xref: /freebsd-11-stable/lib/libc/sys/thr_wake.2 (revision 56478d9c1a89440a19e257e547430576d7981e7e)
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31.Dd September 23, 2016
32.Dt THR_WAKE 2
33.Os
34.Sh NAME
35.Nm thr_wake
36.Nd wake up the suspended thread
37.Sh LIBRARY
38.Lb libc
39.Sh SYNOPSIS
40.In sys/thr.h
41.Ft int
42.Fn thr_wake "long id"
43.Sh DESCRIPTION
44.Bf -symbolic
45This function is intended for implementing threading.
46Normal applications should use
47.Xr pthread_cond_timedwait 3
48together with
49.Xr pthread_cond_broadcast 3
50for typical safe suspension with cooperation of the thread
51being suspended, or
52.Xr pthread_suspend_np 3
53and
54.Xr pthread_resume_np 3
55in some specific situations, instead.
56.Ef
57.Pp
58Passing the thread identifier of the calling thread
59.Po
60see
61.Xr thr_self 2
62.Pc
63to
64.Fn thr_wake
65sets a thread's flag to cause the next signal-interruptible sleep
66of that thread in the kernel to fail immediately with the
67.Er EINTR
68error.
69The flag is cleared by an interruptible sleep attempt or by a call to
70.Xr thr_suspend 2 .
71This is used by the system threading library to implement cancellation.
72.Pp
73If
74.Fa id
75is not equal to the current thread identifier, the specified thread is
76woken up if suspended by the
77.Xr thr_suspend
78system call.
79If the thread is not suspended at the time of the
80.Nm
81call, the wake is remembered and the next attempt of the thread to
82suspend itself with the
83.Xr thr_suspend 2
84results in immediate return with success.
85Only one wake is remembered.
86.Sh RETURN VALUES
87.Rv -std thr_wake
88.Sh ERRORS
89The
90.Fn thr_wake
91operation returns these errors:
92.Bl -tag -width Er
93.It Bq Er ESRCH
94The specified thread was not found or does not belong to the process
95of the calling thread.
96.El
97.Sh SEE ALSO
98.Xr ps 1 ,
99.Xr thr_self 2 ,
100.Xr thr_suspend 2 ,
101.Xr pthread_cancel 3 ,
102.Xr pthread_resume_np 3 ,
103.Xr pthread_suspend_np 3
104.Sh STANDARDS
105The
106.Fn thr_suspend
107system call is non-standard and is used by
108.Lb libthr
109to implement
110.St -p1003.1-2001
111.Xr pthread 3
112functionality.
113