ares_library_cleanup - c-ares library deinitialization
function uninitializes the c-ares library,
freeing all resources previously acquired by ares_library_init(3)
the library was initialized, provided there was only one single previous call
. If there was more than one previous call to
, this function uninitializes the c-ares library
only if it is the call matching the call to ares_library_init(3)
initialized the library (usually the very first call to
). 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
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)
DllMain function. Doing so will produce deadlocks and other problems.
This function was first introduced in c-ares version 1.7.0 along with the
definition of preprocessor symbol CARES_HAVE_ARES_LIBRARY_CLEANUP
indication of the availability of this function. Reference counting in
, 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
due to the fact that currently
nearly a do-nothing function on non-Win32/64 platforms.
Copyright 1998 by the Massachusetts Institute of Technology.
Copyright (C) 2004-2009 by Daniel Stenberg.