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- <meta name="created" content="Sat Nov 24 05:58:35 2007" />
+ <meta name="created" content="Sat Nov 24 10:48:32 2007" />
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<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><a href="#SUMMARY_OF_GENERIC_WATCHER_FUNCTIONS">SUMMARY OF GENERIC WATCHER FUNCTIONS</a></li>
+<li><a href="#ASSOCIATING_CUSTOM_DATA_WITH_A_WATCH">ASSOCIATING CUSTOM DATA WITH A WATCHER</a></li>
</ul>
</li>
<li><a href="#WATCHER_TYPES">WATCHER TYPES</a>
<dt>ev_default_destroy ()</dt>
<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 cannot rely on this :).</p>
+etc.). None of the active event watchers will be stopped in the normal
+sense, so e.g. <code>ev_is_active</code> might still return true. It is your
+responsibility to either stop all watchers cleanly yoursef <i>before</i>
+calling this function, or cope with the fact afterwards (which is usually
+the easiest thing, youc na just ignore the watchers and/or <code>free ()</code> them
+for example).</p>
</dd>
<dt>ev_loop_destroy (loop)</dt>
<dd>
corresponding stop function (<code>ev_<type>_stop (loop, watcher *)</code>.</p>
<p>As long as your watcher is active (has been started but not stopped) you
must not touch the values stored in it. Most specifically you must never
-reinitialise it or call its set macro.</p>
-<p>You can check whether an event is active by calling the <code>ev_is_active
-(watcher *)</code> macro. To see whether an event is outstanding (but the
-callback for it has not been called yet) you can use the <code>ev_is_pending
-(watcher *)</code> macro.</p>
+reinitialise it or call its <code>set</code> macro.</p>
<p>Each and every callback receives the event loop pointer as first, the
registered watcher structure as second, and a bitset of received events as
third argument.</p>
</dd>
</dl>
+</div>
+<h2 id="SUMMARY_OF_GENERIC_WATCHER_FUNCTIONS">SUMMARY OF GENERIC WATCHER FUNCTIONS</h2>
+<div id="SUMMARY_OF_GENERIC_WATCHER_FUNCTIONS-2">
+<p>In the following description, <code>TYPE</code> stands for the watcher type,
+e.g. <code>timer</code> for <code>ev_timer</code> watchers and <code>io</code> for <code>ev_io</code> watchers.</p>
+<dl>
+ <dt><code>ev_init</code> (ev_TYPE *watcher, callback)</dt>
+ <dd>
+ <p>This macro initialises the generic portion of a watcher. The contents
+of the watcher object can be arbitrary (so <code>malloc</code> will do). Only
+the generic parts of the watcher are initialised, you <i>need</i> to call
+the type-specific <code>ev_TYPE_set</code> macro afterwards to initialise the
+type-specific parts. For each type there is also a <code>ev_TYPE_init</code> macro
+which rolls both calls into one.</p>
+ <p>You can reinitialise a watcher at any time as long as it has been stopped
+(or never started) and there are no pending events outstanding.</p>
+ <p>The callbakc is always of type <code>void (*)(ev_loop *loop, ev_TYPE *watcher,
+int revents)</code>.</p>
+ </dd>
+ <dt><code>ev_TYPE_set</code> (ev_TYPE *, [args])</dt>
+ <dd>
+ <p>This macro initialises the type-specific parts of a watcher. You need to
+call <code>ev_init</code> at least once before you call this macro, but you can
+call <code>ev_TYPE_set</code> any number of times. You must not, however, call this
+macro on a watcher that is active (it can be pending, however, which is a
+difference to the <code>ev_init</code> macro).</p>
+ <p>Although some watcher types do not have type-specific arguments
+(e.g. <code>ev_prepare</code>) you still need to call its <code>set</code> macro.</p>
+ </dd>
+ <dt><code>ev_TYPE_init</code> (ev_TYPE *watcher, callback, [args])</dt>
+ <dd>
+ <p>This convinience macro rolls both <code>ev_init</code> and <code>ev_TYPE_set</code> macro
+calls into a single call. This is the most convinient method to initialise
+a watcher. The same limitations apply, of course.</p>
+ </dd>
+ <dt><code>ev_TYPE_start</code> (loop *, ev_TYPE *watcher)</dt>
+ <dd>
+ <p>Starts (activates) the given watcher. Only active watchers will receive
+events. If the watcher is already active nothing will happen.</p>
+ </dd>
+ <dt><code>ev_TYPE_stop</code> (loop *, ev_TYPE *watcher)</dt>
+ <dd>
+ <p>Stops the given watcher again (if active) and clears the pending
+status. It is possible that stopped watchers are pending (for example,
+non-repeating timers are being stopped when they become pending), but
+<code>ev_TYPE_stop</code> ensures that the watcher is neither active nor pending. If
+you want to free or reuse the memory used by the watcher it is therefore a
+good idea to always call its <code>ev_TYPE_stop</code> function.</p>
+ </dd>
+ <dt>bool ev_is_active (ev_TYPE *watcher)</dt>
+ <dd>
+ <p>Returns a true value iff the watcher is active (i.e. it has been started
+and not yet been stopped). As long as a watcher is active you must not modify
+it.</p>
+ </dd>
+ <dt>bool ev_is_pending (ev_TYPE *watcher)</dt>
+ <dd>
+ <p>Returns a true value iff the watcher is pending, (i.e. it has outstanding
+events but its callback has not yet been invoked). As long as a watcher
+is pending (but not active) you must not call an init function on it (but
+<code>ev_TYPE_set</code> is safe) and you must make sure the watcher is available to
+libev (e.g. you cnanot <code>free ()</code> it).</p>
