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Marc Alexander Lehmann 2007-11-12 08:29:11 +00:00
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68
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="Mon Nov 12 09:20:02 2007" />
<meta name="created" content="Mon Nov 12 09:29:10 2007" />
<meta name="generator" content="Pod::Xhtml 1.57" />
<link rel="stylesheet" href="http://res.tst.eu/pod.css"/></head>
<body>
@ -109,7 +109,7 @@ you linked against by calling the functions <code>ev_version_major</code> and
<code>ev_version_minor</code>. If you want, you can compare against the global
symbols <code>EV_VERSION_MAJOR</code> and <code>EV_VERSION_MINOR</code>, which specify the
version of the library your program was compiled against.</p>
<p>Usually, its a good idea to terminate if the major versions mismatch,
<p>Usually, it's a good idea to terminate if the major versions mismatch,
as this indicates an incompatible change. Minor versions are usually
compatible to older versions, so a larger minor version alone is usually
not a problem.</p>
@ -148,7 +148,7 @@ in your main thread (or in a separate thrad) and for each thread you
create, you also create another event loop. Libev itself does no locking
whatsoever, so if you mix calls to the same event loop in different
threads, make sure you lock (this is usually a bad idea, though, even if
done correctly, because its hideous and inefficient).</p>
done correctly, because it's hideous and inefficient).</p>
<dl>
<dt>struct ev_loop *ev_default_loop (unsigned int flags)</dt>
<dd>
@ -165,7 +165,7 @@ backends to use, and is usually specified as 0 (or EVFLAG_AUTO).</p>
<dl>
<dt>EVFLAG_AUTO</dt>
<dd>
<p>The default flags value. Use this if you have no clue (its the right
<p>The default flags value. Use this if you have no clue (it's the right
thing, believe me).</p>
</dd>
<dt>EVFLAG_NOENV</dt>
@ -177,12 +177,12 @@ override the flags completely if it is found in the environment. This is
useful to try out specific backends to test their performance, or to work
around bugs.</p>
</dd>
<dt>EVMETHOD_SELECT portable select backend</dt>
<dt>EVMETHOD_POLL poll backend (everywhere except windows)</dt>
<dt>EVMETHOD_EPOLL linux only</dt>
<dt>EVMETHOD_KQUEUE some bsds only</dt>
<dt>EVMETHOD_DEVPOLL solaris 8 only</dt>
<dt>EVMETHOD_PORT solaris 10 only</dt>
<dt>EVMETHOD_SELECT (portable select backend)</dt>
<dt>EVMETHOD_POLL (poll backend, available everywhere except on windows)</dt>
<dt>EVMETHOD_EPOLL (linux only)</dt>
<dt>EVMETHOD_KQUEUE (some bsds only)</dt>
<dt>EVMETHOD_DEVPOLL (solaris 8 only)</dt>
<dt>EVMETHOD_PORT (solaris 10 only)</dt>
<dd>
<p>If one or more of these are ored into the flags value, then only these
backends will be tried (in the reverse order as given here). If one are
@ -202,7 +202,7 @@ undefined behaviour (or a failed assertion if assertions are enabled).</p>
<dd>
<p>Destroys the default loop again (frees all memory and kernel state
etc.). This stops all registered event watchers (by not touching them in
any way whatsoever, although you cnanot rely on this :).</p>
any way whatsoever, although you cannot rely on this :).</p>
</dd>
<dt>ev_loop_destroy (loop)</dt>
<dd>
@ -218,7 +218,7 @@ again makes little sense).</p>
<p>You <i>must</i> call this function after forking if and only if you want to
use the event library in both processes. If you just fork+exec, you don't
have to call it.</p>
<p>The function itself is quite fast and its usually not a problem to call
<p>The function itself is quite fast and it's usually not a problem to call
it just in case after a fork. To make this easy, the function will fit in
quite nicely into a call to <code>pthread_atfork</code>:</p>
<pre> pthread_atfork (0, 0, ev_default_fork);
@ -236,7 +236,7 @@ after fork, and how you do this is entirely your own problem.</p>
<p>Returns one of the <code>EVMETHOD_*</code> flags indicating the event backend in
use.</p>
</dd>
<dt>ev_tstamp = ev_now (loop)</dt>
<dt>ev_tstamp ev_now (loop)</dt>
<dd>
<p>Returns the current &quot;event loop time&quot;, which is the time the event loop
got events and started processing them. This timestamp does not change
@ -253,33 +253,35 @@ events.</p>
no event watchers are active anymore or <code>ev_unloop</code> was called.</p>
<p>A flags value of <code>EVLOOP_NONBLOCK</code> will look for new events, will handle
those events and any outstanding ones, but will not block your process in
case there are no events.</p>
