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Revision 1.39 by root, Fri Dec 7 19:15:39 2007 UTC vs.
Revision 1.44 by root, Sat Dec 8 15:30:26 2007 UTC

… …
127.\} 127.\}
128.rm #[ #] #H #V #F C 128.rm #[ #] #H #V #F C
129.\" ======================================================================== 129.\" ========================================================================
130.\" 130.\"
131.IX Title ""<STANDARD INPUT>" 1" 131.IX Title ""<STANDARD INPUT>" 1"
132.TH "<STANDARD INPUT>" 1 "2007-12-07" "perl v5.8.8" "User Contributed Perl Documentation" 132.TH "<STANDARD INPUT>" 1 "2007-12-08" "perl v5.8.8" "User Contributed Perl Documentation"
133.SH "NAME" 133.SH "NAME"
134libev \- a high performance full\-featured event loop written in C 134libev \- a high performance full\-featured event loop written in C
135.SH "SYNOPSIS" 135.SH "SYNOPSIS"
136.IX Header "SYNOPSIS" 136.IX Header "SYNOPSIS"
137.Vb 1 137.Vb 1
… …
889.IP "bool ev_is_pending (ev_TYPE *watcher)" 4 889.IP "bool ev_is_pending (ev_TYPE *watcher)" 4
890.IX Item "bool ev_is_pending (ev_TYPE *watcher)" 890.IX Item "bool ev_is_pending (ev_TYPE *watcher)"
891Returns a true value iff the watcher is pending, (i.e. it has outstanding 891Returns a true value iff the watcher is pending, (i.e. it has outstanding
892events but its callback has not yet been invoked). As long as a watcher 892events but its callback has not yet been invoked). As long as a watcher
893is pending (but not active) you must not call an init function on it (but 893is pending (but not active) you must not call an init function on it (but
894\&\f(CW\*(C`ev_TYPE_set\*(C'\fR is safe) and you must make sure the watcher is available to 894\&\f(CW\*(C`ev_TYPE_set\*(C'\fR is safe), you must not change its priority, and you must
895libev (e.g. you cnanot \f(CW\*(C`free ()\*(C'\fR it). 895make sure the watcher is available to libev (e.g. you cannot \f(CW\*(C`free ()\*(C'\fR
896it).
896.IP "callback ev_cb (ev_TYPE *watcher)" 4 897.IP "callback ev_cb (ev_TYPE *watcher)" 4
897.IX Item "callback ev_cb (ev_TYPE *watcher)" 898.IX Item "callback ev_cb (ev_TYPE *watcher)"
898Returns the callback currently set on the watcher. 899Returns the callback currently set on the watcher.
899.IP "ev_cb_set (ev_TYPE *watcher, callback)" 4 900.IP "ev_cb_set (ev_TYPE *watcher, callback)" 4
900.IX Item "ev_cb_set (ev_TYPE *watcher, callback)" 901.IX Item "ev_cb_set (ev_TYPE *watcher, callback)"
… …
918watchers on the same event and make sure one is called first. 919watchers on the same event and make sure one is called first.
919.Sp 920.Sp
920If you need to suppress invocation when higher priority events are pending 921If you need to suppress invocation when higher priority events are pending
921you need to look at \f(CW\*(C`ev_idle\*(C'\fR watchers, which provide this functionality. 922you need to look at \f(CW\*(C`ev_idle\*(C'\fR watchers, which provide this functionality.
922.Sp 923.Sp
924You \fImust not\fR change the priority of a watcher as long as it is active or
925pending.
926.Sp
923The default priority used by watchers when no priority has been set is 927The default priority used by watchers when no priority has been set is
924always \f(CW0\fR, which is supposed to not be too high and not be too low :). 928always \f(CW0\fR, which is supposed to not be too high and not be too low :).
925.Sp 929.Sp
926Setting a priority outside the range of \f(CW\*(C`EV_MINPRI\*(C'\fR to \f(CW\*(C`EV_MAXPRI\*(C'\fR is 930Setting a priority outside the range of \f(CW\*(C`EV_MINPRI\*(C'\fR to \f(CW\*(C`EV_MAXPRI\*(C'\fR is
927fine, as long as you do not mind that the priority value you query might 931fine, as long as you do not mind that the priority value you query might
928or might not have been adjusted to be within valid range. 932or might not have been adjusted to be within valid range.
