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).
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', {}));
import { makeCacheMapKit } from '@endo/cache-map';
const { cache, getMetrics } = makeCacheMapKit(100, { makeMap: Map });
cache.set('unweakable key', 'ok');
assert(cache.get('unweakable key') === 'ok');