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4 | <head> |
4 | <head> |
5 | <title>libev</title> |
5 | <title>libev</title> |
6 | <meta name="description" content="Pod documentation for libev" /> |
6 | <meta name="description" content="Pod documentation for libev" /> |
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14 | <!-- INDEX START --> |
14 | <!-- INDEX START --> |
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119 | </pre> |
119 | </pre> |
120 | |
120 | |
121 | </div> |
121 | </div> |
122 | <h1 id="DESCRIPTION">DESCRIPTION</h1> |
122 | <h1 id="DESCRIPTION">DESCRIPTION</h1> |
123 | <div id="DESCRIPTION_CONTENT"> |
123 | <div id="DESCRIPTION_CONTENT"> |
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124 | <p>The newest version of this document is also available as a html-formatted |
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125 | web page you might find easier to navigate when reading it for the first |
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126 | time: <a href="http://cvs.schmorp.de/libev/ev.html">http://cvs.schmorp.de/libev/ev.html</a>.</p> |
124 | <p>Libev is an event loop: you register interest in certain events (such as a |
127 | <p>Libev is an event loop: you register interest in certain events (such as a |
125 | file descriptor being readable or a timeout occuring), and it will manage |
128 | file descriptor being readable or a timeout occuring), and it will manage |
126 | these event sources and provide your program with events.</p> |
129 | these event sources and provide your program with events.</p> |
127 | <p>To do this, it must take more or less complete control over your process |
130 | <p>To do this, it must take more or less complete control over your process |
128 | (or thread) by executing the <i>event loop</i> handler, and will then |
131 | (or thread) by executing the <i>event loop</i> handler, and will then |
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326 | <code>LIBEV_FLAGS</code>. Otherwise (the default), this environment variable will |
329 | <code>LIBEV_FLAGS</code>. Otherwise (the default), this environment variable will |
327 | override the flags completely if it is found in the environment. This is |
330 | override the flags completely if it is found in the environment. This is |
328 | useful to try out specific backends to test their performance, or to work |
331 | useful to try out specific backends to test their performance, or to work |
329 | around bugs.</p> |
332 | around bugs.</p> |
330 | </dd> |
333 | </dd> |
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334 | <dt><code>EVFLAG_FORKCHECK</code></dt> |
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335 | <dd> |
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336 | <p>Instead of calling <code>ev_default_fork</code> or <code>ev_loop_fork</code> manually after |
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337 | a fork, you can also make libev check for a fork in each iteration by |
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338 | enabling this flag.</p> |
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339 | <p>This works by calling <code>getpid ()</code> on every iteration of the loop, |
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340 | and thus this might slow down your event loop if you do a lot of loop |
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341 | iterations and little real work, but is usually not noticeable (on my |
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342 | Linux system for example, <code>getpid</code> is actually a simple 5-insn sequence |
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343 | without a syscall and thus <i>very</i> fast, but my Linux system also has |
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344 | <code>pthread_atfork</code> which is even faster).</p> |
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345 | <p>The big advantage of this flag is that you can forget about fork (and |
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346 | forget about forgetting to tell libev about forking) when you use this |
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347 | flag.</p> |
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348 | <p>This flag setting cannot be overriden or specified in the <code>LIBEV_FLAGS</code> |
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349 | environment variable.</p> |
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350 | </dd> |
331 | <dt><code>EVBACKEND_SELECT</code> (value 1, portable select backend)</dt> |
351 | <dt><code>EVBACKEND_SELECT</code> (value 1, portable select backend)</dt> |
332 | <dd> |
352 | <dd> |
333 | <p>This is your standard select(2) backend. Not <i>completely</i> standard, as |
353 | <p>This is your standard select(2) backend. Not <i>completely</i> standard, as |
