69 lines
3.7 KiB
OCaml
69 lines
3.7 KiB
OCaml
(***********************************************************************)
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(* *)
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(* Objective Caml *)
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(* *)
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(* David Nowak and Xavier Leroy, projet Cristal, INRIA Rocquencourt *)
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(* *)
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(* Copyright 1996 Institut National de Recherche en Informatique et *)
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(* en Automatique. All rights reserved. This file is distributed *)
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(* under the terms of the GNU Library General Public License. *)
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(* *)
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(***********************************************************************)
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(* $Id$ *)
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(* Module [Event]: first-class synchronous communication *)
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(* This module implements synchronous inter-thread communications over
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channels. As in John Reppy's Concurrent ML system, the communication
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events are first-class values: they can be built and combined
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independently before being offered for communication. *)
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type 'a channel
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(* The type of communication channels carrying values of type ['a]. *)
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val new_channel: unit -> 'a channel
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(* Return a new channel. *)
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type 'a event
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(* The type of communication events returning a result of type ['a]. *)
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val send: 'a channel -> 'a -> unit event
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(* [send ch v] returns the event consisting in sending the value [v]
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over the channel [ch]. The result value of this event is [()]. *)
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val receive: 'a channel -> 'a event
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(* [receive ch] returns the event consisting in receiving a value
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from the channel [ch]. The result value of this event is the
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value received. *)
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val always: 'a -> 'a event
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(* [always v] returns an event that is always ready for
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synchronization. The result value of this event is [v]. *)
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val choose: 'a event list -> 'a event
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(* [choose evl] returns the event that is the alternative of
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all the events in the list [evl]. *)
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val wrap: 'a event -> ('a -> 'b) -> 'b event
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(* [wrap ev fn] returns the event that performs the same communications
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as [ev], then applies the post-processing function [fn]
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on the return value. *)
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val wrap_abort: 'a event -> (unit -> unit) -> 'a event
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(* [wrap_abort ev fn] returns the event that performs
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the same communications as [ev], but if it is not selected
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the function [fn] is called after the synchronization. *)
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val guard: (unit -> 'a event) -> 'a event
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(* [guard fn] returns the event that, when synchronized, computes
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[fn()] and behaves as the resulting event. This allows to
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compute events with side-effects at the time of the synchronization
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operation. *)
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val sync: 'a event -> 'a
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(* ``Synchronize'' on an event: offer all the communication
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possibilities specified in the event to the outside world,
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and block until one of the communications succeed. The result
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value of that communication is returned. *)
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val select: 'a event list -> 'a
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(* ``Synchronize'' on an alternative of events.
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[select evl] is shorthand for [sync(choose evl)]. *)
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val poll: 'a event -> 'a option
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(* Non-blocking version of [sync]: offer all the communication
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possibilities specified in the event to the outside world,
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and if one can take place immediately, perform it and return
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[Some r] where [r] is the result value of that communication.
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Otherwise, return [None] without blocking. *)
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