'\" t .TH "SD_EVENT_SOURCE_SET_FLOATING" "3" "" "systemd 256.7" "sd_event_source_set_floating" .\" ----------------------------------------------------------------- .\" * Define some portability stuff .\" ----------------------------------------------------------------- .\" ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ .\" http://bugs.debian.org/507673 .\" http://lists.gnu.org/archive/html/groff/2009-02/msg00013.html .\" ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ .ie \n(.g .ds Aq \(aq .el .ds Aq ' .\" ----------------------------------------------------------------- .\" * set default formatting .\" ----------------------------------------------------------------- .\" disable hyphenation .nh .\" disable justification (adjust text to left margin only) .ad l .\" ----------------------------------------------------------------- .\" * MAIN CONTENT STARTS HERE * .\" ----------------------------------------------------------------- .SH "NAME" sd_event_source_set_floating, sd_event_source_get_floating \- Set or retrieve \*(Aqfloating\*(Aq state of event sources .SH "SYNOPSIS" .sp .ft B .nf #include .fi .ft .HP \w'int\ sd_event_source_set_floating('u .BI "int sd_event_source_set_floating(sd_event_source\ *" "source" ", int\ " "floating" ");" .HP \w'int\ sd_event_source_get_floating('u .BI "int sd_event_source_get_floating(sd_event_source\ *" "source" ");" .SH "DESCRIPTION" .PP \fBsd_event_source_set_floating()\fR takes a boolean and sets the \*(Aqfloating\*(Aq state of the specified event source object\&. This is used to change the direction of reference counts for the object and the event loop it is associated with\&. In non\-floating mode, the event source object holds a reference to the event loop object, but not vice versa\&. The creator of the event source object must hold a reference to it as long as the source should exist\&. In floating mode, the event loop holds a reference to the source object, and will decrease the reference count when being freed\&. This means that a reference to the event loop should be held to prevent both from being destroyed\&. .PP Various calls that allocate event source objects (i\&.e\&. \fBsd_event_add_io\fR(3), \fBsd_event_add_time\fR(3) and similar) will automatically set an event source object to \*(Aqfloating\*(Aq mode if the caller passed \fBNULL\fR in the parameter used to return a reference to the event source object\&. Nevertheless, it may be necessary to gain temporary access to the source object, for example to adjust event source properties after allocation (e\&.g\&. its priority or description string)\&. In those cases the object may be created in non\-floating mode, and the returned reference used to adjust the properties, and the object marked as floating afterwards, and the reference in the caller dropped\&. .PP \fBsd_event_source_get_floating()\fR may be used to query the current \*(Aqfloating\*(Aq state of the event source object \fIsource\fR\&. It returns zero if \*(Aqfloating\*(Aq mode is off, positive if it is on\&. .SH "RETURN VALUE" .PP On success, \fBsd_event_source_set_floating()\fR and \fBsd_event_source_get_floating()\fR return a non\-negative integer\&. On failure, they return a negative errno\-style error code\&. .SS "Errors" .PP Returned errors may indicate the following problems: .PP \fB\-EINVAL\fR .RS 4 \fIsource\fR is not a valid pointer to an sd_event_source object\&. .sp Added in version 244\&. .RE .PP \fB\-ECHILD\fR .RS 4 The event loop has been created in a different process, library or module instance\&. .sp Added in version 244\&. .RE .SH "NOTES" .PP Functions described here are available as a shared library, which can be compiled against and linked to with the \fBlibsystemd\fR\ \&\fBpkg-config\fR(1) file\&. .PP The code described here uses \fBgetenv\fR(3), which is declared to be not multi\-thread\-safe\&. This means that the code calling the functions described here must not call \fBsetenv\fR(3) from a parallel thread\&. It is recommended to only do calls to \fBsetenv()\fR from an early phase of the program when no other threads have been started\&. .SH "HISTORY" .PP \fBsd_event_source_set_floating()\fR and \fBsd_event_source_get_floating()\fR were added in version 244\&. .SH "SEE ALSO" .PP \fBsd-event\fR(3), \fBsd_event_add_io\fR(3), \fBsd_event_add_time\fR(3), \fBsd_event_add_signal\fR(3), \fBsd_event_add_child\fR(3), \fBsd_event_add_inotify\fR(3), \fBsd_event_add_defer\fR(3), \fBsd_event_source_set_description\fR(3), \fBsd_event_source_set_priority\fR(3)