t.Fatalf("should be deleted")
 		}
 	}

simplelru/lru.go

@@ -1,3 +1,6 @@
+// Copyright (c) HashiCorp, Inc.
+// SPDX-License-Identifier: MPL-2.0
+
 package simplelru
 
 import (
@@ -100,8 +103,7 @@ func (c *LRU[K, V]) Remove(key K) (present bool) {
 
 // RemoveOldest removes the oldest item from the cache.
 func (c *LRU[K, V]) RemoveOldest() (key K, value V, ok bool) {
-	ent := c.evictList.back()
-	if ent != nil {
+	if ent := c.evictList.back(); ent != nil {
 		c.removeElement(ent)
 		return ent.key, ent.value, true
 	}
@@ -110,8 +112,7 @@ func (c *LRU[K, V]) RemoveOldest() (key K, value V, ok bool) {
 
 // GetOldest returns the oldest entry
 func (c *LRU[K, V]) GetOldest() (key K, value V, ok bool) {
-	ent := c.evictList.back()
-	if ent != nil {
+	if ent := c.evictList.back(); ent != nil {
 		return ent.key, ent.value, true
 	}
 	return
@@ -148,8 +149,7 @@ func (c *LRU[K, V]) Resize(size int) (evicted int) {
 
 // removeOldest removes the oldest item from the cache.
 func (c *LRU[K, V]) removeOldest() {
-	ent := c.evictList.back()
-	if ent != nil {
+	if ent := c.evictList.back(); ent != nil {
 		c.removeElement(ent)
 	}
 }

simplelru/lru_interface.go

@@ -1,3 +1,6 @@
+// Copyright (c) HashiCorp, Inc.
+// SPDX-License-Identifier: MPL-2.0
+
 // Package simplelru provides simple LRU implementation based on build-in container/list.
 package simplelru