*** empty log message ***

[software/libev.git] / ev.3

diff --git a/ev.3 b/ev.3
index 9e1c613d42eacb8e87c62c0c4e4ff48651b3535f..4f3bfef260a4f1ff7f864522a6e7256967f64b6b 100644 (file)
--- a/ev.3
+++ b/ev.3
@@ -129,7 +129,7 @@
 .\" ========================================================================
 .\"
 .IX Title ""<STANDARD INPUT>" 1"
 .\" ========================================================================
 .\"
 .IX Title ""<STANDARD INPUT>" 1"

-.TH "<STANDARD INPUT>" 1 "2007-11-28" "perl v5.8.8" "User Contributed Perl Documentation"
+.TH "<STANDARD INPUT>" 1 "2007-12-09" "perl v5.8.8" "User Contributed Perl Documentation"

 .SH "NAME"
 libev \- a high performance full\-featured event loop written in C
 .SH "SYNOPSIS"
 .SH "NAME"
 libev \- a high performance full\-featured event loop written in C
 .SH "SYNOPSIS"


@@ -198,6 +198,10 @@ libev \- a high performance full\-featured event loop written in C
 .Ve
 .SH "DESCRIPTION"
 .IX Header "DESCRIPTION"
 .Ve
 .SH "DESCRIPTION"
 .IX Header "DESCRIPTION"

+The newest version of this document is also available as a html-formatted
+web page you might find easier to navigate when reading it for the first
+time: <http://cvs.schmorp.de/libev/ev.html>.
+.PP

 Libev is an event loop: you register interest in certain events (such as a
 file descriptor being readable or a timeout occuring), and it will manage
 these event sources and provide your program with events.
 Libev is an event loop: you register interest in certain events (such as a
 file descriptor being readable or a timeout occuring), and it will manage
 these event sources and provide your program with events.


@@ -257,14 +261,17 @@ you actually want to know.
 .IP "int ev_version_minor ()" 4
 .IX Item "int ev_version_minor ()"
 .PD
 .IP "int ev_version_minor ()" 4
 .IX Item "int ev_version_minor ()"
 .PD

-You can find out the major and minor version numbers of the library
+You can find out the major and minor \s-1ABI\s0 version numbers of the library

 you linked against by calling the functions \f(CW\*(C`ev_version_major\*(C'\fR and
 \&\f(CW\*(C`ev_version_minor\*(C'\fR. If you want, you can compare against the global
 symbols \f(CW\*(C`EV_VERSION_MAJOR\*(C'\fR and \f(CW\*(C`EV_VERSION_MINOR\*(C'\fR, which specify the
 version of the library your program was compiled against.
 .Sp
 you linked against by calling the functions \f(CW\*(C`ev_version_major\*(C'\fR and
 \&\f(CW\*(C`ev_version_minor\*(C'\fR. If you want, you can compare against the global
 symbols \f(CW\*(C`EV_VERSION_MAJOR\*(C'\fR and \f(CW\*(C`EV_VERSION_MINOR\*(C'\fR, which specify the
 version of the library your program was compiled against.
 .Sp

+These version numbers refer to the \s-1ABI\s0 version of the library, not the
+release version.
+.Sp

 Usually, it's a good idea to terminate if the major versions mismatch,
 Usually, it's a good idea to terminate if the major versions mismatch,

-as this indicates an incompatible change.  Minor versions are usually
+as this indicates an incompatible change. Minor versions are usually

 compatible to older versions, so a larger minor version alone is usually
 not a problem.
 .Sp
 compatible to older versions, so a larger minor version alone is usually
 not a problem.
 .Sp


@@ -413,6 +420,26 @@ or setgid) then libev will \fInot\fR look at the environment variable
 override the flags completely if it is found in the environment. This is
 useful to try out specific backends to test their performance, or to work
 around bugs.
 override the flags completely if it is found in the environment. This is
 useful to try out specific backends to test their performance, or to work
 around bugs.

