Module Condition

module Condition: sig .. end

Condition variables to synchronize between threads.

Condition variables are used when one thread wants to wait until another thread has finished doing something: the former thread ``waits'' on the condition variable, the latter thread ``signals'' the condition when it is done. Condition variables should always be protected by a mutex. The typical use is (if D is a shared data structure, m its mutex, and c is a condition variable):

     Mutex.lock m;

     while (* some predicate P over D is not satisfied *) do

       Condition.wait c m

     done;

     (* Modify D *)

     if (* the predicate P over D is now satified *) then Condition.signal c;

     Mutex.unlock m

type t

The type of condition variables.

val create : unit -> t

Return a new condition variable.

val wait : t -> Mutex.t -> unit

wait c m atomically unlocks the mutex m and suspends the calling process on the condition variable c. The process will restart after the condition variable c has been signalled. The mutex m is locked again before wait returns.

val signal : t -> unit

signal c restarts one of the processes waiting on the condition variable c.

val broadcast : t -> unit

broadcast c restarts all processes waiting on the condition variable c.