sd_event_source_unref

systemd
sd_event_source_unref 3
sd_event_source_unref sd_event_source_unrefp sd_event_source_ref sd_event_source_disable_unref sd_event_source_disable_unrefp Increase or decrease event source reference counters

    #include <systemd/sd-event.h>

sd_event_source* `sd_event_source_unref` sd_event_source *source void `sd_event_source_unrefp` sd_event_source **source sd_event_source* `sd_event_source_ref` sd_event_source *source sd_event_source* `sd_event_source_disable_unref` sd_event_source *source void `sd_event_source_disable_unrefp` sd_event_source **source

## Description

`sd_event_source_unref()` may be used to decrement by one the reference counter of the event source object specified as source. The reference counter is initially set to one, when the event source is created with calls such as sd_event_add_io 3 or sd_event_add_time 3. When the reference counter reaches zero it is removed from its event loop object and destroyed.

`sd_event_source_unrefp()` is similar to `sd_event_source_unref()` but takes a pointer to a pointer to an sd_event_source object. This call is useful in conjunction with GCC's and LLVM's Clean-up Variable Attribute. Note that this function is defined as inline function.

`sd_event_source_ref()` may be used to increase by one the reference counter of the event source object specified as source.

`sd_event_source_unref()`, `sd_bus_creds_unrefp()` and `sd_bus_creds_ref()` execute no operation if the passed event source object is `NULL`.

Note that event source objects stay alive and may be dispatched as long as they have a reference counter greater than zero. In order to drop a reference of an event source and make sure the associated event source handler function is not called anymore it is recommended to combine a call of `sd_event_source_unref()` with a prior call to `sd_event_source_set_enabled()` with `SD_EVENT_OFF` or call `sd_event_source_disable_unref()`, see below.

`sd_event_source_disable_unref()` combines a call to `sd_event_source_set_enabled()` with `SD_EVENT_OFF` with `sd_event_source_unref()`. This ensures that the source is disabled before the local reference to it is lost. The source parameter is allowed to be `NULL`.

`sd_event_source_disable_unrefp()` is similar to `sd_event_source_unrefp()`, but in addition disables the source first. This call is useful in conjunction with GCC's and LLVM's Clean-up Variable Attribute. Note that this function is defined as inline function.

## Return Value

`sd_event_source_unref()` and `sd_event_source_disable_unref()` always return `NULL`. `sd_event_source_ref()` always returns the event source object passed in.

## See Also

sd-event 3, sd_event_add_io 3, sd_event_add_time 3, sd_event_add_signal 3, sd_event_add_child 3, sd_event_add_inotify 3, sd_event_add_defer 3, sd_event_source_set_enabled 3