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- <meta name="created" content="Mon Nov 12 10:06:08 2007" />
+ <meta name="created" content="Sun Nov 18 04:43:20 2007" />
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<dl>
<dt>ev_tstamp ev_time ()</dt>
<dd>
- <p>Returns the current time as libev would use it.</p>
+ <p>Returns the current time as libev would use it. Please note that the
+<code>ev_now</code> function is usually faster and also often returns the timestamp
+you actually want to know.</p>
</dd>
<dt>int ev_version_major ()</dt>
<dt>int ev_version_minor ()</dt>
<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>
+ <p>Here are the gory details of what ev_loop does:</p>
+<pre> 1. If there are no active watchers (reference count is zero), return.
+ 2. Queue and immediately call all prepare watchers.
+ 3. If we have been forked, recreate the kernel state.
+ 4. Update the kernel state with all outstanding changes.
+ 5. Update the "event loop time".
+ 6. Calculate for how long to block.
+ 7. Block the process, waiting for events.
+ 8. Update the "event loop time" and do time jump handling.
+ 9. Queue all outstanding timers.
+ 10. Queue all outstanding periodics.
+ 11. If no events are pending now, queue all idle watchers.
+ 12. Queue all check watchers.
+ 13. Call all queued watchers in reverse order (i.e. check watchers first).
+ 14. If ev_unloop has been called or EVLOOP_ONESHOT or EVLOOP_NONBLOCK
+ was used, return, otherwise continue with step #1.
+
+</pre>
</dd>
<dt>ev_unloop (loop, how)</dt>
<dd>
<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_ONE</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>
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 "file open").</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>
<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. "Roughly" because
-detecting time jumps is hard, and soem inaccuracies are unavoidable (the
+detecting time jumps is hard, and some 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>
+of the event triggering whatever timeout you are modifying/starting. If
+you suspect event processing to be delayed and you <i>need</i> to base the timeout
+on the current time, use something like this to adjust for this:</p>
<pre> ev_timer_set (&timer, after + ev_now () - ev_time (), 0.);
</pre>
+<p>The callback is guarenteed to be invoked only when its timeout has passed,
+but if multiple timers become ready during the same loop iteration then
+order of execution is undefined.</p>
<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>
<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>
again).</p>
<p>They can also be used to implement vastly more complex timers, such as
triggering an event on eahc midnight, local time.</p>
+<p>As with timers, the callback is guarenteed to be invoked only when the
+time (<code>at</code>) has been passed, but if multiple periodic timers become ready
+during the same loop iteration then order of execution is undefined.</p>
<dl>
<dt>ev_periodic_init (ev_periodic *, callback, ev_tstamp at, ev_tstamp interval, reschedule_cb)</dt>
<dt>ev_periodic_set (ev_periodic *, ev_tstamp after, ev_tstamp repeat, reschedule_cb)</dt>
<dd>
<p>Lots of arguments, lets sort it out... There are basically three modes of
operation, and we will explain them from simplest to complex:</p>
-
-
-
-
<p>
<dl>
<dt>* absolute timer (interval = reschedule_cb = 0)</dt>
<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
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)
</div>
<h1 id="LIBEVENT_EMULATION">LIBEVENT EMULATION</h1><p><a href="#TOP" class="toplink">Top</a></p>
<div id="LIBEVENT_EMULATION_CONTENT">
-<p>TBD.</p>
+<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 <event.h>, 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>
projects / software / libev.git / blobdiff