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
|
/*-
* Copyright (c) 2014-2016 MongoDB, Inc.
* Copyright (c) 2008-2014 WiredTiger, Inc.
* All rights reserved.
*
* See the file LICENSE for redistribution information.
*/
#include "wt_internal.h"
/*
* __wt_cond_alloc --
* Allocate and initialize a condition variable.
*/
int
__wt_cond_alloc(WT_SESSION_IMPL *session,
const char *name, bool is_signalled, WT_CONDVAR **condp)
{
WT_CONDVAR *cond;
WT_DECL_RET;
/*
* !!!
* This function MUST handle a NULL session handle.
*/
WT_RET(__wt_calloc_one(session, &cond));
WT_ERR(pthread_mutex_init(&cond->mtx, NULL));
/* Initialize the condition variable to permit self-blocking. */
WT_ERR(pthread_cond_init(&cond->cond, NULL));
cond->name = name;
cond->waiters = is_signalled ? -1 : 0;
*condp = cond;
return (0);
err: __wt_free(session, cond);
return (ret);
}
/*
* __wt_cond_wait_signal --
* Wait on a mutex, optionally timing out. If we get it
* before the time out period expires, let the caller know.
*/
int
__wt_cond_wait_signal(
WT_SESSION_IMPL *session, WT_CONDVAR *cond, uint64_t usecs, bool *signalled)
{
struct timespec ts;
WT_DECL_RET;
bool locked;
locked = false;
/* Fast path if already signalled. */
*signalled = true;
if (__wt_atomic_addi32(&cond->waiters, 1) == 0)
return (0);
/*
* !!!
* This function MUST handle a NULL session handle.
*/
if (session != NULL) {
WT_RET(__wt_verbose(session, WT_VERB_MUTEX,
"wait %s cond (%p)", cond->name, cond));
WT_STAT_FAST_CONN_INCR(session, cond_wait);
}
WT_ERR(pthread_mutex_lock(&cond->mtx));
locked = true;
if (usecs > 0) {
WT_ERR(__wt_epoch(session, &ts));
ts.tv_sec += (time_t)
(((uint64_t)ts.tv_nsec + WT_THOUSAND * usecs) / WT_BILLION);
ts.tv_nsec = (long)
(((uint64_t)ts.tv_nsec + WT_THOUSAND * usecs) % WT_BILLION);
ret = pthread_cond_timedwait(&cond->cond, &cond->mtx, &ts);
} else
ret = pthread_cond_wait(&cond->cond, &cond->mtx);
/*
* Check pthread_cond_wait() return for EINTR, ETIME and
* ETIMEDOUT, some systems return these errors.
*/
if (ret == EINTR ||
#ifdef ETIME
ret == ETIME ||
#endif
ret == ETIMEDOUT) {
*signalled = false;
ret = 0;
}
(void)__wt_atomic_subi32(&cond->waiters, 1);
err: if (locked)
WT_TRET(pthread_mutex_unlock(&cond->mtx));
if (ret == 0)
return (0);
WT_RET_MSG(session, ret, "pthread_cond_wait");
}
/*
* __wt_cond_signal --
* Signal a waiting thread.
*/
int
__wt_cond_signal(WT_SESSION_IMPL *session, WT_CONDVAR *cond)
{
WT_DECL_RET;
bool locked;
locked = false;
/*
* !!!
* This function MUST handle a NULL session handle.
*/
if (session != NULL)
WT_RET(__wt_verbose(session, WT_VERB_MUTEX,
"signal %s cond (%p)", cond->name, cond));
/* Fast path if already signalled. */
if (cond->waiters == -1)
return (0);
if (cond->waiters > 0 || !__wt_atomic_casi32(&cond->waiters, 0, -1)) {
WT_ERR(pthread_mutex_lock(&cond->mtx));
locked = true;
WT_ERR(pthread_cond_broadcast(&cond->cond));
}
err: if (locked)
WT_TRET(pthread_mutex_unlock(&cond->mtx));
if (ret == 0)
return (0);
WT_RET_MSG(session, ret, "pthread_cond_broadcast");
}
/*
* __wt_cond_destroy --
* Destroy a condition variable.
*/
int
__wt_cond_destroy(WT_SESSION_IMPL *session, WT_CONDVAR **condp)
{
WT_CONDVAR *cond;
WT_DECL_RET;
cond = *condp;
if (cond == NULL)
return (0);
ret = pthread_cond_destroy(&cond->cond);
WT_TRET(pthread_mutex_destroy(&cond->mtx));
__wt_free(session, *condp);
return (ret);
}
|
