Weak Cache

Weak cache is a Map implementation that uses WeakReferences for holding values and Finalizer to manage it's storage.

You can use it to cache data for a small amount of time until next garbage collection cycle.

Note: Values cannot be numbers, strings, booleans, records, null, dart:ffi pointers, dart:ffi structs, or dart:ffi unions.

Features

• Uses WeakReference for storing values.
• Uses Finalizer to remove objects from internal storage upon their deletion.
• Allows you iterate over keys/values.

  While iterating, all stored values are temporarily made into strong references, to prevent concurrent edit of storage, while iterating over it.

• Optimized containsValue via internal managed Expando.
• Implements full Map<K, V> interface.
• WeakCache itself can be safely garbage collected and doesn't hold unto any stored.

Usage

Create cache, add values, and they'll be removed when all other strong references to them are lost.

// ID - Object cache
final cache = WeakCache<int, Object>();

Object? obj = Object();
cache[0] = obj;
// ...
obj = null;
// ...
// After garbage collection cache[0] will be removed.
cache[0] == null;

See example for detailed test case.