334 | libev tries to roll its own fd_set with no limits on the number of fds, |
354 | libev tries to roll its own fd_set with no limits on the number of fds, |
335 | but if that fails, expect a fairly low limit on the number of fds when |
355 | but if that fails, expect a fairly low limit on the number of fds when |
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463 | <dt>ev_loop_fork (loop)</dt> |
483 | <dt>ev_loop_fork (loop)</dt> |
464 | <dd> |
484 | <dd> |
465 | <p>Like <code>ev_default_fork</code>, but acts on an event loop created by |
485 | <p>Like <code>ev_default_fork</code>, but acts on an event loop created by |
466 | <code>ev_loop_new</code>. Yes, you have to call this on every allocated event loop |
486 | <code>ev_loop_new</code>. Yes, you have to call this on every allocated event loop |
467 | after fork, and how you do this is entirely your own problem.</p> |
487 | after fork, and how you do this is entirely your own problem.</p> |
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488 | </dd> |
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489 | <dt>unsigned int ev_loop_count (loop)</dt> |
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490 | <dd> |
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491 | <p>Returns the count of loop iterations for the loop, which is identical to |
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492 | the number of times libev did poll for new events. It starts at <code>0</code> and |
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493 | happily wraps around with enough iterations.</p> |
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494 | <p>This value can sometimes be useful as a generation counter of sorts (it |
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495 | "ticks" the number of loop iterations), as it roughly corresponds with |
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496 | <code>ev_prepare</code> and <code>ev_check</code> calls.</p> |
468 | </dd> |
497 | </dd> |
469 | <dt>unsigned int ev_backend (loop)</dt> |
498 | <dt>unsigned int ev_backend (loop)</dt> |
470 | <dd> |
499 | <dd> |
471 | <p>Returns one of the <code>EVBACKEND_*</code> flags indicating the event backend in |
500 | <p>Returns one of the <code>EVBACKEND_*</code> flags indicating the event backend in |
472 | use.</p> |
501 | use.</p> |
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740 | <dt>bool ev_is_pending (ev_TYPE *watcher)</dt> |
769 | <dt>bool ev_is_pending (ev_TYPE *watcher)</dt> |
741 | <dd> |
770 | <dd> |
742 | <p>Returns a true value iff the watcher is pending, (i.e. it has outstanding |
771 | <p>Returns a true value iff the watcher is pending, (i.e. it has outstanding |
743 | events but its callback has not yet been invoked). As long as a watcher |
772 | events but its callback has not yet been invoked). As long as a watcher |
744 | is pending (but not active) you must not call an init function on it (but |
773 | is pending (but not active) you must not call an init function on it (but |
745 | <code>ev_TYPE_set</code> is safe) and you must make sure the watcher is available to |
774 | <code>ev_TYPE_set</code> is safe), you must not change its priority, and you must |
746 | libev (e.g. you cnanot <code>free ()</code> it).</p> |
775 | make sure the watcher is available to libev (e.g. you cannot <code>free ()</code> |
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776 | it).</p> |
747 | </dd> |
777 | </dd> |
748 | <dt>callback ev_cb (ev_TYPE *watcher)</dt> |
778 | <dt>callback ev_cb (ev_TYPE *watcher)</dt> |
749 | <dd> |
779 | <dd> |
750 | <p>Returns the callback currently set on the watcher.</p> |
780 | <p>Returns the callback currently set on the watcher.</p> |
751 | </dd> |
781 | </dd> |
752 | <dt>ev_cb_set (ev_TYPE *watcher, callback)</dt> |
782 | <dt>ev_cb_set (ev_TYPE *watcher, callback)</dt> |
753 | <dd> |
783 | <dd> |
754 | <p>Change the callback. You can change the callback at virtually any time |
784 | <p>Change the callback. You can change the callback at virtually any time |
755 | (modulo threads).</p> |
785 | (modulo threads).</p> |
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|
786 | </dd> |
|
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787 | <dt>ev_set_priority (ev_TYPE *watcher, priority)</dt> |
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788 | <dt>int ev_priority (ev_TYPE *watcher)</dt> |
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|
789 | <dd> |
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|
790 | <p>Set and query the priority of the watcher. The priority is a small |
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791 | integer between <code>EV_MAXPRI</code> (default: <code>2</code>) and <code>EV_MINPRI</code> |
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792 | (default: <code>-2</code>). Pending watchers with higher priority will be invoked |
