class

Sync::Future(T)

An object that will eventually hold a value.

You can for example delegate the computation of a value to another fiber, that can resolve is asynchronously, without blocking the current fiber, that can regularly poll for the value, or explicitly wait until the value is resolved.

For example:

result = Future(Int32).new

spawn do
  result.set(compute_some_value)
rescue exception
  result.fail(exception)
end

loop do
  do_something

  if value = result.get?
    p value
    break
  end
end

Constructors

new

Source

Instance methods

fail(reason : Exception | String | Nil = nil) : Nil

Sets the future as failed, then wakes up pending fibers.

Raises a RuntimeError if the future has already been resolved or has already failed.

Source

get

Returns the value. Blocks the current fiber until the future is resolved. Raises an exception if the future has failed.

Source

get?

Returns the value if resolved, otherwise returns nil immediately. Raises an exception if the future has failed.

Source

set(value : T) : T

Sets the value, then wakes up pending fibers.

Raises a RuntimeError if the future has already been resolved or has already failed.

Source