One post tagged with "once"

Concurrent callers sometimes need the same expensive result at the same time: a short-lived credential that several requests must refresh, a remote directory that several operations need to exist, or a report that several queries want built. Running the work once per caller multiplies load on whatever produces the result, and every caller waits for its own duplicate execution.

Asyncband's singleflight::Group coalesces these calls: while work for a key is in flight, later callers for that key wait and, on success, receive a clone of the value. This post covers sharing one execution, what happens when the shared execution fails or is cancelled, and how to choose between a group and the once family, whose members retain completed state.