933.IP "ev_invoke (loop, ev_TYPE *watcher, int revents)" 4
934.IX Item "ev_invoke (loop, ev_TYPE *watcher, int revents)"
935Invoke the \f(CW\*(C`watcher\*(C'\fR with the given \f(CW\*(C`loop\*(C'\fR and \f(CW\*(C`revents\*(C'\fR. Neither
936\&\f(CW\*(C`loop\*(C'\fR nor \f(CW\*(C`revents\*(C'\fR need to be valid as long as the watcher callback
937can deal with that fact.
938.IP "int ev_clear_pending (loop, ev_TYPE *watcher)" 4
939.IX Item "int ev_clear_pending (loop, ev_TYPE *watcher)"
940If the watcher is pending, this function returns clears its pending status
941and returns its \f(CW\*(C`revents\*(C'\fR bitset (as if its callback was invoked). If the
942watcher isn't pending it does nothing and returns \f(CW0\fR.
929.Sh "\s-1ASSOCIATING\s0 \s-1CUSTOM\s0 \s-1DATA\s0 \s-1WITH\s0 A \s-1WATCHER\s0" 943.Sh "\s-1ASSOCIATING\s0 \s-1CUSTOM\s0 \s-1DATA\s0 \s-1WITH\s0 A \s-1WATCHER\s0"
930.IX Subsection "ASSOCIATING CUSTOM DATA WITH A WATCHER" 944.IX Subsection "ASSOCIATING CUSTOM DATA WITH A WATCHER"
931Each watcher has, by default, a member \f(CW\*(C`void *data\*(C'\fR that you can change 945Each watcher has, by default, a member \f(CW\*(C`void *data\*(C'\fR that you can change
932and read at any time, libev will completely ignore it. This can be used 946and read at any time, libev will completely ignore it. This can be used
933to associate arbitrary data with your watcher. If you need more data and 947to associate arbitrary data with your watcher. If you need more data and
… …
1630.PD 1644.PD
1631Initialises and configures the prepare or check watcher \- they have no 1645Initialises and configures the prepare or check watcher \- they have no
1632parameters of any kind. There are \f(CW\*(C`ev_prepare_set\*(C'\fR and \f(CW\*(C`ev_check_set\*(C'\fR 1646parameters of any kind. There are \f(CW\*(C`ev_prepare_set\*(C'\fR and \f(CW\*(C`ev_check_set\*(C'\fR
1633macros, but using them is utterly, utterly and completely pointless. 1647macros, but using them is utterly, utterly and completely pointless.
1634.PP 1648.PP
1635Example: To include a library such as adns, you would add \s-1IO\s0 watchers 1649There are a number of principal ways to embed other event loops or modules
1636and a timeout watcher in a prepare handler, as required by libadns, and 1650into libev. Here are some ideas on how to include libadns into libev
1651(there is a Perl module named \f(CW\*(C`EV::ADNS\*(C'\fR that does this, which you could
1652use for an actually working example. Another Perl module named \f(CW\*(C`EV::Glib\*(C'\fR
1653embeds a Glib main context into libev, and finally, \f(CW\*(C`Glib::EV\*(C'\fR embeds \s-1EV\s0
1654into the Glib event loop).
1655.PP
1656Method 1: Add \s-1IO\s0 watchers and a timeout watcher in a prepare handler,
1637in a check watcher, destroy them and call into libadns. What follows is 1657and in a check watcher, destroy them and call into libadns. What follows
1638pseudo-code only of course: 1658is pseudo-code only of course. This requires you to either use a low
1659priority for the check watcher or use \f(CW\*(C`ev_clear_pending\*(C'\fR explicitly, as
1660the callbacks for the IO/timeout watchers might not have been called yet.