+.ie n .IP """EVFLAG_FORKCHECK""" 4
+.el .IP "\f(CWEVFLAG_FORKCHECK\fR" 4
+.IX Item "EVFLAG_FORKCHECK"
+Instead of calling \f(CW\*(C`ev_default_fork\*(C'\fR or \f(CW\*(C`ev_loop_fork\*(C'\fR manually after
+a fork, you can also make libev check for a fork in each iteration by
+enabling this flag.
+.Sp
+This works by calling \f(CW\*(C`getpid ()\*(C'\fR on every iteration of the loop,
+and thus this might slow down your event loop if you do a lot of loop
+iterations and little real work, but is usually not noticeable (on my
+Linux system for example, \f(CW\*(C`getpid\*(C'\fR is actually a simple 5\-insn sequence
+without a syscall and thus \fIvery\fR fast, but my Linux system also has
+\&\f(CW\*(C`pthread_atfork\*(C'\fR which is even faster).
+.Sp
+The big advantage of this flag is that you can forget about fork (and
+forget about forgetting to tell libev about forking) when you use this
+flag.
+.Sp
+This flag setting cannot be overriden or specified in the \f(CW\*(C`LIBEV_FLAGS\*(C'\fR
+environment variable.

 .ie n .IP """EVBACKEND_SELECT""  (value 1, portable select backend)" 4
 .el .IP "\f(CWEVBACKEND_SELECT\fR  (value 1, portable select backend)" 4
 .IX Item "EVBACKEND_SELECT  (value 1, portable select backend)"
 .ie n .IP """EVBACKEND_SELECT""  (value 1, portable select backend)" 4
 .el .IP "\f(CWEVBACKEND_SELECT\fR  (value 1, portable select backend)" 4
 .IX Item "EVBACKEND_SELECT  (value 1, portable select backend)"


@@ -563,6 +590,15 @@ do not need to care.
 Like \f(CW\*(C`ev_default_fork\*(C'\fR, but acts on an event loop created by
 \&\f(CW\*(C`ev_loop_new\*(C'\fR. Yes, you have to call this on every allocated event loop
 after fork, and how you do this is entirely your own problem.
 Like \f(CW\*(C`ev_default_fork\*(C'\fR, but acts on an event loop created by
 \&\f(CW\*(C`ev_loop_new\*(C'\fR. Yes, you have to call this on every allocated event loop
 after fork, and how you do this is entirely your own problem.

+.IP "unsigned int ev_loop_count (loop)" 4
+.IX Item "unsigned int ev_loop_count (loop)"
+Returns the count of loop iterations for the loop, which is identical to
+the number of times libev did poll for new events. It starts at \f(CW0\fR and
+happily wraps around with enough iterations.
+.Sp
+This value can sometimes be useful as a generation counter of sorts (it
+\&\*(L"ticks\*(R" the number of loop iterations), as it roughly corresponds with
+\&\f(CW\*(C`ev_prepare\*(C'\fR and \f(CW\*(C`ev_check\*(C'\fR calls.

 .IP "unsigned int ev_backend (loop)" 4
 .IX Item "unsigned int ev_backend (loop)"
 Returns one of the \f(CW\*(C`EVBACKEND_*\*(C'\fR flags indicating the event backend in
 .IP "unsigned int ev_backend (loop)" 4
 .IX Item "unsigned int ev_backend (loop)"
 Returns one of the \f(CW\*(C`EVBACKEND_*\*(C'\fR flags indicating the event backend in


@@ -603,9 +639,10 @@ usually a better approach for this kind of thing.
 .Sp
 Here are the gory details of what \f(CW\*(C`ev_loop\*(C'\fR does:
 .Sp
 .Sp
 Here are the gory details of what \f(CW\*(C`ev_loop\*(C'\fR does:
 .Sp

-.Vb 18
+.Vb 19
+\&   - Before the first iteration, call any pending watchers.

 \&   * If there are no active watchers (reference count is zero), return.
 \&   * If there are no active watchers (reference count is zero), return.

-\&   - Queue prepare watchers and then call all outstanding watchers.
+\&   - Queue all prepare watchers and then call all outstanding watchers.

 \&   - If we have been forked, recreate the kernel state.
 \&   - Update the kernel state with all outstanding changes.
 \&   - Update the "event loop time".
 \&   - If we have been forked, recreate the kernel state.
 \&   - Update the kernel state with all outstanding changes.
 \&   - Update the "event loop time".