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793 | before watchers with lower priority, but priority will not keep watchers |
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794 | from being executed (except for <code>ev_idle</code> watchers).</p> |
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795 | <p>This means that priorities are <i>only</i> used for ordering callback |
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796 | invocation after new events have been received. This is useful, for |
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797 | example, to reduce latency after idling, or more often, to bind two |
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798 | watchers on the same event and make sure one is called first.</p> |
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799 | <p>If you need to suppress invocation when higher priority events are pending |
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800 | you need to look at <code>ev_idle</code> watchers, which provide this functionality.</p> |
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801 | <p>You <i>must not</i> change the priority of a watcher as long as it is active or |
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802 | pending.</p> |
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|
803 | <p>The default priority used by watchers when no priority has been set is |
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804 | always <code>0</code>, which is supposed to not be too high and not be too low :).</p> |
|
|
805 | <p>Setting a priority outside the range of <code>EV_MINPRI</code> to <code>EV_MAXPRI</code> is |
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806 | fine, as long as you do not mind that the priority value you query might |
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807 | or might not have been adjusted to be within valid range.</p> |
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808 | </dd> |
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809 | <dt>ev_invoke (loop, ev_TYPE *watcher, int revents)</dt> |
|
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810 | <dd> |
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|
811 | <p>Invoke the <code>watcher</code> with the given <code>loop</code> and <code>revents</code>. Neither |
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812 | <code>loop</code> nor <code>revents</code> need to be valid as long as the watcher callback |
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813 | can deal with that fact.</p> |
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814 | </dd> |
|
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815 | <dt>int ev_clear_pending (loop, ev_TYPE *watcher)</dt> |
|
|
816 | <dd> |
|
|
817 | <p>If the watcher is pending, this function returns clears its pending status |
|
|
818 | and returns its <code>revents</code> bitset (as if its callback was invoked). If the |
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819 | watcher isn't pending it does nothing and returns <code>0</code>.</p> |
756 | </dd> |
820 | </dd> |
757 | </dl> |
821 | </dl> |
758 | |
822 | |
759 | |
823 | |
760 | |
824 | |
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871 | this situation even with a relatively standard program structure. Thus |
935 | this situation even with a relatively standard program structure. Thus |
872 | it is best to always use non-blocking I/O: An extra <code>read</code>(2) returning |
936 | it is best to always use non-blocking I/O: An extra <code>read</code>(2) returning |
873 | <code>EAGAIN</code> is far preferable to a program hanging until some data arrives.</p> |
937 | <code>EAGAIN</code> is far preferable to a program hanging until some data arrives.</p> |
874 | <p>If you cannot run the fd in non-blocking mode (for example you should not |
938 | <p>If you cannot run the fd in non-blocking mode (for example you should not |
875 | play around with an Xlib connection), then you have to seperately re-test |
939 | play around with an Xlib connection), then you have to seperately re-test |
876 | wether a file descriptor is really ready with a known-to-be good interface |
940 | whether a file descriptor is really ready with a known-to-be good interface |
877 | such as poll (fortunately in our Xlib example, Xlib already does this on |
941 | such as poll (fortunately in our Xlib example, Xlib already does this on |
878 | its own, so its quite safe to use).</p> |
942 | its own, so its quite safe to use).</p> |
879 | <dl> |
943 | <dl> |
880 | <dt>ev_io_init (ev_io *, callback, int fd, int events)</dt> |
944 | <dt>ev_io_init (ev_io *, callback, int fd, int events)</dt> |
881 | <dt>ev_io_set (ev_io *, int fd, int events)</dt> |
945 | <dt>ev_io_set (ev_io *, int fd, int events)</dt> |
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1341 | </pre> |
1405 | </pre> |
1342 | |
1406 | |
1343 | </div> |
1407 | </div> |
