manual/threads.texi

   1 @node POSIX Threads
   2 @c @node POSIX Threads, Internal Probes, Cryptographic Functions, Top
   3 @chapter POSIX Threads
   4 @c %MENU% POSIX Threads
   5 @cindex pthreads
   6
   7 This chapter describes the @glibcadj{} POSIX Threads implementation.
   8
   9 @menu
  10 * Thread-specific Data::          Support for creating and
  11                                   managing thread-specific data
  12 * Non-POSIX Extensions::          Additional functions to extend
  13                                   POSIX Thread functionality
  14 @end menu
  15
  16 @node Thread-specific Data
  17 @section Thread-specific Data
  18
  19 The @glibcadj{} implements functions to allow users to create and manage
  20 data specific to a thread.  Such data may be destroyed at thread exit,
  21 if a destructor is provided.  The following functions are defined:
  22
  23 @deftypefun int pthread_key_create (pthread_key_t *@var{key}, void (*@var{destructor})(void*))
  24 @standards{POSIX, pthread.h}
  25 @safety{@prelim{}@mtsafe{}@assafe{}@acsafe{}}
  26 @c pthread_key_create ok
  27 @c  KEY_UNUSED ok
  28 @c  KEY_USABLE ok
  29 Create a thread-specific data key for the calling thread, referenced by
  30 @var{key}.
  31
  32 Objects declared with the C++11 @code{thread_local} keyword are destroyed
  33 before thread-specific data, so they should not be used in thread-specific
  34 data destructors or even as members of the thread-specific data, since the
  35 latter is passed as an argument to the destructor function.
  36 @end deftypefun
  37
  38 @deftypefun int pthread_key_delete (pthread_key_t @var{key})
  39 @standards{POSIX, pthread.h}
  40 @safety{@prelim{}@mtsafe{}@assafe{}@acsafe{}}
  41 @c pthread_key_delete ok
  42 @c   This uses atomic compare and exchange to increment the seq number
  43 @c   after testing it's not a KEY_UNUSED seq number.
  44 @c  KEY_UNUSED dup ok
  45 Destroy the thread-specific data @var{key} in the calling thread.  The
  46 destructor for the thread-specific data is not called during destruction, nor
  47 is it called during thread exit.
  48 @end deftypefun
  49
  50 @deftypefun void *pthread_getspecific (pthread_key_t @var{key})
  51 @standards{POSIX, pthread.h}
  52 @safety{@prelim{}@mtsafe{}@assafe{}@acsafe{}}
  53 @c pthread_getspecific ok
  54 Return the thread-specific data associated with @var{key} in the calling
  55 thread.
  56 @end deftypefun
  57
  58 @deftypefun int pthread_setspecific (pthread_key_t @var{key}, const void *@var{value})
  59 @standards{POSIX, pthread.h}
  60 @safety{@prelim{}@mtsafe{}@asunsafe{@asucorrupt{} @ascuheap{}}@acunsafe{@acucorrupt{} @acsmem{}}}
  61 @c pthread_setspecific @asucorrupt @ascuheap @acucorrupt @acsmem
  62 @c   a level2 block may be allocated by a signal handler after
  63 @c   another call already made a decision to allocate it, thus losing
  64 @c   the allocated value.  the seq number is updated before the
  65 @c   value, which might cause an earlier-generation value to seem
  66 @c   current if setspecific is cancelled or interrupted by a signal
  67 @c  KEY_UNUSED ok
  68 @c  calloc dup @ascuheap @acsmem
  69 Associate the thread-specific @var{value} with @var{key} in the calling thread.
  70 @end deftypefun
  71
  72
  73 @node Non-POSIX Extensions
  74 @section Non-POSIX Extensions
  75
  76 In addition to implementing the POSIX API for threads, @theglibc{} provides
  77 additional functions and interfaces to provide functionality not specified in
  78 the standard.
  79
  80 @menu
  81 * Default Thread Attributes::             Setting default attributes for
  82                                           threads in a process.
  83 @end menu
  84
  85 @node Default Thread Attributes
  86 @subsection Setting Process-wide defaults for thread attributes
  87
  88 @Theglibc{} provides non-standard API functions to set and get the default
  89 attributes used in the creation of threads in a process.
  90
  91 @deftypefun int pthread_getattr_default_np (pthread_attr_t *@var{attr})
  92 @standards{GNU, pthread.h}
  93 @safety{@prelim{}@mtsafe{}@asunsafe{@asulock{}}@acunsafe{@aculock{}}}
  94 @c Takes lock around read from default_pthread_attr.
  95 Get the default attribute values and set @var{attr} to match.  This
  96 function returns @math{0} on success and a non-zero error code on
  97 failure.
  98 @end deftypefun
  99
 100 @deftypefun int pthread_setattr_default_np (pthread_attr_t *@var{attr})
 101 @standards{GNU, pthread.h}
 102 @safety{@prelim{}@mtsafe{}@asunsafe{@ascuheap{} @asulock{}}@acunsafe{@aculock{} @acsmem{}}}
 103 @c pthread_setattr_default_np @ascuheap @asulock @aculock @acsmem
 104 @c  check_sched_policy_attr ok
 105 @c  check_sched_priority_attr ok
 106 @c   sched_get_priority_min dup ok
 107 @c   sched_get_priority_max dup ok
 108 @c  check_stacksize_attr ok
 109 @c  lll_lock @asulock @aculock
 110 @c  free dup @ascuheap @acsmem
 111 @c  realloc dup @ascuheap @acsmem
 112 @c  memcpy dup ok
 113 @c  lll_unlock @asulock @aculock
 114 Set the default attribute values to match the values in @var{attr}.  The
 115 function returns @math{0} on success and a non-zero error code on failure.
