'\" t .TH "SD_EVENT_ADD_TIME" "3" "" "systemd 219" "sd_event_add_time" .\" ----------------------------------------------------------------- .\" * 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_add_time, sd_event_source_get_time, sd_event_source_set_time, sd_event_source_get_time_accuracy, sd_event_source_set_time_accuracy, sd_event_source_get_time_clock \- Add a timer event source to an event loop .SH "SYNOPSIS" .sp .ft B .nf #include .fi .ft .HP \w'int\ sd_event_add_time('u .BI "int sd_event_add_time(sd_event\ *" "event" ", sd_event_source\ **" "source" ", clockid_t\ " "clock" ", uint64_t\ " "usec" ", uint64_t\ " "accuracy" ", sd_event_time_handler_t\ " "handler" ", void\ *" "userdata" ");" .HP \w'typedef\ int\ (*sd_event_time_handler_t)('u .BI "typedef int (*sd_event_time_handler_t)(sd_event_source\ *" "s" ", uint64_t\ " "usec" ", void\ *" "userdata" ");" .HP \w'int\ sd_event_source_get_time('u .BI "int sd_event_source_get_time(sd_event_source\ *" "source" ", usec_t\ *" "usec" ");" .HP \w'int\ sd_event_source_set_time('u .BI "int sd_event_source_set_time(sd_event_source\ *" "source" ", usec_t\ " "usec" ");" .HP \w'int\ sd_event_source_get_time_accuracy('u .BI "int sd_event_source_get_time_accuracy(sd_event_source\ *" "source" ", usec_t\ *" "usec" ");" .HP \w'int\ sd_event_source_set_time_accuracy('u .BI "int sd_event_source_set_time_accuracy(sd_event_source\ *" "source" ", usec_t\ " "usec" ");" .HP \w'int\ sd_event_source_get_time_clock('u .BI "int sd_event_source_get_time_clock(sd_event_source\ *" "source" ", clockid_t\ *" "clock" ");" .SH "DESCRIPTION" .PP \fBsd_event_add_time()\fR adds a new timer event source to an event loop object\&. The event loop is specified in \fIevent\fR, the event source is returned in the \fIsource\fR parameter\&. The \fIclock\fR parameter takes a clock identifier, one of \fBCLOCK_REALTIME\fR, \fBCLOCK_MONOTONIC\fR and \fBCLOCK_BOOTTIME_ALARM\fR\&. See \fBtimerfd_create\fR(2) for details regarding the various types of clocks\&. The \fIusec\fR parameter takes a time value in microseconds, relative to the clock\*(Aqs epoch specifying when the timer shall elapse the earliest\&. The \fIaccuracy\fR parameter takes an additional accuracy value in microseconds specifying a time the timer event may be delayed\&. Specify 0 for selecting the default accuracy (250ms)\&. Specify 1 for most accurate timers\&. Consider specifying 60000000 or larger (1h) for long\-running events that may be delayed substantially\&. Picking higher accuracy values allows the system to coalesce timer events more aggressively, thus improving power efficiency\&. The \fIhandler\fR shall reference a function to call when the timer elapses\&. The handler function will be passed the \fIuserdata\fR pointer, which may be chosen freely by the caller\&. The handler is also passed the configured time it was triggered, however it might actually have been called at a slightly later time, subject to the specified accuracy value, the kernel timer slack (see \fBprctl\fR(2)) and additional scheduling latencies\&. .PP By default, the timer will elapse once (\fBSD_EVENT_ONESHOT\fR), but this may be changed with \fBsd_event_source_set_enabled\fR(3)\&. If the handler function returns a negative error code, it will be disabled after the invocation, even if \fBSD_EVENT_ON\fR mode is set\&. .PP \fBsd_event_source_get_time()\fR retrieves the configured time value of a timer event source created previously with \fBsd_event_add_time()\fR\&. It takes the event source object and a pointer to a variable to store the time in microseconds in\&. .PP \fBsd_event_source_set_time()\fR changes the configured time value of a timer event source created previously with \fBsd_event_add_time()\fR\&. It takes the event source object and a time relative to the selected clock\*(Aqs epoch, in microseconds\&. .PP \fBsd_event_source_get_time_accuracy()\fR retrieves the configured accuracy value of a timer event source created previously with \fBsd_event_add_time()\fR\&. It takes the event source object and a pointer to a variable to store the accuracy in microseconds in\&. .PP \fBsd_event_source_set_time_accuracy()\fR changes the configured accuracy of a timer event source created previously with \fBsd_event_add_time()\fR\&. It takes the event source object and an accuracy, in microseconds\&. .PP \fBsd_event_source_get_time_clock()\fR retrieves the configured clock of a timer event source created previously with \fBsd_event_add_time()\fR\&. It takes the event source object and a pointer to a variable to store the clock identifier in\&. .SH "RETURN VALUE" .PP On success, these functions return 0 or a positive integer\&. On failure, they return a negative errno\-style error code\&. .SH "ERRORS" .PP Returned errors may indicate the following problems: .PP \fB\-ENOMEM\fR .RS 4 Not enough memory to allocate an object\&. .RE .PP \fB\-EINVAL\fR .RS 4 An invalid argument has been passed\&. .RE .PP \fB\-ESTALE\fR .RS 4 The event loop is already terminated\&. .RE .PP \fB\-ECHILD\fR .RS 4 The event loop has been created in a different process\&. .RE .PP \fB\-ENOTSUP\fR .RS 4 The selected clock is not supported by the event loop implementation\&. .RE .SH "NOTES" .PP \fBsd_event_add_time()\fR and the other functions described here are available as a shared library, which can be compiled and linked to with the \fBlibsystemd\fR\ \&\fBpkg-config\fR(1) file\&. .SH "SEE ALSO" .PP \fBsystemd\fR(1), \fBsd-event\fR(3), \fBsd_event_new\fR(3), \fBsd_event_add_signal\fR(3), \fBsd_event_add_child\fR(3), \fBsd_event_add_defer\fR(3), \fBclock_gettime\fR(2), \fBsd_event_source_set_enabled\fR(3)