ares_library_cleanup(3) Library Functions Manual ares_library_cleanup(3)
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 ares_library_init(3) when
the library was initialized, provided there was only one single
previous call to ares_library_init(3). If there was more than one
previous call to ares_library_init(3), this function uninitializes the
c-ares library only if it is the call matching the call to
ares_library_init(3) which initialized the library (usually the very
first call to ares_library_init(3)). Other calls to
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
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 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 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 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(3) and ares_library_cleanup(3), 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(3).
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
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)
19 May 2009 ares_library_cleanup(3)
c-ares 1.30.0 - Generated Thu Jun 13 10:46:36 CDT 2024