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Comparing libev/ev.pod (file contents):
Revision 1.55 by root, Tue Nov 27 20:38:07 2007 UTC vs.
Revision 1.58 by root, Wed Nov 28 11:31:34 2007 UTC

… …
63details of the event, and then hand it over to libev by I<starting> the 63details of the event, and then hand it over to libev by I<starting> the
64watcher. 64watcher.
65 65
66=head1 FEATURES 66=head1 FEATURES
67 67
68Libev supports C<select>, C<poll>, the linux-specific C<epoll>, the 68Libev supports C<select>, C<poll>, the Linux-specific C<epoll>, the
69bsd-specific C<kqueue> and the solaris-specific event port mechanisms 69BSD-specific C<kqueue> and the Solaris-specific event port mechanisms
70for file descriptor events (C<ev_io>), relative timers (C<ev_timer>), 70for file descriptor events (C<ev_io>), the Linux C<inotify> interface
71(for C<ev_stat>), relative timers (C<ev_timer>), absolute timers
71absolute timers with customised rescheduling (C<ev_periodic>), synchronous 72with customised rescheduling (C<ev_periodic>), synchronous signals
72signals (C<ev_signal>), process status change events (C<ev_child>), and 73(C<ev_signal>), process status change events (C<ev_child>), and event
73event watchers dealing with the event loop mechanism itself (C<ev_idle>, 74watchers dealing with the event loop mechanism itself (C<ev_idle>,
74C<ev_embed>, C<ev_prepare> and C<ev_check> watchers) as well as 75C<ev_embed>, C<ev_prepare> and C<ev_check> watchers) as well as
75file watchers (C<ev_stat>) and even limited support for fork events 76file watchers (C<ev_stat>) and even limited support for fork events
76(C<ev_fork>). 77(C<ev_fork>).
77 78
78It also is quite fast (see this 79It also is quite fast (see this
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1222not exist" is signified by the C<st_nlink> field being zero (which is 1223not exist" is signified by the C<st_nlink> field being zero (which is
1223otherwise always forced to be at least one) and all the other fields of 1224otherwise always forced to be at least one) and all the other fields of
1224the stat buffer having unspecified contents. 1225the stat buffer having unspecified contents.
1225 1226
1226Since there is no standard to do this, the portable implementation simply 1227Since there is no standard to do this, the portable implementation simply
1227calls C<stat (2)> regulalry on the path to see if it changed somehow. You 1228calls C<stat (2)> regularly on the path to see if it changed somehow. You
1228can specify a recommended polling interval for this case. If you specify 1229can specify a recommended polling interval for this case. If you specify
1229a polling interval of C<0> (highly recommended!) then a I<suitable, 1230a polling interval of C<0> (highly recommended!) then a I<suitable,
1230unspecified default> value will be used (which you can expect to be around 1231unspecified default> value will be used (which you can expect to be around
1231five seconds, although this might change dynamically). Libev will also 1232five seconds, although this might change dynamically). Libev will also
1232impose a minimum interval which is currently around C<0.1>, but thats 1233impose a minimum interval which is currently around C<0.1>, but thats
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1234 1235
1235This watcher type is not meant for massive numbers of stat watchers, 1236This watcher type is not meant for massive numbers of stat watchers,
1236as even with OS-supported change notifications, this can be 1237as even with OS-supported change notifications, this can be
1237resource-intensive. 1238resource-intensive.
1238 1239
1239At the time of this writing, no specific OS backends are implemented, but 1240At the time of this writing, only the Linux inotify interface is
1240if demand increases, at least a kqueue and inotify backend will be added. 1241implemented (implementing kqueue support is left as an exercise for the
1242reader). Inotify will be used to give hints only and should not change the
1243semantics of C<ev_stat> watchers, which means that libev sometimes needs
1244to fall back to regular polling again even with inotify, but changes are
1245usually detected immediately, and if the file exists there will be no
1246polling.
1241 1247
1242=over 4 1248=over 4
1243 1249
1244=item ev_stat_init (ev_stat *, callback, const char *path, ev_tstamp interval) 1250=item ev_stat_init (ev_stat *, callback, const char *path, ev_tstamp interval)
1245 1251
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2014 2020
2015=item EV_USE_DEVPOLL 2021=item EV_USE_DEVPOLL
2016 2022
2017reserved for future expansion, works like the USE symbols above. 2023reserved for future expansion, works like the USE symbols above.
2018 2024
2025=item EV_USE_INOTIFY
2026
2027If defined to be C<1>, libev will compile in support for the Linux inotify
2028interface to speed up C<ev_stat> watchers. Its actual availability will
2029be detected at runtime.
2030
2019=item EV_H 2031=item EV_H
2020 2032
2021The name of the F<ev.h> header file used to include it. The default if 2033The name of the F<ev.h> header file used to include it. The default if
2022undefined is C<< <ev.h> >> in F<event.h> and C<"ev.h"> in F<ev.c>. This 2034undefined is C<< <ev.h> >> in F<event.h> and C<"ev.h"> in F<ev.c>. This
2023can be used to virtually rename the F<ev.h> header file in case of conflicts. 2035can be used to virtually rename the F<ev.h> header file in case of conflicts.
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2078=item EV_PID_HASHSIZE 2090=item EV_PID_HASHSIZE
2079 2091
2080C<ev_child> watchers use a small hash table to distribute workload by 2092C<ev_child> watchers use a small hash table to distribute workload by
2081pid. The default size is C<16> (or C<1> with C<EV_MINIMAL>), usually more 2093pid. The default size is C<16> (or C<1> with C<EV_MINIMAL>), usually more
2082than enough. If you need to manage thousands of children you might want to 2094than enough. If you need to manage thousands of children you might want to
2083increase this value. 2095increase this value (I<must> be a power of two).
2096
2097=item EV_INOTIFY_HASHSIZE
2098
2099C<ev_staz> watchers use a small hash table to distribute workload by
2100inotify watch id. The default size is C<16> (or C<1> with C<EV_MINIMAL>),
2101usually more than enough. If you need to manage thousands of C<ev_stat>
2102watchers you might want to increase this value (I<must> be a power of
2103two).
2084 2104
2085=item EV_COMMON 2105=item EV_COMMON
2086 2106
2087By default, all watchers have a C<void *data> member. By redefining 2107By default, all watchers have a C<void *data> member. By redefining
2088this macro to a something else you can include more and other types of 2108this macro to a something else you can include more and other types of
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2148 2168
2149=item Starting io/check/prepare/idle/signal/child watchers: O(1) 2169=item Starting io/check/prepare/idle/signal/child watchers: O(1)
2150 2170
2151=item Stopping check/prepare/idle watchers: O(1) 2171=item Stopping check/prepare/idle watchers: O(1)
2152 2172
2153=item Stopping an io/signal/child watcher: O(number_of_watchers_for_this_(fd/signal/pid % 16)) 2173=item Stopping an io/signal/child watcher: O(number_of_watchers_for_this_(fd/signal/pid % EV_PID_HASHSIZE))
2154 2174
2155=item Finding the next timer per loop iteration: O(1) 2175=item Finding the next timer per loop iteration: O(1)
2156 2176
2157=item Each change on a file descriptor per loop iteration: O(number_of_watchers_for_this_fd) 2177=item Each change on a file descriptor per loop iteration: O(number_of_watchers_for_this_fd)
2158 2178

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