Overview

Implements cancellation of promises as well as futures that depend on a canceled promise. See spec issue 191 for details.

Issue numbers for any defects discovered or addressed: impl issue 536, spec issue 191

Documentation

Has in-repo user documentation been adjusted appropriately? N/A

Has in-repo design documentation been adjusted appropriately? Yes

Has the ChangeLog been updated with any user-facing improvements or breaking changes? Yes

Is there a Spec PR or Spec Issue to update the Spec for any normative changes? Yes (spec issue 191)

Expected performance impact

None if assertions are disabled. If assertions are enabled, adds an extra field to future_header to keep track of the number of successors, which should have a minor impact on memory and execution time.

Status

Is this PR ready to review? Yes