Allow passing external lru cache instance.

Author: dlongley

CHANGELOG.md

@@ -1,5 +1,15 @@
 # did-io ChangeLog
 
+## 2.1.0 - 2026-mm-dd
+
+### Added
+- Add option to allow a compatible external cache instance to be passed to
+  passed to `CachedResolver`. The cache instance must minimally support
+  `memoize()` with a signature that matches `@digitalbazaar/lru-memoize@4`.
+  This option allows applications to use different versions of the
+  cache with their own initialization code, provided that it maintains
+  the necessary interface.
+
 ## 2.0.0 - 2022-06-02
 
 ### Changed

lib/CachedResolver.js

@@ -1,12 +1,16 @@
 /*!
- * Copyright (c) 2021 Digital Bazaar, Inc. All rights reserved.
+ * Copyright (c) 2021-2026 Digital Bazaar, Inc. All rights reserved.
  */
 import {parseDid} from './did-io.js';
 import {LruCache} from '@digitalbazaar/lru-memoize';
 
 export class CachedResolver {
   /**
    * @param {object} [options={}] - Options hashmap.
+   * @param {object} [options.cache] - The cache instance to use; it must have
+   *   an interface compatible with `@digitalbazaar/lru-memoize`'s `LruCache`
+   *   object, minimally implementing `memoize()`; if this option is used,
+   *   then all other options are ignored.
    * @param {number} [options.max=100] - Max number of items in the cache.
    * @param {number} [options.maxAge=5000] - Max age of a cache item, in ms.
    * @param {boolean} [options.updateAgeOnGet=false] - When using time-expiring
@@ -15,9 +19,13 @@ export class CachedResolver {
    *   cache, thereby extending the expiration date of the entry.
    * @param {object} [options.cacheOptions] - Additional `lru-cache` options.
    */
-  constructor({max = 100, maxAge = 5000, updateAgeOnGet = false,
-    ...cacheOptions} = {}) {
-    this._cache = new LruCache({max, maxAge, updateAgeOnGet, ...cacheOptions});
+  constructor({
+    cache, max = 100, maxAge = 5000, updateAgeOnGet = false,
+    ...cacheOptions
+  } = {}) {
+    this._cache = cache ?? new LruCache({
+      max, maxAge, updateAgeOnGet, ...cacheOptions
+    });
     this._methods = new Map();
   }