From f33e813210308ac2042fed1893bc24b9e08356d2 Mon Sep 17 00:00:00 2001
From: Yiling-J <njjyl723@gmail.com>
Date: Thu, 24 Oct 2024 17:32:52 +0800
Subject: [PATCH] fix demote bug

---
 internal/tlfu.go      | 19 +++++--------------
 internal/tlfu_test.go | 34 +++++++++++++++++++++++++++++++++-
 2 files changed, 38 insertions(+), 15 deletions(-)

diff --git a/internal/tlfu.go b/internal/tlfu.go
index e1f3933..597ce67 100644
--- a/internal/tlfu.go
+++ b/internal/tlfu.go
@@ -96,14 +96,6 @@ func (t *TinyLfu[K, V]) decreaseWindow(amount int) int {
 
 func (t *TinyLfu[K, V]) resizeWindow() {
 
-	if t.amount == 0 {
-		// when processing read buffer,
-		// probation entries might be promoted to protected,
-		// and protected might exceed it's cap
-		t.demoteFromProtected()
-		return
-	}
-
 	t.window.capacity += uint(t.amount)
 	t.slru.protected.capacity -= uint(t.amount)
 	t.demoteFromProtected()
@@ -168,7 +160,7 @@ func (t *TinyLfu[K, V]) climb() {
 
 	// decrease window, min window size is 1
 	if t.amount < 0 && -t.amount > int(t.window.capacity-1) {
-		t.amount = -int(t.window.capacity)
+		t.amount = -int(t.window.capacity - 1)
 	}
 }
 
@@ -176,11 +168,6 @@ func (t *TinyLfu[K, V]) Set(entry *Entry[K, V]) {
 
 	t.weightedSize += uint(entry.policyWeight)
 
-	// try finish unfinished climb first
-	if t.amount != 0 && t.counter&15 == 0 {
-		t.resizeWindow()
-	}
-
 	if entry.meta.prev == nil {
 		t.window.PushFront(entry)
 	}
@@ -195,6 +182,10 @@ func (t *TinyLfu[K, V]) Access(item ReadBufItem[K, V]) {
 		t.counter = 0
 	}
 
+	if t.counter&15 == 0 {
+		t.demoteFromProtected()
+	}
+
 	if entry := item.entry; entry != nil {
 		t.sketch.Add(item.hash)
 		if entry.meta.prev != nil {
diff --git a/internal/tlfu_test.go b/internal/tlfu_test.go
index 8c2bc3c..6aaedaa 100644
--- a/internal/tlfu_test.go
+++ b/internal/tlfu_test.go
@@ -159,7 +159,7 @@ var weightTests = []testCase{
 		"11/10:5/3/2/1/0:4",
 	},
 	{
-		"update protected, demote",
+		"update protected, demote ",
 		[]testEvent{
 			{TestEventRemove, 14, 1},
 			{TestEventRemove, 13, 1},
@@ -175,6 +175,38 @@ var weightTests = []testCase{
 		// protected cap exceed, demote
 		"11/10:4/5/3/2/1/0:",
 	},
+	{
+		"update protected, demote not run",
+		[]testEvent{
+			{TestEventRemove, 14, 1},
+			{TestEventRemove, 13, 1},
+			{TestEventRemove, 12, 1},
+			{TestEventRemove, 9, 1},
+			{TestEventRemove, 8, 1},
+			{TestEventRemove, 7, 1},
+			{TestEventRemove, 6, 1},
+			{TestEventGet, 4, 1},
+			{TestEventUpdate, 4, 5},
+			{TestEventGet, 4, 1},
+		},
+		"11/10:5/3/2/1/0:4",
+	},
+	{
+		"update protected, demote auto run",
+		[]testEvent{
+			{TestEventRemove, 14, 1},
+			{TestEventRemove, 13, 1},
+			{TestEventRemove, 12, 1},
+			{TestEventRemove, 9, 1},
+			{TestEventRemove, 8, 1},
+			{TestEventRemove, 7, 1},
+			{TestEventRemove, 6, 1},
+			{TestEventGet, 4, 1},
+			{TestEventUpdate, 4, 5},
+			{TestEventGet, 3, 20},
+		},
+		"11/10:4/5/2/1/0:3",
+	},
 	{
 		"window too large",
 		[]testEvent{