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.

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.