README.md

@@ -79,6 +79,11 @@ away.
   it'll be called whenever a `set()` operation overwrites an existing
   key.  If you set this option, `dispose()` will only be called when a
   key falls out of the cache, not when it is overwritten.
+* `updateAgeOnGet` When using time-expiring entries with `maxAge`,
+  setting this to `true` will make each item's effective time update
+  to the current time whenever it is retrieved from cache, causing it
+  to not expire.  (It can still fall out of cache based on recency of
+  use, of course.)
 
 ## API
 

index.js

@@ -12,6 +12,7 @@ const DISPOSE = Symbol('dispose')
 const NO_DISPOSE_ON_SET = Symbol('noDisposeOnSet')
 const LRU_LIST = Symbol('lruList')
 const CACHE = Symbol('cache')
+const UPDATE_AGE_ON_GET = Symbol('updateAgeOnGet')
 
 const naiveLength = () => 1
 
@@ -44,6 +45,7 @@ class LRUCache {
     this[MAX_AGE] = options.maxAge || 0
     this[DISPOSE] = options.dispose
     this[NO_DISPOSE_ON_SET] = options.noDisposeOnSet || false
+    this[UPDATE_AGE_ON_GET] = options.updateAgeOnGet || false
     this.reset()
   }
 
@@ -260,8 +262,11 @@ const get = (self, key, doUse) => {
       if (!self[ALLOW_STALE])
         return undefined
     } else {
-      if (doUse)
+      if (doUse) {
+        if (self[UPDATE_AGE_ON_GET])
+          node.value.now = Date.now()
         self[LRU_LIST].unshiftNode(node)
+      }
     }
     return hit.value
   }

package.json

@@ -1,7 +1,7 @@
 {
   "name": "lru-cache",
   "description": "A cache object that deletes the least-recently-used items.",
-  "version": "5.0.1",
+  "version": "5.1.0",
   "author": "Isaac Z. Schlueter <i@izs.me>",
   "keywords": [
     "mru",

test/basic.js

@@ -542,3 +542,20 @@ test('bad max/maxAge options', t => {
   t.throws(() => { new LRU().max = 'foo' }, 'max must be a non-negative number')
   t.end()
 })
+
+test('update age on get', t => {
+  const l = new LRU({ updateAgeOnGet: true, maxAge: 10 })
+  l.set('foo', 'bar')
+  const e1 = l.dump()[0].e
+  // spin for 5ms
+  for (let then = Date.now() + 5; then > Date.now(); );
+  l.get('foo')
+  const e2 = l.dump()[0].e
+  // spin for 5ms
+  for (let then = Date.now() + 5; then > Date.now(); );
+  l.get('foo')
+  const e3 = l.dump()[0].e
+  t.ok(e1 < e2, 'time updated on first get')
+  t.ok(e2 < e3, 'time updated on second get')
+  t.end()
+})