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THR_WAKE(2) FreeBSD System Calls Manual THR_WAKE(2)
NAME
thr_wake - wake up the suspended thread
LIBRARY
Standard C Library (libc, -lc)
SYNOPSIS
#include <sys/thr.h>
int
thr_wake(long id);
DESCRIPTION
This function is intended for implementing threading. Normal
applications should use pthread_cond_timedwait(3) together with
pthread_cond_broadcast(3) for typical safe suspension with cooperation of
the thread being suspended, or pthread_suspend_np(3) and
pthread_resume_np(3) in some specific situations, instead.
Passing the thread identifier of the calling thread (see thr_self(2)) to
thr_wake() sets a thread's flag to cause the next signal-interruptible
sleep of that thread in the kernel to fail immediately with the EINTR
error. The flag is cleared by an interruptible sleep attempt or by a
call to thr_suspend(2). This is used by the system threading library to
implement cancellation.
If id is not equal to the current thread identifier, the specified thread
is woken up if suspended by the thr_suspend(2) system call. If the
thread is not suspended at the time of the thr_wake call, the wake is
remembered and the next attempt of the thread to suspend itself with the
thr_suspend(2) results in immediate return with success. Only one wake
is remembered.
RETURN VALUES
The thr_wake() function returns the value 0 if successful; otherwise the
value -1 is returned and the global variable errno is set to indicate the
error.
ERRORS
The thr_wake() operation returns these errors:
[ESRCH] The specified thread was not found or does not belong
to the process of the calling thread.
SEE ALSO
ps(1), thr_self(2), thr_suspend(2), pthread_cancel(3),
pthread_resume_np(3), pthread_suspend_np(3)
STANDARDS
The thr_suspend() system call is non-standard and is used by 1:1
Threading Library (libthr, -lthr) to implement IEEE Std 1003.1-2001
("POSIX.1") pthread(3) functionality.
HISTORY
The thr_suspend() system call first appeared in FreeBSD 5.2.
FreeBSD 14.0-RELEASE-p11 May 5, 2020 FreeBSD 14.0-RELEASE-p11