From 112b816e539cc0035123a785e86aa481887016f5 Mon Sep 17 00:00:00 2001
From: MrMelon54 <github@mrmelon54.com>
Date: Sun, 20 Oct 2024 22:20:45 +0100
Subject: [PATCH] Don't delete changed items on original expiry

Use compare and delete to ensure item has not changed before deleting it

Fixes #1
---
 cache.go      |  2 +-
 cache_test.go | 20 ++++++++++++++++++++
 2 files changed, 21 insertions(+), 1 deletion(-)

diff --git a/cache.go b/cache.go
index 19297a0..ab11cb4 100644
--- a/cache.go
+++ b/cache.go
@@ -116,7 +116,7 @@ func (c *Cache[K, V]) cleaner() {
 
 			// remove all expired entries
 			for c.chain != nil && c.chain.HasExpired() {
-				c.items.Delete(c.chain.data)
+				c.items.CompareAndDelete(c.chain.data, c.chain.item)
 				c.chain = c.chain.next
 			}
 		}
diff --git a/cache_test.go b/cache_test.go
index 4793d4b..0d8ee23 100644
--- a/cache_test.go
+++ b/cache_test.go
@@ -132,3 +132,23 @@ func TestCache_Cleaner(t *testing.T) {
 	c.sched.Wait()
 	assert.Nil(t, c.chain)
 }
+
+func TestCache_UpdateExpiry(t *testing.T) {
+	timeNow = func() time.Time { return time.Now() }
+
+	c := New[string, string]()
+	c.Set("a", "b", time.Now().Add(2*time.Second))
+
+	time.Sleep(time.Second)
+	get, b := c.Get("a")
+	assert.True(t, b)
+	assert.Equal(t, "b", get)
+
+	c.Set("a", "b", time.Now().Add(5*time.Second))
+
+	// after expiry of the first set call
+	time.Sleep(2 * time.Second)
+	get, b = c.Get("a")
+	assert.True(t, b)
+	assert.Equal(t, "b", get)
+}