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Revision 1.39 by root, Fri Dec 7 19:15:39 2007 UTC vs.
Revision 1.43 by root, Sat Dec 8 14:27:38 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
… …
1894.PP 1908.PP
1895.Vb 1 1909.Vb 1
1896\& #include <ev++.h> 1910\& #include <ev++.h>
1897.Ve 1911.Ve
1898.PP 1912.PP
1899(it is not installed by default). This automatically includes \fIev.h\fR 1913This 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 1914of 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. 1915put into the \f(CW\*(C`ev\*(C'\fR namespace. It should support all the same embedding
1916options as \fIev.h\fR, most notably \f(CW\*(C`EV_MULTIPLICITY\*(C'\fR.
1902.PP 1917.PP
1903It should support all the same embedding options as \fIev.h\fR, most notably 1918Care has been taken to keep the overhead low. The only data member the \*(C+
1904\&\f(CW\*(C`EV_MULTIPLICITY\*(C'\fR. 1919classes add (compared to plain C\-style watchers) is the event loop pointer
1920that the watcher is associated with (or no additional members at all if
1921you disable \f(CW\*(C`EV_MULTIPLICITY\*(C'\fR when embedding libev).
1922.PP
1923Currently, functions, and static and non-static member functions can be
1924used as callbacks. Other types should be easy to add as long as they only
1925need one additional pointer for context. If you need support for other
1926types of functors please contact the author (preferably after implementing
1927it).
1905.PP 1928.PP
1906Here is a list of things available in the \f(CW\*(C`ev\*(C'\fR namespace: 1929Here 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 1930.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 1931.el .IP "\f(CWev::READ\fR, \f(CWev::WRITE\fR etc." 4
1909.IX Item "ev::READ, ev::WRITE etc." 1932.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 1944which 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. 1945defines by many implementations.
1923.Sp 1946.Sp
1924All of those classes have these methods: 1947All of those classes have these methods:
1925.RS 4 1948.RS 4
1926.IP "ev::TYPE::TYPE (object *, object::method *)" 4 1949.IP "ev::TYPE::TYPE ()" 4
1927.IX Item "ev::TYPE::TYPE (object *, object::method *)" 1950.IX Item "ev::TYPE::TYPE ()"
1928.PD 0 1951.PD 0
1929.IP "ev::TYPE::TYPE (object *, object::method *, struct ev_loop *)" 4 1952.IP "ev::TYPE::TYPE (struct ev_loop *)" 4
1930.IX Item "ev::TYPE::TYPE (object *, object::method *, struct ev_loop *)" 1953.IX Item "ev::TYPE::TYPE (struct ev_loop *)"
1931.IP "ev::TYPE::~TYPE" 4 1954.IP "ev::TYPE::~TYPE" 4
1932.IX Item "ev::TYPE::~TYPE" 1955.IX Item "ev::TYPE::~TYPE"
1933.PD 1956.PD
1934The constructor takes a pointer to an object and a method pointer to 1957The constructor (optionally) takes an event loop to associate the watcher
1935the event handler callback to call in this class. The constructor calls 1958with. 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 1959.Sp
1937before starting it. If you do not specify a loop then the constructor 1960The 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. 1961\&\f(CW\*(C`set\*(C'\fR method before starting it.
1962.Sp
1963It will not set a callback, however: You have to call the templated \f(CW\*(C`set\*(C'\fR
1964method to set a callback before you can start the watcher.
1965.Sp
1966(The reason why you have to use a method is a limitation in \*(C+ which does
1967not allow explicit template arguments for constructors).
1939.Sp 1968.Sp
1940The destructor automatically stops the watcher if it is active. 1969The destructor automatically stops the watcher if it is active.
1970.IP "w\->set<class, &class::method> (object *)" 4
1971.IX Item "w->set<class, &class::method> (object *)"
1972This method sets the callback method to call. The method has to have a
1973signature of \f(CW\*(C`void (*)(ev_TYPE &, int)\*(C'\fR, it receives the watcher as
1974first argument and the \f(CW\*(C`revents\*(C'\fR as second. The object must be given as
1975parameter and is stored in the \f(CW\*(C`data\*(C'\fR member of the watcher.
1976.Sp
1977This method synthesizes efficient thunking code to call your method from
1978the C callback that libev requires. If your compiler can inline your
1979callback (i.e. it is visible to it at the place of the \f(CW\*(C`set\*(C'\fR call and
1980your compiler is good :), then the method will be fully inlined into the
1981thunking function, making it as fast as a direct C callback.
1982.Sp
1983Example: simple class declaration and watcher initialisation
1984.Sp
1985.Vb 4
1986\& struct myclass
1987\& {
1988\& void io_cb (ev::io &w, int revents) { }
1989\& }
1990.Ve
1991.Sp
1992.Vb 3
1993\& myclass obj;
1994\& ev::io iow;
1995\& iow.set <myclass, &myclass::io_cb> (&obj);
1996.Ve
1997.IP "w\->set<function> (void *data = 0)" 4
1998.IX Item "w->set<function> (void *data = 0)"
1999Also sets a callback, but uses a static method or plain function as
2000callback. The optional \f(CW\*(C`data\*(C'\fR argument will be stored in the watcher's
2001\&\f(CW\*(C`data\*(C'\fR member and is free for you to use.
