16.3 Will Executors🔗ℹ

A will executor support finalization by maintaining a collection of will functions associated to Rhombus objects. When an object becomes unreachable, its will are ready to be executed. See Wills and Will Executors for more information.

A will executor can be used as a synchronizable event. A will executor is ready for synchronization when will.Executor.execute would not block, and the synchronization result is the executor itself.

The v_will argument is strongly referenced by executor until it is executed, which is why v is supplied back to v_will instead of expecting v to be in v_will’s closure.

See will.Executor.execute for an example.

If no will is ready for immediate execution, will.Executor.execute blocks until one is ready, while will.Executor.maybe_execute returns none immediately.

The following example reflects a relatively simple pattern where will functions can run at any time, so a thread is created to run wills as soon as they become available.

block:

def exor = will.Executor()

def th:

thread:

while #true:

exor.execute()

def mutable box_to_track = Box(#false)

exor.register(box_to_track,

fun (bx):

println("a-box is now garbage"))

memory.gc()

box_to_track := #false

memory.gc()

// printing is likely at this point

Evt.system_idle.sync()

#void