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103 lines
4.1 KiB
Groff
103 lines
4.1 KiB
Groff
'\" t
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.TH "SD_EVENT_NEW" "3" "" "systemd 219" "sd_event_new"
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.\" -----------------------------------------------------------------
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.\" * Define some portability stuff
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.\" -----------------------------------------------------------------
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.\" ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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.\" http://bugs.debian.org/507673
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.\" http://lists.gnu.org/archive/html/groff/2009-02/msg00013.html
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.\" ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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.ie \n(.g .ds Aq \(aq
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.el .ds Aq '
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.\" -----------------------------------------------------------------
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.\" * set default formatting
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.\" -----------------------------------------------------------------
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.\" disable hyphenation
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.nh
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.\" disable justification (adjust text to left margin only)
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.ad l
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.\" -----------------------------------------------------------------
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.\" * MAIN CONTENT STARTS HERE *
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.\" -----------------------------------------------------------------
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.SH "NAME"
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sd_event_new, sd_event_default, sd_event_ref, sd_event_unref \- Acquire and release an event loop object
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.SH "SYNOPSIS"
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.sp
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.ft B
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.nf
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#include <systemd/sd\-bus\&.h>
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.fi
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.ft
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.HP \w'int\ sd_event_new('u
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.BI "int sd_event_new(sd_bus\ **" "event" ");"
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.HP \w'int\ sd_event_default('u
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.BI "int sd_event_default(sd_bus\ **" "event" ");"
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.HP \w'sd_bus\ *sd_event_ref('u
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.BI "sd_bus *sd_event_ref(sd_bus\ *" "event" ");"
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.HP \w'sd_bus\ *sd_event_unref('u
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.BI "sd_bus *sd_event_unref(sd_bus\ *" "event" ");"
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.SH "DESCRIPTION"
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.PP
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\fBsd_event_new()\fR
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allocates a new event loop object\&. The event loop object is returned in the
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\fIevent\fR
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parameter\&. After use, drop the returned reference with
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\fBsd_event_unref()\fR\&. When the last reference is dropped, the object is freed\&.
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.PP
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\fBsd_event_default()\fR
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acquires a reference to the default event loop object of the calling thread, possibly allocating a new object if no default event loop object has been allocated yet for the thread\&. After use, drop the returned reference with
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\fBsd_event_unref()\fR\&. When the last reference is dropped, the event loop is freed\&. If this function is called while the object returned from a previous call from the same thread is still referenced, the same object is returned again, but the reference is increased by one\&. It is recommended to use this call instead of
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\fBsd_event_new()\fR
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in order to share event loop objects between various components that are dispatched in the same thread\&. All threads have exactly either zero or one default event loop objects associated, but never more\&.
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.PP
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\fBsd_event_ref()\fR
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increases the reference count of the specified event loop object by one\&.
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.PP
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\fBsd_event_unref()\fR
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decreases the reference count of the specified event loop object by one\&. If the count hits zero, the object is freed\&. Note that it is freed regardless of whether it is the default event loop object for a thread or not\&. This means that allocating an event loop with
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\fBsd_event_default()\fR, then releasing it, and then acquiring a new one with
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\fBsd_event_default()\fR
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will result in two distinct objects\&. Note that in order to free an event loop object, all remaining event sources of the event loop also need to be freed as each keeps a reference to it\&.
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.SH "RETURN VALUE"
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.PP
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On success,
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\fBsd_event_new()\fR
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and
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\fBsd_event_default()\fR
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return 0 or a positive integer\&. On failure, they return a negative errno\-style error code\&.
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\fBsd_event_ref()\fR
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always returns a pointer to the event loop object passed in\&.
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\fBsd_event_unref()\fR
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always returns
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\fBNULL\fR\&.
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.SH "ERRORS"
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.PP
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Returned errors may indicate the following problems:
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.PP
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\fB\-ENOMEM\fR
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.RS 4
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Not enough memory to allocate the object\&.
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.RE
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.PP
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\fB\-EMFILE\fR
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.RS 4
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The maximum number of event loops has been allocated\&.
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.RE
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.SH "NOTES"
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.PP
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\fBsd_event_new()\fR
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and the other functions described here are available as a shared library, which can be compiled and linked to with the
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\fBlibsystemd\fR\ \&\fBpkg-config\fR(1)
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file\&.
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.SH "SEE ALSO"
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.PP
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\fBsystemd\fR(1),
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\fBsd-event\fR(3),
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\fBsd_event_add_io\fR(3),
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\fBsd_event_add_time\fR(3),
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\fBsd_event_add_signal\fR(3),
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\fBsd_event_add_child\fR(3),
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\fBsd_event_add_defer\fR(3),
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\fBsd_event_add_post\fR(3),
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\fBsd_event_add_exit\fR(3)
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