@@ -858,8 +895,9 @@ it.
 Returns a true value iff the watcher is pending, (i.e. it has outstanding
 events but its callback has not yet been invoked). As long as a watcher
 is pending (but not active) you must not call an init function on it (but
 Returns a true value iff the watcher is pending, (i.e. it has outstanding
 events but its callback has not yet been invoked). As long as a watcher
 is pending (but not active) you must not call an init function on it (but

-\&\f(CW\*(C`ev_TYPE_set\*(C'\fR is safe) and you must make sure the watcher is available to
-libev (e.g. you cnanot \f(CW\*(C`free ()\*(C'\fR it).
+\&\f(CW\*(C`ev_TYPE_set\*(C'\fR is safe), you must not change its priority, and you must
+make sure the watcher is available to libev (e.g. you cannot \f(CW\*(C`free ()\*(C'\fR
+it).

 .IP "callback ev_cb (ev_TYPE *watcher)" 4
 .IX Item "callback ev_cb (ev_TYPE *watcher)"
 Returns the callback currently set on the watcher.
 .IP "callback ev_cb (ev_TYPE *watcher)" 4
 .IX Item "callback ev_cb (ev_TYPE *watcher)"
 Returns the callback currently set on the watcher.


@@ -867,6 +905,45 @@ Returns the callback currently set on the watcher.
 .IX Item "ev_cb_set (ev_TYPE *watcher, callback)"
 Change the callback. You can change the callback at virtually any time
 (modulo threads).
 .IX Item "ev_cb_set (ev_TYPE *watcher, callback)"
 Change the callback. You can change the callback at virtually any time
 (modulo threads).

+.IP "ev_set_priority (ev_TYPE *watcher, priority)" 4
+.IX Item "ev_set_priority (ev_TYPE *watcher, priority)"
+.PD 0
+.IP "int ev_priority (ev_TYPE *watcher)" 4
+.IX Item "int ev_priority (ev_TYPE *watcher)"
+.PD
+Set and query the priority of the watcher. The priority is a small
+integer between \f(CW\*(C`EV_MAXPRI\*(C'\fR (default: \f(CW2\fR) and \f(CW\*(C`EV_MINPRI\*(C'\fR
+(default: \f(CW\*(C`\-2\*(C'\fR). Pending watchers with higher priority will be invoked
+before watchers with lower priority, but priority will not keep watchers
+from being executed (except for \f(CW\*(C`ev_idle\*(C'\fR watchers).
+.Sp
+This means that priorities are \fIonly\fR used for ordering callback
+invocation after new events have been received. This is useful, for
+example, to reduce latency after idling, or more often, to bind two
+watchers on the same event and make sure one is called first.
+.Sp
+If you need to suppress invocation when higher priority events are pending
+you need to look at \f(CW\*(C`ev_idle\*(C'\fR watchers, which provide this functionality.
+.Sp
+You \fImust not\fR change the priority of a watcher as long as it is active or
+pending.
+.Sp
+The default priority used by watchers when no priority has been set is
+always \f(CW0\fR, which is supposed to not be too high and not be too low :).
+.Sp
+Setting a priority outside the range of \f(CW\*(C`EV_MINPRI\*(C'\fR to \f(CW\*(C`EV_MAXPRI\*(C'\fR is
+fine, as long as you do not mind that the priority value you query might
+or might not have been adjusted to be within valid range.
+.IP "ev_invoke (loop, ev_TYPE *watcher, int revents)" 4
+.IX Item "ev_invoke (loop, ev_TYPE *watcher, int revents)"
+Invoke the \f(CW\*(C`watcher\*(C'\fR with the given \f(CW\*(C`loop\*(C'\fR and \f(CW\*(C`revents\*(C'\fR. Neither
+\&\f(CW\*(C`loop\*(C'\fR nor \f(CW\*(C`revents\*(C'\fR need to be valid as long as the watcher callback
+can deal with that fact.
+.IP "int ev_clear_pending (loop, ev_TYPE *watcher)" 4
+.IX Item "int ev_clear_pending (loop, ev_TYPE *watcher)"
+If the watcher is pending, this function returns clears its pending status
+and returns its \f(CW\*(C`revents\*(C'\fR bitset (as if its callback was invoked). If the
+watcher isn't pending it does nothing and returns \f(CW0\fR.