1639.PP 1661.PP
1640.Vb 2 1662.Vb 2
1641\& static ev_io iow [nfd]; 1663\& static ev_io iow [nfd];
1642\& static ev_timer tw; 1664\& static ev_timer tw;
1643.Ve 1665.Ve
1644.PP 1666.PP
1645.Vb 9 1667.Vb 4
1646\& static void 1668\& static void
1647\& io_cb (ev_loop *loop, ev_io *w, int revents) 1669\& io_cb (ev_loop *loop, ev_io *w, int revents)
1648\& { 1670\& {
1649\& // set the relevant poll flags
1650\& // could also call adns_processreadable etc. here
1651\& struct pollfd *fd = (struct pollfd *)w->data;
1652\& if (revents & EV_READ ) fd->revents |= fd->events & POLLIN;
1653\& if (revents & EV_WRITE) fd->revents |= fd->events & POLLOUT;
1654\& } 1671\& }
1655.Ve 1672.Ve
1656.PP 1673.PP
1657.Vb 8 1674.Vb 8
1658\& // create io watchers for each fd and a timer before blocking 1675\& // create io watchers for each fd and a timer before blocking
… …
1670\& ev_timer_init (&tw, 0, timeout * 1e-3); 1687\& ev_timer_init (&tw, 0, timeout * 1e-3);
1671\& ev_timer_start (loop, &tw); 1688\& ev_timer_start (loop, &tw);
1672.Ve 1689.Ve
1673.PP 1690.PP
1674.Vb 6 1691.Vb 6
1675\& // create on ev_io per pollfd 1692\& // create one ev_io per pollfd
1676\& for (int i = 0; i < nfd; ++i) 1693\& for (int i = 0; i < nfd; ++i)
1677\& { 1694\& {
1678\& ev_io_init (iow + i, io_cb, fds [i].fd, 1695\& ev_io_init (iow + i, io_cb, fds [i].fd,
1679\& ((fds [i].events & POLLIN ? EV_READ : 0) 1696\& ((fds [i].events & POLLIN ? EV_READ : 0)
1680\& | (fds [i].events & POLLOUT ? EV_WRITE : 0))); 1697\& | (fds [i].events & POLLOUT ? EV_WRITE : 0)));
1681.Ve 1698.Ve
1682.PP 1699.PP
1683.Vb 5 1700.Vb 4
1684\& fds [i].revents = 0; 1701\& fds [i].revents = 0;
1685\& iow [i].data = fds + i;
1686\& ev_io_start (loop, iow + i); 1702\& ev_io_start (loop, iow + i);
1687\& } 1703\& }
1688\& } 1704\& }
1689.Ve 1705.Ve
1690.PP 1706.PP
… …
1694\& adns_check_cb (ev_loop *loop, ev_check *w, int revents) 1710\& adns_check_cb (ev_loop *loop, ev_check *w, int revents)
1695\& { 1711\& {
1696\& ev_timer_stop (loop, &tw); 1712\& ev_timer_stop (loop, &tw);
1697.Ve 1713.Ve
1698.PP 1714.PP
1699.Vb 2 1715.Vb 8
1700\& for (int i = 0; i < nfd; ++i) 1716\& for (int i = 0; i < nfd; ++i)
1717\& {
1718\& // set the relevant poll flags
1719\& // could also call adns_processreadable etc. here
1720\& struct pollfd *fd = fds + i;
1721\& int revents = ev_clear_pending (iow + i);
1722\& if (revents & EV_READ ) fd->revents |= fd->events & POLLIN;
1723\& if (revents & EV_WRITE) fd->revents |= fd->events & POLLOUT;
1724.Ve
1725.PP
1726.Vb 3
1727\& // now stop the watcher
1701\& ev_io_stop (loop, iow + i); 1728\& ev_io_stop (loop, iow + i);
1729\& }
1702.Ve 1730.Ve
1703.PP 1731.PP
1704.Vb 2 1732.Vb 2
1705\& adns_afterpoll (adns, fds, nfd, timeval_from (ev_now (loop)); 1733\& adns_afterpoll (adns, fds, nfd, timeval_from (ev_now (loop));
1734\& }
1735.Ve
1736.PP
1737Method 2: This would be just like method 1, but you run \f(CW\*(C`adns_afterpoll\*(C'\fR
1738in the prepare watcher and would dispose of the check watcher.
1739.PP
1740Method 3: If the module to be embedded supports explicit event
1741notification (adns does), you can also make use of the actual watcher
1742callbacks, and only destroy/create the watchers in the prepare watcher.