2002.Sp
2003The prototype of the \f(CW\*(C`function\*(C'\fR must be \f(CW\*(C`void (*)(ev::TYPE &w, int)\*(C'\fR.
2004.Sp
2005See the method\-\f(CW\*(C`set\*(C'\fR above for more details.
2006.Sp
2007Example:
2008.Sp
2009.Vb 2
2010\& static void io_cb (ev::io &w, int revents) { }
2011\& iow.set <io_cb> ();
2012.Ve
1941.IP "w\->set (struct ev_loop *)" 4 2013.IP "w\->set (struct ev_loop *)" 4
1942.IX Item "w->set (struct ev_loop *)" 2014.IX Item "w->set (struct ev_loop *)"
1943Associates a different \f(CW\*(C`struct ev_loop\*(C'\fR with this watcher. You can only 2015Associates 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). 2016do this when the watcher is inactive (and not pending either).
1945.IP "w\->set ([args])" 4 2017.IP "w\->set ([args])" 4
1946.IX Item "w->set ([args])" 2018.IX Item "w->set ([args])"
1947Basically the same as \f(CW\*(C`ev_TYPE_set\*(C'\fR, with the same args. Must be 2019Basically 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 2020called at least once. Unlike the C counterpart, an active watcher gets
1949automatically stopped and restarted. 2021automatically stopped and restarted when reconfiguring it with this
2022method.
1950.IP "w\->start ()" 4 2023.IP "w\->start ()" 4
1951.IX Item "w->start ()" 2024.IX Item "w->start ()"
1952Starts the watcher. Note that there is no \f(CW\*(C`loop\*(C'\fR argument as the 2025Starts the watcher. Note that there is no \f(CW\*(C`loop\*(C'\fR argument, as the
1953constructor already takes the loop. 2026constructor already stores the event loop.
1954.IP "w\->stop ()" 4 2027.IP "w\->stop ()" 4
1955.IX Item "w->stop ()" 2028.IX Item "w->stop ()"
1956Stops the watcher if it is active. Again, no \f(CW\*(C`loop\*(C'\fR argument. 2029Stops 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 2030.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 2031.el .IP "w\->again () \f(CWev::timer\fR, \f(CWev::periodic\fR only" 4
… …
1984.Vb 2 2057.Vb 2
1985\& myclass (); 2058\& myclass ();
1986\& } 2059\& }
1987.Ve 2060.Ve
1988.PP 2061.PP
1989.Vb 6 2062.Vb 4
1990\& myclass::myclass (int fd) 2063\& myclass::myclass (int fd)
1991\& : io (this, &myclass::io_cb),
1992\& idle (this, &myclass::idle_cb)
1993\& { 2064\& {
2065\& io .set <myclass, &myclass::io_cb > (this);
2066\& idle.set <myclass, &myclass::idle_cb> (this);
2067.Ve
2068.PP
2069.Vb 2
1994\& io.start (fd, ev::READ); 2070\& io.start (fd, ev::READ);
1995\& } 2071\& }
1996.Ve 2072.Ve
1997.SH "MACRO MAGIC" 2073.SH "MACRO MAGIC"
1998.IX Header "MACRO MAGIC" 2074.IX Header "MACRO MAGIC"
… …
2404.SH "COMPLEXITIES" 2480.SH "COMPLEXITIES"
2405.IX Header "COMPLEXITIES" 2481.IX Header "COMPLEXITIES"
2406In this section the complexities of (many of) the algorithms used inside 2482In this section the complexities of (many of) the algorithms used inside
2407libev will be explained. For complexity discussions about backends see the 2483libev will be explained. For complexity discussions about backends see the
2408documentation for \f(CW\*(C`ev_default_init\*(C'\fR. 2484documentation for \f(CW\*(C`ev_default_init\*(C'\fR.
2485.Sp
2486All of the following are about amortised time: If an array needs to be
2487extended, libev needs to realloc and move the whole array, but this
2488happens asymptotically never with higher number of elements, so O(1) might
2489mean it might do a lengthy realloc operation in rare cases, but on average
2490it is much faster and asymptotically approaches constant time.
2409.RS 4 2491.RS 4
2410.IP "Starting and stopping timer/periodic watchers: O(log skipped_other_timers)" 4 2492.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)" 2493.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 2494This 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 2495there 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)" 2498.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 2499That 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. 2500as 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 2501.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)" 2502.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 2503These 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)" 2504=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 2505.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))" 2506.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 2507These 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 2508correct watcher to remove. The lists are usually short (you don't usually
2433have many watchers waiting for the same fd or signal). 2509have many watchers waiting for the same fd or signal).
2434.IP "Finding the next timer per loop iteration: O(1)" 4 2510.IP "Finding the next timer per loop iteration: O(1)" 4
2435.IX Item "Finding the next timer per loop iteration: O(1)" 2511.IX Item "Finding the next timer per loop iteration: O(1)"

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