iv_signal(3) ivykis programmer's manual iv_signal(3)NAME
IV_SIGNAL_INIT, iv_signal_register, iv_signal_unregister - ivykis sig‐
nal handling
SYNOPSIS
#include <iv_signal.h>
struct iv_signal {
int signum;
unsigned int flags;
void *cookie;
void (*handler)(void *);
};
void IV_SIGNAL_INIT(struct iv_signal *this);
int iv_signal_register(struct iv_signal *this);
void iv_signal_unregister(struct iv_signal *this);
DESCRIPTION
iv_signal provides a way for ivykis(3) applications to handle POSIX
signals, by integrating them with the ivykis event loop.
An ivykis application desiring signal notification registers a struct
iv_signal object by calling iv_signal_register, after having ini‐
tialised it with IV_SIGNAL_INIT and subsequently having filled in the
->signum, ->cookie and ->handler members.
Once the signal indicated by ->signum is delivered to any thread in the
current process, the callback specified by ->handler is scheduled to be
called in the thread that the struct iv_signal object was registered
in, with ->cookie as its sole argument.
If the same signal arrives again while the callback function is still
running, the callback function is guaranteed to be called again after
it returns.
It is permitted to register multiple struct iv_signal objects for the
same signal number. If all such objects are registered with IV_SIG‐
NAL_FLAG_EXCLUSIVE in ->flags unset, then all objects will have their
callback functions called upon arrival of the signal, in no guaranteed
order.
Invoking callback functions stops at the first struct iv_signal object
with IV_SIGNAL_FLAG_EXCLUSIVE in ->flags set, so that if all objects
have IV_SIGNAL_FLAG_EXCLUSIVE set, only one callback function will be
invoked.
To deinitialize a struct iv_signal object, call iv_signal_unregister
from the same thread that iv_signal_register was called from on that
object.
It is permitted to unregister a struct iv_signal object from any ivykis
callback function in the thread it was registered in, including from a
callback function triggered by this object, and it is permitted to free
the memory corresponding to an unregistered object from its own call‐
back function.
It is guaranteed that signals delivered to child processes that were
created by fork(2) but that have not yet called execve(2) will not
cause iv_signal callbacks to be invoked in the parent process.
Internally, iv_signal is implemented using iv_event_raw(3).
SEE ALSOivykis(3), iv_event_raw(3), sigaction(2)ivykis 2010-09-03 iv_signal(3)
