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
|
/* -*- mode: C; c-file-style: "gnu" -*- */
/* dbus-threads.h D-BUS threads handling
*
* Copyright (C) 2002 Red Hat Inc.
*
* Licensed under the Academic Free License version 1.2
*
* 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; either version 2 of the License, or
* (at your option) any later version.
*
* 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, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*
*/
#include "dbus-threads.h"
#include "dbus-internals.h"
static DBusThreadFunctions thread_functions =
{
0,
NULL, NULL, NULL, NULL,
NULL, NULL, NULL, NULL,
NULL, NULL, NULL, NULL
};
static DBusMutex *static_mutex_init_lock = NULL;
/** This is used for the no-op default mutex pointer, just to be distinct from #NULL */
#define _DBUS_DUMMY_MUTEX ((void*)0xABCDEF)
/**
* @defgroup DBusThreads Thread functions
* @ingroup DBus
* @brief dbus_threads_init(), dbus_mutex_lock(), etc.
*
* Functions and macros related to threads and thread locks.
*
* @{
*/
/**
* Creates a new mutex using the function supplied to dbus_threads_init(),
* or creates a no-op mutex if threads are not initialized.
* May return #NULL even if threads are initialized, indicating
* out-of-memory.
*
* @returns new mutex or #NULL
*/
DBusMutex*
dbus_mutex_new (void)
{
if (thread_functions.mutex_new)
return (* thread_functions.mutex_new) ();
else
return _DBUS_DUMMY_MUTEX;
}
/**
* Frees a mutex created with dbus_mutex_new(); does
* nothing if passed a #NULL pointer.
*/
void
dbus_mutex_free (DBusMutex *mutex)
{
if (mutex && thread_functions.mutex_free)
(* thread_functions.mutex_free) (mutex);
}
/**
* Locks a mutex. Does nothing if passed a #NULL pointer.
* Locks are not recursive.
*
* @returns #TRUE on success
*/
dbus_bool_t
dbus_mutex_lock (DBusMutex *mutex)
{
if (mutex && thread_functions.mutex_lock)
return (* thread_functions.mutex_lock) (mutex);
else
return TRUE;
}
/**
* Unlocks a mutex. Does nothing if passed a #NULL pointer.
*
* @returns #TRUE on success
*/
dbus_bool_t
dbus_mutex_unlock (DBusMutex *mutex)
{
if (mutex && thread_functions.mutex_unlock)
return (* thread_functions.mutex_unlock) (mutex);
else
return TRUE;
}
/**
* Initializes threads. If this function is not called,
* the D-BUS library will not lock any data structures.
* If it is called, D-BUS will do locking, at some cost
* in efficiency. Note that this function must be called
* BEFORE using any other D-BUS functions.
*
* @todo right now this function can only be called once,
* maybe we should instead silently ignore multiple calls.
*
* @param functions functions for using threads
* @returns #TRUE on success, #FALSE if no memory
*/
dbus_bool_t
dbus_threads_init (const DBusThreadFunctions *functions)
{
_dbus_assert (functions != NULL);
/* these base functions are required. Future additions to
* DBusThreadFunctions may be optional.
*/
_dbus_assert (functions->mask & DBUS_THREAD_FUNCTIONS_NEW_MASK);
_dbus_assert (functions->mask & DBUS_THREAD_FUNCTIONS_FREE_MASK);
_dbus_assert (functions->mask & DBUS_THREAD_FUNCTIONS_LOCK_MASK);
_dbus_assert (functions->mask & DBUS_THREAD_FUNCTIONS_UNLOCK_MASK);
_dbus_assert (functions->mutex_new != NULL);
_dbus_assert (functions->mutex_free != NULL);
_dbus_assert (functions->mutex_lock != NULL);
_dbus_assert (functions->mutex_unlock != NULL);
/* Check that all bits in the mask actually are valid mask bits.
* ensures people won't write code that breaks when we add
* new bits.
*/
_dbus_assert ((functions->mask & ~DBUS_THREAD_FUNCTIONS_ALL_MASK) == 0);
if (thread_functions.mask != 0)
{
_dbus_warn ("dbus_threads_init() may only be called one time\n");
return FALSE;
}
thread_functions.mutex_new = functions->mutex_new;
thread_functions.mutex_free = functions->mutex_free;
thread_functions.mutex_lock = functions->mutex_lock;
thread_functions.mutex_unlock = functions->mutex_unlock;
thread_functions.mask = functions->mask;
static_mutex_init_lock = dbus_mutex_new ();
if (static_mutex_init_lock == NULL)
{
thread_functions.mask = 0;
return FALSE;
}
return TRUE;
}
/** Accesses the field of DBusStaticMutex that
* stores the DBusMutex used to implement.
*/
#define _DBUS_STATIC_MUTEX_IMPL(mutex) ((mutex)->pad1)
/**
* Lock a static mutex
*
* @param mutex the mutex to lock
* @returns #TRUE on success
*/
dbus_bool_t
dbus_static_mutex_lock (DBusStaticMutex *mutex)
{
if (_DBUS_STATIC_MUTEX_IMPL (mutex))
return dbus_mutex_lock (_DBUS_STATIC_MUTEX_IMPL (mutex));
if (!dbus_mutex_lock (static_mutex_init_lock))
return FALSE;
if (_DBUS_STATIC_MUTEX_IMPL (mutex) == NULL)
_DBUS_STATIC_MUTEX_IMPL (mutex) = dbus_mutex_new ();
dbus_mutex_unlock (static_mutex_init_lock);
if (_DBUS_STATIC_MUTEX_IMPL (mutex))
return dbus_mutex_lock (_DBUS_STATIC_MUTEX_IMPL (mutex));
else
return FALSE;
}
/**
* Unlock a static mutex
* @param mutex the mutex to lock
* @returns #TRUE on success
*/
dbus_bool_t
dbus_static_mutex_unlock (DBusStaticMutex *mutex)
{
_dbus_assert (_DBUS_STATIC_MUTEX_IMPL (mutex) != NULL);
return dbus_mutex_unlock (_DBUS_STATIC_MUTEX_IMPL (mutex));
}
/** @} */
|