 .Sh "\s-1ASSOCIATING\s0 \s-1CUSTOM\s0 \s-1DATA\s0 \s-1WITH\s0 A \s-1WATCHER\s0"
 .IX Subsection "ASSOCIATING CUSTOM DATA WITH A WATCHER"
 Each watcher has, by default, a member \f(CW\*(C`void *data\*(C'\fR that you can change
 .Sh "\s-1ASSOCIATING\s0 \s-1CUSTOM\s0 \s-1DATA\s0 \s-1WITH\s0 A \s-1WATCHER\s0"
 .IX Subsection "ASSOCIATING CUSTOM DATA WITH A WATCHER"
 Each watcher has, by default, a member \f(CW\*(C`void *data\*(C'\fR that you can change


@@ -987,7 +1064,7 @@ it is best to always use non-blocking I/O: An extra \f(CW\*(C`read\*(C'\fR(2) re
 .PP
 If you cannot run the fd in non-blocking mode (for example you should not
 play around with an Xlib connection), then you have to seperately re-test
 .PP
 If you cannot run the fd in non-blocking mode (for example you should not
 play around with an Xlib connection), then you have to seperately re-test

-wether a file descriptor is really ready with a known-to-be good interface
+whether a file descriptor is really ready with a known-to-be good interface

 such as poll (fortunately in our Xlib example, Xlib already does this on
 its own, so its quite safe to use).
 .IP "ev_io_init (ev_io *, callback, int fd, int events)" 4
 such as poll (fortunately in our Xlib example, Xlib already does this on
 its own, so its quite safe to use).
 .IP "ev_io_init (ev_io *, callback, int fd, int events)" 4


@@ -1073,23 +1150,25 @@ timer will not fire more than once per event loop iteration.
 This will act as if the timer timed out and restart it again if it is
 repeating. The exact semantics are:
 .Sp
 This will act as if the timer timed out and restart it again if it is
 repeating. The exact semantics are:
 .Sp

-If the timer is started but nonrepeating, stop it.
+If the timer is pending, its pending status is cleared.

 .Sp
 .Sp

-If the timer is repeating, either start it if necessary (with the repeat
-value), or reset the running timer to the repeat value.
+If the timer is started but nonrepeating, stop it (as if it timed out).
+.Sp
+If the timer is repeating, either start it if necessary (with the
+\&\f(CW\*(C`repeat\*(C'\fR value), or reset the running timer to the \f(CW\*(C`repeat\*(C'\fR value.

 .Sp
 This sounds a bit complicated, but here is a useful and typical
 .Sp
 This sounds a bit complicated, but here is a useful and typical

-example: Imagine you have a tcp connection and you want a so-called
-idle timeout, that is, you want to be called when there have been,
-say, 60 seconds of inactivity on the socket. The easiest way to do
-this is to configure an \f(CW\*(C`ev_timer\*(C'\fR with \f(CW\*(C`after\*(C'\fR=\f(CW\*(C`repeat\*(C'\fR=\f(CW60\fR and calling
+example: Imagine you have a tcp connection and you want a so-called idle
+timeout, that is, you want to be called when there have been, say, 60
+seconds of inactivity on the socket. The easiest way to do this is to
+configure an \f(CW\*(C`ev_timer\*(C'\fR with a \f(CW\*(C`repeat\*(C'\fR value of \f(CW60\fR and then call

 \&\f(CW\*(C`ev_timer_again\*(C'\fR each time you successfully read or write some data. If
 you go into an idle state where you do not expect data to travel on the
 \&\f(CW\*(C`ev_timer_again\*(C'\fR each time you successfully read or write some data. If
 you go into an idle state where you do not expect data to travel on the

-socket, you can stop the timer, and again will automatically restart it if
-need be.
+socket, you can \f(CW\*(C`ev_timer_stop\*(C'\fR the timer, and \f(CW\*(C`ev_timer_again\*(C'\fR will
+automatically restart it if need be.

