path: root/ares_library_cleanup.3
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authorYang Tse <>2009-05-20 11:26:26 (GMT)
committerYang Tse <>2009-05-20 11:26:26 (GMT)
commitdec9775cd60418a23765c9e3604ae0d4229c0ee7 (patch)
tree533770a29aa06320e1e40caeeff23b100050d428 /ares_library_cleanup.3
parentcf2882882d67fd8eddb8fa2c49fc78111f5a3f5d (diff)
Initial ares_library_cleanup(3) man page
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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.
+ares_library_cleanup \- c-ares library deinitialization
+.B #include <ares.h>
+.B void ares_library_cleanup(void)
+.B cc file.c -lcares
+.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.
+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.
+This function does not cancel any pending c-ares lookups or requests
+previously done. Program must use \fIares_cancel(3)\fP for this purpose.
+.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.
+Win32/64 application DLLs shall not call ares_library_cleanup() from the
+DllMain function. Doing so will produce deadlocks and other problems.
+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.
+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 1.6.1 without calling
+ares_library_cleanup() due to the fact that it is nearly a do-nothing
+function on non-Win32/64 platforms.
+.BR ares_library_init(3),
+.BR ares_cancel(3)
+Yang Tse
+Copyright 1998 by the Massachusetts Institute of Technology.
+Copyright (C) 2004-2009 by Daniel Stenberg.