From 47b3476eb75d10d6578eb0bd27fe7e6d4fa8459d Mon Sep 17 00:00:00 2001
From: Andrew Dunham <andrew@du.nham.ca>
Date: Fri, 17 May 2024 19:50:28 -0400
Subject: [PATCH] util/lru: add Clear method

Updates tailscale/corp#20109

Signed-off-by: Andrew Dunham <andrew@du.nham.ca>
Change-Id: I751a669251a70f0134dd1540c19b274a97608a93
---
 util/lru/lru.go      | 6 ++++++
 util/lru/lru_test.go | 4 ++++
 2 files changed, 10 insertions(+)

diff --git a/util/lru/lru.go b/util/lru/lru.go
index aab175156..8e4dd417b 100644
--- a/util/lru/lru.go
+++ b/util/lru/lru.go
@@ -68,6 +68,12 @@ func (c *Cache[K, V]) Set(key K, value V) {
 	}
 }
 
+// Clear removes all items from the cache.
+func (c *Cache[K, V]) Clear() {
+	c.head = nil
+	c.lookup = nil
+}
+
 // Get looks up a key's value from the cache, returning either
 // the value or the zero value if it not present.
 //
diff --git a/util/lru/lru_test.go b/util/lru/lru_test.go
index 3c4228a3f..fb538efbe 100644
--- a/util/lru/lru_test.go
+++ b/util/lru/lru_test.go
@@ -47,6 +47,10 @@ func TestLRU(t *testing.T) {
 	if c.Contains(3) {
 		t.Errorf("contains 3; should not")
 	}
+	c.Clear()
+	if g, w := c.Len(), 0; g != w {
+		t.Errorf("Len = %d; want %d", g, w)
+	}
 }
 
 func TestLRUDeleteCorruption(t *testing.T) {