1743.PP
1744.Vb 5
1745\& static void
1746\& timer_cb (EV_P_ ev_timer *w, int revents)
1747\& {
1748\& adns_state ads = (adns_state)w->data;
1749\& update_now (EV_A);
1750.Ve
1751.PP
1752.Vb 2
1753\& adns_processtimeouts (ads, &tv_now);
1754\& }
1755.Ve
1756.PP
1757.Vb 5
1758\& static void
1759\& io_cb (EV_P_ ev_io *w, int revents)
1760\& {
1761\& adns_state ads = (adns_state)w->data;
1762\& update_now (EV_A);
1763.Ve
1764.PP
1765.Vb 3
1766\& if (revents & EV_READ ) adns_processreadable (ads, w->fd, &tv_now);
1767\& if (revents & EV_WRITE) adns_processwriteable (ads, w->fd, &tv_now);
1768\& }
1769.Ve
1770.PP
1771.Vb 1
1772\& // do not ever call adns_afterpoll
1773.Ve
1774.PP
1775Method 4: Do not use a prepare or check watcher because the module you
1776want to embed is too inflexible to support it. Instead, youc na override
1777their poll function. The drawback with this solution is that the main
1778loop is now no longer controllable by \s-1EV\s0. The \f(CW\*(C`Glib::EV\*(C'\fR module does
1779this.
1780.PP
1781.Vb 4
1782\& static gint
1783\& event_poll_func (GPollFD *fds, guint nfds, gint timeout)
1784\& {
1785\& int got_events = 0;
1786.Ve
1787.PP
1788.Vb 2
1789\& for (n = 0; n < nfds; ++n)
1790\& // create/start io watcher that sets the relevant bits in fds[n] and increment got_events
1791.Ve
1792.PP
1793.Vb 2
1794\& if (timeout >= 0)
1795\& // create/start timer
1796.Ve
1797.PP
1798.Vb 2
1799\& // poll
1800\& ev_loop (EV_A_ 0);
1801.Ve
1802.PP
1803.Vb 3
1804\& // stop timer again
1805\& if (timeout >= 0)
1806\& ev_timer_stop (EV_A_ &to);
1807.Ve
1808.PP
1809.Vb 3
1810\& // stop io watchers again - their callbacks should have set
1811\& for (n = 0; n < nfds; ++n)
1812\& ev_io_stop (EV_A_ iow [n]);
1813.Ve
1814.PP
1815.Vb 2
1816\& return got_events;
1706\& } 1817\& }
1707.Ve 1818.Ve
1708.ie n .Sh """ev_embed"" \- when one backend isn't enough..." 1819.ie n .Sh """ev_embed"" \- when one backend isn't enough..."
1709.el .Sh "\f(CWev_embed\fP \- when one backend isn't enough..." 1820.el .Sh "\f(CWev_embed\fP \- when one backend isn't enough..."
1710.IX Subsection "ev_embed - when one backend isn't enough..." 1821.IX Subsection "ev_embed - when one backend isn't enough..."
… …
1894.PP 2005.PP
1895.Vb 1 2006.Vb 1
1896\& #include <ev++.h> 2007\& #include <ev++.h>
1897.Ve 2008.Ve
1898.PP 2009.PP
1899(it is not installed by default). This automatically includes \fIev.h\fR 2010This automatically includes \fIev.h\fR and puts all of its definitions (many
1900and puts all of its definitions (many of them macros) into the global 2011of them macros) into the global namespace. All \*(C+ specific things are
1901namespace. All \*(C+ specific things are put into the \f(CW\*(C`ev\*(C'\fR namespace. 2012put into the \f(CW\*(C`ev\*(C'\fR namespace. It should support all the same embedding
2013options as \fIev.h\fR, most notably \f(CW\*(C`EV_MULTIPLICITY\*(C'\fR.
1902.PP 2014.PP
1903It should support all the same embedding options as \fIev.h\fR, most notably 2015Care has been taken to keep the overhead low. The only data member the \*(C+
1904\&\f(CW\*(C`EV_MULTIPLICITY\*(C'\fR. 2016classes add (compared to plain C\-style watchers) is the event loop pointer
2017that the watcher is associated with (or no additional members at all if
2018you disable \f(CW\*(C`EV_MULTIPLICITY\*(C'\fR when embedding libev).
2019.PP
2020Currently, functions, and static and non-static member functions can be
2021used as callbacks. Other types should be easy to add as long as they only
2022need one additional pointer for context. If you need support for other
2023types of functors please contact the author (preferably after implementing
2024it).