case there are no events and will return after one iteration of the loop.</p>
<p>A flags value of <code>EVLOOP_ONESHOT</code> will look for new events (waiting if
neccessary) and will handle those and any outstanding ones. It will block
your process until at least one new event arrives.</p>
your process until at least one new event arrives, and will return after
one iteration of the loop.</p>
<p>This flags value could be used to implement alternative looping
constructs, but the <code>prepare</code> and <code>check</code> watchers provide a better and
more generic mechanism.</p>
</dd>
<dt>ev_unloop (loop, how)</dt>
<dd>
<p>Can be used to make a call to <code>ev_loop</code> return early. The <code>how</code> argument
must be either <code>EVUNLOOP_ONCE</code>, which will make the innermost <code>ev_loop</code>
call return, or <code>EVUNLOOP_ALL</code>, which will make all nested <code>ev_loop</code>
calls return.</p>
<p>Can be used to make a call to <code>ev_loop</code> return early (but only after it
has processed all outstanding events). The <code>how</code> argument must be either
<code>EVUNLOOP_ONCE</code>, which will make the innermost <code>ev_loop</code> call return, or
<code>EVUNLOOP_ALL</code>, which will make all nested <code>ev_loop</code> calls return.</p>
</dd>
<dt>ev_ref (loop)</dt>
<dt>ev_unref (loop)</dt>
<dd>
<p>Ref/unref can be used to add or remove a refcount on the event loop: Every
watcher keeps one reference. If you have a long-runing watcher you never
unregister that should not keep ev_loop from running, ev_unref() after
starting, and ev_ref() before stopping it. Libev itself uses this for
example for its internal signal pipe: It is not visible to you as a user
and should not keep <code>ev_loop</code> from exiting if the work is done. It is
also an excellent way to do this for generic recurring timers or from
within third-party libraries. Just remember to unref after start and ref
before stop.</p>
<p>Ref/unref can be used to add or remove a reference count on the event
loop: Every watcher keeps one reference, and as long as the reference
count is nonzero, <code>ev_loop</code> will not return on its own. If you have
a watcher you never unregister that should not keep <code>ev_loop</code> from
returning, ev_unref() after starting, and ev_ref() before stopping it. For
example, libev itself uses this for its internal signal pipe: It is not
visible to the libev user and should not keep <code>ev_loop</code> from exiting if
no event watchers registered by it are active. It is also an excellent
way to do this for generic recurring timers or from within third-party
libraries. Just remember to <i>unref after start</i> and <i>ref before stop</i>.</p>
</dd>
</dl>
@ -464,6 +466,14 @@ times out after an hour and youreset your system clock to last years
time, it will still time out after (roughly) and hour. &quot;Roughly&quot; because
detecting time jumps is hard, and soem inaccuracies are unavoidable (the
monotonic clock option helps a lot here).</p>
<p>The relative timeouts are calculated relative to the <code>ev_now ()</code>
time. This is usually the right thing as this timestamp refers to the time
of the event triggering whatever timeout you are modifying/starting. If
you suspect event processing to be delayed and you *need* to base the timeout
ion the current time, use something like this to adjust for this:</p>
<pre> ev_timer_set (&amp;timer, after + ev_now () - ev_time (), 0.);
</pre>
<dl>
<dt>ev_timer_init (ev_timer *, callback, ev_tstamp after, ev_tstamp repeat)</dt>
<dt>ev_timer_set (ev_timer *, ev_tstamp after, ev_tstamp repeat)</dt>
@ -591,7 +601,7 @@ program when the crontabs have changed).</p>
<div id="ev_signal_signal_me_when_a_signal_ge-2">
<p>Signal watchers will trigger an event when the process receives a specific
signal one or more times. Even though signals are very asynchronous, libev
will try its best to deliver signals synchronously, i.e. as part of the
will try it's best to deliver signals synchronously, i.e. as part of the
normal event processing, like any other event.</p>
<p>You cna configure as many watchers as you like per signal. Only when the
first watcher gets started will libev actually register a signal watcher

90
ev.pod
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@ -126,12 +126,12 @@ It supports the following flags:
=over 4
=item EVFLAG_AUTO
=item C<EVFLAG_AUTO>
The default flags value. Use this if you have no clue (it's the right
thing, believe me).
