A callback used in case of cancellation

A fiber returning a value of type 'a.

Future result of the fiber.

Callbacks that are called when a fiber is done.

Type erased fiber

self () is the current fiber. Must be run from inside a fiber.

• raises Failure

  if not run from inside a fiber.

Peek inside the future result

Has the fiber completed?

Has the fiber completed with a failure?

Has the fiber completed with a value?

await fib is like Fut.await (res fib)

wait_block_exn fib is Fut.wait_block_exn (res fib). NOTE: See Fut.wait_block for warnings about deadlocks.

wait_block fib is Fut.wait_block (res fib). NOTE: See Fut.wait_block for warnings about deadlocks.

Check if the current fiber is cancelled, in which case this raises. Must be run from inside a fiber.

• raises e

  if the current fiber is cancelled with exception e

• raises Failure

  if not run from a fiber.

Yield control to the scheduler from the current fiber.

• raises Failure

  if not run from inside a fiber.

An opaque handle for a single cancel callback in a fiber

add_on_cancel fib cb adds cb to the list of cancel callbacks for fib. If fib is already cancelled, cb is called immediately.

remove_on_cancel fib h removes the cancel callback associated with handle h.

with_on_cancel fib cb (fun () -> <e>) evaluates e in a scope in which, if the fiber fib is cancelled, cb() is called. If e returns without the fiber being cancelled, this callback is removed.

with_on_self_cancel cb f calls f() in a scope where cb is added to the cancel callbacks of the current fiber; and f() terminates, cb is removed from the list.

Wait for fiber to be done and call the callback with the result. If the fiber is done already then the callback is invoked immediately with its result.

spawn_top ~on f spawns a new (toplevel) fiber onto the given runner. This fiber is not the child of any other fiber: its lifetime is only determined by the lifetime of f().

spawn ~protect f spawns a sub-fiber f_child from a running fiber parent. The sub-fiber f_child is attached to the current fiber and fails if the current fiber parent fails.

• parameter on

  if provided, start the fiber on the given runner. If not provided, use the parent's runner.

• parameter protect

  if true, when f_child fails, it does not affect parent. If false, f_child failing also causes parent to fail (and therefore all other children of parent). Default is true.

Must be run from inside a fiber.

• raises Failure

  if not run from inside a fiber.

spawn_ignore f is ignore (spawn f). The fiber will still affect termination of the parent, ie. the parent will exit only after this new fiber exits.

Like spawn_top but ignores the result.

• since 0.7

main f runs f() in a scope that handles effects, including Fiber.await.

This scope can run background tasks as well, in a cooperative fashion.