Group and completion model

• ContextGroup manages multiple current scheduler contexts through one group handle.
• Default construction and INIT create an empty group.
• spawn adds one member and returns no per-member handle.
• Grouped callables use output schema (); member outputs are neither retained nor exposed.
• cancel only requests cancellation of the current members and returns immediately.
• wait returns only when the group becomes empty.
• Destroying a non-empty group waits until all current members finish and then releases the group state.

Methods

• INIT
• spawn
• wait
• cancel

Waiting and cancellation semantics

• wait on an empty group returns immediately.
• If the current context is already canceled when wait begins, wait first requests cancellation of every current member and then waits until the group becomes empty.
• If the current context is not canceled when wait begins, later cancellation of that waiting context requests cancellation of every current member.
• Only one unfinished wait may target the same non-empty group at a time.
• Later spawn calls create later members that are not implicitly canceled by an earlier cancel call.

Examples

Wait on an empty group

"sync/ContextGroup" use
"String" use
"control" use

{} Int32 {} [
  group: ContextGroup;
  @group.wait
  ("done" LF) printList
  0
] "main" exportFunction

Expected Output

done

Spawn two contexts and wait for the group

"sync/ContextGroup" use
"String" use
"control" use

{} Int32 {} [
  group: ContextGroup;
  [("one" LF) printList] @group.spawn
  [("two" LF) printList] @group.spawn
  @group.wait
  ("done" LF) printList
  0
] "main" exportFunction

Expected Output

one
two
done

Cancel current members

"sync/ContextGroup" use
"sync/sync" use
"String" use
"control" use

{} Int32 {} [
  group: ContextGroup;
  [10.0r64 sleepFor canceled? [
    ("canceled" LF) printList
  ] [
    ("not-canceled" LF) printList
  ] if] @group.spawn
  [10.0r64 sleepFor canceled? [
    ("canceled" LF) printList
  ] [
    ("not-canceled" LF) printList
  ] if] @group.spawn
  @group.cancel
  @group.wait
  ("done" LF) printList
  0
] "main" exportFunction

Expected Output

canceled
canceled
done

See also

• sync/Context: Spawned context handle with waiting, output retrieval, and cancellation.
• sync/sync: Cross-platform scheduling, sleep, time, IPv4 formatting, and TCP helpers.
• sync/Event: Persistent event state with clear, set, wait, wake, and wakeOne.