| 1 | /** @file
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| 2 | * IPRT - Execute Once.
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| 3 | */
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| 4 |
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| 5 | /*
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| 6 | * Copyright (C) 2006-2007 Oracle Corporation
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| 7 | *
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| 8 | * This file is part of VirtualBox Open Source Edition (OSE), as
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| 9 | * available from http://www.virtualbox.org. This file is free software;
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| 10 | * you can redistribute it and/or modify it under the terms of the GNU
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| 11 | * General Public License (GPL) as published by the Free Software
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| 12 | * Foundation, in version 2 as it comes in the "COPYING" file of the
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| 13 | * VirtualBox OSE distribution. VirtualBox OSE is distributed in the
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| 14 | * hope that it will be useful, but WITHOUT ANY WARRANTY of any kind.
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| 15 | *
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| 16 | * The contents of this file may alternatively be used under the terms
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| 17 | * of the Common Development and Distribution License Version 1.0
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| 18 | * (CDDL) only, as it comes in the "COPYING.CDDL" file of the
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| 19 | * VirtualBox OSE distribution, in which case the provisions of the
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| 20 | * CDDL are applicable instead of those of the GPL.
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| 21 | *
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| 22 | * You may elect to license modified versions of this file under the
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| 23 | * terms and conditions of either the GPL or the CDDL or both.
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| 24 | */
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| 25 |
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| 26 | #ifndef ___iprt_once_h
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| 27 | #define ___iprt_once_h
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| 28 |
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| 29 | #include <iprt/cdefs.h>
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| 30 | #include <iprt/types.h>
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| 31 | #include <iprt/err.h>
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| 32 |
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| 33 | RT_C_DECLS_BEGIN
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| 34 |
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| 35 | /** @defgroup grp_rt_once RTOnce - Execute Once
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| 36 | * @ingroup grp_rt
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| 37 | * @{
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| 38 | */
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| 39 |
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| 40 | /**
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| 41 | * Execute once structure.
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| 42 | *
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| 43 | * This is typically a global variable that is statically initialized
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| 44 | * by RTONCE_INITIALIZER.
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| 45 | */
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| 46 | typedef struct RTONCE
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| 47 | {
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| 48 | /** Event semaphore that the other guys are blocking on. */
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| 49 | RTSEMEVENTMULTI volatile hEventMulti;
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| 50 | /** Reference counter for hEventMulti. */
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| 51 | int32_t volatile cEventRefs;
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| 52 | /** -1 when uninitialized, 1 when initializing (busy) and 2 when done. */
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| 53 | int32_t volatile iState;
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| 54 | /** The return code of pfnOnce. */
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| 55 | int32_t volatile rc;
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| 56 | } RTONCE;
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| 57 | /** Pointer to a execute once struct. */
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| 58 | typedef RTONCE *PRTONCE;
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| 59 |
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| 60 | /** Static initializer for RTONCE variables. */
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| 61 | #define RTONCE_INITIALIZER { NIL_RTSEMEVENTMULTI, 0, -1, VERR_INTERNAL_ERROR }
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| 62 |
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| 63 |
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| 64 | /**
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| 65 | * Callback that gets executed once.
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| 66 | *
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| 67 | * @returns IPRT style status code, RTOnce returns this.
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| 68 | *
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| 69 | * @param pvUser1 The first user parameter.
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| 70 | * @param pvUser2 The second user parameter.
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| 71 | */
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| 72 | typedef DECLCALLBACK(int32_t) FNRTONCE(void *pvUser1, void *pvUser2);
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| 73 | /** Pointer to a FNRTONCE. */
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| 74 | typedef FNRTONCE *PFNRTONCE;
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| 75 |
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| 76 | /**
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| 77 | * Serializes execution of the pfnOnce function, making sure it's
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| 78 | * executed exactly once and that nobody returns from RTOnce before
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| 79 | * it has executed successfully.
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| 80 | *
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| 81 | * @returns IPRT like status code returned by pfnOnce.
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| 82 | *
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| 83 | * @param pOnce Pointer to the execute once variable.
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| 84 | * @param pfnOnce The function to executed once.
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| 85 | * @param pvUser1 The first user parameter for pfnOnce.
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| 86 | * @param pvUser2 The second user parameter for pfnOnce.
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| 87 | */
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| 88 | RTDECL(int) RTOnce(PRTONCE pOnce, PFNRTONCE pfnOnce, void *pvUser1, void *pvUser2);
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| 89 |
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| 90 | /**
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| 91 | * Resets an execute once variable.
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| 92 | *
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| 93 | * The caller is responsible for making sure there are no concurrent accesses to
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| 94 | * the execute once variable.
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| 95 | *
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| 96 | * @param pOnce Pointer to the execute once variable.
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| 97 | */
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| 98 | RTDECL(void) RTOnceReset(PRTONCE pOnce);
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| 99 |
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| 100 | /** @} */
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| 101 |
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| 102 | RT_C_DECLS_END
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| 103 |
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| 104 | #endif
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| 105 |
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