Module Async_kernel.Async_kernel_scheduler

within_context context f runs f () right now with the specified execution context. If f raises, then the exception is sent to the monitor of context, and Error () is returned.

within' f ~monitor ~priority runs f () right now, with the specified block group, monitor, and priority set as specified. They will be reset to their original values when f returns. If f raises, then the result of within' will never become determined, but the exception will end up in the specified monitor.

within is like within', but doesn't require the thunk to return a deferred.

within_v is like within, but allows a value to be returned by f.

with_local key value ~f, when run in the current execution context, e, runs f right now in a new execution context, e', that is identical to e except that find_local key = value. As usual, e' will be in effect in asynchronous computations started by f. When with_local returns, the execution context is restored to e.

find_local key returns the value associated to key in the current execution context.

Just like within', but instead of running the thunk right now, adds it to the Async queue to be run with other Async jobs.

Just like schedule', but doesn't require the thunk to return a deferred.

eneque_job execution_context.t f a enqueues into the scheduler's job queue a job that will run f a in execution_context.

thread_safe_enqueue_job is like enqueue_job, except it is for use from a thread that doesn't hold the Async lock.

preserve_execution_context t f saves the current execution context and returns a function g such that g a runs f a in the saved execution context. g a becomes determined when f a becomes determined.

cycle_start () returns the result of Time.now () called at the beginning of cycle.

cycle_times () returns a stream that is extended with an element at the start of each Async cycle, with the amount of time that the previous cycle took, as determined by calls to Time.now at the beginning and end of the cycle.

last_cycle_time returns the time spent in the most recently completed cycle.

long_cycles ~at_least returns a stream of cycles whose duration is at least at_least. long_cycles is more efficient than cycle_times because it only allocates a stream entry when there is a long cycle, rather than on every cycle.

cycle_count () returns the total number of Async cycles that have happened.

total_cycle_time () returns the total (wall) time spent executing jobs in Async cycles.

The alarm_precision of the timing-wheel used to implement Async's Clock.

force_current_cycle_to_end () causes no more normal priority jobs to run in the current cycle, and for the end-of-cycle jobs (i.e., writes) to run, and then for the cycle to end.

set_max_num_jobs_per_priority_per_cycle int sets the maximum number of jobs that will be done at each priority within each Async cycle. The default is 500. max_num_jobs_per_priority_per_cycle retrieves the current value.

set_record_backtraces do_record sets whether Async should keep in the execution context the history of stack backtraces (obtained via Backtrace.get) that led to the current job. If an Async job has an unhandled exception, this backtrace history will be recorded in the exception. In particular the history will appear in an unhandled exception that reaches the main monitor. This can have a substantial performance impact, both in running time and space usage.

yield () returns a deferred that becomes determined after the current cycle completes. This can be useful to improve fairness by yielding within a computation to give other jobs a chance to run.

yield_until_no_jobs_remain () returns a deferred that becomes determined the next time Async's job queue is empty. This is useful in tests when one needs to wait for the completion of all the jobs based on what's in the queue, when those jobs might create other jobs -- without depending on I/O or the passage of wall-clock time.

may_return_immediately determines how yield_until_no_jobs_remain behaves if the job queue is currently empty. If may_return_immediately = true, then yield_until_no_jobs_remain will return (). If may_return_immediately = false, then yield_until_no_jobs_remain's result will become determined after the next Async cycle. We hope to someday change the default may_return_immediately from false to true.

yield_every ~n returns a function that will act as yield every n calls and as return () the rest of the time. This is useful for improving fairness in circumstances where you don't have good control of the batch size, but can insert a deferred into every iteration.

yield_every raises if n <= 0.

num_jobs_run () returns the number of jobs that have been run since starting. The returned value includes the currently running job.

num_pending_jobs returns the number of jobs that are queued to run by the scheduler.