Overview

WeakCache provides duplicate function call suppression combined with a weakly referenced cache for storing results.

This means:

• Concurrent calls with the same key will be collapsed into a single execution making sure that only one execution is in-flight for a given key at a time.
• Results are cached and reused if available — but only as long as they are still held by a weak pointer. Once garbage collected, the result is gone from cache.

WeakCache use modified version of Go’s x/sync/singleflight. The key differences of weakCache singleflight are:

• The main difference is that Group is now generic. This means that the function passed to Do has to return a type which was used to create Group.
• The DoChan method is removed. I might add it back in the future as a generic version.

Example

w := NewWeakCache[int]()

r, err := w.Do("key", func() (int, error) {
    time.Sleep(10 * time.Microsecond)
    return 1, nil
})

• If another goroutine calls Do("key", ...) while the first one is still running, it will block and reuse the results from the first one. This is singleflight behavior.
• Later calls to Do("key", ...) will reuse the cached result, as long as it hasn’t been collected by the GC.