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84 lines
3.6 KiB
84 lines
3.6 KiB
.\" |
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.\" Copyright 1998 by the Massachusetts Institute of Technology. |
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.\" Copyright (C) 2004-2009 by Daniel Stenberg |
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.\" |
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.\" Permission to use, copy, modify, and distribute this |
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.\" software and its documentation for any purpose and without |
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.\" fee is hereby granted, provided that the above copyright |
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.\" notice appear in all copies and that both that copyright |
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.\" notice and this permission notice appear in supporting |
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.\" documentation, and that the name of M.I.T. not be used in |
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.\" advertising or publicity pertaining to distribution of the |
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.\" software without specific, written prior permission. |
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.\" M.I.T. makes no representations about the suitability of |
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.\" this software for any purpose. It is provided "as is" |
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.\" without express or implied warranty. |
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.\" |
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.TH ARES_LIBRARY_CLEANUP 3 "19 May 2009" |
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.SH NAME |
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ares_library_cleanup \- c-ares library deinitialization |
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.SH SYNOPSIS |
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.nf |
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#include <ares.h> |
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|
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void ares_library_cleanup(void) |
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.fi |
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.SH DESCRIPTION |
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.PP |
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The |
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.B ares_library_cleanup |
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function uninitializes the c-ares library, freeing all resources |
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previously acquired by \fIares_library_init(3)\fP when the library |
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was initialized, provided there was only one single previous call to |
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\fIares_library_init(3)\fP. If there was more than one previous call to |
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\fIares_library_init(3)\fP, this function uninitializes the c-ares |
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library only if it is the call matching the call to |
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\fIares_library_init(3)\fP which initialized the library |
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(usually the very first call to \fIares_library_init(3)\fP). |
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Other calls to \fIares_library_cleanup(3)\fP have no effect other than |
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decrementing an internal counter. |
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.PP |
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This function must be called when the program using c-ares will |
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no longer need any c-ares function. Once the program has called |
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\fIares_library_cleanup(3)\fP sufficiently often such that the |
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library is uninitialised, it shall not make any further call to any |
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c-ares function. |
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.PP |
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This function does not cancel any pending c-ares lookups or requests |
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previously done. Program must use \fIares_cancel(3)\fP for this purpose. |
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.PP |
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.B This function is not thread safe. |
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You have to call it once the program is about to terminate, but this call must |
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be done once the program has terminated every single thread that it could have |
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initiated. This is required to avoid potential race conditions in library |
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deinitialization, and also due to the fact that \fIares_library_cleanup(3)\fP |
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might call functions from other libraries that are thread unsafe, and could |
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conflict with any other thread that is already using these other libraries. |
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.PP |
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Win32/64 application DLLs shall not call \fIares_library_cleanup(3)\fP from |
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the DllMain function. Doing so will produce deadlocks and other problems. |
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.SH AVAILABILITY |
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This function was first introduced in c-ares version 1.7.0 along with the |
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definition of preprocessor symbol \fICARES_HAVE_ARES_LIBRARY_CLEANUP\fP as an |
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indication of the availability of this function. Reference counting in |
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\fIares_library_init()\fP and \fIares_library_cleanup()\fP, which requires |
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calls to the former function to match calls to the latter, is present since |
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c-ares version 1.10.0. |
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Earlier versions would deinitialize the library on the first call |
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to \fIares_library_cleanup()\fP. |
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.PP |
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Since the introduction of this function, it is absolutely mandatory to call it |
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for any Win32/64 program using c-ares. |
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.PP |
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Non-Win32/64 systems can still use c-ares version 1.7.0 without calling |
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\fIares_library_cleanup(3)\fP due to the fact that \fIcurrently\fP it is nearly |
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a do-nothing function on non-Win32/64 platforms. |
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.SH SEE ALSO |
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.BR ares_library_init(3), |
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.BR ares_cancel(3) |
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.SH AUTHOR |
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Yang Tse |
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.PP |
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Copyright 1998 by the Massachusetts Institute of Technology. |
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.br |
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Copyright (C) 2004-2009 by Daniel Stenberg.
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