From fb973bb80728e2a703b326d99d295ad881e11d96 Mon Sep 17 00:00:00 2001
From: clover caruso <git@paperclover.net>
Date: Tue, 3 Feb 2026 03:26:50 -0800
Subject: [PATCH] fix: lru revival must revive all state

resolves #44 (tho cant reproduce it's exact error in a test).
coverage on this module is really high so its probably a revive bug.
---
 lib/Lru.test.ts | 16 ++++++++++++++++
 lib/Lru.ts      | 10 ++++++++--
 2 files changed, 24 insertions(+), 2 deletions(-)

diff --git a/lib/Lru.test.ts b/lib/Lru.test.ts
index 003a250e6874d6c481eeae108263bf2383424520..39fb0bbc73eee8075bcd31dfb81c8510c2ce9110 100644
--- a/lib/Lru.test.ts
+++ b/lib/Lru.test.ts
@@ -23,6 +23,7 @@ test("lru basic", () => {
     ["c", 5, 1],
   ]);
   lru.capacity = 10;
+  lru.set("a", -1);
   lru.set("a", 0);
   lru.set("z", 1);
   lru.set("x", 1);
@@ -132,6 +133,21 @@ test("throws on evicting a locked item", () => {
   void lru.lock("e");
   assert.throws(() => lru.ensureUnusedCapacity(3), RangeError);
 });
+test("revival", () => {
+  let lru = new Lru<string, number>({ capacity: 3, sizeFn: (v) => 1 });
+  lru.set("a", 1);
+  lru.set("b", 2);
+  lru.set("c", 3);
+  lru.set("d", 4);
+  const state = lru.serialize();
+  lru = new Lru({ capacity: 3, sizeFn: (v) => 1 });
+  lru.revive(state);
+  assert.equal(lru.get("c"), 3);
+  assert.equal(lru.get("a"), undefined);
+  lru.set("e", 5);
+  assert.equal(lru.get("d"), 4);
+  assert.equal(lru.get("e"), 5);
+});
 
 import assert from "node:assert";
 import { test } from "node:test";
diff --git a/lib/Lru.ts b/lib/Lru.ts
index 474f484ba3fba40382c423fc829342a4c79741c1..4cb35d4cac1139eb80477beb3b0135fa16c27c12 100644
--- a/lib/Lru.ts
+++ b/lib/Lru.ts
@@ -232,7 +232,8 @@ export class Lru<K, V> extends Map<K, V> {
     const order = this.#order;
     let prev: Order<K> | null = null;
     let pk!: K;
-    for (let i = entries.length - 1; i > 0; i -= 1) {
+    let totalSize = 0;
+    for (let i = entries.length - 1; i >= 0; i -= 1) {
       const [ik, iv, size] = UNWRAP(entries[i]);
       const kv = map(ik, iv);
       if (!kv) continue;
@@ -240,9 +241,14 @@ export class Lru<K, V> extends Map<K, V> {
       super.set(k, v);
       const current: Order<K> = [size, none, prev ? pk : none, 0];
       if (prev) prev[1] = k;
-      order.set(k, prev = current);
+      else this.#tail = k;
+      order.set(k, current);
+      prev = current;
       pk = k;
+      totalSize += size;
     }
+    if (prev) this.#head = pk;
+    this.#used = totalSize;
   }
 }
 
-- 
2.54.0