From d582c453703398d4d70e3fa70d3f812ecc85a1c6 Mon Sep 17 00:00:00 2001
From: zhuliquan <zlqlovecode@foxmail.com>
Date: Thu, 11 Jan 2024 00:15:48 +0800
Subject: [PATCH] feature: add Cap interface{} (#145)

* feature: add Cap interface{}
* feature: add Cap for 2q and fix bug on arc.Cap
* feature: add Cap for expireable_lru
* test: add Cap for expire lru
---
 2q.go                           | 5 +++++
 2q_test.go                      | 3 +++
 arc/arc.go                      | 5 +++++
 arc/arc_test.go                 | 9 +++++++++
 expirable/expirable_lru.go      | 5 +++++
 expirable/expirable_lru_test.go | 4 ++++
 lru.go                          | 5 +++++
 lru_test.go                     | 3 +++
 simplelru/lru.go                | 5 +++++
 simplelru/lru_interface.go      | 3 +++
 simplelru/lru_test.go           | 3 +++
 11 files changed, 50 insertions(+)

diff --git a/2q.go b/2q.go
index 8c95252..16c8a66 100644
--- a/2q.go
+++ b/2q.go
@@ -175,6 +175,11 @@ func (c *TwoQueueCache[K, V]) Len() int {
 	return c.recent.Len() + c.frequent.Len()
 }
 
+// Cap returns the capacity of the cache
+func (c *TwoQueueCache[K, V]) Cap() int {
+	return c.size
+}
+
 // Resize changes the cache size.
 func (c *TwoQueueCache[K, V]) Resize(size int) (evicted int) {
 	c.lock.Lock()
diff --git a/2q_test.go b/2q_test.go
index efa6e86..b8b2c94 100644
--- a/2q_test.go
+++ b/2q_test.go
@@ -299,6 +299,9 @@ func Test2Q(t *testing.T) {
 	if l.Len() != 128 {
 		t.Fatalf("bad len: %v", l.Len())
 	}
+	if l.Cap() != 128 {
+		t.Fatalf("expect %d, but %d", 128, l.Cap())
+	}
 
 	for i, k := range l.Keys() {
 		if v, ok := l.Get(k); !ok || v != k || v != i+128 {
diff --git a/arc/arc.go b/arc/arc.go
index 724f5fe..116cb70 100644
--- a/arc/arc.go
+++ b/arc/arc.go
@@ -202,6 +202,11 @@ func (c *ARCCache[K, V]) Len() int {
 	return c.t1.Len() + c.t2.Len()
 }
 
+// Cap returns the capacity of the cache
+func (c *ARCCache[K, V]) Cap() int {
+	return c.size
+}
+
 // Keys returns all the cached keys
 func (c *ARCCache[K, V]) Keys() []K {
 	c.lock.RLock()
diff --git a/arc/arc_test.go b/arc/arc_test.go
index 913abca..7c3ded4 100644
--- a/arc/arc_test.go
+++ b/arc/arc_test.go
@@ -313,6 +313,9 @@ func TestARC(t *testing.T) {
 	if l.Len() != 128 {
 		t.Fatalf("bad len: %v", l.Len())
 	}
+	if l.Cap() != 128 {
+		t.Fatalf("expect %d, but %d", 128, l.Cap())
+	}
 
 	for i, k := range l.Keys() {
 		if v, ok := l.Get(k); !ok || v != k || v != i+128 {
@@ -340,6 +343,9 @@ func TestARC(t *testing.T) {
 			t.Fatalf("should be deleted")
 		}
 	}
+	if l.Cap() != 128 {
+		t.Fatalf("expect %d, but %d", 128, l.Cap())
+	}
 
 	l.Purge()
 	if l.Len() != 0 {
@@ -348,6 +354,9 @@ func TestARC(t *testing.T) {
 	if _, ok := l.Get(200); ok {
 		t.Fatalf("should contain nothing")
 	}
+	if l.Cap() != 128 {
+		t.Fatalf("expect %d, but %d", 128, l.Cap())
+	}
 }
 
