Module Async_kernel.Time_source

A time source with now t given by wall-clock time (i.e., Time_ns.now) and that is advanced automatically as time passes (specifically, at the start of each Async cycle). There is only one wall-clock time source; every call to wall_clock () returns the same value. The behavior of now is special for wall_clock (); it always calls Time_ns.now (), so it can return times that the time source has not yet been advanced to.

Removes the special behavior of now for wall_clock; it always returns the timing_wheel's notion of now.

Unlike in Synchronous_time_source, the advance function here only approximately determines the set of events to fire. You should also call fire_past_alarms if you want precision (see docs for Timing_wheel_ns.advance_clock vs. Timing_wheel_ns.fire_past_alarms).

advance_by_alarms t repeatedly calls advance t to drive the time forward in steps, where each step is the minimum of to_ and the next alarm time. After each step, advance_by_alarms waits on Scheduler.yield () to allow a chance for the triggered alarms to run before moving forward, which also allows triggered timers to execute and potentially rearm for subsequent steps. The returned deferred is filled when to_ is reached.

advance_by_alarms is useful in simulation when one wants to efficiently advance to a time in the future while giving periodic timers (e.g., resulting from every) a chance to fire with approximately the same timing as they would live.

See Clock.every for documentation.

See Clock.every' for documentation.

Time_source and Synchronous_time_source are the same data structure and use the same underlying timing wheel. The types are freely interchangeable.