@endo/cache-map

cache-map

This @endo/cache-map package creates bounded-size caches having WeakMap-compatible has/get/set/delete methods. Key validity, comparison, and referential strength are controlled by a makeMap option, which defaults to WeakMap but can be set to any producer of objects with those methods (e.g., using Map allows for arbitrary keys which will be strongly held). Cache eviction policy is not currently configurable, but strives for a hit ratio at least as good as LRU (e.g., it might be CLOCK or SIEVE).

Usage

Weak Cache

import { makeCacheMapKit } from '@endo/cache-map';

const { cache: weakCache, getMetrics } = makeCacheMapKit(2);
const entries = [
  { key: Symbol('key 1'), value: Symbol('value 1') },
  { key: Symbol('key 2'), value: Symbol('value 2') },
  { key: Symbol('key 3'), value: Symbol('value 3') },
];
for (const { key, value } of entries) weakCache.set(key, value);

assert(!weakCache.has(entries[0].key));
assert(weakCache.has(entries[1].key));
assert(weakCache.get(entries[2].key) === entries[2].value);

weakCache.delete(entries[2].key);
weakCache.set(entries[1].key, entries[0]);

assert(!weakCache.has(entries[0].key));
assert(!weakCache.has(entries[2].key));
assert(weakCache.get(entries[1].key) === entries[0]);

assert.throws(() => weakCache.set('unweakable key', {}));

Strong Cache

import { makeCacheMapKit } from '@endo/cache-map';

const { cache, getMetrics } = makeCacheMapKit(100, { makeMap: Map });
cache.set('unweakable key', 'ok');
assert(cache.get('unweakable key') === 'ok');

License

Apache License, Version 2.0