1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
|
/** @file
* IPRT - Execute Once.
*/
/*
* Copyright (C) 2006-2022 Oracle and/or its affiliates.
*
* This file is part of VirtualBox base platform packages, as
* available from https://www.virtualbox.org.
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation, in version 3 of the
* License.
*
* This program is distributed in the hope that it will be useful, but
* WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, see <https://www.gnu.org/licenses>.
*
* The contents of this file may alternatively be used under the terms
* of the Common Development and Distribution License Version 1.0
* (CDDL), a copy of it is provided in the "COPYING.CDDL" file included
* in the VirtualBox distribution, in which case the provisions of the
* CDDL are applicable instead of those of the GPL.
*
* You may elect to license modified versions of this file under the
* terms and conditions of either the GPL or the CDDL or both.
*
* SPDX-License-Identifier: GPL-3.0-only OR CDDL-1.0
*/
#ifndef IPRT_INCLUDED_once_h
#define IPRT_INCLUDED_once_h
#ifndef RT_WITHOUT_PRAGMA_ONCE
# pragma once
#endif
#include <iprt/cdefs.h>
#include <iprt/types.h>
#include <iprt/asm.h>
#include <iprt/errcore.h>
#include <iprt/list.h>
RT_C_DECLS_BEGIN
/** @defgroup grp_rt_once RTOnce - Execute Once
* @ingroup grp_rt
* @{
*/
/**
* Callback that gets executed once.
*
* @returns IPRT style status code, RTOnce returns this.
*
* @param pvUser The user parameter.
*/
typedef DECLCALLBACKTYPE(int32_t, FNRTONCE,(void *pvUser));
/** Pointer to a FNRTONCE. */
typedef FNRTONCE *PFNRTONCE;
/**
* Callback that gets executed on IPRT/process termination.
*
* @param pvUser The user parameter.
* @param fLazyCleanUpOk Indicates whether lazy clean-up is OK (see
* initterm.h).
*/
typedef DECLCALLBACKTYPE(void, FNRTONCECLEANUP,(void *pvUser, bool fLazyCleanUpOk));
/** Pointer to a FNRTONCE. */
typedef FNRTONCECLEANUP *PFNRTONCECLEANUP;
/**
* Execute once structure.
*
* This is typically a global variable that is statically initialized
* by RTONCE_INITIALIZER.
*/
typedef struct RTONCE
{
/** Event semaphore that the other guys are blocking on. */
RTSEMEVENTMULTI volatile hEventMulti;
/** Reference counter for hEventMulti. */
int32_t volatile cEventRefs;
/** See RTONCESTATE. */
int32_t volatile iState;
/** The return code of pfnOnce. */
int32_t volatile rc;
/** Pointer to the clean-up function. */
PFNRTONCECLEANUP pfnCleanUp;
/** Argument to hand to the clean-up function. */
void *pvUser;
/** Clean-up list entry. */
RTLISTNODE CleanUpNode;
} RTONCE;
/** Pointer to a execute once struct. */
typedef RTONCE *PRTONCE;
/**
* The execute once statemachine.
*/
typedef enum RTONCESTATE
{
/** RTOnce() has not been called.
* Next: NO_SEM */
RTONCESTATE_UNINITIALIZED = 1,
/** RTOnce() is busy, no race.
* Next: CREATING_SEM, DONE */
RTONCESTATE_BUSY_NO_SEM,
/** More than one RTOnce() caller is busy.
* Next: BUSY_HAVE_SEM, BUSY_SPIN, DONE_CREATING_SEM, DONE */
RTONCESTATE_BUSY_CREATING_SEM,
/** More than one RTOnce() caller, the first is busy, the others are
* waiting.
* Next: DONE */
RTONCESTATE_BUSY_HAVE_SEM,
/** More than one RTOnce() caller, the first is busy, the others failed to
* create a semaphore and are spinning.
* Next: DONE */
RTONCESTATE_BUSY_SPIN,
/** More than one RTOnce() caller, the first has completed, the others
* are busy creating the semaphore.
* Next: DONE_HAVE_SEM */
RTONCESTATE_DONE_CREATING_SEM,
/** More than one RTOnce() caller, the first is busy grabbing the
* semaphore, while the others are waiting.
