TimerInfo(), TimerInfo_r()

Get information about a timer

Synopsis:

#include <sys/neutrino.h>

int TimerInfo( pid_t pid,
               timer_t id,
               int flags,
               struct _timer_info* info );

int TimerInfo_r( pid_t pid,
                 timer_t id,
                 int flags,
                 struct _timer_info* info );

Arguments:

pid

The process ID that you're requesting the timer information for.

id

The ID of the timer, as returned by TimerCreate().

flags

Supported flags are:

• _NTO_TIMER_SEARCH — if this flag is specified and the timer ID doesn't exist, return information on the next timer ID. This provides a mechanism to discover all of the timers in the process.
• _NTO_TIMER_RESET_OVERRUNS — reset the timer's overrun count to zero.

info

A pointer to a _timer_info structure where the function can store the information about the specified timer. For more details, see “struct _timer_info,” below.

You can pass NULL for this argument if the only bit set in flags is _NTO_TIMER_RESET_OVERRUNS.

Library:

libc

Use the -l c option to qcc to link against this library. This library is usually included automatically.

Description:

These kernel calls get information about a previously created timer specified by id, and stores the information in the buffer pointed to by info.

The TimerInfo() and TimerInfo_r() functions are identical except in the way they indicate errors. See the Returns section for details.

---

Instead of using these kernel calls directly, consider calling timer_getexpstatus(), timer_getoverrun(), or timer_gettime(). There's no generic way to query when a timer was activated. However, you can determine the activation time by reading the timer information after activation ( TimerSettime()() activates the timer) but before the first time the timer is fired, and then subtract the known initial interval (that is, for TimerSettime()(), the value of struct _itimer nsec).

---

struct _timer_info

The _timer_info structure pointed to by info contains at least these members:

uint32_t flags

One or more of these bits:

_NTO_TI_ABSOLUTE

The timer is waiting for an absolute time to occur; otherwise, the timer is relative.

_NTO_TI_ACTIVE

The timer is active.

_NTO_TI_EXPIRED

The timer has expired.

_NTO_TI_TARGET_PROCESS

The timer targets the process, not a specific thread.

_NTO_TI_TOD_BASED

The timer the timer is based relative to the beginning of the Epoch (January 1, 1970, 00:00:00 GMT); otherwise, it's relative to the time that QNX Neutrino was started on the machine (see the system page qtime boot_time member).

int32_t tid

The thread to which the timer is directed (0 if it's directed to the process).

int32_t notify

The bottom 16 bits are the value of sigev_notify for the associated sigevent. The other bits are used internally.

clockid_t clockid

The type of clock used.

uint32_t overruns

The number of overruns.

struct sigevent event

The event dispatched when the timer expires.

struct _itimer itime

A struct _itimer with the following fields:

uint64_t nsec

When the timer is next scheduled to fire.

uint64_t interval_nsec

The timer's interval.

struct _itimer otime

Time remaining before the timer expires.

For more information, see the description of TimerCreate().

Blocking states

These calls don't block.

Returns:

The ID of the timer that the information is for. If an error occurs:

• TimerInfo() returns -1 and sets errno.
• TimerInfo_r() returns the negative of a value from the Errors section and doesn't set errno.

Errors:

EINVAL

The timer specified by id doesn't exist.

ESRCH

The process specified by pid doesn't exist.

Classification:

QNX Neutrino

See also:

sigevent, timer_getexpstatus(), timer_getoverrun(), timer_gettime(), TimerCreate()

Clocks, Timers, and Getting a Kick Every So Often chapter of Getting Started with QNX Neutrino

Tick, Tock: Understanding the Neutrino Microkernel's Concept of Time chapter of the QNX Neutrino Programmer's Guide