=item EVFLAG_NOENV
=item C<EVFLAG_NOENV>
If this flag bit is ored into the flag value (or the program runs setuid
or setgid) then libev will I<not> look at the environment variable
@ -140,17 +140,17 @@ override the flags completely if it is found in the environment. This is
useful to try out specific backends to test their performance, or to work
around bugs.
=item EVMETHOD_SELECT (portable select backend)
=item C<EVMETHOD_SELECT> (portable select backend)
=item EVMETHOD_POLL (poll backend, available everywhere except on windows)
=item C<EVMETHOD_POLL> (poll backend, available everywhere except on windows)
=item EVMETHOD_EPOLL (linux only)
=item C<EVMETHOD_EPOLL> (linux only)
=item EVMETHOD_KQUEUE (some bsds only)
=item C<EVMETHOD_KQUEUE> (some bsds only)
=item EVMETHOD_DEVPOLL (solaris 8 only)
=item C<EVMETHOD_DEVPOLL> (solaris 8 only)
=item EVMETHOD_PORT (solaris 10 only)
=item C<EVMETHOD_PORT> (solaris 10 only)
If one or more of these are ored into the flags value, then only these
backends will be tried (in the reverse order as given here). If one are
@ -262,7 +262,7 @@ libraries. Just remember to I<unref after start> and I<ref before stop>.
A watcher is a structure that you create and register to record your
interest in some event. For instance, if you want to wait for STDIN to
become readable, you would create an ev_io watcher for that:
become readable, you would create an C<ev_io> watcher for that:
static void my_cb (struct ev_loop *loop, struct ev_io *w, int revents)
{
@ -316,46 +316,46 @@ are:
=over 4
=item EV_READ
=item C<EV_READ>
=item EV_WRITE
=item C<EV_WRITE>
The file descriptor in the ev_io watcher has become readable and/or
The file descriptor in the C<ev_io> watcher has become readable and/or
writable.
=item EV_TIMEOUT
=item C<EV_TIMEOUT>
The ev_timer watcher has timed out.
The C<ev_timer> watcher has timed out.
=item EV_PERIODIC
=item C<EV_PERIODIC>
The ev_periodic watcher has timed out.
The C<ev_periodic> watcher has timed out.
=item EV_SIGNAL
=item C<EV_SIGNAL>
The signal specified in the ev_signal watcher has been received by a thread.
The signal specified in the C<ev_signal> watcher has been received by a thread.
=item EV_CHILD
=item C<EV_CHILD>
The pid specified in the ev_child watcher has received a status change.
The pid specified in the C<ev_child> watcher has received a status change.
=item EV_IDLE
=item C<EV_IDLE>
The ev_idle watcher has determined that you have nothing better to do.
The C<ev_idle> watcher has determined that you have nothing better to do.
=item EV_PREPARE
=item C<EV_PREPARE>
=item EV_CHECK
=item C<EV_CHECK>
All ev_prepare watchers are invoked just I<before> C<ev_loop> starts
to gather new events, and all ev_check watchers are invoked just after
All C<ev_prepare> watchers are invoked just I<before> C<ev_loop> starts
to gather new events, and all C<ev_check> watchers are invoked just after
C<ev_loop> has gathered them, but before it invokes any callbacks for any
received events. Callbacks of both watcher types can start and stop as
many watchers as they want, and all of them will be taken into account
(for example, a ev_prepare watcher might start an idle watcher to keep
(for example, a C<ev_prepare> watcher might start an idle watcher to keep
C<ev_loop> from blocking).
=item EV_ERROR
=item C<EV_ERROR>
An unspecified error has occured, the watcher has been stopped. This might
happen because the watcher could not be properly started because libev
@ -406,7 +406,7 @@ have been omitted....
This section describes each watcher in detail, but will not repeat
information given in the last section.
=head2 struct ev_io - is my file descriptor readable or writable
=head2 C<ev_io> - is this file descriptor readable or writable
I/O watchers check whether a file descriptor is readable or writable
in each iteration of the event loop (This behaviour is called
@ -434,13 +434,13 @@ EVMETHOD_POLL).
=item ev_io_set (ev_io *, int fd, int events)
Configures an ev_io watcher. The fd is the file descriptor to rceeive
Configures an C<ev_io> watcher. The fd is the file descriptor to rceeive
events for and events is either C<EV_READ>, C<EV_WRITE> or C<EV_READ |
EV_WRITE> to receive the given events.
=back
=head2 struct ev_timer - relative and optionally recurring timeouts
=head2 C<ev_timer> - relative and optionally recurring timeouts
Timer watchers are simple relative timers that generate an event after a
given time, and optionally repeating in regular intervals after that.
