From 48e179a75c20cd73b0e9d43c40c7f50d2085b90b Mon Sep 17 00:00:00 2001
From: Kyle Scott <kyscott@umich.edu>
Date: Thu, 5 Sep 2024 15:54:46 -0400
Subject: [PATCH] Fix LRU cache not updating touched keys

---
 .changeset/dull-dancers-hear.md |  5 +++++
 src/utils/lru.test.ts           | 17 +++++++++++++++++
 src/utils/lru.ts                | 11 +++++++++++
 3 files changed, 33 insertions(+)
 create mode 100644 .changeset/dull-dancers-hear.md

diff --git a/.changeset/dull-dancers-hear.md b/.changeset/dull-dancers-hear.md
new file mode 100644
index 0000000000..7406c7800f
--- /dev/null
+++ b/.changeset/dull-dancers-hear.md
@@ -0,0 +1,5 @@
+---
+"viem": patch
+---
+
+Fixed LRU algorithm to update touched keys.
diff --git a/src/utils/lru.test.ts b/src/utils/lru.test.ts
index 60fb159f27..2449644863 100644
--- a/src/utils/lru.test.ts
+++ b/src/utils/lru.test.ts
@@ -19,3 +19,20 @@ test('default', () => {
   expect(cache.get('f')).toBe(6)
   expect(cache.get('g')).toBe(7)
 })
+
+test('update touched keys', () => {
+  const cache = new LruMap(5)
+  cache.set('a', 1)
+  cache.set('b', 2)
+  cache.set('c', 3)
+  cache.set('d', 4)
+  cache.set('e', 5)
+  expect(cache.size).toBe(5)
+  cache.get('a')
+  cache.set('f', 6)
+  cache.set('g', 7)
+  expect(cache.has('a')).toBe(true)
+  expect(cache.has('b')).toBe(false)
+  expect(cache.has('c')).toBe(false)
+  expect(cache.has('d')).toBe(true)
+})
diff --git a/src/utils/lru.ts b/src/utils/lru.ts
index 49c8151b80..193dc80d5c 100644
--- a/src/utils/lru.ts
+++ b/src/utils/lru.ts
@@ -11,6 +11,17 @@ export class LruMap<value = unknown> extends Map<string, value> {
     this.maxSize = size
   }
 
+  override get(key: string) {
+    const value = super.get(key)
+
+    if (value !== undefined) {
+      this.delete(key)
+      super.set(key, value)
+    }
+
+    return value
+  }
+
   override set(key: string, value: value) {
     super.set(key, value)
     if (this.maxSize && this.size > this.maxSize)