1905.PP 2025.PP
1906Here is a list of things available in the \f(CW\*(C`ev\*(C'\fR namespace: 2026Here is a list of things available in the \f(CW\*(C`ev\*(C'\fR namespace:
1907.ie n .IP """ev::READ""\fR, \f(CW""ev::WRITE"" etc." 4 2027.ie n .IP """ev::READ""\fR, \f(CW""ev::WRITE"" etc." 4
1908.el .IP "\f(CWev::READ\fR, \f(CWev::WRITE\fR etc." 4 2028.el .IP "\f(CWev::READ\fR, \f(CWev::WRITE\fR etc." 4
1909.IX Item "ev::READ, ev::WRITE etc." 2029.IX Item "ev::READ, ev::WRITE etc."
… …
1921which is called \f(CW\*(C`ev::sig\*(C'\fR to avoid clashes with the \f(CW\*(C`signal\*(C'\fR macro 2041which is called \f(CW\*(C`ev::sig\*(C'\fR to avoid clashes with the \f(CW\*(C`signal\*(C'\fR macro
1922defines by many implementations. 2042defines by many implementations.
1923.Sp 2043.Sp
1924All of those classes have these methods: 2044All of those classes have these methods:
1925.RS 4 2045.RS 4
1926.IP "ev::TYPE::TYPE (object *, object::method *)" 4 2046.IP "ev::TYPE::TYPE ()" 4
1927.IX Item "ev::TYPE::TYPE (object *, object::method *)" 2047.IX Item "ev::TYPE::TYPE ()"
1928.PD 0 2048.PD 0
1929.IP "ev::TYPE::TYPE (object *, object::method *, struct ev_loop *)" 4 2049.IP "ev::TYPE::TYPE (struct ev_loop *)" 4
1930.IX Item "ev::TYPE::TYPE (object *, object::method *, struct ev_loop *)" 2050.IX Item "ev::TYPE::TYPE (struct ev_loop *)"
1931.IP "ev::TYPE::~TYPE" 4 2051.IP "ev::TYPE::~TYPE" 4
1932.IX Item "ev::TYPE::~TYPE" 2052.IX Item "ev::TYPE::~TYPE"
1933.PD 2053.PD
1934The constructor takes a pointer to an object and a method pointer to 2054The constructor (optionally) takes an event loop to associate the watcher
1935the event handler callback to call in this class. The constructor calls 2055with. If it is omitted, it will use \f(CW\*(C`EV_DEFAULT\*(C'\fR.
1936\&\f(CW\*(C`ev_init\*(C'\fR for you, which means you have to call the \f(CW\*(C`set\*(C'\fR method 2056.Sp
1937before starting it. If you do not specify a loop then the constructor 2057The constructor calls \f(CW\*(C`ev_init\*(C'\fR for you, which means you have to call the
1938automatically associates the default loop with this watcher. 2058\&\f(CW\*(C`set\*(C'\fR method before starting it.
2059.Sp
2060It will not set a callback, however: You have to call the templated \f(CW\*(C`set\*(C'\fR
2061method to set a callback before you can start the watcher.
2062.Sp
2063(The reason why you have to use a method is a limitation in \*(C+ which does
2064not allow explicit template arguments for constructors).
1939.Sp 2065.Sp
1940The destructor automatically stops the watcher if it is active. 2066The destructor automatically stops the watcher if it is active.
2067.IP "w\->set<class, &class::method> (object *)" 4
2068.IX Item "w->set<class, &class::method> (object *)"
2069This method sets the callback method to call. The method has to have a
2070signature of \f(CW\*(C`void (*)(ev_TYPE &, int)\*(C'\fR, it receives the watcher as
2071first argument and the \f(CW\*(C`revents\*(C'\fR as second. The object must be given as
2072parameter and is stored in the \f(CW\*(C`data\*(C'\fR member of the watcher.
2073.Sp
2074This method synthesizes efficient thunking code to call your method from
2075the C callback that libev requires. If your compiler can inline your
2076callback (i.e. it is visible to it at the place of the \f(CW\*(C`set\*(C'\fR call and
2077your compiler is good :), then the method will be fully inlined into the
2078thunking function, making it as fast as a direct C callback.
