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
|
/* Copyright (c) 2003-2004, Roger Dingledine
* Copyright (c) 2004-2006, Roger Dingledine, Nick Mathewson.
* Copyright (c) 2007-2020, The Tor Project, Inc. */
/* See LICENSE for licensing information */
/**
* \file compat_threads.c
*
* \brief Cross-platform threading and inter-thread communication logic.
* (Platform-specific parts are written in the other compat_*threads
* modules.)
*/
#include "orconfig.h"
#include <stdlib.h>
#include "lib/thread/threads.h"
#include "lib/thread/thread_sys.h"
#include "lib/log/log.h"
#include "lib/log/util_bug.h"
#include "lib/subsys/subsys.h"
#include <string.h>
/** Allocate and return a new condition variable. */
tor_cond_t *
tor_cond_new(void)
{
tor_cond_t *cond = tor_malloc(sizeof(tor_cond_t));
if (BUG(tor_cond_init(cond)<0))
tor_free(cond); // LCOV_EXCL_LINE
return cond;
}
/** Free all storage held in <b>c</b>. */
void
tor_cond_free_(tor_cond_t *c)
{
if (!c)
return;
tor_cond_uninit(c);
tor_free(c);
}
/** Identity of the "main" thread */
static unsigned long main_thread_id = -1;
/** Start considering the current thread to be the 'main thread'. This has
* no effect on anything besides in_main_thread(). */
void
set_main_thread(void)
{
main_thread_id = tor_get_thread_id();
}
/** Return true iff called from the main thread. */
int
in_main_thread(void)
{
return main_thread_id == tor_get_thread_id();
}
#ifndef HAVE_WORKING_STDATOMIC
/** Initialize a new atomic counter with the value 0 */
void
atomic_counter_init(atomic_counter_t *counter)
{
memset(counter, 0, sizeof(*counter));
tor_mutex_init_nonrecursive(&counter->mutex);
}
/** Clean up all resources held by an atomic counter.
*
* Destroying a locked mutex is undefined behaviour. Global mutexes may be
* locked when they are passed to this function, because multiple threads can
* still access them. So we can either:
* - destroy on shutdown, and re-initialise when tor re-initialises, or
* - skip destroying and re-initialisation, using a sentinel variable.
* See #31735 for details.
*/
void
atomic_counter_destroy(atomic_counter_t *counter)
{
tor_mutex_uninit(&counter->mutex);
memset(counter, 0, sizeof(*counter));
}
/** Add a value to an atomic counter. */
void
atomic_counter_add(atomic_counter_t *counter, size_t add)
{
tor_mutex_acquire(&counter->mutex);
counter->val += add;
tor_mutex_release(&counter->mutex);
}
/** Subtract a value from an atomic counter. */
void
atomic_counter_sub(atomic_counter_t *counter, size_t sub)
{
// this relies on unsigned overflow, but that's fine.
atomic_counter_add(counter, -sub);
}
/** Return the current value of an atomic counter */
size_t
atomic_counter_get(atomic_counter_t *counter)
{
size_t val;
tor_mutex_acquire(&counter->mutex);
val = counter->val;
tor_mutex_release(&counter->mutex);
return val;
}
/** Replace the value of an atomic counter; return the old one. */
size_t
atomic_counter_exchange(atomic_counter_t *counter, size_t newval)
{
size_t oldval;
tor_mutex_acquire(&counter->mutex);
oldval = counter->val;
counter->val = newval;
tor_mutex_release(&counter->mutex);
return oldval;
}
#endif /* !defined(HAVE_WORKING_STDATOMIC) */
static int
subsys_threads_initialize(void)
{
tor_threads_init();
return 0;
}
const subsys_fns_t sys_threads = {
.name = "threads",
SUBSYS_DECLARE_LOCATION(),
.supported = true,
.level = -89,
.initialize = subsys_threads_initialize,
};
|
