ARES_LIBRARY_CLEANUP(3)                       FreeBSD Library Functions Manual

NAME
       ares_library_cleanup - c-ares library deinitialization

SYNOPSIS
       #include <ares.h>

       void ares_library_cleanup(void)

DESCRIPTION
       The ares_library_cleanup function uninitializes the c-ares library,
       freeing all resources previously acquired by _library_init&section=3">ares_library_init(3) when
       the library was initialized, provided there was only one single
       previous call to _library_init&section=3">ares_library_init(3). If there was more than one
       previous call to _library_init&section=3">ares_library_init(3), this function uninitializes the
       c-ares library only if it is the call matching the call to
       _library_init&section=3">ares_library_init(3) which initialized the library (usually the very
       first call to _library_init&section=3">ares_library_init(3)).  Other calls to
       _library_cleanup&section=3">ares_library_cleanup(3) have no effect other than decrementing an
       internal counter.

       This function must be called when the program using c-ares will no
       longer need any c-ares function. Once the program has called
       _library_cleanup&section=3">ares_library_cleanup(3) sufficiently often such that the library is
       uninitialised, it shall not make any further call to any c-ares
       function.

       This function does not cancel any pending c-ares lookups or requests
       previously done. Program  must use _cancel&section=3">ares_cancel(3) for this purpose.

       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 _library_cleanup&section=3">ares_library_cleanup(3)
       might call functions from other libraries that are thread unsafe, and
       could conflict with any other thread that is already using these other
       libraries.

       Win32/64 application DLLs shall not call _library_cleanup&section=3">ares_library_cleanup(3) from
       the DllMain function. Doing so will produce deadlocks and other
       problems.

AVAILABILITY
       This function was first introduced in c-ares version 1.7.0 along with
       the definition of preprocessor symbol CARES_HAVE_ARES_LIBRARY_CLEANUP
       as an indication of the availability of this function. Reference
       counting in ares_library_init() and ares_library_cleanup(), which
       requires calls to the former function to match calls to the latter, is
       present since c-ares version 1.10.0.  Earlier versions would
       deinitialize the library on the first call to ares_library_cleanup().

       Since the introduction of this function, it is absolutely mandatory to
       call it for any Win32/64 program using c-ares.

       Non-Win32/64 systems can still use c-ares version 1.7.0 without calling
       _library_cleanup&section=3">ares_library_cleanup(3) due to the fact that currently it is nearly a
       do-nothing function on non-Win32/64 platforms.

SEE ALSO
       ares_library_init(3), ares_cancel(3)

AUTHOR
       Yang Tse

       Copyright 1998 by the Massachusetts Institute of Technology.
       Copyright (C) 2004-2009 by Daniel Stenberg.

                                  19 May 2009          ARES_LIBRARY_CLEANUP(3)