1344 | <h2 id="code_ev_idle_code_when_you_ve_got_no"><code>ev_idle</code> - when you've got nothing better to do...</h2> |
1408 | <h2 id="code_ev_idle_code_when_you_ve_got_no"><code>ev_idle</code> - when you've got nothing better to do...</h2> |
1345 | <div id="code_ev_idle_code_when_you_ve_got_no-2"> |
1409 | <div id="code_ev_idle_code_when_you_ve_got_no-2"> |
1346 | <p>Idle watchers trigger events when there are no other events are pending |
1410 | <p>Idle watchers trigger events when no other events of the same or higher |
1347 | (prepare, check and other idle watchers do not count). That is, as long |
1411 | priority are pending (prepare, check and other idle watchers do not |
1348 | as your process is busy handling sockets or timeouts (or even signals, |
1412 | count).</p> |
1349 | imagine) it will not be triggered. But when your process is idle all idle |
1413 | <p>That is, as long as your process is busy handling sockets or timeouts |
1350 | watchers are being called again and again, once per event loop iteration - |
1414 | (or even signals, imagine) of the same or higher priority it will not be |
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1415 | triggered. But when your process is idle (or only lower-priority watchers |
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1416 | are pending), the idle watchers are being called once per event loop |
1351 | until stopped, that is, or your process receives more events and becomes |
1417 | iteration - until stopped, that is, or your process receives more events |
1352 | busy.</p> |
1418 | and becomes busy again with higher priority stuff.</p> |
1353 | <p>The most noteworthy effect is that as long as any idle watchers are |
1419 | <p>The most noteworthy effect is that as long as any idle watchers are |
1354 | active, the process will not block when waiting for new events.</p> |
1420 | active, the process will not block when waiting for new events.</p> |
1355 | <p>Apart from keeping your process non-blocking (which is a useful |
1421 | <p>Apart from keeping your process non-blocking (which is a useful |
1356 | effect on its own sometimes), idle watchers are a good place to do |
1422 | effect on its own sometimes), idle watchers are a good place to do |
1357 | "pseudo-background processing", or delay processing stuff to after the |
1423 | "pseudo-background processing", or delay processing stuff to after the |
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1447 | |
1513 | |
1448 | // create io watchers for each fd and a timer before blocking |
1514 | // create io watchers for each fd and a timer before blocking |
1449 | static void |
1515 | static void |
1450 | adns_prepare_cb (ev_loop *loop, ev_prepare *w, int revents) |
1516 | adns_prepare_cb (ev_loop *loop, ev_prepare *w, int revents) |
1451 | { |
1517 | { |
1452 | int timeout = 3600000;truct pollfd fds [nfd]; |
1518 | int timeout = 3600000; |
|
|
1519 | struct pollfd fds [nfd]; |
1453 | // actual code will need to loop here and realloc etc. |
1520 | // actual code will need to loop here and realloc etc. |
1454 | adns_beforepoll (ads, fds, &nfd, &timeout, timeval_from (ev_time ())); |
1521 | adns_beforepoll (ads, fds, &nfd, &timeout, timeval_from (ev_time ())); |
1455 | |
1522 | |
1456 | /* the callback is illegal, but won't be called as we stop during check */ |
1523 | /* the callback is illegal, but won't be called as we stop during check */ |
1457 | ev_timer_init (&tw, 0, timeout * 1e-3); |
1524 | ev_timer_init (&tw, 0, timeout * 1e-3); |
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… | |
1684 | the callback model to a model using method callbacks on objects.</p> |
1751 | the callback model to a model using method callbacks on objects.</p> |
1685 | <p>To use it,</p> |
1752 | <p>To use it,</p> |
1686 | <pre> #include <ev++.h> |
1753 | <pre> #include <ev++.h> |
1687 | |
1754 | |
1688 | </pre> |
1755 | </pre> |
1689 | <p>(it is not installed by default). This automatically includes <cite>ev.h</cite> |
1756 | <p>This automatically includes <cite>ev.h</cite> and puts all of its definitions (many |
1690 | and puts all of its definitions (many of them macros) into the global |
1757 | of them macros) into the global namespace. All C++ specific things are |
1691 | namespace. All C++ specific things are put into the <code>ev</code> namespace.</p> |
1758 | put into the <code>ev</code> namespace. It should support all the same embedding |
1692 | <p>It should support all the same embedding options as <cite>ev.h</cite>, most notably |
1759 | options as <cite>ev.h</cite>, most notably <code>EV_MULTIPLICITY</code>.</p> |
1693 | <code>EV_MULTIPLICITY</code>.</p> |
1760 | <p>Care has been taken to keep the overhead low. The only data member the C++ |
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1761 | classes add (compared to plain C-style watchers) is the event loop pointer |
