From ece93bf87d0050509583f512bf7ccee76b9a827f Mon Sep 17 00:00:00 2001
From: Karl Seguin <k@openmymind.io>
Date: Tue, 13 Dec 2022 20:33:58 +0800
Subject: [PATCH] On delete, always set promotions == -2 and node == nil

Also, item.promotions doesn't need to be loaded/stored using atomic. Once upon a
time it did. Cache was updated long ago to not use atomic operations on it, but
LayeredCache wasn't. They are both consistent now (they don't use atomic
operations).

Fixes: https://github.com/karlseguin/ccache/issues/76
---
 cache.go             | 2 ++
 cache_test.go        | 2 +-
 layeredcache.go      | 8 +++++---
 layeredcache_test.go | 2 +-
 4 files changed, 9 insertions(+), 5 deletions(-)

diff --git a/cache.go b/cache.go
index d8a929f..f27b075 100644
--- a/cache.go
+++ b/cache.go
@@ -394,6 +394,8 @@ func (c *Cache[T]) doDelete(item *Item[T]) {
 			c.onDelete(item)
 		}
 		c.list.Remove(item.node)
+		item.node = nil
+		item.promotions = -2
 	}
 }
 
diff --git a/cache_test.go b/cache_test.go
index f8cc06c..c7ba85f 100644
--- a/cache_test.go
+++ b/cache_test.go
@@ -332,7 +332,7 @@ func Test_CachePrune(t *testing.T) {
 			cache.Set(key, key, 5*time.Minute)
 		}
 		if epoch%500 == 0 {
-			assert.True(t, cache.GetSize() < 500)
+			assert.True(t, cache.GetSize() <= 500)
 		}
 	}
 }
diff --git a/layeredcache.go b/layeredcache.go
index b6798dd..e6a632b 100644
--- a/layeredcache.go
+++ b/layeredcache.go
@@ -266,13 +266,15 @@ func (c *LayeredCache[T]) worker() {
 	}
 	deleteItem := func(item *Item[T]) {
 		if item.node == nil {
-			atomic.StoreInt32(&item.promotions, -2)
+			item.promotions = -2
 		} else {
 			c.size -= item.size
 			if c.onDelete != nil {
 				c.onDelete(item)
 			}
 			c.list.Remove(item.node)
+			item.node = nil
+			item.promotions = -2
 		}
 	}
 	for {
@@ -318,13 +320,13 @@ func (c *LayeredCache[T]) worker() {
 
 func (c *LayeredCache[T]) doPromote(item *Item[T]) bool {
 	// deleted before it ever got promoted
-	if atomic.LoadInt32(&item.promotions) == -2 {
+	if item.promotions == -2 {
 		return false
 	}
 	if item.node != nil { //not a new item
 		if item.shouldPromote(c.getsPerPromote) {
 			c.list.MoveToFront(item.node)
-			atomic.StoreInt32(&item.promotions, 0)
+			item.promotions = 0
 		}
 		return false
 	}
diff --git a/layeredcache_test.go b/layeredcache_test.go
index adf5483..f8b3e2f 100644
--- a/layeredcache_test.go
+++ b/layeredcache_test.go
@@ -391,7 +391,7 @@ func Test_LayeredCachePrune(t *testing.T) {
 			cache.Set(key, key, key, 5*time.Minute)
 		}
 		if epoch%500 == 0 {
-			assert.True(t, cache.GetSize() < 500)
+			assert.True(t, cache.GetSize() <= 500)
 		}
 	}
 }