[ViewVC] Diff of: cvs/libev/ev.html

Comparing libev/ev.html (file contents):
Revision 1.14 by root, Mon Nov 12 08:45:49 2007 UTC vs.
Revision 1.26 by root, Mon Nov 12 19:20:05 2007 UTC

 <head>
 	<title>libev</title>
 	<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 09:45:48 2007" />
+	<meta name="created" content="Mon Nov 12 20:19:59 2007" />
 	<meta name="generator" content="Pod::Xhtml 1.57" />
 <link rel="stylesheet" href="http://res.tst.eu/pod.css"/></head>
 <body>
 <div class="pod">
 <!-- INDEX START -->
 <ul><li><a href="#NAME">NAME</a></li>
 <li><a href="#SYNOPSIS">SYNOPSIS</a></li>
 <li><a href="#DESCRIPTION">DESCRIPTION</a></li>
 <li><a href="#FEATURES">FEATURES</a></li>
 <li><a href="#CONVENTIONS">CONVENTIONS</a></li>
+<li><a href="#TIME_REPRESENTATION">TIME REPRESENTATION</a></li>
-<li><a href="#TIME_AND_OTHER_GLOBAL_FUNCTIONS">TIME AND OTHER GLOBAL FUNCTIONS</a></li>
+<li><a href="#GLOBAL_FUNCTIONS">GLOBAL FUNCTIONS</a></li>
 <li><a href="#FUNCTIONS_CONTROLLING_THE_EVENT_LOOP">FUNCTIONS CONTROLLING THE EVENT LOOP</a></li>
 <li><a href="#ANATOMY_OF_A_WATCHER">ANATOMY OF A WATCHER</a>
 <ul><li><a href="#ASSOCIATING_CUSTOM_DATA_WITH_A_WATCH">ASSOCIATING CUSTOM DATA WITH A WATCHER</a></li>
 </ul>
 </li>
 <li><a href="#code_ev_timer_code_relative_and_opti"><code>ev_timer</code> - relative and optionally recurring timeouts</a></li>
 <li><a href="#code_ev_periodic_code_to_cron_or_not"><code>ev_periodic</code> - to cron or not to cron</a></li>
 <li><a href="#code_ev_signal_code_signal_me_when_a"><code>ev_signal</code> - signal me when a signal gets signalled</a></li>
 <li><a href="#code_ev_child_code_wait_for_pid_stat"><code>ev_child</code> - wait for pid status changes</a></li>
 <li><a href="#code_ev_idle_code_when_you_ve_got_no"><code>ev_idle</code> - when you've got nothing better to do</a></li>
-<li><a href="#prepare_and_check_your_hooks_into_th">prepare and check - your hooks into the event loop</a></li>
+<li><a href="#code_ev_prepare_code_and_code_ev_che"><code>ev_prepare</code> and <code>ev_check</code> - customise your event loop</a></li>
 </ul>
 </li>
 <li><a href="#OTHER_FUNCTIONS">OTHER FUNCTIONS</a></li>
+<li><a href="#LIBEVENT_EMULATION">LIBEVENT EMULATION</a></li>
+<li><a href="#C_SUPPORT">C++ SUPPORT</a></li>
 <li><a href="#AUTHOR">AUTHOR</a>
 </li>
 </ul><hr />
 <!-- INDEX END -->
 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>)
 will not have this argument.</p>
 </div>
-<h1 id="TIME_AND_OTHER_GLOBAL_FUNCTIONS">TIME AND OTHER GLOBAL FUNCTIONS</h1><p><a href="#TOP" class="toplink">Top</a></p>
+<h1 id="TIME_REPRESENTATION">TIME REPRESENTATION</h1><p><a href="#TOP" class="toplink">Top</a></p>
-<div id="TIME_AND_OTHER_GLOBAL_FUNCTIONS_CONT">
+<div id="TIME_REPRESENTATION_CONTENT">
 <p>Libev represents time as a single floating point number, representing the
 (fractional) number of seconds since the (POSIX) epoch (somewhere near
 the beginning of 1970, details are complicated, don't ask). This type is
 called <code>ev_tstamp</code>, which is what you should use too. It usually aliases
 to the double type in C.</p>
+</div>
+<h1 id="GLOBAL_FUNCTIONS">GLOBAL FUNCTIONS</h1><p><a href="#TOP" class="toplink">Top</a></p>
+<div id="GLOBAL_FUNCTIONS_CONTENT">
+<p>These functions can be called anytime, even before initialising the
+library in any way.</p>
 <dl>
 	<dt>ev_tstamp ev_time ()</dt>
 	<dd>
 		<p>Returns the current time as libev would use it.</p>
 	</dd>
 <div id="FUNCTIONS_CONTROLLING_THE_EVENT_LOOP-2">
 <p>An event loop is described by a <code>struct ev_loop *</code>. The library knows two
 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
+in your main thread (or in a separate thread) 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 it's hideous and inefficient).</p>
 <dl>
 <p>I/O watchers check whether a file descriptor is readable or writable
 in each iteration of the event loop (This behaviour is called
 level-triggering because you keep receiving events as long as the
 condition persists. Remember you can stop the watcher if you don't want to
 act on the event and neither want to receive future events).</p>
-<p>In general you can register as many read and/or write event watchers oer
+<p>In general you can register as many read and/or write event watchers per
 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).</p>
 <p>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.</p>
+to the same underlying file/socket etc. description (that is, they share
+the same underlying &quot;file open&quot;).</p>
 <p>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).</p>
 <dl>
 	<dt>ev_io_init (ev_io *, callback, int fd, int events)</dt>