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1762 | that the watcher is associated with (or no additional members at all if |
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1763 | you disable <code>EV_MULTIPLICITY</code> when embedding libev).</p> |
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1764 | <p>Currently, functions, and static and non-static member functions can be |
|
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1765 | used as callbacks. Other types should be easy to add as long as they only |
|
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1766 | need one additional pointer for context. If you need support for other |
|
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1767 | types of functors please contact the author (preferably after implementing |
|
|
1768 | it).</p> |
1694 | <p>Here is a list of things available in the <code>ev</code> namespace:</p> |
1769 | <p>Here is a list of things available in the <code>ev</code> namespace:</p> |
1695 | <dl> |
1770 | <dl> |
1696 | <dt><code>ev::READ</code>, <code>ev::WRITE</code> etc.</dt> |
1771 | <dt><code>ev::READ</code>, <code>ev::WRITE</code> etc.</dt> |
1697 | <dd> |
1772 | <dd> |
1698 | <p>These are just enum values with the same values as the <code>EV_READ</code> etc. |
1773 | <p>These are just enum values with the same values as the <code>EV_READ</code> etc. |
… | |
… | |
1709 | which is called <code>ev::sig</code> to avoid clashes with the <code>signal</code> macro |
1784 | which is called <code>ev::sig</code> to avoid clashes with the <code>signal</code> macro |
1710 | defines by many implementations.</p> |
1785 | defines by many implementations.</p> |
1711 | <p>All of those classes have these methods:</p> |
1786 | <p>All of those classes have these methods:</p> |
1712 | <p> |
1787 | <p> |
1713 | <dl> |
1788 | <dl> |
1714 | <dt>ev::TYPE::TYPE (object *, object::method *)</dt> |
1789 | <dt>ev::TYPE::TYPE ()</dt> |
1715 | <dt>ev::TYPE::TYPE (object *, object::method *, struct ev_loop *)</dt> |
1790 | <dt>ev::TYPE::TYPE (struct ev_loop *)</dt> |
1716 | <dt>ev::TYPE::~TYPE</dt> |
1791 | <dt>ev::TYPE::~TYPE</dt> |
1717 | <dd> |
1792 | <dd> |
1718 | <p>The constructor takes a pointer to an object and a method pointer to |
1793 | <p>The constructor (optionally) takes an event loop to associate the watcher |
1719 | the event handler callback to call in this class. The constructor calls |
1794 | with. If it is omitted, it will use <code>EV_DEFAULT</code>.</p> |
1720 | <code>ev_init</code> for you, which means you have to call the <code>set</code> method |
1795 | <p>The constructor calls <code>ev_init</code> for you, which means you have to call the |
1721 | before starting it. If you do not specify a loop then the constructor |
1796 | <code>set</code> method before starting it.</p> |
1722 | automatically associates the default loop with this watcher.</p> |
1797 | <p>It will not set a callback, however: You have to call the templated <code>set</code> |
|
|
1798 | method to set a callback before you can start the watcher.</p> |
|
|
1799 | <p>(The reason why you have to use a method is a limitation in C++ which does |
|
|
1800 | not allow explicit template arguments for constructors).</p> |
1723 | <p>The destructor automatically stops the watcher if it is active.</p> |
1801 | <p>The destructor automatically stops the watcher if it is active.</p> |
|
|
1802 | </dd> |
|
|
1803 | <dt>w->set<class, &class::method> (object *)</dt> |
|
|
1804 | <dd> |
|
|
1805 | <p>This method sets the callback method to call. The method has to have a |
|
|
1806 | signature of <code>void (*)(ev_TYPE &, int)</code>, it receives the watcher as |
|
|
1807 | first argument and the <code>revents</code> as second. The object must be given as |
|
|
1808 | parameter and is stored in the <code>data</code> member of the watcher.</p> |
|
|
1809 | <p>This method synthesizes efficient thunking code to call your method from |
|
|
1810 | the C callback that libev requires. If your compiler can inline your |
|
|
1811 | callback (i.e. it is visible to it at the place of the <code>set</code> call and |
|
|
1812 | your compiler is good :), then the method will be fully inlined into the |
|
|
1813 | thunking function, making it as fast as a direct C callback.</p> |
|
|
1814 | <p>Example: simple class declaration and watcher initialisation</p> |
|
|
1815 | <pre> struct myclass |
|
|
1816 | { |
|
|
1817 | void io_cb (ev::io &w, int revents) { } |
|
|
1818 | } |
|
|
1819 | |
|
|
1820 | myclass obj; |
|
|
1821 | ev::io iow; |
|
|
1822 | iow.set <myclass, &myclass::io_cb> (&obj); |
|
|
1823 | |
|
|
1824 | </pre> |
|
|
1825 | </dd> |
|
|
1826 | <dt>w->set<function> (void *data = 0)</dt> |
|
|
1827 | <dd> |
|
|
1828 | <p>Also sets a callback, but uses a static method or plain function as |
|
|
1829 | callback. The optional <code>data</code> argument will be stored in the watcher's |
|
|
1830 | <code>data</code> member and is free for you to use.</p> |
