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Marc Alexander Lehmann 2007-12-07 16:49:49 +00:00
parent 9d22d620d3
commit 0873426345
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66
ev.3
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@ -129,7 +129,7 @@
.\" ========================================================================
.\"
.IX Title ""<STANDARD INPUT>" 1"
.TH "<STANDARD INPUT>" 1 "2007-11-29" "perl v5.8.8" "User Contributed Perl Documentation"
.TH "<STANDARD INPUT>" 1 "2007-12-07" "perl v5.8.8" "User Contributed Perl Documentation"
.SH "NAME"
libev \- a high performance full\-featured event loop written in C
.SH "SYNOPSIS"
@ -422,7 +422,7 @@ enabling this flag.
.Sp
This works by calling \f(CW\*(C`getpid ()\*(C'\fR on every iteration of the loop,
and thus this might slow down your event loop if you do a lot of loop
iterations and little real work, but is usually not noticable (on my
iterations and little real work, but is usually not noticeable (on my
Linux system for example, \f(CW\*(C`getpid\*(C'\fR is actually a simple 5\-insn sequence
without a syscall and thus \fIvery\fR fast, but my Linux system also has
\&\f(CW\*(C`pthread_atfork\*(C'\fR which is even faster).
@ -583,6 +583,15 @@ do not need to care.
Like \f(CW\*(C`ev_default_fork\*(C'\fR, but acts on an event loop created by
\&\f(CW\*(C`ev_loop_new\*(C'\fR. Yes, you have to call this on every allocated event loop
after fork, and how you do this is entirely your own problem.
.IP "unsigned int ev_loop_count (loop)" 4
.IX Item "unsigned int ev_loop_count (loop)"
Returns the count of loop iterations for the loop, which is identical to
the number of times libev did poll for new events. It starts at \f(CW0\fR and
happily wraps around with enough iterations.
.Sp
This value can sometimes be useful as a generation counter of sorts (it
\&\*(L"ticks\*(R" the number of loop iterations), as it roughly corresponds with
\&\f(CW\*(C`ev_prepare\*(C'\fR and \f(CW\*(C`ev_check\*(C'\fR calls.
.IP "unsigned int ev_backend (loop)" 4
.IX Item "unsigned int ev_backend (loop)"
Returns one of the \f(CW\*(C`EVBACKEND_*\*(C'\fR flags indicating the event backend in
@ -887,6 +896,32 @@ Returns the callback currently set on the watcher.
.IX Item "ev_cb_set (ev_TYPE *watcher, callback)"
Change the callback. You can change the callback at virtually any time
(modulo threads).
.IP "ev_set_priority (ev_TYPE *watcher, priority)" 4
.IX Item "ev_set_priority (ev_TYPE *watcher, priority)"
.PD 0
.IP "int ev_priority (ev_TYPE *watcher)" 4
.IX Item "int ev_priority (ev_TYPE *watcher)"
.PD
Set and query the priority of the watcher. The priority is a small
integer between \f(CW\*(C`EV_MAXPRI\*(C'\fR (default: \f(CW2\fR) and \f(CW\*(C`EV_MINPRI\*(C'\fR
(default: \f(CW\*(C`\-2\*(C'\fR). Pending watchers with higher priority will be invoked
before watchers with lower priority, but priority will not keep watchers
from being executed (except for \f(CW\*(C`ev_idle\*(C'\fR watchers).
.Sp
This means that priorities are \fIonly\fR used for ordering callback
invocation after new events have been received. This is useful, for
example, to reduce latency after idling, or more often, to bind two
watchers on the same event and make sure one is called first.
.Sp
If you need to suppress invocation when higher priority events are pending
you need to look at \f(CW\*(C`ev_idle\*(C'\fR watchers, which provide this functionality.
.Sp
The default priority used by watchers when no priority has been set is
always \f(CW0\fR, which is supposed to not be too high and not be too low :).
.Sp
Setting a priority outside the range of \f(CW\*(C`EV_MINPRI\*(C'\fR to \f(CW\*(C`EV_MAXPRI\*(C'\fR is
fine, as long as you do not mind that the priority value you query might
or might not have been adjusted to be within valid range.
