---
name: "iv_timer"
section: "3"
platform: "linux"
package: "libivykis-dev"
version: "0.43.2-1+b1"
release: "Debian 13 (Trixie)"
platforms: ["linux"]
url: "https://new.carta.tech/iv_timer"
---

# iv\_timer(3)

deal with ivykis timers

## NAME

iv\_timer\_register, iv\_timer\_unregister, iv\_timer\_registered - deal with ivykis timers

## SYNOPSIS

**#include \<iv.h\>**

```
struct iv_timer {
        struct timespec         expires;
        void                    *cookie;
        void                    (*handler)(void *);
};
```

**void IV\_TIMER\_INIT(struct iv\_timer \****timer***);**\
 **void iv\_timer\_register(struct iv\_timer \****timer***);**\
 **void iv\_timer\_unregister(struct iv\_timer \****timer***);**\
 **int iv\_timer\_registered(const struct iv\_timer \****timer***);**\

## DESCRIPTION

The functions **iv\_timer\_register** and **iv\_timer\_unregister** register, respectively unregister, a timer with the current thread's ivykis event loop. **iv\_timer\_registered** on a timer returns true if that timer is currently registered with ivykis.

When a timer that is registered becomes 'ready', due to the current system clock value becoming greater than or equal to the timer's **-\>expires** member field, the callback function specified by **-\>handler** is called in the thread that the timer was registered in, with **-\>cookie** as its first and sole argument.  When this happens, the timer is transparently unregistered.

The application is allowed to change the **-\>cookie** and **-\>handler** members at any time.  The application is not allowed to change the **-\>expires** member while the timer is registered.

A given **struct iv\_timer** can only be registered in one thread at a time, and a timer can only be unregistered in the thread that it was registered from.

There is no limit on the number of timers registered at once.

See [**iv\_examples**(3)](/iv_examples/3.md) for programming examples.

## SEE ALSO

[**ivykis**(3)](/ivykis/3.md), [**iv\_examples**(3)](/iv_examples/3.md)