2079.Sp
2080Example: simple class declaration and watcher initialisation
2081.Sp
2082.Vb 4
2083\& struct myclass
2084\& {
2085\& void io_cb (ev::io &w, int revents) { }
2086\& }
2087.Ve
2088.Sp
2089.Vb 3
2090\& myclass obj;
2091\& ev::io iow;
2092\& iow.set <myclass, &myclass::io_cb> (&obj);
2093.Ve
2094.IP "w\->set<function> (void *data = 0)" 4
2095.IX Item "w->set<function> (void *data = 0)"
2096Also sets a callback, but uses a static method or plain function as
2097callback. The optional \f(CW\*(C`data\*(C'\fR argument will be stored in the watcher's
2098\&\f(CW\*(C`data\*(C'\fR member and is free for you to use.
2099.Sp
2100The prototype of the \f(CW\*(C`function\*(C'\fR must be \f(CW\*(C`void (*)(ev::TYPE &w, int)\*(C'\fR.
2101.Sp
2102See the method\-\f(CW\*(C`set\*(C'\fR above for more details.
2103.Sp
2104Example:
2105.Sp
2106.Vb 2
2107\& static void io_cb (ev::io &w, int revents) { }
2108\& iow.set <io_cb> ();
2109.Ve
1941.IP "w\->set (struct ev_loop *)" 4 2110.IP "w\->set (struct ev_loop *)" 4
1942.IX Item "w->set (struct ev_loop *)" 2111.IX Item "w->set (struct ev_loop *)"
1943Associates a different \f(CW\*(C`struct ev_loop\*(C'\fR with this watcher. You can only 2112Associates a different \f(CW\*(C`struct ev_loop\*(C'\fR with this watcher. You can only
1944do this when the watcher is inactive (and not pending either). 2113do this when the watcher is inactive (and not pending either).
1945.IP "w\->set ([args])" 4 2114.IP "w\->set ([args])" 4
1946.IX Item "w->set ([args])" 2115.IX Item "w->set ([args])"
1947Basically the same as \f(CW\*(C`ev_TYPE_set\*(C'\fR, with the same args. Must be 2116Basically the same as \f(CW\*(C`ev_TYPE_set\*(C'\fR, with the same args. Must be
1948called at least once. Unlike the C counterpart, an active watcher gets 2117called at least once. Unlike the C counterpart, an active watcher gets
1949automatically stopped and restarted. 2118automatically stopped and restarted when reconfiguring it with this
2119method.
1950.IP "w\->start ()" 4 2120.IP "w\->start ()" 4
1951.IX Item "w->start ()" 2121.IX Item "w->start ()"
1952Starts the watcher. Note that there is no \f(CW\*(C`loop\*(C'\fR argument as the 2122Starts the watcher. Note that there is no \f(CW\*(C`loop\*(C'\fR argument, as the
1953constructor already takes the loop. 2123constructor already stores the event loop.
1954.IP "w\->stop ()" 4 2124.IP "w\->stop ()" 4
1955.IX Item "w->stop ()" 2125.IX Item "w->stop ()"
1956Stops the watcher if it is active. Again, no \f(CW\*(C`loop\*(C'\fR argument. 2126Stops the watcher if it is active. Again, no \f(CW\*(C`loop\*(C'\fR argument.
1957.ie n .IP "w\->again () ""ev::timer""\fR, \f(CW""ev::periodic"" only" 4 2127.ie n .IP "w\->again () ""ev::timer""\fR, \f(CW""ev::periodic"" only" 4
1958.el .IP "w\->again () \f(CWev::timer\fR, \f(CWev::periodic\fR only" 4 2128.el .IP "w\->again () \f(CWev::timer\fR, \f(CWev::periodic\fR only" 4
… …
1984.Vb 2 2154.Vb 2
1985\& myclass (); 2155\& myclass ();
1986\& } 2156\& }
1987.Ve 2157.Ve
1988.PP 2158.PP
1989.Vb 6 2159.Vb 4
1990\& myclass::myclass (int fd) 2160\& myclass::myclass (int fd)
1991\& : io (this, &myclass::io_cb),
1992\& idle (this, &myclass::idle_cb)
1993\& { 2161\& {
2162\& io .set <myclass, &myclass::io_cb > (this);
2163\& idle.set <myclass, &myclass::idle_cb> (this);
2164.Ve
2165.PP
2166.Vb 2
1994\& io.start (fd, ev::READ); 2167\& io.start (fd, ev::READ);
1995\& } 2168\& }
1996.Ve 2169.Ve
1997.SH "MACRO MAGIC" 2170.SH "MACRO MAGIC"
1998.IX Header "MACRO MAGIC" 2171.IX Header "MACRO MAGIC"
… …
2404.SH "COMPLEXITIES" 2577.SH "COMPLEXITIES"
2405.IX Header "COMPLEXITIES" 2578.IX Header "COMPLEXITIES"
2406In this section the complexities of (many of) the algorithms used inside 2579In this section the complexities of (many of) the algorithms used inside
2407libev will be explained. For complexity discussions about backends see the 2580libev will be explained. For complexity discussions about backends see the
2408documentation for \f(CW\*(C`ev_default_init\*(C'\fR. 2581documentation for \f(CW\*(C`ev_default_init\*(C'\fR.