 // Test that Contains doesn't update recent-ness
diff --git a/expirable/expirable_lru.go b/expirable/expirable_lru.go
index 9f600a4..8e70082 100644
--- a/expirable/expirable_lru.go
+++ b/expirable/expirable_lru.go
@@ -339,3 +339,8 @@ func (c *LRU[K, V]) addToBucket(e *internal.Entry[K, V]) {
 func (c *LRU[K, V]) removeFromBucket(e *internal.Entry[K, V]) {
 	delete(c.buckets[e.ExpireBucket].entries, e.Key)
 }
+
+// Cap returns the capacity of the cache
+func (c *LRU[K, V]) Cap() int {
+	return c.size
+}
\ No newline at end of file
diff --git a/expirable/expirable_lru_test.go b/expirable/expirable_lru_test.go
index fd3b255..e01c68d 100644
--- a/expirable/expirable_lru_test.go
+++ b/expirable/expirable_lru_test.go
@@ -425,6 +425,10 @@ func TestLoadingExpired(t *testing.T) {
 func TestLRURemoveOldest(t *testing.T) {
 	lc := NewLRU[string, string](2, nil, 0)
 
+	if lc.Cap() != 2 {
+		t.Fatalf("expect cap is 2")
+	}
+
 	k, v, ok := lc.RemoveOldest()
 	if k != "" {
 		t.Fatalf("should be empty")
diff --git a/lru.go b/lru.go
index a2655f1..2bb07fd 100644
--- a/lru.go
+++ b/lru.go
@@ -248,3 +248,8 @@ func (c *Cache[K, V]) Len() int {
 	c.lock.RUnlock()
 	return length
 }
+
+// Cap returns the capacity of the cache
+func (c *Cache[K, V]) Cap() int {
+	return c.lru.Cap()
+}
diff --git a/lru_test.go b/lru_test.go
index 36cbfff..7ecc7ae 100644
--- a/lru_test.go
+++ b/lru_test.go
@@ -86,6 +86,9 @@ func TestLRU(t *testing.T) {
 	if l.Len() != 128 {
 		t.Fatalf("bad len: %v", l.Len())
 	}
+	if l.Cap() != 128 {
+		t.Fatalf("expect %d, but %d", 128, l.Cap())
+	}
 
 	if evictCounter != 128 {
 		t.Fatalf("bad evict count: %v", evictCounter)
diff --git a/simplelru/lru.go b/simplelru/lru.go
index f697923..8f45d2e 100644
--- a/simplelru/lru.go
+++ b/simplelru/lru.go
@@ -147,6 +147,11 @@ func (c *LRU[K, V]) Len() int {
 	return c.evictList.Length()
 }
 
+// Cap returns the capacity of the cache
+func (c *LRU[K, V]) Cap() int {
+	return c.size
+}
+
 // Resize changes the cache size.
 func (c *LRU[K, V]) Resize(size int) (evicted int) {
 	diff := c.Len() - size
diff --git a/simplelru/lru_interface.go b/simplelru/lru_interface.go
index 043b8bc..495652b 100644
--- a/simplelru/lru_interface.go
+++ b/simplelru/lru_interface.go
@@ -38,6 +38,9 @@ type LRUCache[K comparable, V any] interface {
 	// Returns the number of items in the cache.
 	Len() int
 
+	// Returns the capacity of the cache.
+	Cap() int
+
 	// Clears all cache entries.
 	Purge()
 
diff --git a/simplelru/lru_test.go b/simplelru/lru_test.go
index 19a8fac..91a1d1b 100644
--- a/simplelru/lru_test.go
+++ b/simplelru/lru_test.go
@@ -27,6 +27,9 @@ func TestLRU(t *testing.T) {
 	if l.Len() != 128 {
 		t.Fatalf("bad len: %v", l.Len())
 	}
+	if l.Cap() != 128 {
+		t.Fatalf("expect %d, but %d", 128, l.Cap())
+	}
 
 	if evictCounter != 128 {
 		t.Fatalf("bad evict count: %v", evictCounter)