|
|
1831 | <p>The prototype of the <code>function</code> must be <code>void (*)(ev::TYPE &w, int)</code>.</p> |
|
|
1832 | <p>See the method-<code>set</code> above for more details.</p> |
|
|
1833 | <p>Example:</p> |
|
|
1834 | <pre> static void io_cb (ev::io &w, int revents) { } |
|
|
1835 | iow.set <io_cb> (); |
|
|
1836 | |
|
|
1837 | </pre> |
1724 | </dd> |
1838 | </dd> |
1725 | <dt>w->set (struct ev_loop *)</dt> |
1839 | <dt>w->set (struct ev_loop *)</dt> |
1726 | <dd> |
1840 | <dd> |
1727 | <p>Associates a different <code>struct ev_loop</code> with this watcher. You can only |
1841 | <p>Associates a different <code>struct ev_loop</code> with this watcher. You can only |
1728 | do this when the watcher is inactive (and not pending either).</p> |
1842 | do this when the watcher is inactive (and not pending either).</p> |
1729 | </dd> |
1843 | </dd> |
1730 | <dt>w->set ([args])</dt> |
1844 | <dt>w->set ([args])</dt> |
1731 | <dd> |
1845 | <dd> |
1732 | <p>Basically the same as <code>ev_TYPE_set</code>, with the same args. Must be |
1846 | <p>Basically the same as <code>ev_TYPE_set</code>, with the same args. Must be |
1733 | called at least once. Unlike the C counterpart, an active watcher gets |
1847 | called at least once. Unlike the C counterpart, an active watcher gets |
1734 | automatically stopped and restarted.</p> |
1848 | automatically stopped and restarted when reconfiguring it with this |
|
|
1849 | method.</p> |
1735 | </dd> |
1850 | </dd> |
1736 | <dt>w->start ()</dt> |
1851 | <dt>w->start ()</dt> |
1737 | <dd> |
1852 | <dd> |
1738 | <p>Starts the watcher. Note that there is no <code>loop</code> argument as the |
1853 | <p>Starts the watcher. Note that there is no <code>loop</code> argument, as the |
1739 | constructor already takes the loop.</p> |
1854 | constructor already stores the event loop.</p> |
1740 | </dd> |
1855 | </dd> |
1741 | <dt>w->stop ()</dt> |
1856 | <dt>w->stop ()</dt> |
1742 | <dd> |
1857 | <dd> |
1743 | <p>Stops the watcher if it is active. Again, no <code>loop</code> argument.</p> |
1858 | <p>Stops the watcher if it is active. Again, no <code>loop</code> argument.</p> |
1744 | </dd> |
1859 | </dd> |
… | |
… | |
1768 | |
1883 | |
1769 | myclass (); |
1884 | myclass (); |
1770 | } |
1885 | } |
1771 | |
1886 | |
1772 | myclass::myclass (int fd) |
1887 | myclass::myclass (int fd) |
1773 | : io (this, &myclass::io_cb), |
|
|
1774 | idle (this, &myclass::idle_cb) |
|
|
1775 | { |
1888 | { |
|
|
1889 | io .set <myclass, &myclass::io_cb > (this); |
|
|
1890 | idle.set <myclass, &myclass::idle_cb> (this); |
|
|
1891 | |
1776 | io.start (fd, ev::READ); |
1892 | io.start (fd, ev::READ); |
1777 | } |
1893 | } |
1778 | |
1894 | |
1779 | |
1895 | |
1780 | |
1896 | |
… | |
… | |
1783 | |
1899 | |
1784 | </div> |
1900 | </div> |
1785 | <h1 id="MACRO_MAGIC">MACRO MAGIC</h1> |
1901 | <h1 id="MACRO_MAGIC">MACRO MAGIC</h1> |
1786 | <div id="MACRO_MAGIC_CONTENT"> |
1902 | <div id="MACRO_MAGIC_CONTENT"> |
1787 | <p>Libev can be compiled with a variety of options, the most fundemantal is |
1903 | <p>Libev can be compiled with a variety of options, the most fundemantal is |
1788 | <code>EV_MULTIPLICITY</code>. This option determines wether (most) functions and |
1904 | <code>EV_MULTIPLICITY</code>. This option determines whether (most) functions and |
1789 | callbacks have an initial <code>struct ev_loop *</code> argument.</p> |
1905 | callbacks have an initial <code>struct ev_loop *</code> argument.</p> |
1790 | <p>To make it easier to write programs that cope with either variant, the |
1906 | <p>To make it easier to write programs that cope with either variant, the |
1791 | following macros are defined:</p> |
1907 | following macros are defined:</p> |
1792 | <dl> |
1908 | <dl> |
1793 | <dt><code>EV_A</code>, <code>EV_A_</code></dt> |
1909 | <dt><code>EV_A</code>, <code>EV_A_</code></dt> |
… | |
… | |
1822 | <dd> |
1938 | <dd> |
1823 | <p>Similar to the other two macros, this gives you the value of the default |
1939 | <p>Similar to the other two macros, this gives you the value of the default |
1824 | loop, if multiple loops are supported ("ev loop default").</p> |
1940 | loop, if multiple loops are supported ("ev loop default").</p> |
1825 | </dd> |
1941 | </dd> |
1826 | </dl> |
1942 | </dl> |
1827 | <p>Example: Declare and initialise a check watcher, working regardless of |
1943 | <p>Example: Declare and initialise a check watcher, utilising the above |
1828 | wether multiple loops are supported or not.</p> |
1944 | macros so it will work regardless of whether multiple loops are supported |
|
|
1945 | or not.</p> |
1829 | <pre> static void |
1946 | <pre> static void |
1830 | check_cb (EV_P_ ev_timer *w, int revents) |
1947 | check_cb (EV_P_ ev_timer *w, int revents) |
1831 | { |
1948 | { |
1832 | ev_check_stop (EV_A_ w); |
1949 | ev_check_stop (EV_A_ w); |
1833 | } |
1950 | } |
1834 | |
1951 | |