* Next: DONE */
RTONCESTATE_DONE_HAVE_SEM,
/** The execute once stuff has completed. */
RTONCESTATE_DONE = 16
} RTONCESTATE;
/** Static initializer for RTONCE variables. */
#define RTONCE_INITIALIZER \
{ NIL_RTSEMEVENTMULTI, 0, RTONCESTATE_UNINITIALIZED, VERR_INTERNAL_ERROR, NULL, NULL, { NULL, NULL } }
/**
* Serializes execution of the pfnOnce function, making sure it's
* executed exactly once and that nobody returns from RTOnce before
* it has executed successfully.
*
* @returns IPRT like status code returned by pfnOnce.
*
* @param pOnce Pointer to the execute once variable.
* @param pfnOnce The function to executed once.
* @param pfnCleanUp The function that will be doing the cleaning up.
* Optional.
* @param pvUser The user parameter for pfnOnce.
*/
RTDECL(int) RTOnceSlow(PRTONCE pOnce, PFNRTONCE pfnOnce, FNRTONCECLEANUP pfnCleanUp, void *pvUser);
/**
* Serializes execution of the pfnOnce function, making sure it's
* executed exactly once and that nobody returns from RTOnce before
* it has executed successfully.
*
* @returns IPRT like status code returned by pfnOnce.
*
* @param pOnce Pointer to the execute once variable.
* @param pfnOnce The function to executed once.
* @param pvUser The user parameter for pfnOnce.
*/
DECLINLINE(int) RTOnce(PRTONCE pOnce, PFNRTONCE pfnOnce, void *pvUser)
{
int32_t iState = ASMAtomicUoReadS32(&pOnce->iState);
if (RT_LIKELY( iState == RTONCESTATE_DONE
|| iState == RTONCESTATE_DONE_CREATING_SEM
|| iState == RTONCESTATE_DONE_HAVE_SEM ))
return ASMAtomicUoReadS32(&pOnce->rc);
return RTOnceSlow(pOnce, pfnOnce, NULL, pvUser);
}
/**
* Execute pfnOnce once and register a termination clean-up callback.
*
* Serializes execution of the pfnOnce function, making sure it's
* executed exactly once and that nobody returns from RTOnce before
* it has executed successfully.
*
* @returns IPRT like status code returned by pfnOnce.
*
* @param pOnce Pointer to the execute once variable.
* @param pfnOnce The function to executed once.
* @param pfnCleanUp The function that will be doing the cleaning up.
* @param pvUser The user parameter for pfnOnce.
*/
DECLINLINE(int) RTOnceEx(PRTONCE pOnce, PFNRTONCE pfnOnce, PFNRTONCECLEANUP pfnCleanUp, void *pvUser)
{
int32_t iState = ASMAtomicUoReadS32(&pOnce->iState);
if (RT_LIKELY( iState == RTONCESTATE_DONE
|| iState == RTONCESTATE_DONE_CREATING_SEM
|| iState == RTONCESTATE_DONE_HAVE_SEM ))
return ASMAtomicUoReadS32(&pOnce->rc);
return RTOnceSlow(pOnce, pfnOnce, pfnCleanUp, pvUser);
}
/**
* Resets an execute once variable.
*
* The caller is responsible for making sure there are no concurrent accesses to
* the execute once variable.
*
* @param pOnce Pointer to the execute once variable.
*/
RTDECL(void) RTOnceReset(PRTONCE pOnce);
/**
* Check whether the execute once variable was successfullly initialized.
*/
DECLINLINE(bool) RTOnceWasInitialized(PRTONCE pOnce)
{
int32_t const iState = ASMAtomicUoReadS32(&pOnce->iState);
int32_t const rc = ASMAtomicUoReadS32(&pOnce->rc);
return RT_SUCCESS(rc)
&& ( iState == RTONCESTATE_DONE
|| iState == RTONCESTATE_DONE_CREATING_SEM
|| iState == RTONCESTATE_DONE_HAVE_SEM);
}
/** @} */
RT_C_DECLS_END
#endif /* !IPRT_INCLUDED_once_h */
|
