1ARES_LIBRARY_CLEANUP(3)    Library Functions Manual    ARES_LIBRARY_CLEANUP(3)
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NAME

6       ares_library_cleanup - c-ares library deinitialization
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SYNOPSIS

9       #include <ares.h>
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11       void ares_library_cleanup(void)
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DESCRIPTION

14       The  ares_library_cleanup  function  uninitializes  the c-ares library,
15       freeing all resources previously acquired by ares_library_init(3)  when
16       the  library was initialized, provided there was only one single previ‐
17       ous call to ares_library_init(3). If there was more than  one  previous
18       call  to  ares_library_init(3),  this function uninitializes the c-ares
19       library  only  if  it  is  the  call  matching  the  call  to  ares_li‐
20       brary_init(3)  which  initialized  the  library (usually the very first
21       call to ares_library_init(3)).  Other calls to  ares_library_cleanup(3)
22       have no effect other than decrementing an internal counter.
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24       This  function  must  be  called  when the program using c-ares will no
25       longer need any c-ares function. Once the program has  called  ares_li‐
26       brary_cleanup(3)  sufficiently  often  such  that the library is unini‐
27       tialised, it shall not make any further call to any c-ares function.
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29       This function does not cancel any pending c-ares  lookups  or  requests
30       previously done. Program  must use ares_cancel(3) for this purpose.
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32       This function is not thread safe.  You have to call it once the program
33       is about to terminate, but this call must be done once the program  has
34       terminated  every  single  thread that it could have initiated. This is
35       required to avoid potential race conditions  in  library  deinitializa‐
36       tion,  and also due to the fact that ares_library_cleanup(3) might call
37       functions from other libraries that are thread unsafe, and  could  con‐
38       flict  with  any  other  thread  that  is already using these other li‐
39       braries.
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41       Win32/64 application DLLs shall not call  ares_library_cleanup(3)  from
42       the  DllMain  function. Doing so will produce deadlocks and other prob‐
43       lems.
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AVAILABILITY

46       This function was first introduced in c-ares version 1.7.0  along  with
47       the  definition  of preprocessor symbol CARES_HAVE_ARES_LIBRARY_CLEANUP
48       as an indication of the availability of this function. Reference count‐
49       ing in ares_library_init(3) and ares_library_cleanup(3), which requires
50       calls to the former function to match calls to the latter,  is  present
51       since  c-ares  version 1.10.0.  Earlier versions would deinitialize the
52       library on the first call to ares_library_cleanup(3).
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54       Since the introduction of this function, it is absolutely mandatory  to
55       call it for any Win32/64 program using c-ares.
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57       Non-Win32/64 systems can still use c-ares version 1.7.0 without calling
58       ares_library_cleanup(3) due to the fact that currently it is  nearly  a
59       do-nothing function on non-Win32/64 platforms.
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SEE ALSO

62       ares_library_init(3), ares_cancel(3)
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AUTHOR

65       Yang Tse
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67       Copyright 1998 by the Massachusetts Institute of Technology.
68       Copyright (C) 2004-2009 by Daniel Stenberg.
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72                                  19 May 2009          ARES_LIBRARY_CLEANUP(3)
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