1SD_EVENT_SOURCE_UNREF(3) sd_event_source_unref SD_EVENT_SOURCE_UNREF(3)
2
6 sd_event_source_unref, sd_event_source_unrefp, sd_event_source_ref,
7 sd_event_source_disable_unref, sd_event_source_disable_unrefp -
8 Increase or decrease event source reference counters
9
11 #include <systemd/sd-event.h>
12 sd_event_source* sd_event_source_unref(sd_event_source *source);
14 void sd_event_source_unrefp(sd_event_source **source);
16 sd_event_source* sd_event_source_ref(sd_event_source *source);
18 sd_event_source*
20 sd_event_source_disable_unref(sd_event_source *source);
21 void sd_event_source_disable_unrefp(sd_event_source **source);
23
25 sd_event_source_unref() may be used to decrement by one the internal
26 reference counter of the event source object specified as source. The
27 reference counter is initially set to one, when the event source is
28 created with calls such as sd_event_add_io(3) or sd_event_add_time(3).
29 When the reference counter reaches zero, the object is detached from
30 the event loop object and destroyed.
31 sd_event_source_unrefp() is similar to sd_event_source_unref() but
33 takes a pointer to a pointer to an sd_event_source object. This call is
34 useful in conjunction with GCC's and LLVM's Clean-up Variable
35 Attribute[1]. Note that this function is defined as inline function.
36 sd_event_source_ref() may be used to increase by one the internal
38 reference counter of the event source object specified as source.
39 sd_event_source_unref(), sd_bus_creds_unrefp() and sd_bus_creds_ref()
41 execute no operation if the passed event source object is NULL.
42 Note that event source objects stay alive and may be dispatched as long
44 as they have a reference counter greater than zero. In order to drop a
45 reference of an event source and make sure the associated event source
46 handler function is not called anymore it is recommended to combine a
47 call of sd_event_source_unref() with a prior call to
48 sd_event_source_set_enabled() with SD_EVENT_OFF or call
49 sd_event_source_disable_unref(), see below.
50 sd_event_source_disable_unref() combines a call to
52 sd_event_source_set_enabled() with SD_EVENT_OFF with
53 sd_event_source_unref(). This ensures that the source is disabled
54 before the local reference to it is lost. The source parameter is
55 allowed to be NULL.
56 sd_event_source_disable_unrefp() is similar to
58 sd_event_source_unrefp(), but in addition disables the source first.
59 This call is useful in conjunction with GCC's and LLVM's Clean-up
60 Variable Attribute[1]. Note that this function is defined as inline
61 function.
62
64 sd_event_source_unref() and sd_event_source_disable_unref() always
65 return NULL. sd_event_source_ref() always returns the event source
66 object passed in.
67
69 Functions described here are available as a shared library, which can
70 be compiled against and linked to with the libsystemd pkg-config(1)
71 file.
72 The code described here uses getenv(3), which is declared to be not
74 multi-thread-safe. This means that the code calling the functions
75 described here must not call setenv(3) from a parallel thread. It is
76 recommended to only do calls to setenv() from an early phase of the
77 program when no other threads have been started.
78
80 sd-event(3), sd_event_add_io(3), sd_event_add_time(3),
81 sd_event_add_signal(3), sd_event_add_child(3), sd_event_add_inotify(3),
82 sd_event_add_defer(3), sd_event_source_set_enabled(3)
83
85 1. Clean-up Variable Attribute
86 https://gcc.gnu.org/onlinedocs/gcc/Common-Variable-Attributes.html
87systemd 254 SD_EVENT_SOURCE_UNREF(3)