#include <ev.h>
-=head1 EXAMPLE PROGRAM
+=head2 EXAMPLE PROGRAM
#include <ev.h>
details of the event, and then hand it over to libev by I<starting> the
watcher.
-=head1 FEATURES
+=head2 FEATURES
Libev supports C<select>, C<poll>, the Linux-specific C<epoll>, the
BSD-specific C<kqueue> and the Solaris-specific event port mechanisms
L<benchmark|http://libev.schmorp.de/bench.html> comparing it to libevent
for example).
-=head1 CONVENTIONS
+=head2 CONVENTIONS
Libev is very configurable. In this manual the default configuration will
be described, which supports multiple event loops. For more info about
loops, then all functions taking an initial argument of name C<loop>
(which is always of type C<struct ev_loop *>) will not have this argument.
-=head1 TIME REPRESENTATION
+=head2 TIME REPRESENTATION
Libev represents time as a single floating point number, representing the
(fractional) number of seconds since the (POSIX) epoch (somewhere near
This means that, when you have a watcher that triggers in one hour and
there are 100 watchers that would trigger before that then inserting will
-have to skip those 100 watchers.
+have to skip roughly seven (C<ld 100>) of these watchers.
-=item Changing timer/periodic watchers (by autorepeat, again): O(log skipped_other_timers)
+=item Changing timer/periodic watchers (by autorepeat or calling again): O(log skipped_other_timers)
-That means that for changing a timer costs less than removing/adding them
+That means that changing a timer costs less than removing/adding them
as only the relative motion in the event queue has to be paid for.
=item Starting io/check/prepare/idle/signal/child watchers: O(1)
These just add the watcher into an array or at the head of a list.
+
=item Stopping check/prepare/idle watchers: O(1)
=item Stopping an io/signal/child watcher: O(number_of_watchers_for_this_(fd/signal/pid % EV_PID_HASHSIZE))
correct watcher to remove. The lists are usually short (you don't usually
have many watchers waiting for the same fd or signal).
-=item Finding the next timer per loop iteration: O(1)
+=item Finding the next timer in each loop iteration: O(1)
+
+By virtue of using a binary heap, the next timer is always found at the
+beginning of the storage array.
=item Each change on a file descriptor per loop iteration: O(number_of_watchers_for_this_fd)
A change means an I/O watcher gets started or stopped, which requires
-libev to recalculate its status (and possibly tell the kernel).
+libev to recalculate its status (and possibly tell the kernel, depending
+on backend and wether C<ev_io_set> was used).
-=item Activating one watcher: O(1)
+=item Activating one watcher (putting it into the pending state): O(1)
=item Priority handling: O(number_of_priorities)
Priorities are implemented by allocating some space for each
priority. When doing priority-based operations, libev usually has to
-linearly search all the priorities.
+linearly search all the priorities, but starting/stopping and activating
+watchers becomes O(1) w.r.t. prioritiy handling.
=back
projects / software / libev.git / blobdiff