1835 | ev_check check; |
1952 | ev_check check; |
1836 | ev_check_init (&check, check_cb); |
1953 | ev_check_init (&check, check_cb); |
1837 | ev_check_start (EV_DEFAULT_ &check); |
1954 | ev_check_start (EV_DEFAULT_ &check); |
1838 | ev_loop (EV_DEFAULT_ 0); |
1955 | ev_loop (EV_DEFAULT_ 0); |
1839 | |
|
|
1840 | |
|
|
1841 | |
|
|
1842 | |
1956 | |
1843 | </pre> |
1957 | </pre> |
1844 | |
1958 | |
1845 | </div> |
1959 | </div> |
1846 | <h1 id="EMBEDDING">EMBEDDING</h1> |
1960 | <h1 id="EMBEDDING">EMBEDDING</h1> |
… | |
… | |
1888 | ev_vars.h |
2002 | ev_vars.h |
1889 | ev_wrap.h |
2003 | ev_wrap.h |
1890 | |
2004 | |
1891 | ev_win32.c required on win32 platforms only |
2005 | ev_win32.c required on win32 platforms only |
1892 | |
2006 | |
1893 | ev_select.c only when select backend is enabled (which is by default) |
2007 | ev_select.c only when select backend is enabled (which is enabled by default) |
1894 | ev_poll.c only when poll backend is enabled (disabled by default) |
2008 | ev_poll.c only when poll backend is enabled (disabled by default) |
1895 | ev_epoll.c only when the epoll backend is enabled (disabled by default) |
2009 | ev_epoll.c only when the epoll backend is enabled (disabled by default) |
1896 | ev_kqueue.c only when the kqueue backend is enabled (disabled by default) |
2010 | ev_kqueue.c only when the kqueue backend is enabled (disabled by default) |
1897 | ev_port.c only when the solaris port backend is enabled (disabled by default) |
2011 | ev_port.c only when the solaris port backend is enabled (disabled by default) |
1898 | |
2012 | |
… | |
… | |
2063 | will have the <code>struct ev_loop *</code> as first argument, and you can create |
2177 | will have the <code>struct ev_loop *</code> as first argument, and you can create |
2064 | additional independent event loops. Otherwise there will be no support |
2178 | additional independent event loops. Otherwise there will be no support |
2065 | for multiple event loops and there is no first event loop pointer |
2179 | for multiple event loops and there is no first event loop pointer |
2066 | argument. Instead, all functions act on the single default loop.</p> |
2180 | argument. Instead, all functions act on the single default loop.</p> |
2067 | </dd> |
2181 | </dd> |
|
|
2182 | <dt>EV_MINPRI</dt> |
|
|
2183 | <dt>EV_MAXPRI</dt> |
|
|
2184 | <dd> |
|
|
2185 | <p>The range of allowed priorities. <code>EV_MINPRI</code> must be smaller or equal to |
|
|
2186 | <code>EV_MAXPRI</code>, but otherwise there are no non-obvious limitations. You can |
|
|
2187 | provide for more priorities by overriding those symbols (usually defined |
|
|
2188 | to be <code>-2</code> and <code>2</code>, respectively).</p> |
|
|
2189 | <p>When doing priority-based operations, libev usually has to linearly search |
|
|
2190 | all the priorities, so having many of them (hundreds) uses a lot of space |
|
|
2191 | and time, so using the defaults of five priorities (-2 .. +2) is usually |
|
|
2192 | fine.</p> |
|
|
2193 | <p>If your embedding app does not need any priorities, defining these both to |
|
|
2194 | <code>0</code> will save some memory and cpu.</p> |
|
|
2195 | </dd> |
2068 | <dt>EV_PERIODIC_ENABLE</dt> |
2196 | <dt>EV_PERIODIC_ENABLE</dt> |
2069 | <dd> |
2197 | <dd> |
2070 | <p>If undefined or defined to be <code>1</code>, then periodic timers are supported. If |
2198 | <p>If undefined or defined to be <code>1</code>, then periodic timers are supported. If |
|
|
2199 | defined to be <code>0</code>, then they are not. Disabling them saves a few kB of |
|
|
2200 | code.</p> |
|
|
2201 | </dd> |
|
|
2202 | <dt>EV_IDLE_ENABLE</dt> |
|
|
2203 | <dd> |
|
|
2204 | <p>If undefined or defined to be <code>1</code>, then idle watchers are supported. If |
2071 | defined to be <code>0</code>, then they are not. Disabling them saves a few kB of |
2205 | defined to be <code>0</code>, then they are not. Disabling them saves a few kB of |
2072 | code.</p> |
2206 | code.</p> |
2073 | </dd> |
2207 | </dd> |
2074 | <dt>EV_EMBED_ENABLE</dt> |
2208 | <dt>EV_EMBED_ENABLE</dt> |
2075 | <dd> |
2209 | <dd> |
… | |
… | |
2140 | the <cite>libev/</cite> subdirectory and includes them in the <cite>EV/EVAPI.h</cite> (public |
2274 | the <cite>libev/</cite> subdirectory and includes them in the <cite>EV/EVAPI.h</cite> (public |
2141 | interface) and <cite>EV.xs</cite> (implementation) files. Only the <cite>EV.xs</cite> file |
2275 | interface) and <cite>EV.xs</cite> (implementation) files. Only the <cite>EV.xs</cite> file |
2142 | will be compiled. It is pretty complex because it provides its own header |
2276 | will be compiled. It is pretty complex because it provides its own header |
2143 | file.</p> |
2277 | file.</p> |
2144 | <p>The usage in rxvt-unicode is simpler. It has a <cite>ev_cpp.h</cite> header file |
2278 | <p>The usage in rxvt-unicode is simpler. It has a <cite>ev_cpp.h</cite> header file |