 .Sp
 .Sp

-You can also ignore the \f(CW\*(C`after\*(C'\fR value and \f(CW\*(C`ev_timer_start\*(C'\fR altogether
-and only ever use the \f(CW\*(C`repeat\*(C'\fR value:
+That means you can ignore the \f(CW\*(C`after\*(C'\fR value and \f(CW\*(C`ev_timer_start\*(C'\fR
+altogether and only ever use the \f(CW\*(C`repeat\*(C'\fR value and \f(CW\*(C`ev_timer_again\*(C'\fR:

 .Sp
 .Vb 8
 \&   ev_timer_init (timer, callback, 0., 5.);
 .Sp
 .Vb 8
 \&   ev_timer_init (timer, callback, 0., 5.);


@@ -1102,8 +1181,8 @@ and only ever use the \f(CW\*(C`repeat\*(C'\fR value:
 \&   ev_timer_again (loop, timer);
 .Ve
 .Sp
 \&   ev_timer_again (loop, timer);
 .Ve
 .Sp

-This is more efficient then stopping/starting the timer eahc time you want
-to modify its timeout value.
+This is more slightly efficient then stopping/starting the timer each time
+you want to modify its timeout value.

 .IP "ev_tstamp repeat [read\-write]" 4
 .IX Item "ev_tstamp repeat [read-write]"
 The current \f(CW\*(C`repeat\*(C'\fR value. Will be used each time the watcher times out
 .IP "ev_tstamp repeat [read\-write]" 4
 .IX Item "ev_tstamp repeat [read-write]"
 The current \f(CW\*(C`repeat\*(C'\fR value. Will be used each time the watcher times out


@@ -1161,11 +1240,11 @@ to trigger \*(L"at\*(R" some specific point in time. For example, if you tell a
 periodic watcher to trigger in 10 seconds (by specifiying e.g. \f(CW\*(C`ev_now ()
 + 10.\*(C'\fR) and then reset your system clock to the last year, then it will
 take a year to trigger the event (unlike an \f(CW\*(C`ev_timer\*(C'\fR, which would trigger
 periodic watcher to trigger in 10 seconds (by specifiying e.g. \f(CW\*(C`ev_now ()
 + 10.\*(C'\fR) and then reset your system clock to the last year, then it will
 take a year to trigger the event (unlike an \f(CW\*(C`ev_timer\*(C'\fR, which would trigger

-roughly 10 seconds later and of course not if you reset your system time
-again).
+roughly 10 seconds later).

 .PP
 They can also be used to implement vastly more complex timers, such as
 .PP
 They can also be used to implement vastly more complex timers, such as

-triggering an event on eahc midnight, local time.
+triggering an event on each midnight, local time or other, complicated,
+rules.

 .PP
 As with timers, the callback is guarenteed to be invoked only when the
 time (\f(CW\*(C`at\*(C'\fR) has been passed, but if multiple periodic timers become ready
 .PP
 As with timers, the callback is guarenteed to be invoked only when the
 time (\f(CW\*(C`at\*(C'\fR) has been passed, but if multiple periodic timers become ready


@@ -1179,17 +1258,17 @@ during the same loop iteration then order of execution is undefined.
 Lots of arguments, lets sort it out... There are basically three modes of
 operation, and we will explain them from simplest to complex:
 .RS 4
 Lots of arguments, lets sort it out... There are basically three modes of
 operation, and we will explain them from simplest to complex:
 .RS 4

-.IP "* absolute timer (interval = reschedule_cb = 0)" 4
-.IX Item "absolute timer (interval = reschedule_cb = 0)"
+.IP "* absolute timer (at = time, interval = reschedule_cb = 0)" 4
+.IX Item "absolute timer (at = time, interval = reschedule_cb = 0)"

 In this configuration the watcher triggers an event at the wallclock time
 \&\f(CW\*(C`at\*(C'\fR and doesn't repeat. It will not adjust when a time jump occurs,
 that is, if it is to be run at January 1st 2011 then it will run when the
 system time reaches or surpasses this time.
 In this configuration the watcher triggers an event at the wallclock time
 \&\f(CW\*(C`at\*(C'\fR and doesn't repeat. It will not adjust when a time jump occurs,
 that is, if it is to be run at January 1st 2011 then it will run when the
 system time reaches or surpasses this time.