.Sh "\s-1ASSOCIATING\s0 \s-1CUSTOM\s0 \s-1DATA\s0 \s-1WITH\s0 A \s-1WATCHER\s0"
.IX Subsection "ASSOCIATING CUSTOM DATA WITH A WATCHER"
Each watcher has, by default, a member \f(CW\*(C`void *data\*(C'\fR that you can change
@ -1501,13 +1536,16 @@ Example: Watch \f(CW\*(C`/etc/passwd\*(C'\fR for attribute changes.
.ie n .Sh """ev_idle"" \- when you've got nothing better to do..."
.el .Sh "\f(CWev_idle\fP \- when you've got nothing better to do..."
.IX Subsection "ev_idle - when you've got nothing better to do..."
Idle watchers trigger events when there are no other events are pending
(prepare, check and other idle watchers do not count). That is, as long
as your process is busy handling sockets or timeouts (or even signals,
imagine) it will not be triggered. But when your process is idle all idle
watchers are being called again and again, once per event loop iteration \-
until stopped, that is, or your process receives more events and becomes
busy.
Idle watchers trigger events when no other events of the same or higher
priority are pending (prepare, check and other idle watchers do not
count).
.PP
That is, as long as your process is busy handling sockets or timeouts
(or even signals, imagine) of the same or higher priority it will not be
triggered. But when your process is idle (or only lower-priority watchers
are pending), the idle watchers are being called once per event loop
iteration \- until stopped, that is, or your process receives more events
and becomes busy again with higher priority stuff.
.PP
The most noteworthy effect is that as long as any idle watchers are
active, the process will not block when waiting for new events.
@ -1612,12 +1650,13 @@ pseudo-code only of course:
\& }
.Ve
.PP
.Vb 7
.Vb 8
\& // create io watchers for each fd and a timer before blocking
\& static void
\& adns_prepare_cb (ev_loop *loop, ev_prepare *w, int revents)
\& {
\& int timeout = 3600000;truct pollfd fds [nfd];
\& int timeout = 3600000;
\& struct pollfd fds [nfd];
\& // actual code will need to loop here and realloc etc.
\& adns_beforepoll (ads, fds, &nfd, &timeout, timeval_from (ev_time ()));
.Ve
@ -2242,6 +2281,11 @@ argument. Instead, all functions act on the single default loop.
If undefined or defined to be \f(CW1\fR, then periodic timers are supported. If
defined to be \f(CW0\fR, then they are not. Disabling them saves a few kB of
code.
.IP "\s-1EV_IDLE_ENABLE\s0" 4
.IX Item "EV_IDLE_ENABLE"
If undefined or defined to be \f(CW1\fR, then idle watchers are supported. If
defined to be \f(CW0\fR, then they are not. Disabling them saves a few kB of
code.
.IP "\s-1EV_EMBED_ENABLE\s0" 4
.IX Item "EV_EMBED_ENABLE"
If undefined or defined to be \f(CW1\fR, then embed watchers are supported. If

58
ev.html
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@ -6,7 +6,7 @@
<meta name="description" content="Pod documentation for libev" />
<meta name="inputfile" content="&lt;standard input&gt;" />
<meta name="outputfile" content="&lt;standard output&gt;" />
<meta name="created" content="Thu Nov 29 21:05:58 2007" />
<meta name="created" content="Fri Dec 7 17:49:47 2007" />
<meta name="generator" content="Pod::Xhtml 1.57" />
<link rel="stylesheet" href="http://res.tst.eu/pod.css"/></head>
<body>
@ -335,7 +335,7 @@ a fork, you can also make libev check for a fork in each iteration by
enabling this flag.</p>
<p>This works by calling <code>getpid ()</code> on every iteration of the loop,
and thus this might slow down your event loop if you do a lot of loop
iterations and little real work, but is usually not noticable (on my
iterations and little real work, but is usually not noticeable (on my
Linux system for example, <code>getpid</code> is actually a simple 5-insn sequence
without a syscall and thus <i>very</i> fast, but my Linux system also has
<code>pthread_atfork</code> which is even faster).</p>
@ -482,6 +482,15 @@ do not need to care.</p>
<p>Like <code>ev_default_fork</code>, but acts on an event loop created by
<code>ev_loop_new</code>. Yes, you have to call this on every allocated event loop
after fork, and how you do this is entirely your own problem.</p>
</dd>
<dt>unsigned int ev_loop_count (loop)</dt>
<dd>
<p>Returns the count of loop iterations for the loop, which is identical to