 <h2 id="code_ev_timer_code_relative_and_opti"><code>ev_timer</code> - relative and optionally recurring timeouts</h2>
 <div id="code_ev_timer_code_relative_and_opti-2">
 <p>Timer watchers are simple relative timers that generate an event after a
 given time, and optionally repeating in regular intervals after that.</p>
 <p>The timers are based on real time, that is, if you register an event that
-times out after an hour and youreset your system clock to last years
+times out after an hour and you reset 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>
+on 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>
 timer will automatically be configured to trigger again <code>repeat</code> seconds
 later, again, and again, until stopped manually.</p>
 		<p>The timer itself will do a best-effort at avoiding drift, that is, if you
 configure a timer to trigger every 10 seconds, then it will trigger at
 exactly 10 second intervals. If, however, your program cannot keep up with
-the timer (ecause it takes longer than those 10 seconds to do stuff) the
+the timer (because it takes longer than those 10 seconds to do stuff) the
 timer will not fire more than once per event loop iteration.</p>
 	</dd>
 	<dt>ev_timer_again (loop)</dt>
 	<dd>
 		<p>This will act as if the timer timed out and restart it again if it is
 				<dd>
 					<p>In this mode the values for <code>interval</code> and <code>at</code> are both being
 ignored. Instead, each time the periodic watcher gets scheduled, the
 reschedule callback will be called with the watcher as first, and the
 current time as second argument.</p>
-					<p>NOTE: <i>This callback MUST NOT stop or destroy the periodic or any other
+					<p>NOTE: <i>This callback MUST NOT stop or destroy any periodic watcher,
-periodic watcher, ever, or make any event loop modifications</i>. If you need
+ever, or make any event loop modifications</i>. If you need to stop it,
-to stop it, return <code>now + 1e30</code> (or so, fudge fudge) and stop it afterwards.</p>
+return <code>now + 1e30</code> (or so, fudge fudge) and stop it afterwards (e.g. by
-					<p>Also, <i>this callback must always return a time that is later than the
+starting a prepare watcher).</p>
-passed <code>now</code> value</i>. Not even <code>now</code> itself will be ok.</p>
 					<p>Its prototype is <code>ev_tstamp (*reschedule_cb)(struct ev_periodic *w,
 ev_tstamp now)</code>, e.g.:</p>
 <pre>   static ev_tstamp my_rescheduler (struct ev_periodic *w, ev_tstamp now)
    {
      return now + 60.;
 </pre>
 					<p>It must return the next time to trigger, based on the passed time value
 (that is, the lowest time value larger than to the second argument). It
 will usually be called just before the callback will be triggered, but
 might be called at other times, too.</p>
+					<p>NOTE: <i>This callback must always return a time that is later than the
+passed <code>now</code> value</i>. Not even <code>now</code> itself will do, it <i>must</i> be larger.</p>
 					<p>This can be used to create very complex timers, such as a timer that
 triggers on each midnight, local time. To do this, you would calculate the
-next midnight after <code>now</code> and return the timestamp value for this. How you do this
+next midnight after <code>now</code> and return the timestamp value for this. How
-is, again, up to you (but it is not trivial).</p>
+you do this is, again, up to you (but it is not trivial, which is the main
+reason I omitted it as an example).</p>
 				</dd>
 			</dl>
 		</p>
 	</dd>
 	<dt>ev_periodic_again (loop, ev_periodic *)</dt>
 believe me.</p>
 	</dd>
 </dl>
 </div>
-<h2 id="prepare_and_check_your_hooks_into_th">prepare and check - your hooks into the event loop</h2>
+<h2 id="code_ev_prepare_code_and_code_ev_che"><code>ev_prepare</code> and <code>ev_check</code> - customise your event loop</h2>
-<div id="prepare_and_check_your_hooks_into_th-2">
+<div id="code_ev_prepare_code_and_code_ev_che-2">
 <p>Prepare and check watchers are usually (but not always) used in tandem:
-Prepare watchers get invoked before the process blocks and check watchers
+prepare watchers get invoked before the process blocks and check watchers
 afterwards.</p>
 <p>Their main purpose is to integrate other event mechanisms into libev. This
 could be used, for example, to track variable changes, implement your own
 watchers, integrate net-snmp or a coroutine library and lots more.</p>
 <p>This is done by examining in each prepare call which file descriptors need
 to be watched by the other library, registering <code>ev_io</code> watchers for
 them and starting an <code>ev_timer</code> watcher for any timeouts (many libraries
 provide just this functionality). Then, in the check watcher you check for
