ares_library_cleanup.3


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.\" $Id$
.\"
.\" Copyright 1998 by the Massachusetts Institute of Technology.
.\" Copyright (C) 2004-2009 by Daniel Stenberg
.\"
.\" Permission to use, copy, modify, and distribute this
.\" software and its documentation for any purpose and without
.\" fee is hereby granted, provided that the above copyright
.\" notice appear in all copies and that both that copyright
.\" notice and this permission notice appear in supporting
.\" documentation, and that the name of M.I.T. not be used in
.\" advertising or publicity pertaining to distribution of the
.\" software without specific, written prior permission.
.\" M.I.T. makes no representations about the suitability of
.\" this software for any purpose.  It is provided "as is"
.\" without express or implied warranty.
.\"
.TH ARES_LIBRARY_CLEANUP 3 "19 May 2009"
.SH NAME
ares_library_cleanup \- c-ares library deinitialization
.SH SYNOPSIS
.nf
.B #include <ares.h>
.PP
.B void ares_library_cleanup(void)
.PP
.B cc file.c -lcares
.fi
.SH DESCRIPTION
.PP
The
.B ares_library_cleanup
function uninitializes the c-ares library, freeing all resources
previously aquired by \fIares_library_init(3)\fP when the library
was initialized.
.PP
This function must be called when the program using c-ares will
no longer need any c-ares function. Once the program has called
ares_library_cleanup() it shall not make any further call to any
c-ares function.
.PP
This function does not cancel any pending c-ares lookups or requests
previously done. Program  must use \fIares_cancel(3)\fP for this purpose.
.PP
.B This function is not thread safe.
You have to call it once the program
is about to terminate, but this call must be done once the program has
terminated every single thread that it could have initiated. This is
required to avoid potential race conditions in library deinitialization,
and also due to the fact that ares_library_cleanup() might call functions
from other libraries that are thread unsafe, and could conflict with any
other thread that is already using these other libraries.
.PP
Win32/64 application DLLs shall not call ares_library_cleanup() from the
DllMain function. Doing so will produce deadlocks and other problems.
.SH NOTES
This function was first introduced in c-ares version 1.6.1 along with
the definition of preprocessor symbol \fICARES_HAVE_ARES_LIBRARY_CLEANUP\fP
as an indication of the availability of this function.
.PP
Since the introduction of this function, it is absolutely mandatory to
call it for any Win32/64 program using c-ares.
.PP
Non-Win32/64 systems can still use c-ares version 1.6.1 without calling
ares_library_cleanup() due to the fact that it is nearly a do-nothing
function on non-Win32/64 platforms.
.SH SEE ALSO
.BR ares_library_init(3),
.BR ares_cancel(3)
.SH AUTHOR
Yang Tse
.PP
Copyright 1998 by the Massachusetts Institute of Technology.
.br
Copyright (C) 2004-2009 by Daniel Stenberg.