sd_event_run

systemd
Developer Tom Gundersen teg@jklm.no
sd_event_run 3
sd_event_run sd_event_loop Run an event loop

    #include <systemd/sd-event.h>

int `sd_event_run` sd_event *event uint64_t usec int `sd_event_loop` sd_event *event

## Description

`sd_event_run()` may be used to run a single iteration of the event loop specified in the event parameter. The function waits until an event to process is available, and dispatches the registered handler for it. The usec parameter specifies the maximum time (in microseconds) to wait for an event. Use `(uint64_t) -1` to specify an infinite timeout.

`sd_event_loop()` invokes `sd_event_run()` in a loop, thus implementing the actual event loop. The call returns as soon as exiting was requested using sd_event_exit 3.

The event loop object event is created with sd_event_new 3. Events sources to wait for and their handlers may be registered with sd_event_add_io 3, sd_event_add_time 3, sd_event_add_signal 3, sd_event_add_child 3, sd_event_add_defer 3, sd_event_add_post 3 and sd_event_add_exit 3.

For low-level control of event loop execution, use sd_event_prepare 3, sd_event_wait 3 and sd_event_dispatch 3 which are wrapped by `sd_event_run()`. Along with sd_event_get_fd 3, these functions allow integration of an sd-event 3 event loop into foreign event loop implementations.

## Return Value

On failure, these functions return a negative errno-style error code. `sd_event_run()` returns a positive, non-zero integer if an event source was dispatched, and zero when the specified timeout hit before an event source has seen any event, and hence no event source was dispatched. `sd_event_loop()` returns the exit code specified when invoking `sd_event_exit()`.

## Errors

Returned errors may indicate the following problems:

`-EINVAL`

  The event parameter is invalid or `NULL`.

`-EBUSY`

  The event loop object is not in the right state (see sd_event_prepare 3 for an explanation of possible states).

`-ESTALE`

  The event loop is already terminated.

`-ECHILD`

  The event loop has been created in a different process.

Other errors are possible, too.

## See Also

systemd 1, sd_event_new 3, sd_event_add_io 3, sd_event_add_time 3, sd_event_add_signal 3, sd_event_add_defer 3, sd_event_add_exit 3, sd_event_add_post 3, sd_event_exit 3, sd_event_get_fd 3, sd_event_wait 3, GLib Main Event Loop.