-.IP "* non-repeating interval timer (interval > 0, reschedule_cb = 0)" 4
-.IX Item "non-repeating interval timer (interval > 0, reschedule_cb = 0)"
+.IP "* non-repeating interval timer (at = offset, interval > 0, reschedule_cb = 0)" 4
+.IX Item "non-repeating interval timer (at = offset, interval > 0, reschedule_cb = 0)"

 In this mode the watcher will always be scheduled to time out at the next
 In this mode the watcher will always be scheduled to time out at the next

-\&\f(CW\*(C`at + N * interval\*(C'\fR time (for some integer N) and then repeat, regardless
-of any time jumps.
+\&\f(CW\*(C`at + N * interval\*(C'\fR time (for some integer N, which can also be negative)
+and then repeat, regardless of any time jumps.

 .Sp
 This can be used to create timers that do not drift with respect to system
 time:
 .Sp
 This can be used to create timers that do not drift with respect to system
 time:


@@ -1206,8 +1285,12 @@ by 3600.
 Another way to think about it (for the mathematically inclined) is that
 \&\f(CW\*(C`ev_periodic\*(C'\fR will try to run the callback in this mode at the next possible
 time where \f(CW\*(C`time = at (mod interval)\*(C'\fR, regardless of any time jumps.
 Another way to think about it (for the mathematically inclined) is that
 \&\f(CW\*(C`ev_periodic\*(C'\fR will try to run the callback in this mode at the next possible
 time where \f(CW\*(C`time = at (mod interval)\*(C'\fR, regardless of any time jumps.

-.IP "* manual reschedule mode (reschedule_cb = callback)" 4
-.IX Item "manual reschedule mode (reschedule_cb = callback)"
+.Sp
+For numerical stability it is preferable that the \f(CW\*(C`at\*(C'\fR value is near
+\&\f(CW\*(C`ev_now ()\*(C'\fR (the current time), but there is no range requirement for
+this value.
+.IP "* manual reschedule mode (at and interval ignored, reschedule_cb = callback)" 4
+.IX Item "manual reschedule mode (at and interval ignored, reschedule_cb = callback)"

 In this mode the values for \f(CW\*(C`interval\*(C'\fR and \f(CW\*(C`at\*(C'\fR are both being
 ignored. Instead, each time the periodic watcher gets scheduled, the
 reschedule callback will be called with the watcher as first, and the
 In this mode the values for \f(CW\*(C`interval\*(C'\fR and \f(CW\*(C`at\*(C'\fR are both being
 ignored. Instead, each time the periodic watcher gets scheduled, the
 reschedule callback will be called with the watcher as first, and the


@@ -1216,7 +1299,7 @@ current time as second argument.
 \&\s-1NOTE:\s0 \fIThis callback \s-1MUST\s0 \s-1NOT\s0 stop or destroy any periodic watcher,
 ever, or make any event loop modifications\fR. If you need to stop it,
 return \f(CW\*(C`now + 1e30\*(C'\fR (or so, fudge fudge) and stop it afterwards (e.g. by
 \&\s-1NOTE:\s0 \fIThis callback \s-1MUST\s0 \s-1NOT\s0 stop or destroy any periodic watcher,
 ever, or make any event loop modifications\fR. If you need to stop it,
 return \f(CW\*(C`now + 1e30\*(C'\fR (or so, fudge fudge) and stop it afterwards (e.g. by

-starting a prepare watcher).
+starting an \f(CW\*(C`ev_prepare\*(C'\fR watcher, which is legal).

 .Sp
 Its prototype is \f(CW\*(C`ev_tstamp (*reschedule_cb)(struct ev_periodic *w,
 ev_tstamp now)\*(C'\fR, e.g.:
 .Sp
 Its prototype is \f(CW\*(C`ev_tstamp (*reschedule_cb)(struct ev_periodic *w,
 ev_tstamp now)\*(C'\fR, e.g.:


@@ -1250,6 +1333,13 @@ Simply stops and restarts the periodic watcher again. This is only useful
 when you changed some parameters or the reschedule callback would return
 a different time than the last time it was called (e.g. in a crond like
 program when the crontabs have changed).
 when you changed some parameters or the reschedule callback would return
 a different time than the last time it was called (e.g. in a crond like
 program when the crontabs have changed).