2582.Sp
2583All of the following are about amortised time: If an array needs to be
2584extended, libev needs to realloc and move the whole array, but this
2585happens asymptotically never with higher number of elements, so O(1) might
2586mean it might do a lengthy realloc operation in rare cases, but on average
2587it is much faster and asymptotically approaches constant time.
2409.RS 4 2588.RS 4
2410.IP "Starting and stopping timer/periodic watchers: O(log skipped_other_timers)" 4 2589.IP "Starting and stopping timer/periodic watchers: O(log skipped_other_timers)" 4
2411.IX Item "Starting and stopping timer/periodic watchers: O(log skipped_other_timers)" 2590.IX Item "Starting and stopping timer/periodic watchers: O(log skipped_other_timers)"
2412This means that, when you have a watcher that triggers in one hour and 2591This means that, when you have a watcher that triggers in one hour and
2413there are 100 watchers that would trigger before that then inserting will 2592there are 100 watchers that would trigger before that then inserting will
… …
2416.IX Item "Changing timer/periodic watchers (by autorepeat, again): O(log skipped_other_timers)" 2595.IX Item "Changing timer/periodic watchers (by autorepeat, again): O(log skipped_other_timers)"
2417That means that for changing a timer costs less than removing/adding them 2596That means that for changing a timer costs less than removing/adding them
2418as only the relative motion in the event queue has to be paid for. 2597as only the relative motion in the event queue has to be paid for.
2419.IP "Starting io/check/prepare/idle/signal/child watchers: O(1)" 4 2598.IP "Starting io/check/prepare/idle/signal/child watchers: O(1)" 4
2420.IX Item "Starting io/check/prepare/idle/signal/child watchers: O(1)" 2599.IX Item "Starting io/check/prepare/idle/signal/child watchers: O(1)"
2421These just add the watcher into an array or at the head of a list. If 2600These just add the watcher into an array or at the head of a list.
2422the array needs to be extended libev needs to realloc and move the whole
2423array, but this happen asymptotically less and less with more watchers,
2424thus amortised O(1).
2425.IP "Stopping check/prepare/idle watchers: O(1)" 4
2426.IX Item "Stopping check/prepare/idle watchers: O(1)" 2601=item Stopping check/prepare/idle watchers: O(1)
2427.PD 0
2428.IP "Stopping an io/signal/child watcher: O(number_of_watchers_for_this_(fd/signal/pid % \s-1EV_PID_HASHSIZE\s0))" 4 2602.IP "Stopping an io/signal/child watcher: O(number_of_watchers_for_this_(fd/signal/pid % \s-1EV_PID_HASHSIZE\s0))" 4
2429.IX Item "Stopping an io/signal/child watcher: O(number_of_watchers_for_this_(fd/signal/pid % EV_PID_HASHSIZE))" 2603.IX Item "Stopping an io/signal/child watcher: O(number_of_watchers_for_this_(fd/signal/pid % EV_PID_HASHSIZE))"
2430.PD
2431These watchers are stored in lists then need to be walked to find the 2604These watchers are stored in lists then need to be walked to find the
2432correct watcher to remove. The lists are usually short (you don't usually 2605correct watcher to remove. The lists are usually short (you don't usually
2433have many watchers waiting for the same fd or signal). 2606have many watchers waiting for the same fd or signal).
2434.IP "Finding the next timer per loop iteration: O(1)" 4 2607.IP "Finding the next timer per loop iteration: O(1)" 4
2435.IX Item "Finding the next timer per loop iteration: O(1)" 2608.IX Item "Finding the next timer per loop iteration: O(1)"

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