@ -490,24 +490,24 @@ This sounds a bit complicated, but here is a useful and typical
example: Imagine you have a tcp connection and you want a so-called idle
timeout, that is, you want to be called when there have been, say, 60
seconds of inactivity on the socket. The easiest way to do this is to
configure an ev_timer with after=repeat=60 and calling ev_timer_again each
configure an C<ev_timer> with after=repeat=60 and calling ev_timer_again each
time you successfully read or write some data. If you go into an idle
state where you do not expect data to travel on the socket, you can stop
the timer, and again will automatically restart it if need be.
=back
=head2 ev_periodic - to cron or not to cron it
=head2 C<ev_periodic> - to cron or not to cron it
Periodic watchers are also timers of a kind, but they are very versatile
(and unfortunately a bit complex).
Unlike ev_timer's, they are not based on real time (or relative time)
Unlike C<ev_timer>'s, they are not based on real time (or relative time)
but on wallclock time (absolute time). You can tell a periodic watcher
to trigger "at" some specific point in time. For example, if you tell a
periodic watcher to trigger in 10 seconds (by specifiying e.g. c<ev_now ()
+ 10.>) and then reset your system clock to the last year, then it will
take a year to trigger the event (unlike an ev_timer, which would trigger
take a year to trigger the event (unlike an C<ev_timer>, which would trigger
roughly 10 seconds later and of course not if you reset your system time
again).
@ -550,7 +550,7 @@ full hour (UTC), or more correct, when the system time is evenly divisible
by 3600.
Another way to think about it (for the mathematically inclined) is that
ev_periodic will try to run the callback in this mode at the next possible
C<ev_periodic> will try to run the callback in this mode at the next possible
time where C<time = at (mod interval)>, regardless of any time jumps.
=item * manual reschedule mode (reschedule_cb = callback)
@ -593,7 +593,7 @@ program when the crontabs have changed).
=back
=head2 ev_signal - signal me when a signal gets signalled
=head2 C<ev_signal> - signal me when a signal gets signalled
Signal watchers will trigger an event when the process receives a specific
signal one or more times. Even though signals are very asynchronous, libev
@ -618,7 +618,7 @@ of the C<SIGxxx> constants).
=back
=head2 ev_child - wait for pid status changes
=head2 C<ev_child> - wait for pid status changes
Child watchers trigger when your process receives a SIGCHLD in response to
some child status changes (most typically when a child of yours dies).
@ -637,7 +637,7 @@ contains the pid of the process causing the status change.
=back
=head2 ev_idle - when you've got nothing better to do
=head2 C<ev_idle> - when you've got nothing better to do
Idle watchers trigger events when there are no other I/O or timer (or
periodic) events pending. That is, as long as your process is busy
@ -674,8 +674,8 @@ could be used, for example, to track variable changes, implement your own
watchers, integrate net-snmp or a coroutine library and lots more.
This is done by examining in each prepare call which file descriptors need
to be watched by the other library, registering ev_io watchers for them
and starting an ev_timer watcher for any timeouts (many libraries provide
to be watched by the other library, registering C<ev_io> watchers for them
and starting an C<ev_timer> watcher for any timeouts (many libraries provide
just this functionality). Then, in the check watcher you check for any
events that occured (by making your callbacks set soem flags for example)
and call back into the library.
@ -712,16 +712,16 @@ or timeout without havign to allocate/configure/start/stop/free one or
more watchers yourself.
If C<fd> is less than 0, then no I/O watcher will be started and events is
ignored. Otherwise, an ev_io watcher for the given C<fd> and C<events> set
ignored. Otherwise, an C<ev_io> watcher for the given C<fd> and C<events> set
will be craeted and started.
If C<timeout> is less than 0, then no timeout watcher will be
started. Otherwise an ev_timer watcher with after = C<timeout> (and repeat
started. Otherwise an C<ev_timer> watcher with after = C<timeout> (and repeat
= 0) will be started.
The callback has the type C<void (*cb)(int revents, void *arg)> and
gets passed an events set (normally a combination of EV_ERROR, EV_READ,
EV_WRITE or EV_TIMEOUT) and the C<arg> value passed to C<ev_once>:
gets passed an events set (normally a combination of C<EV_ERROR>, C<EV_READ>,
C<EV_WRITE> or C<EV_TIMEOUT>) and the C<arg> value passed to C<ev_once>:
static void stdin_ready (int revents, void *arg)
{