summaryrefslogtreecommitdiff
path: root/manual/threads.texi
blob: 769d974d504c54a1893b5b3d3db80989059390b2 (plain)
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
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
@node POSIX Threads
@c @node POSIX Threads, Internal Probes, Cryptographic Functions, Top
@chapter POSIX Threads
@c %MENU% POSIX Threads
@cindex pthreads

This chapter describes the @glibcadj{} POSIX Threads implementation.

@menu
* Thread-specific Data::          Support for creating and
				  managing thread-specific data
* Non-POSIX Extensions::          Additional functions to extend
				  POSIX Thread functionality
@end menu

@node Thread-specific Data
@section Thread-specific Data

The @glibcadj{} implements functions to allow users to create and manage
data specific to a thread.  Such data may be destroyed at thread exit,
if a destructor is provided.  The following functions are defined:

@deftypefun int pthread_key_create (pthread_key_t *@var{key}, void (*@var{destructor})(void*))
@standards{POSIX, pthread.h}
@safety{@prelim{}@mtsafe{}@assafe{}@acsafe{}}
@c pthread_key_create ok
@c  KEY_UNUSED ok
@c  KEY_USABLE ok
Create a thread-specific data key for the calling thread, referenced by
@var{key}.

Objects declared with the C++11 @code{thread_local} keyword are destroyed
before thread-specific data, so they should not be used in thread-specific
data destructors or even as members of the thread-specific data, since the
latter is passed as an argument to the destructor function.
@end deftypefun

@deftypefun int pthread_key_delete (pthread_key_t @var{key})
@standards{POSIX, pthread.h}
@safety{@prelim{}@mtsafe{}@assafe{}@acsafe{}}
@c pthread_key_delete ok
@c   This uses atomic compare and exchange to increment the seq number
@c   after testing it's not a KEY_UNUSED seq number.
@c  KEY_UNUSED dup ok
Destroy the thread-specific data @var{key} in the calling thread.  The
destructor for the thread-specific data is not called during destruction, nor
is it called during thread exit.
@end deftypefun

@deftypefun void *pthread_getspecific (pthread_key_t @var{key})
@standards{POSIX, pthread.h}
@safety{@prelim{}@mtsafe{}@assafe{}@acsafe{}}
@c pthread_getspecific ok
Return the thread-specific data associated with @var{key} in the calling
thread.
@end deftypefun

@deftypefun int pthread_setspecific (pthread_key_t @var{key}, const void *@var{value})
@standards{POSIX, pthread.h}
@safety{@prelim{}@mtsafe{}@asunsafe{@asucorrupt{} @ascuheap{}}@acunsafe{@acucorrupt{} @acsmem{}}}
@c pthread_setspecific @asucorrupt @ascuheap @acucorrupt @acsmem
@c   a level2 block may be allocated by a signal handler after
@c   another call already made a decision to allocate it, thus losing
@c   the allocated value.  the seq number is updated before the
@c   value, which might cause an earlier-generation value to seem
@c   current if setspecific is cancelled or interrupted by a signal
@c  KEY_UNUSED ok
@c  calloc dup @ascuheap @acsmem
Associate the thread-specific @var{value} with @var{key} in the calling thread.
@end deftypefun


@node Non-POSIX Extensions
@section Non-POSIX Extensions

In addition to implementing the POSIX API for threads, @theglibc{} provides
additional functions and interfaces to provide functionality not specified in
the standard.

@menu
* Default Thread Attributes::             Setting default attributes for
					  threads in a process.
@end menu

@node Default Thread Attributes
@subsection Setting Process-wide defaults for thread attributes

@Theglibc{} provides non-standard API functions to set and get the default
attributes used in the creation of threads in a process.

@deftypefun int pthread_getattr_default_np (pthread_attr_t *@var{attr})
@standards{GNU, pthread.h}
@safety{@prelim{}@mtsafe{}@asunsafe{@asulock{}}@acunsafe{@aculock{}}}
@c Takes lock around read from default_pthread_attr.
Get the default attribute values and set @var{attr} to match.  This
function returns @math{0} on success and a non-zero error code on
failure.
@end deftypefun

@deftypefun int pthread_setattr_default_np (pthread_attr_t *@var{attr})
@standards{GNU, pthread.h}
@safety{@prelim{}@mtsafe{}@asunsafe{@ascuheap{} @asulock{}}@acunsafe{@aculock{} @acsmem{}}}
@c pthread_setattr_default_np @ascuheap @asulock @aculock @acsmem
@c  check_sched_policy_attr ok
@c  check_sched_priority_attr ok
@c   sched_get_priority_min dup ok
@c   sched_get_priority_max dup ok
@c  check_stacksize_attr ok
@c  lll_lock @asulock @aculock
@c  free dup @ascuheap @acsmem
@c  realloc dup @ascuheap @acsmem
@c  memcpy dup ok
@c  lll_unlock @asulock @aculock
Set the default attribute values to match the values in @var{attr}.  The
function returns @math{0} on success and a non-zero error code on failure.
The following error codes are defined for this function:

