Module Await_sync.Semaphore

Represents a poisonable counting semaphore.

Maximum counter value allowed by the semaphore implementation.

create n creates a new counting semaphore with the given count n.

The optional padded argument specifies whether to pad the data structure to avoid false sharing. See Atomic.make for a longer explanation.

• raises Invalid_argument

  in case the given count is negative or higher than max_value.

release t increments the count of the semaphore or does nothing in case the semaphore has been poisoned.

• raises Sys_error

  in case the count would overflow.

acquire w t waits until the count of the semaphore is greater than 0 and then atomically decrements the count.

• raises Poisoned

  in case the semaphore has been poisoned.

acquire_or_cancel w c t is Completed (acquire w t) if c is not canceled, otherwise it is Canceled.

try_acquire t attempts to atomically and in a wait-free way decrement the count of the semaphore, unless the count is already 0. Returns Acquired if the semaphore was successfully acquired, or Would_block if the count is already 0 and the operation would block

• raises Poisoned

  in case the semaphore has been poisoned.

get_value t returns the current count of the semaphore or 0 in case the semaphore has been poisoned.

This should only be used for debugging or informational messages.

poison t marks the semaphore as poisoned.

is_poisoned t determines whether the semaphore has been poisoned.