+ </dd>
+ <dt>callback = ev_cb (ev_TYPE *watcher)</dt>
+ <dd>
+ <p>Returns the callback currently set on the watcher.</p>
+ </dd>
+ <dt>ev_cb_set (ev_TYPE *watcher, callback)</dt>
+ <dd>
+ <p>Change the callback. You can change the callback at virtually any time
+(modulo threads).</p>
+ </dd>
+</dl>
+
+
+
+
+
</div>
<h2 id="ASSOCIATING_CUSTOM_DATA_WITH_A_WATCH">ASSOCIATING CUSTOM DATA WITH A WATCHER</h2>
<div id="ASSOCIATING_CUSTOM_DATA_WITH_A_WATCH-2">
<p>Unlike <code>ev_timer</code>'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
+periodic watcher to trigger in 10 seconds (by specifiying e.g. <code>ev_now ()
++ 10.</code>) and then reset your system clock to the last year, then it will
take a year to trigger the event (unlike an <code>ev_timer</code>, which would trigger
roughly 10 seconds later and of course not if you reset your system time
again).</p>
<h2 id="code_ev_embed_code_when_one_backend_"><code>ev_embed</code> - when one backend isn't enough</h2>
<div id="code_ev_embed_code_when_one_backend_-2">
<p>This is a rather advanced watcher type that lets you embed one event loop
-into another.</p>
+into another (currently only <code>ev_io</code> events are supported in the embedded
+loop, other types of watchers might be handled in a delayed or incorrect
+fashion and must not be used).</p>
<p>There are primarily two reasons you would want that: work around bugs and
prioritise I/O.</p>
<p>As an example for a bug workaround, the kqueue backend might only support
priorities and idle watchers might have too much overhead. In this case
you would put all the high priority stuff in one loop and all the rest in
a second one, and embed the second one in the first.</p>
+<p>As long as the watcher is active, the callback will be invoked every time
+there might be events pending in the embedded loop. The callback must then
+call <code>ev_embed_sweep (mainloop, watcher)</code> to make a single sweep and invoke
+their callbacks (you could also start an idle watcher to give the embedded
+loop strictly lower priority for example). You can also set the callback
+to <code>0</code>, in which case the embed watcher will automatically execute the
+embedded loop sweep.</p>
<p>As long as the watcher is started it will automatically handle events. The
callback will be invoked whenever some events have been handled. You can
set the callback to <code>0</code> to avoid having to specify one if you are not
</pre>
<dl>
- <dt>ev_embed_init (ev_embed *, callback, struct ev_loop *loop)</dt>
- <dt>ev_embed_set (ev_embed *, callback, struct ev_loop *loop)</dt>
+ <dt>ev_embed_init (ev_embed *, callback, struct ev_loop *embedded_loop)</dt>
+ <dt>ev_embed_set (ev_embed *, callback, struct ev_loop *embedded_loop)</dt>
+ <dd>
+ <p>Configures the watcher to embed the given loop, which must be
+embeddable. If the callback is <code>0</code>, then <code>ev_embed_sweep</code> will be
+invoked automatically, otherwise it is the responsibility of the callback
+to invoke it (it will continue to be called until the sweep has been done,
+if you do not want thta, you need to temporarily stop the embed watcher).</p>
+ </dd>
+ <dt>ev_embed_sweep (loop, ev_embed *)</dt>
<dd>
- <p>Configures the watcher to embed the given loop, which must be embeddable.</p>
+ <p>Make a single, non-blocking sweep over the embedded loop. This works
+similarly to <code>ev_loop (embedded_loop, EVLOOP_NONBLOCK)</code>, but in the most
+apropriate way for embedded loops.</p>
</dd>
</dl>
</pre>
</dd>
- <dt>ev_feed_event (loop, watcher, int events)</dt>
+ <dt>ev_feed_event (ev_loop *, watcher *, int revents)</dt>
<dd>
<p>Feeds the given event set into the event loop, as if the specified event
had happened for the specified watcher (which must be a pointer to an
initialised but not necessarily started event watcher).</p>
</dd>
- <dt>ev_feed_fd_event (loop, int fd, int revents)</dt>
+ <dt>ev_feed_fd_event (ev_loop *, int fd, int revents)</dt>
<dd>
<p>Feed an event on the given fd, as if a file descriptor backend detected
the given events it.</p>
</dd>
- <dt>ev_feed_signal_event (loop, int signum)</dt>
+ <dt>ev_feed_signal_event (ev_loop *loop, int signum)</dt>
<dd>
- <p>Feed an event as if the given signal occured (loop must be the default loop!).</p>
+ <p>Feed an event as if the given signal occured (<code>loop</code> must be the default
+loop!).</p>
</dd>
</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>
+<p>Libev comes with some simplistic wrapper classes for C++ that mainly allow
+you to use some convinience methods to start/stop watchers and also change
+the callback model to a model using method callbacks on objects.</p>
+<p>To use it,</p>
+<pre> #include <ev++.h>
+
+</pre>
+<p>(it is not installed by default). This automatically includes <cite>ev.h</cite>
+and puts all of its definitions (many of them macros) into the global
+namespace. All C++ specific things are put into the <code>ev</code> namespace.</p>
+<p>It should support all the same embedding options as <cite>ev.h</cite>, most notably
+<code>EV_MULTIPLICITY</code>.</p>
+<p>Here is a list of things available in the <code>ev</code> namespace:</p>
+<dl>
+ <dt><code>ev::READ</code>, <code>ev::WRITE</code> etc.</dt>
+ <dd>
+ <p>These are just enum values with the same values as the <code>EV_READ</code> etc.