the number of times libev did poll for new events. It starts at <code>0</code> and
happily wraps around with enough iterations.</p>
<p>This value can sometimes be useful as a generation counter of sorts (it
&quot;ticks&quot; the number of loop iterations), as it roughly corresponds with
<code>ev_prepare</code> and <code>ev_check</code> calls.</p>
</dd>
<dt>unsigned int ev_backend (loop)</dt>
<dd>
@ -771,6 +780,26 @@ libev (e.g. you cnanot <code>free ()</code> it).</p>
<p>Change the callback. You can change the callback at virtually any time
(modulo threads).</p>
</dd>
<dt>ev_set_priority (ev_TYPE *watcher, priority)</dt>
<dt>int ev_priority (ev_TYPE *watcher)</dt>
<dd>
<p>Set and query the priority of the watcher. The priority is a small
integer between <code>EV_MAXPRI</code> (default: <code>2</code>) and <code>EV_MINPRI</code>
(default: <code>-2</code>). Pending watchers with higher priority will be invoked
before watchers with lower priority, but priority will not keep watchers
from being executed (except for <code>ev_idle</code> watchers).</p>
<p>This means that priorities are <i>only</i> used for ordering callback
invocation after new events have been received. This is useful, for
example, to reduce latency after idling, or more often, to bind two
watchers on the same event and make sure one is called first.</p>
<p>If you need to suppress invocation when higher priority events are pending
you need to look at <code>ev_idle</code> watchers, which provide this functionality.</p>
<p>The default priority used by watchers when no priority has been set is
always <code>0</code>, which is supposed to not be too high and not be too low :).</p>
<p>Setting a priority outside the range of <code>EV_MINPRI</code> to <code>EV_MAXPRI</code> is
fine, as long as you do not mind that the priority value you query might
or might not have been adjusted to be within valid range.</p>
</dd>
</dl>
@ -1360,13 +1389,15 @@ was some error while <code>stat</code>ing the file.</p>
</div>
<h2 id="code_ev_idle_code_when_you_ve_got_no"><code>ev_idle</code> - when you've got nothing better to do...</h2>
<div id="code_ev_idle_code_when_you_ve_got_no-2">
<p>Idle watchers trigger events when there are no other events are pending
(prepare, check and other idle watchers do not count). That is, as long
as your process is busy handling sockets or timeouts (or even signals,
imagine) it will not be triggered. But when your process is idle all idle
watchers are being called again and again, once per event loop iteration -
until stopped, that is, or your process receives more events and becomes
busy.</p>
<p>Idle watchers trigger events when no other events of the same or higher
priority are pending (prepare, check and other idle watchers do not
count).</p>
<p>That is, as long as your process is busy handling sockets or timeouts
(or even signals, imagine) of the same or higher priority it will not be
triggered. But when your process is idle (or only lower-priority watchers
are pending), the idle watchers are being called once per event loop
iteration - until stopped, that is, or your process receives more events
and becomes busy again with higher priority stuff.</p>
<p>The most noteworthy effect is that as long as any idle watchers are
active, the process will not block when waiting for new events.</p>
<p>Apart from keeping your process non-blocking (which is a useful
@ -1466,7 +1497,8 @@ pseudo-code only of course:</p>
static void
adns_prepare_cb (ev_loop *loop, ev_prepare *w, int revents)
{
int timeout = 3600000;truct pollfd fds [nfd];
int timeout = 3600000;
struct pollfd fds [nfd];
// actual code will need to loop here and realloc etc.
adns_beforepoll (ads, fds, &amp;nfd, &amp;timeout, timeval_from (ev_time ()));
@ -2084,6 +2116,12 @@ argument. Instead, all functions act on the single default loop.</p>
<dd>
<p>If undefined or defined to be <code>1</code>, then periodic timers are supported. If
defined to be <code>0</code>, then they are not. Disabling them saves a few kB of
code.</p>
</dd>
<dt>EV_IDLE_ENABLE</dt>
<dd>
<p>If undefined or defined to be <code>1</code>, then idle watchers are supported. If
defined to be <code>0</code>, then they are not. Disabling them saves a few kB of
code.</p>
</dd>
<dt>EV_EMBED_ENABLE</dt>