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@ -129,7 +129,7 @@
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.\" ========================================================================
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.\"
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.IX Title ""<STANDARD INPUT>" 1"
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.TH "<STANDARD INPUT>" 1 "2007-12-08" "perl v5.8.8" "User Contributed Perl Documentation"
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.TH "<STANDARD INPUT>" 1 "2007-12-09" "perl v5.8.8" "User Contributed Perl Documentation"
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.SH "NAME"
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libev \- a high performance full\-featured event loop written in C
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.SH "SYNOPSIS"
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@ -1237,11 +1237,11 @@ to trigger \*(L"at\*(R" some specific point in time. For example, if you tell a
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periodic watcher to trigger in 10 seconds (by specifiying e.g. \f(CW\*(C`ev_now ()
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+ 10.\*(C'\fR) and then reset your system clock to the last year, then it will
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take a year to trigger the event (unlike an \f(CW\*(C`ev_timer\*(C'\fR, which would trigger
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roughly 10 seconds later and of course not if you reset your system time
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again).
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roughly 10 seconds later).
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.PP
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They can also be used to implement vastly more complex timers, such as
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triggering an event on eahc midnight, local time.
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triggering an event on each midnight, local time or other, complicated,
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rules.
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.PP
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As with timers, the callback is guarenteed to be invoked only when the
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time (\f(CW\*(C`at\*(C'\fR) has been passed, but if multiple periodic timers become ready
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@ -1255,17 +1255,17 @@ during the same loop iteration then order of execution is undefined.
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Lots of arguments, lets sort it out... There are basically three modes of
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operation, and we will explain them from simplest to complex:
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.RS 4
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.IP "* absolute timer (interval = reschedule_cb = 0)" 4
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.IX Item "absolute timer (interval = reschedule_cb = 0)"
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.IP "* absolute timer (at = time, interval = reschedule_cb = 0)" 4
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.IX Item "absolute timer (at = time, interval = reschedule_cb = 0)"
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In this configuration the watcher triggers an event at the wallclock time
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\&\f(CW\*(C`at\*(C'\fR and doesn't repeat. It will not adjust when a time jump occurs,
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that is, if it is to be run at January 1st 2011 then it will run when the
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system time reaches or surpasses this time.
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.IP "* non-repeating interval timer (interval > 0, reschedule_cb = 0)" 4
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.IX Item "non-repeating interval timer (interval > 0, reschedule_cb = 0)"
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.IP "* non-repeating interval timer (at = offset, interval > 0, reschedule_cb = 0)" 4
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.IX Item "non-repeating interval timer (at = offset, interval > 0, reschedule_cb = 0)"
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In this mode the watcher will always be scheduled to time out at the next
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\&\f(CW\*(C`at + N * interval\*(C'\fR time (for some integer N) and then repeat, regardless
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of any time jumps.
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\&\f(CW\*(C`at + N * interval\*(C'\fR time (for some integer N, which can also be negative)
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and then repeat, regardless of any time jumps.
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.Sp
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This can be used to create timers that do not drift with respect to system
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time:
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@ -1282,8 +1282,12 @@ by 3600.
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Another way to think about it (for the mathematically inclined) is that
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\&\f(CW\*(C`ev_periodic\*(C'\fR will try to run the callback in this mode at the next possible
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time where \f(CW\*(C`time = at (mod interval)\*(C'\fR, regardless of any time jumps.
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.IP "* manual reschedule mode (reschedule_cb = callback)" 4
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.IX Item "manual reschedule mode (reschedule_cb = callback)"
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.Sp
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For numerical stability it is preferable that the \f(CW\*(C`at\*(C'\fR value is near
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\&\f(CW\*(C`ev_now ()\*(C'\fR (the current time), but there is no range requirement for
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this value.
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.IP "* manual reschedule mode (at and interval ignored, reschedule_cb = callback)" 4
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.IX Item "manual reschedule mode (at and interval ignored, reschedule_cb = callback)"
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In this mode the values for \f(CW\*(C`interval\*(C'\fR and \f(CW\*(C`at\*(C'\fR are both being
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ignored. Instead, each time the periodic watcher gets scheduled, the
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reschedule callback will be called with the watcher as first, and the
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@ -1292,7 +1296,7 @@ current time as second argument.
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\&\s-1NOTE:\s0 \fIThis callback \s-1MUST\s0 \s-1NOT\s0 stop or destroy any periodic watcher,
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ever, or make any event loop modifications\fR. If you need to stop it,
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return \f(CW\*(C`now + 1e30\*(C'\fR (or so, fudge fudge) and stop it afterwards (e.g. by
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starting a prepare watcher).
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starting an \f(CW\*(C`ev_prepare\*(C'\fR watcher, which is legal).
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.Sp
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Its prototype is \f(CW\*(C`ev_tstamp (*reschedule_cb)(struct ev_periodic *w,
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ev_tstamp now)\*(C'\fR, e.g.:
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@ -1326,6 +1330,13 @@ Simply stops and restarts the periodic watcher again. This is only useful
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when you changed some parameters or the reschedule callback would return
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a different time than the last time it was called (e.g. in a crond like
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program when the crontabs have changed).
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.IP "ev_tstamp offset [read\-write]" 4
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.IX Item "ev_tstamp offset [read-write]"
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When repeating, this contains the offset value, otherwise this is the
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absolute point in time (the \f(CW\*(C`at\*(C'\fR value passed to \f(CW\*(C`ev_periodic_set\*(C'\fR).
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.Sp
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Can be modified any time, but changes only take effect when the periodic
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timer fires or \f(CW\*(C`ev_periodic_again\*(C'\fR is being called.
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.IP "ev_tstamp interval [read\-write]" 4
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.IX Item "ev_tstamp interval [read-write]"
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The current interval value. Can be modified any time, but changes only
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Marc Alexander Lehmann
16 years ago