2145 | that everybody includes and which overrides some autoconf choices:</p> |
2279 | that everybody includes and which overrides some configure choices:</p> |
|
|
2280 | <pre> #define EV_MINIMAL 1 |
2146 | <pre> #define EV_USE_POLL 0 |
2281 | #define EV_USE_POLL 0 |
2147 | #define EV_MULTIPLICITY 0 |
2282 | #define EV_MULTIPLICITY 0 |
2148 | #define EV_PERIODICS 0 |
2283 | #define EV_PERIODIC_ENABLE 0 |
|
|
2284 | #define EV_STAT_ENABLE 0 |
|
|
2285 | #define EV_FORK_ENABLE 0 |
2149 | #define EV_CONFIG_H <config.h> |
2286 | #define EV_CONFIG_H <config.h> |
|
|
2287 | #define EV_MINPRI 0 |
|
|
2288 | #define EV_MAXPRI 0 |
2150 | |
2289 | |
2151 | #include "ev++.h" |
2290 | #include "ev++.h" |
2152 | |
2291 | |
2153 | </pre> |
2292 | </pre> |
2154 | <p>And a <cite>ev_cpp.C</cite> implementation file that contains libev proper and is compiled:</p> |
2293 | <p>And a <cite>ev_cpp.C</cite> implementation file that contains libev proper and is compiled:</p> |
… | |
… | |
2164 | <h1 id="COMPLEXITIES">COMPLEXITIES</h1> |
2303 | <h1 id="COMPLEXITIES">COMPLEXITIES</h1> |
2165 | <div id="COMPLEXITIES_CONTENT"> |
2304 | <div id="COMPLEXITIES_CONTENT"> |
2166 | <p>In this section the complexities of (many of) the algorithms used inside |
2305 | <p>In this section the complexities of (many of) the algorithms used inside |
2167 | libev will be explained. For complexity discussions about backends see the |
2306 | libev will be explained. For complexity discussions about backends see the |
2168 | documentation for <code>ev_default_init</code>.</p> |
2307 | documentation for <code>ev_default_init</code>.</p> |
|
|
2308 | <p>All of the following are about amortised time: If an array needs to be |
|
|
2309 | extended, libev needs to realloc and move the whole array, but this |
|
|
2310 | happens asymptotically never with higher number of elements, so O(1) might |
|
|
2311 | mean it might do a lengthy realloc operation in rare cases, but on average |
|
|
2312 | it is much faster and asymptotically approaches constant time.</p> |
2169 | <p> |
2313 | <p> |
2170 | <dl> |
2314 | <dl> |
2171 | <dt>Starting and stopping timer/periodic watchers: O(log skipped_other_timers)</dt> |
2315 | <dt>Starting and stopping timer/periodic watchers: O(log skipped_other_timers)</dt> |
|
|
2316 | <dd> |
|
|
2317 | <p>This means that, when you have a watcher that triggers in one hour and |
|
|
2318 | there are 100 watchers that would trigger before that then inserting will |
|
|
2319 | have to skip those 100 watchers.</p> |
|
|
2320 | </dd> |
2172 | <dt>Changing timer/periodic watchers (by autorepeat, again): O(log skipped_other_timers)</dt> |
2321 | <dt>Changing timer/periodic watchers (by autorepeat, again): O(log skipped_other_timers)</dt> |
|
|
2322 | <dd> |
|
|
2323 | <p>That means that for changing a timer costs less than removing/adding them |
|
|
2324 | as only the relative motion in the event queue has to be paid for.</p> |
|
|
2325 | </dd> |
2173 | <dt>Starting io/check/prepare/idle/signal/child watchers: O(1)</dt> |
2326 | <dt>Starting io/check/prepare/idle/signal/child watchers: O(1)</dt> |
|
|
2327 | <dd> |
|
|
2328 | <p>These just add the watcher into an array or at the head of a list. |
2174 | <dt>Stopping check/prepare/idle watchers: O(1)</dt> |
2329 | =item Stopping check/prepare/idle watchers: O(1)</p> |
|
|
2330 | </dd> |
2175 | <dt>Stopping an io/signal/child watcher: O(number_of_watchers_for_this_(fd/signal/pid % EV_PID_HASHSIZE))</dt> |
2331 | <dt>Stopping an io/signal/child watcher: O(number_of_watchers_for_this_(fd/signal/pid % EV_PID_HASHSIZE))</dt> |
|
|
2332 | <dd> |
|
|
2333 | <p>These watchers are stored in lists then need to be walked to find the |
|
|
2334 | correct watcher to remove. The lists are usually short (you don't usually |
|
|
2335 | have many watchers waiting for the same fd or signal).</p> |
|
|
2336 | </dd> |
2176 | <dt>Finding the next timer per loop iteration: O(1)</dt> |
2337 | <dt>Finding the next timer per loop iteration: O(1)</dt> |
2177 | <dt>Each change on a file descriptor per loop iteration: O(number_of_watchers_for_this_fd)</dt> |
2338 | <dt>Each change on a file descriptor per loop iteration: O(number_of_watchers_for_this_fd)</dt> |
|
|
2339 | <dd> |
|
|
2340 | <p>A change means an I/O watcher gets started or stopped, which requires |
|
|
2341 | libev to recalculate its status (and possibly tell the kernel).</p> |
|
|
2342 | </dd> |
2178 | <dt>Activating one watcher: O(1)</dt> |
2343 | <dt>Activating one watcher: O(1)</dt> |
|
|
2344 | <dt>Priority handling: O(number_of_priorities)</dt> |
|
|
2345 | <dd> |
|
|
2346 | <p>Priorities are implemented by allocating some space for each |
|
|
2347 | priority. When doing priority-based operations, libev usually has to |
|
|
2348 | linearly search all the priorities.</p> |
|
|
2349 | </dd> |
2179 | </dl> |
2350 | </dl> |
2180 | </p> |
2351 | </p> |
2181 | |
2352 | |
2182 | |
2353 | |
2183 | |
2354 | |