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@ -129,7 +129,7 @@ |
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.\" ======================================================================== |
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.\" |
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.IX Title "EV 1" |
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.TH EV 1 "2007-12-21" "perl v5.8.8" "User Contributed Perl Documentation" |
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.TH EV 1 "2007-12-22" "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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@ -257,6 +257,11 @@ library in any way. |
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Returns the current time as libev would use it. Please note that the |
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\&\f(CW\*(C`ev_now\*(C'\fR function is usually faster and also often returns the timestamp |
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you actually want to know. |
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.IP "void ev_sleep (ev_tstamp interval)" 4 |
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.IX Item "void ev_sleep (ev_tstamp interval)" |
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Sleep for the given interval: The current thread will be blocked until |
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either it is interrupted or the given time interval has passed. Basically |
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this is a subsecond-resolution \f(CW\*(C`sleep ()\*(C'\fR. |
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.IP "int ev_version_major ()" 4 |
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.IX Item "int ev_version_major ()" |
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.PD 0 |
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@ -465,7 +470,7 @@ but it scales phenomenally better. While poll and select usually scale |
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like O(total_fds) where n is the total number of fds (or the highest fd), |
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epoll scales either O(1) or O(active_fds). The epoll design has a number |
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of shortcomings, such as silently dropping events in some hard-to-detect |
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cases and rewuiring a syscall per fd change, no fork support and bad |
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cases and rewiring a syscall per fd change, no fork support and bad |
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support for dup: |
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.Sp |
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While stopping, setting and starting an I/O watcher in the same iteration |
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@ -726,6 +731,41 @@ Example: For some weird reason, unregister the above signal handler again. |
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\& ev_ref (loop); |
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\& ev_signal_stop (loop, &exitsig); |
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.Ve |
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.IP "ev_set_io_collect_interval (ev_tstamp interval)" 4 |
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.IX Item "ev_set_io_collect_interval (ev_tstamp interval)" |
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.PD 0 |
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.IP "ev_set_timeout_collect_interval (ev_tstamp interval)" 4 |
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.IX Item "ev_set_timeout_collect_interval (ev_tstamp interval)" |
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.PD |
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These advanced functions influence the time that libev will spend waiting |
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for events. Both are by default \f(CW0\fR, meaning that libev will try to |
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invoke timer/periodic callbacks and I/O callbacks with minimum latency. |
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.Sp |
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Setting these to a higher value (the \f(CW\*(C`interval\*(C'\fR \fImust\fR be >= \f(CW0\fR) |
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allows libev to delay invocation of I/O and timer/periodic callbacks to |
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increase efficiency of loop iterations. |
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.Sp |
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The background is that sometimes your program runs just fast enough to |
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handle one (or very few) event(s) per loop iteration. While this makes |
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the program responsive, it also wastes a lot of \s-1CPU\s0 time to poll for new |
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events, especially with backends like \f(CW\*(C`select ()\*(C'\fR which have a high |
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overhead for the actual polling but can deliver many events at once. |
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.Sp |
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By setting a higher \fIio collect interval\fR you allow libev to spend more |
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time collecting I/O events, so you can handle more events per iteration, |
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at the cost of increasing latency. Timeouts (both \f(CW\*(C`ev_periodic\*(C'\fR and |
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\&\f(CW\*(C`ev_timer\*(C'\fR) will be not affected. |
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.Sp |
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Likewise, by setting a higher \fItimeout collect interval\fR you allow libev |
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to spend more time collecting timeouts, at the expense of increased |
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latency (the watcher callback will be called later). \f(CW\*(C`ev_io\*(C'\fR watchers |
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will not be affected. |
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.Sp |
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Many programs can usually benefit by setting the io collect interval to |
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a value near \f(CW0.1\fR or so, which is often enough for interactive servers |
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(of course not for games), likewise for timeouts. It usually doesn't make |
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much sense to set it to a lower value than \f(CW0.01\fR, as this approsaches |
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the timing granularity of most systems. |
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.SH "ANATOMY OF A WATCHER" |
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.IX Header "ANATOMY OF A WATCHER" |
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A watcher is a structure that you create and register to record your |
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@ -2503,6 +2543,10 @@ runtime if successful). Otherwise no use of the realtime clock option will |
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be attempted. This effectively replaces \f(CW\*(C`gettimeofday\*(C'\fR by \f(CW\*(C`clock_get |
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(CLOCK_REALTIME, ...)\*(C'\fR and will not normally affect correctness. See the |
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note about libraries in the description of \f(CW\*(C`EV_USE_MONOTONIC\*(C'\fR, though. |
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.IP "\s-1EV_USE_NANOSLEEP\s0" 4 |
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.IX Item "EV_USE_NANOSLEEP" |
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If defined to be \f(CW1\fR, libev will assume that \f(CW\*(C`nanosleep ()\*(C'\fR is available |
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and will use it for delays. Otherwise it will use \f(CW\*(C`select ()\*(C'\fR. |
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.IP "\s-1EV_USE_SELECT\s0" 4 |
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.IX Item "EV_USE_SELECT" |
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If undefined or defined to be \f(CW1\fR, libev will compile in support for the |
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