Metered concurrency: Difference between revisions

=={{header|Oforth}}==

A semaphore can be emulated with a channel starting with n objects.

Acquiring the semaphore is receiving an object from the channel

Releasing the semaphore is sending by the object into the channel.

If the channel is empty a task will wait until it is no more empty.

<lang oforth>

import: parallel

Object Class new: Semaphore(ch)

Semaphore method: initialize(n)

Channel newSize(n) dup := ch

#[ 1 over send drop ] times(n) drop ;

Semaphore method: acquire @ch receive drop ;

Semaphore method: release 1 @ch send drop ;</lang>

Usage :

<lang oforth>: mytask(s)

while( true ) [

s acquire "Semaphore acquired" .cr

2000 sleep

s release "Semaphore released" .cr

] ;

: test(n)

| s i |

Semaphore new(n) ->s

10 loop: i [ #[ s mytask ] & ] ;</lang>