@table @code
@item EINVAL
At least one of the values in @var{attr} does not qualify as valid for the
attributes or the stack address is set in the attribute.
@item ENOMEM
The system does not have sufficient memory.
@end table
@end deftypefun

@c FIXME these are undocumented:
@c pthread_atfork
@c pthread_attr_destroy
@c pthread_attr_getaffinity_np
@c pthread_attr_getdetachstate
@c pthread_attr_getguardsize
@c pthread_attr_getinheritsched
@c pthread_attr_getschedparam
@c pthread_attr_getschedpolicy
@c pthread_attr_getscope
@c pthread_attr_getstack
@c pthread_attr_getstackaddr
@c pthread_attr_getstacksize
@c pthread_attr_init
@c pthread_attr_setaffinity_np
@c pthread_attr_setdetachstate
@c pthread_attr_setguardsize
@c pthread_attr_setinheritsched
@c pthread_attr_setschedparam
@c pthread_attr_setschedpolicy
@c pthread_attr_setscope
@c pthread_attr_setstack
@c pthread_attr_setstackaddr
@c pthread_attr_setstacksize
@c pthread_barrierattr_destroy
@c pthread_barrierattr_getpshared
@c pthread_barrierattr_init
@c pthread_barrierattr_setpshared
@c pthread_barrier_destroy
@c pthread_barrier_init
@c pthread_barrier_wait
@c pthread_cancel
@c pthread_cleanup_push
@c pthread_cleanup_pop
@c pthread_condattr_destroy
@c pthread_condattr_getclock
@c pthread_condattr_getpshared
@c pthread_condattr_init
@c pthread_condattr_setclock
@c pthread_condattr_setpshared
@c pthread_cond_broadcast
@c pthread_cond_destroy
@c pthread_cond_init
@c pthread_cond_signal
@c pthread_cond_timedwait
@c pthread_cond_wait
@c pthread_create
@c pthread_detach
@c pthread_equal
@c pthread_exit
@c pthread_getaffinity_np
@c pthread_getattr_np
@c pthread_getconcurrency
@c pthread_getcpuclockid
@c pthread_getname_np
@c pthread_getschedparam
@c pthread_join
@c pthread_kill
@c pthread_kill_other_threads_np
@c pthread_mutexattr_destroy
@c pthread_mutexattr_getkind_np
@c pthread_mutexattr_getprioceiling
@c pthread_mutexattr_getprotocol
@c pthread_mutexattr_getpshared
@c pthread_mutexattr_getrobust
@c pthread_mutexattr_getrobust_np
@c pthread_mutexattr_gettype
@c pthread_mutexattr_init
@c pthread_mutexattr_setkind_np
@c pthread_mutexattr_setprioceiling
@c pthread_mutexattr_setprotocol
@c pthread_mutexattr_setpshared
@c pthread_mutexattr_setrobust
@c pthread_mutexattr_setrobust_np
@c pthread_mutexattr_settype
@c pthread_mutex_consistent
@c pthread_mutex_consistent_np
@c pthread_mutex_destroy
@c pthread_mutex_getprioceiling
@c pthread_mutex_init
@c pthread_mutex_lock
@c pthread_mutex_setprioceiling
@c pthread_mutex_timedlock
@c pthread_mutex_trylock
@c pthread_mutex_unlock
@c pthread_once
@c pthread_rwlockattr_destroy
@c pthread_rwlockattr_getkind_np
@c pthread_rwlockattr_getpshared
@c pthread_rwlockattr_init
@c pthread_rwlockattr_setkind_np
@c pthread_rwlockattr_setpshared
@c pthread_rwlock_destroy
@c pthread_rwlock_init
@c pthread_rwlock_rdlock
@c pthread_rwlock_timedrdlock
@c pthread_rwlock_timedwrlock
@c pthread_rwlock_tryrdlock
@c pthread_rwlock_trywrlock
@c pthread_rwlock_unlock
@c pthread_rwlock_wrlock
@c pthread_self
@c pthread_setaffinity_np
@c pthread_setcancelstate
@c pthread_setcanceltype
@c pthread_setconcurrency
@c pthread_setname_np
@c pthread_setschedparam
@c pthread_setschedprio
@c pthread_sigmask
@c pthread_sigqueue
@c pthread_spin_destroy
@c pthread_spin_init
@c pthread_spin_lock
@c pthread_spin_trylock
@c pthread_spin_unlock
@c pthread_testcancel
@c pthread_timedjoin_np
@c pthread_tryjoin_np
@c pthread_yield