 any events that occured (by checking the pending status of all watchers
 and stopping them) and call back into the library. The I/O and timer
-callbacks will never actually be called (but must be valid neverthelles,
+callbacks will never actually be called (but must be valid nevertheless,
 because you never know, you know?).</p>
 <p>As another example, the Perl Coro module uses these hooks to integrate
 coroutines into libev programs, by yielding to other active coroutines
 during each prepare and only letting the process block if no coroutines
-are ready to run (its actually more complicated, it only runs coroutines
+are ready to run (it's actually more complicated: it only runs coroutines
-with priority higher than the event loop and one lower priority once,
+with priority higher than or equal to the event loop and one coroutine
-using idle watchers to keep the event loop from blocking if lower-priority
+of lower priority, but only once, using idle watchers to keep the event
-coroutines exist, thus mapping low-priority coroutines to idle/background
+loop from blocking if lower-priority coroutines are active, thus mapping
-tasks).</p>
+low-priority coroutines to idle/background tasks).</p>
 <dl>
 	<dt>ev_prepare_init (ev_prepare *, callback)</dt>
 	<dt>ev_check_init (ev_check *, callback)</dt>
 	<dd>
 		<p>Initialises and configures the prepare or check watcher - they have no
 	<dt>ev_once (loop, int fd, int events, ev_tstamp timeout, callback)</dt>
 	<dd>
 		<p>This function combines a simple timer and an I/O watcher, calls your
 callback on whichever event happens first and automatically stop both
 watchers. This is useful if you want to wait for a single event on an fd
-or timeout without havign to allocate/configure/start/stop/free one or
+or timeout without having to allocate/configure/start/stop/free one or
 more watchers yourself.</p>
 		<p>If <code>fd</code> is less than 0, then no I/O watcher will be started and events
 is being ignored. Otherwise, an <code>ev_io</code> watcher for the given <code>fd</code> and
 <code>events</code> set will be craeted and started.</p>
 		<p>If <code>timeout</code> is less than 0, then no timeout watcher will be
 started. Otherwise an <code>ev_timer</code> watcher with after = <code>timeout</code> (and
 repeat = 0) will be started. While <code>0</code> is a valid timeout, it is of
 dubious value.</p>
 		<p>The callback has the type <code>void (*cb)(int revents, void *arg)</code> and gets
-passed an events set like normal event callbacks (with a combination of
+passed an <code>revents</code> set like normal event callbacks (a combination of
 <code>EV_ERROR</code>, <code>EV_READ</code>, <code>EV_WRITE</code> or <code>EV_TIMEOUT</code>) and the <code>arg</code>
 value passed to <code>ev_once</code>:</p>
 <pre>  static void stdin_ready (int revents, void *arg)
   {
     if (revents &amp; EV_TIMEOUT)
 		<p>Feed an event as if the given signal occured (loop must be the default loop!).</p>
 	</dd>
 </dl>
 </div>
+<h1 id="LIBEVENT_EMULATION">LIBEVENT EMULATION</h1><p><a href="#TOP" class="toplink">Top</a></p>
+<div id="LIBEVENT_EMULATION_CONTENT">
+<p>Libev offers a compatibility emulation layer for libevent. It cannot
+emulate the internals of libevent, so here are some usage hints:</p>
+<dl>
+	<dt>* Use it by including &lt;event.h&gt;, as usual.</dt>
+	<dt>* The following members are fully supported: ev_base, ev_callback,
+ev_arg, ev_fd, ev_res, ev_events.</dt>
+	<dt>* Avoid using ev_flags and the EVLIST_*-macros, while it is
+maintained by libev, it does not work exactly the same way as in libevent (consider
+it a private API).</dt>
+	<dt>* Priorities are not currently supported. Initialising priorities
+will fail and all watchers will have the same priority, even though there
+is an ev_pri field.</dt>
+	<dt>* Other members are not supported.</dt>
+	<dt>* The libev emulation is <i>not</i> ABI compatible to libevent, you need
+to use the libev header file and library.</dt>
+</dl>
+</div>
+<h1 id="C_SUPPORT">C++ SUPPORT</h1><p><a href="#TOP" class="toplink">Top</a></p>
+<div id="C_SUPPORT_CONTENT">
+<p>TBD.</p>
+</div>
 <h1 id="AUTHOR">AUTHOR</h1><p><a href="#TOP" class="toplink">Top</a></p>
 <div id="AUTHOR_CONTENT">
 <p>Marc Lehmann &lt;libev@schmorp.de&gt;.</p>
 </div>

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Comparing libev/ev.html (file contents): Revision 1.14 by root, Mon Nov 12 08:45:49 2007 UTC vs. Revision 1.26 by root, Mon Nov 12 19:20:05 2007 UTC

Diff Legend

Comparing libev/ev.html (file contents):
Revision 1.14 by root, Mon Nov 12 08:45:49 2007 UTC vs.
Revision 1.26 by root, Mon Nov 12 19:20:05 2007 UTC