 116 The following error codes are defined for this function:
 117
 118 @table @code
 119 @item EINVAL
 120 At least one of the values in @var{attr} does not qualify as valid for the
 121 attributes or the stack address is set in the attribute.
 122 @item ENOMEM
 123 The system does not have sufficient memory.
 124 @end table
 125 @end deftypefun
 126
 127 @c FIXME these are undocumented:
 128 @c pthread_atfork
 129 @c pthread_attr_destroy
 130 @c pthread_attr_getaffinity_np
 131 @c pthread_attr_getdetachstate
 132 @c pthread_attr_getguardsize
 133 @c pthread_attr_getinheritsched
 134 @c pthread_attr_getschedparam
 135 @c pthread_attr_getschedpolicy
 136 @c pthread_attr_getscope
 137 @c pthread_attr_getstack
 138 @c pthread_attr_getstackaddr
 139 @c pthread_attr_getstacksize
 140 @c pthread_attr_init
 141 @c pthread_attr_setaffinity_np
 142 @c pthread_attr_setdetachstate
 143 @c pthread_attr_setguardsize
 144 @c pthread_attr_setinheritsched
 145 @c pthread_attr_setschedparam
 146 @c pthread_attr_setschedpolicy
 147 @c pthread_attr_setscope
 148 @c pthread_attr_setstack
 149 @c pthread_attr_setstackaddr
 150 @c pthread_attr_setstacksize
 151 @c pthread_barrierattr_destroy
 152 @c pthread_barrierattr_getpshared
 153 @c pthread_barrierattr_init
 154 @c pthread_barrierattr_setpshared
 155 @c pthread_barrier_destroy
 156 @c pthread_barrier_init
 157 @c pthread_barrier_wait
 158 @c pthread_cancel
 159 @c pthread_cleanup_push
 160 @c pthread_cleanup_pop
 161 @c pthread_condattr_destroy
 162 @c pthread_condattr_getclock
 163 @c pthread_condattr_getpshared
 164 @c pthread_condattr_init
 165 @c pthread_condattr_setclock
 166 @c pthread_condattr_setpshared
 167 @c pthread_cond_broadcast
 168 @c pthread_cond_destroy
 169 @c pthread_cond_init
 170 @c pthread_cond_signal
 171 @c pthread_cond_timedwait
 172 @c pthread_cond_wait
 173 @c pthread_create
 174 @c pthread_detach
 175 @c pthread_equal
 176 @c pthread_exit
 177 @c pthread_getaffinity_np
 178 @c pthread_getattr_np
 179 @c pthread_getconcurrency
 180 @c pthread_getcpuclockid
 181 @c pthread_getname_np
 182 @c pthread_getschedparam
 183 @c pthread_join
 184 @c pthread_kill
 185 @c pthread_kill_other_threads_np
 186 @c pthread_mutexattr_destroy
 187 @c pthread_mutexattr_getkind_np
 188 @c pthread_mutexattr_getprioceiling
 189 @c pthread_mutexattr_getprotocol
 190 @c pthread_mutexattr_getpshared
 191 @c pthread_mutexattr_getrobust
 192 @c pthread_mutexattr_getrobust_np
 193 @c pthread_mutexattr_gettype
 194 @c pthread_mutexattr_init
 195 @c pthread_mutexattr_setkind_np
 196 @c pthread_mutexattr_setprioceiling
 197 @c pthread_mutexattr_setprotocol
 198 @c pthread_mutexattr_setpshared
 199 @c pthread_mutexattr_setrobust
 200 @c pthread_mutexattr_setrobust_np
 201 @c pthread_mutexattr_settype
 202 @c pthread_mutex_consistent
 203 @c pthread_mutex_consistent_np
 204 @c pthread_mutex_destroy
 205 @c pthread_mutex_getprioceiling
 206 @c pthread_mutex_init
 207 @c pthread_mutex_lock
 208 @c pthread_mutex_setprioceiling
 209 @c pthread_mutex_timedlock
 210 @c pthread_mutex_trylock
 211 @c pthread_mutex_unlock
 212 @c pthread_once
 213 @c pthread_rwlockattr_destroy
 214 @c pthread_rwlockattr_getkind_np
 215 @c pthread_rwlockattr_getpshared
 216 @c pthread_rwlockattr_init
 217 @c pthread_rwlockattr_setkind_np
 218 @c pthread_rwlockattr_setpshared
 219 @c pthread_rwlock_destroy
 220 @c pthread_rwlock_init
 221 @c pthread_rwlock_rdlock
 222 @c pthread_rwlock_timedrdlock
 223 @c pthread_rwlock_timedwrlock
 224 @c pthread_rwlock_tryrdlock
 225 @c pthread_rwlock_trywrlock
 226 @c pthread_rwlock_unlock
 227 @c pthread_rwlock_wrlock
 228 @c pthread_self
 229 @c pthread_setaffinity_np
 230 @c pthread_setcancelstate
 231 @c pthread_setcanceltype
 232 @c pthread_setconcurrency
 233 @c pthread_setname_np
 234 @c pthread_setschedparam
 235 @c pthread_setschedprio
 236 @c pthread_sigmask
 237 @c pthread_sigqueue
 238 @c pthread_spin_destroy
 239 @c pthread_spin_init
 240 @c pthread_spin_lock
 241 @c pthread_spin_trylock
 242 @c pthread_spin_unlock
 243 @c pthread_testcancel
 244 @c pthread_timedjoin_np
 245 @c pthread_tryjoin_np
 246 @c pthread_yield