NetBSD/lib/libpuffs/puffs_cc.3

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.\" $NetBSD: puffs_cc.3,v 1.3 2007/01/20 15:11:02 pooka Exp $
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.\" Copyright (c) 2007 Antti Kantee. All rights reserved.
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.Dd January 19, 2007
.Dt PUFFS_CC 3
.Os
.Sh NAME
.Nm puffs_cc
.Nd puffs continuation routines
.Sh LIBRARY
.Lb libpuffs
.Sh SYNOPSIS
.In puffs.h
.Ft struct puffs_usermount *
.Fn puffs_cc_getusermount "struct puffs_cc *pcc"
.Ft void
.Fn puffs_cc_yield "struct puffs_cc *pcc"
.Ft void
.Fn puffs_cc_continue "struct puffs_cc *pcc"
.Ft int
.Fn puffs_docc "struct puffs_cc *pcc" "struct puffs_putreq *ppr"
.Sh DESCRIPTION
.Em IMPORTANT NOTE!
This document describes interfaces which are not yet guaranteed to be
stable.
In case you update your system sources, please recompile everything
and fix complation errors.
If your sources are out-of-sync, incorrect operation may result.
The interfaces in this document will most likely be hugely simplified
in later versions or made transparent to the implementation.
.Pp
These functions enable the use of continuations within the framework.
Every operation callback within a file system implementation is
automatically passed an opaque cookie,
.Va pcc ,
to be used as a continuation handle.
.Pp
File systems using continuations should define their own even loop
instead of using
.Fn puffs_mainloop .
.Pp
Calling
.Fn puffs_cc_yield
will suspend and save the current execution context and return control
to the previous point.
Likewise, calling
.Fn puffs_cc_continue
will suspend current execution and return control to where it was before
before calling
.Fn puffs_cc_yield .
Typically users will want to call
.Fn puffs_docc
instead of
.Fn puffs_cc_continue ,
since the former also properly handles the results of the call in case
it finishes without yielding again.
.Pp
Before calling
.Fn puffs_cc_yield
a file system will typically want to record some cookie value into its
own internal bookkeeping.
This cookie should be hooked to the
.Va pcc
so that the correct continuation can be continued when the event it
was waiting for triggers.
.Pp
The puffs ssh file system is supposed to be the canonical example
for the use of the continuation framework.
.Sh SEE ALSO
.Xr puffs 3 ,
.Xr puffs_req 3 ,
.Xr mount_psshfs 8