116 lines
4.0 KiB
Groff
116 lines
4.0 KiB
Groff
.\" $NetBSD: puffs_cc.3,v 1.6 2007/05/06 13:56:16 pooka Exp $
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.\"
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.\" Copyright (c) 2007 Antti Kantee. All rights reserved.
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.\"
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.\" Redistribution and use in source and binary forms, with or without
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.\" modification, are permitted provided that the following conditions
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.\" are met:
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.\" 1. Redistributions of source code must retain the above copyright
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.\" notice, this list of conditions and the following disclaimer.
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.\" 2. Redistributions in binary form must reproduce the above copyright
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.\" notice, this list of conditions and the following disclaimer in the
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.\" documentation and/or other materials provided with the distribution.
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.\"
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.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
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.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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.\" ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
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.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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.\" SUCH DAMAGE.
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.\"
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.Dd April 19, 2007
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.Dt PUFFS_CC 3
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.Os
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.Sh NAME
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.Nm puffs_cc
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.Nd puffs continuation routines
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.Sh LIBRARY
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.Lb libpuffs
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.Sh SYNOPSIS
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.In puffs.h
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.Ft struct puffs_usermount *
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.Fn puffs_cc_getusermount "struct puffs_cc *pcc"
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.Ft void *
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.Fn puffs_cc_getspecific "struct puffs_cc *pcc"
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.Ft void
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.Fn puffs_cc_yield "struct puffs_cc *pcc"
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.Ft void
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.Fn puffs_cc_continue "struct puffs_cc *pcc"
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.Ft int
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.Fn puffs_docc "struct puffs_cc *pcc" "struct puffs_putreq *ppr"
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.Sh DESCRIPTION
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.Em IMPORTANT NOTE!
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This document describes interfaces which are not yet guaranteed to be
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stable.
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In case you update your system sources, please recompile everything
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and fix complation errors.
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If your sources are out-of-sync, incorrect operation may result.
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The interfaces in this document will most likely be hugely simplified
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in later versions or made transparent to the implementation.
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.Pp
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These functions enable the use of continuations within the framework.
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Every operation callback within a file system implementation is
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automatically passed an opaque cookie,
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.Va pcc ,
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to be used as a continuation handle.
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.Pp
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File systems using continuations should define their own event loop
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instead of using
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.Fn puffs_mainloop .
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.Pp
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.Bl -tag -width xxxx
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.It Fn puffs_cc_getusermount "pcc"
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Returns a pointer to the file system structure
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.Va struct puffs_usermount
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the context is associated with.
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.It Fn puffs_cc_getspecific "pcc"
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Returns a pointer to file system private data.
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This is shorthand for
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calling
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.Fn puffs_getspecific
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with the result from
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.Fn puffs_cc_getusermount .
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.It Fn puffs_cc_yield "pcc"
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Suspend and save the current execution context and return control
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to the previous point.
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In practice, from the file system author perspective, control returns
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back to where either
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.Fn puffs_req_handle
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or
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.Fn puffs_docc
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was called.
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.It Fn puffs_cc_continue pcc
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Will suspend current execution and return control to where it was
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before before calling
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.Fn puffs_cc_yield .
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This is rarely called directly.
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.It Fn puffs_docc "pcc" "ppr"
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Continues request suspended with
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.Fn puffs_cc_yield .
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If the request completes without yielding again, the result can be
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found from
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.Fa ppr .
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.El
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.Pp
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Before calling
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.Fn puffs_cc_yield
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a file system will typically want to record some cookie value into its
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own internal bookkeeping.
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This cookie should be hooked to the
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.Va pcc
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so that the correct continuation can be continued when the event it
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was waiting for triggers.
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.Pp
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The puffs ssh file system is supposed to be the canonical example
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for the use of the continuation framework.
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.Sh SEE ALSO
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.Xr puffs 3 ,
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.Xr puffs_framebuf 3 ,
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.Xr puffs_req 3 ,
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.Xr mount_psshfs 8
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