+macros from <cite>ev.h</cite>.</p>
+ </dd>
+ <dt><code>ev::tstamp</code>, <code>ev::now</code></dt>
+ <dd>
+ <p>Aliases to the same types/functions as with the <code>ev_</code> prefix.</p>
+ </dd>
+ <dt><code>ev::io</code>, <code>ev::timer</code>, <code>ev::periodic</code>, <code>ev::idle</code>, <code>ev::sig</code> etc.</dt>
+ <dd>
+ <p>For each <code>ev_TYPE</code> watcher in <cite>ev.h</cite> there is a corresponding class of
+the same name in the <code>ev</code> namespace, with the exception of <code>ev_signal</code>
+which is called <code>ev::sig</code> to avoid clashes with the <code>signal</code> macro
+defines by many implementations.</p>
+ <p>All of those classes have these methods:</p>
+ <p>
+ <dl>
+ <dt>ev::TYPE::TYPE (object *, object::method *)</dt>
+ <dt>ev::TYPE::TYPE (object *, object::method *, struct ev_loop *)</dt>
+ <dt>ev::TYPE::~TYPE</dt>
+ <dd>
+ <p>The constructor takes a pointer to an object and a method pointer to
+the event handler callback to call in this class. The constructor calls
+<code>ev_init</code> for you, which means you have to call the <code>set</code> method
+before starting it. If you do not specify a loop then the constructor
+automatically associates the default loop with this watcher.</p>
+ <p>The destructor automatically stops the watcher if it is active.</p>
+ </dd>
+ <dt>w->set (struct ev_loop *)</dt>
+ <dd>
+ <p>Associates a different <code>struct ev_loop</code> with this watcher. You can only
+do this when the watcher is inactive (and not pending either).</p>
+ </dd>
+ <dt>w->set ([args])</dt>
+ <dd>
+ <p>Basically the same as <code>ev_TYPE_set</code>, with the same args. Must be
+called at least once. Unlike the C counterpart, an active watcher gets
+automatically stopped and restarted.</p>
+ </dd>
+ <dt>w->start ()</dt>
+ <dd>
+ <p>Starts the watcher. Note that there is no <code>loop</code> argument as the
+constructor already takes the loop.</p>
+ </dd>
+ <dt>w->stop ()</dt>
+ <dd>
+ <p>Stops the watcher if it is active. Again, no <code>loop</code> argument.</p>
+ </dd>
+ <dt>w->again () <code>ev::timer</code>, <code>ev::periodic</code> only</dt>
+ <dd>
+ <p>For <code>ev::timer</code> and <code>ev::periodic</code>, this invokes the corresponding
+<code>ev_TYPE_again</code> function.</p>
+ </dd>
+ <dt>w->sweep () <code>ev::embed</code> only</dt>
+ <dd>
+ <p>Invokes <code>ev_embed_sweep</code>.</p>
+ </dd>
+ </dl>
+ </p>
+ </dd>
+</dl>
+<p>Example: Define a class with an IO and idle watcher, start one of them in
+the constructor.</p>
+<pre> class myclass
+ {
+ ev_io io; void io_cb (ev::io &w, int revents);
+ ev_idle idle void idle_cb (ev::idle &w, int revents);
+
+ myclass ();
+ }
+
+ myclass::myclass (int fd)
+ : io (this, &myclass::io_cb),
+ idle (this, &myclass::idle_cb)
+ {
+ io.start (fd, ev::READ);
+ }
+
+</pre>
</div>
<h1 id="AUTHOR">AUTHOR</h1><p><a href="#TOP" class="toplink">Top</a></p>
projects / software / libev.git / blobdiff