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Marc Alexander Lehmann 2007-11-12 08:16:02 +00:00
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commit d15a558bfc
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25
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 09:12:14 2007" />
<meta name="created" content="Mon Nov 12 09:16:01 2007" />
<meta name="generator" content="Pod::Xhtml 1.57" />
<link rel="stylesheet" href="http://res.tst.eu/pod.css"/></head>
<body>
@ -74,15 +74,15 @@ kqueue mechanisms for file descriptor events, relative timers, absolute
timers with customised rescheduling, signal events, process status change
events (related to SIGCHLD), and event watchers dealing with the event
loop mechanism itself (idle, prepare and check watchers). It also is quite
fast (see a <a href="http://libev.schmorp.de/bench.html">benchmark</a> comparing it
to libevent).</p>
fast (see this <a href="http://libev.schmorp.de/bench.html">benchmark</a> comparing
it to libevent for example).</p>
</div>
<h1 id="CONVENTIONS">CONVENTIONS</h1><p><a href="#TOP" class="toplink">Top</a></p>
<div id="CONVENTIONS_CONTENT">
<p>Libev is very configurable. In this manual the default configuration
will be described, which supports multiple event loops. For more info
about various configuraiton options please have a look at the file
about various configuration options please have a look at the file
<cite>README.embed</cite> in the libev distribution. If libev was configured without
support for multiple event loops, then all functions taking an initial
argument of name <code>loop</code> (which is always of type <code>struct ev_loop *</code>)
@ -117,10 +117,10 @@ not a problem.</p>
<dt>ev_set_allocator (void *(*cb)(void *ptr, long size))</dt>
<dd>
<p>Sets the allocation function to use (the prototype is similar to the
realloc function). It is used to allocate and free memory (no surprises
here). If it returns zero when memory needs to be allocated, the library
might abort or take some potentially destructive action. The default is
your system realloc function.</p>
realloc C function, the semantics are identical). It is used to allocate
and free memory (no surprises here). If it returns zero when memory
needs to be allocated, the library might abort or take some potentially
destructive action. The default is your system realloc function.</p>
<p>You could override this function in high-availability programs to, say,
free some memory if it cannot allocate memory, to use a special allocator,
or even to sleep a while and retry until some memory is available.</p>
@ -131,7 +131,7 @@ or even to sleep a while and retry until some memory is available.</p>
as failed select, poll, epoll_wait). The message is a printable string
indicating the system call or subsystem causing the problem. If this
callback is set, then libev will expect it to remedy the sitution, no
matter what, when it returns. That is, libev will geenrally retry the
matter what, when it returns. That is, libev will generally retry the
requested operation, or, if the condition doesn't go away, do bad stuff
(such as abort).</p>
</dd>
@ -145,9 +145,10 @@ types of such loops, the <i>default</i> loop, which supports signals and child
events, and dynamically created loops which do not.</p>
<p>If you use threads, a common model is to run the default event loop
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 lockign
whatsoever, so if you mix calls to different event loops, make sure you
lock (this is usually a bad idea, though, even if done right).</p>
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>
<dl>
<dt>struct ev_loop *ev_default_loop (unsigned int flags)</dt>
<dd>

50
ev.pod
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@ -28,14 +28,14 @@ kqueue mechanisms for file descriptor events, relative timers, absolute
timers with customised rescheduling, signal events, process status change
events (related to SIGCHLD), and event watchers dealing with the event
loop mechanism itself (idle, prepare and check watchers). It also is quite
fast (see a L<http://libev.schmorp.de/bench.html|benchmark> comparing it
to libevent).
fast (see this L<benchmark|http://libev.schmorp.de/bench.html> comparing
it to libevent for example).
=head1 CONVENTIONS
Libev is very configurable. In this manual the default configuration
will be described, which supports multiple event loops. For more info
about various configuraiton options please have a look at the file
about various configuration options please have a look at the file
F<README.embed> in the libev distribution. If libev was configured without
support for multiple event loops, then all functions taking an initial
argument of name C<loop> (which is always of type C<struct ev_loop *>)
@ -73,10 +73,10 @@ not a problem.
=item ev_set_allocator (void *(*cb)(void *ptr, long size))
Sets the allocation function to use (the prototype is similar to the
realloc function). It is used to allocate and free memory (no surprises
here). If it returns zero when memory needs to be allocated, the library
might abort or take some potentially destructive action. The default is
your system realloc function.
realloc C function, the semantics are identical). It is used to allocate
and free memory (no surprises here). If it returns zero when memory
needs to be allocated, the library might abort or take some potentially
destructive action. The default is your system realloc function.
You could override this function in high-availability programs to, say,
free some memory if it cannot allocate memory, to use a special allocator,
@ -88,7 +88,7 @@ Set the callback function to call on a retryable syscall error (such
as failed select, poll, epoll_wait). The message is a printable string
indicating the system call or subsystem causing the problem. If this
callback is set, then libev will expect it to remedy the sitution, no
matter what, when it returns. That is, libev will geenrally retry the
matter what, when it returns. That is, libev will generally retry the
requested operation, or, if the condition doesn't go away, do bad stuff
(such as abort).
@ -102,9 +102,10 @@ events, and dynamically created loops which do not.
If you use threads, a common model is to run the default event loop
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 lockign
whatsoever, so if you mix calls to different event loops, make sure you
lock (this is usually a bad idea, though, even if done right).
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).
=over 4
@ -119,7 +120,7 @@ If you don't know what event loop to use, use the one returned from this
function.
The flags argument can be used to specify special behaviour or specific
backends to use, and is usually specified as 0 (or EVFLAG_AUTO)
backends to use, and is usually specified as 0 (or EVFLAG_AUTO).
It supports the following flags:
@ -132,11 +133,12 @@ thing, believe me).
=item EVFLAG_NOENV
If this flag bit is ored into the flag value then libev will I<not> look
at the environment variable C<LIBEV_FLAGS>. Otherwise (the default), this
environment variable will override the flags completely. This is useful
to try out specific backends to tets their performance, or to work around
bugs.
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
C<LIBEV_FLAGS>. Otherwise (the default), this environment variable will
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
@ -410,6 +412,20 @@ level-triggering because you keep receiving events as long as the
condition persists. Remember you cna stop the watcher if you don't want to
act on the event and neither want to receive future events).
In general you can register as many read and/or write event watchers oer
fd as you want (as long as you don't confuse yourself). Setting all file
descriptors to non-blocking mode is also usually a good idea (but not
required if you know what you are doing).
You have to be careful with dup'ed file descriptors, though. Some backends
(the linux epoll backend is a notable example) cannot handle dup'ed file
descriptors correctly if you register interest in two or more fds pointing
to the same file/socket etc. description.
If you must do this, then force the use of a known-to-be-good backend
(at the time of this writing, this includes only EVMETHOD_SELECT and
EVMETHOD_POLL).
=over 4
=item ev_io_init (ev_io *, callback, int fd, int events)