fix: purgeStale lockup on list reordering

Fix: ##209

Author: isaacs

Diff for: index.js

@@ -315,12 +315,16 @@ class LRUCache {
 
   purgeStale () {
     let deleted = false
+    const toDelete = []
     for (const i of this.rindexes({ allowStale: true })) {
       if (this.isStale(i)) {
-        this.delete(this.keyList[i])
+        toDelete.push(this.keyList[i])
         deleted = true
       }
     }
+    for (const k of toDelete) {
+      this.delete(k)
+    }
     return deleted
   }
 

Diff for: test/ttl.js

@@ -359,6 +359,23 @@ const runTests = (LRU, t) => {
     t.end()
   })
 
+  t.test('purgeStale() lockup', t => {
+    const c = new LRU({
+      max: 3,
+      ttl: 10,
+      updateAgeOnGet: true,
+    })
+    c.set(1, 1)
+    c.set(2, 2)
+    c.set(3, 3)
+    clock.advance(5)
+    c.get(2)
+    clock.advance(15)
+    c.purgeStale()
+    t.pass('did not get locked up')
+    t.end()
+  })
+
   t.end()
 }