+.IP "ev_tstamp offset [read\-write]" 4
+.IX Item "ev_tstamp offset [read-write]"
+When repeating, this contains the offset value, otherwise this is the
+absolute point in time (the \f(CW\*(C`at\*(C'\fR value passed to \f(CW\*(C`ev_periodic_set\*(C'\fR).
+.Sp
+Can be modified any time, but changes only take effect when the periodic
+timer fires or \f(CW\*(C`ev_periodic_again\*(C'\fR is being called.

 .IP "ev_tstamp interval [read\-write]" 4
 .IX Item "ev_tstamp interval [read-write]"
 The current interval value. Can be modified any time, but changes only
 .IP "ev_tstamp interval [read\-write]" 4
 .IX Item "ev_tstamp interval [read-write]"
 The current interval value. Can be modified any time, but changes only


@@ -1479,13 +1569,16 @@ Example: Watch \f(CW\*(C`/etc/passwd\*(C'\fR for attribute changes.
 .ie n .Sh """ev_idle"" \- when you've got nothing better to do..."
 .el .Sh "\f(CWev_idle\fP \- when you've got nothing better to do..."
 .IX Subsection "ev_idle - when you've got nothing better to do..."
 .ie n .Sh """ev_idle"" \- when you've got nothing better to do..."
 .el .Sh "\f(CWev_idle\fP \- when you've got nothing better to do..."
 .IX Subsection "ev_idle - when you've got nothing better to do..."

-Idle watchers trigger events when there are no other events are pending
-(prepare, check and other idle watchers do not count). That is, as long
-as your process is busy handling sockets or timeouts (or even signals,
-imagine) it will not be triggered. But when your process is idle all idle
-watchers are being called again and again, once per event loop iteration \-
-until stopped, that is, or your process receives more events and becomes
-busy.
+Idle watchers trigger events when no other events of the same or higher
+priority are pending (prepare, check and other idle watchers do not
+count).
+.PP
+That is, as long as your process is busy handling sockets or timeouts
+(or even signals, imagine) of the same or higher priority it will not be
+triggered. But when your process is idle (or only lower-priority watchers
+are pending), the idle watchers are being called once per event loop
+iteration \- until stopped, that is, or your process receives more events
+and becomes busy again with higher priority stuff.

 .PP
 The most noteworthy effect is that as long as any idle watchers are
 active, the process will not block when waiting for new events.
 .PP
 The most noteworthy effect is that as long as any idle watchers are
 active, the process will not block when waiting for new events.


@@ -1558,6 +1651,16 @@ with priority higher than or equal to the event loop and one coroutine
 of lower priority, but only once, using idle watchers to keep the event
 loop from blocking if lower-priority coroutines are active, thus mapping
 low-priority coroutines to idle/background tasks).
 of lower priority, but only once, using idle watchers to keep the event
 loop from blocking if lower-priority coroutines are active, thus mapping
 low-priority coroutines to idle/background tasks).

+.PP
+It is recommended to give \f(CW\*(C`ev_check\*(C'\fR watchers highest (\f(CW\*(C`EV_MAXPRI\*(C'\fR)
+priority, to ensure that they are being run before any other watchers
+after the poll. Also, \f(CW\*(C`ev_check\*(C'\fR watchers (and \f(CW\*(C`ev_prepare\*(C'\fR watchers,
+too) should not activate (\*(L"feed\*(R") events into libev. While libev fully
+supports this, they will be called before other \f(CW\*(C`ev_check\*(C'\fR watchers did
+their job. As \f(CW\*(C`ev_check\*(C'\fR watchers are often used to embed other event
+loops those other event loops might be in an unusable state until their
+\&\f(CW\*(C`ev_check\*(C'\fR watcher ran (always remind yourself to coexist peacefully with
+others).

 .IP "ev_prepare_init (ev_prepare *, callback)" 4
 .IX Item "ev_prepare_init (ev_prepare *, callback)"
 .PD 0
 .IP "ev_prepare_init (ev_prepare *, callback)" 4
 .IX Item "ev_prepare_init (ev_prepare *, callback)"
 .PD 0


@@ -1568,34 +1671,38 @@ Initialises and configures the prepare or check watcher \- they have no
 parameters of any kind. There are \f(CW\*(C`ev_prepare_set\*(C'\fR and \f(CW\*(C`ev_check_set\*(C'\fR
 macros, but using them is utterly, utterly and completely pointless.
 .PP
 parameters of any kind. There are \f(CW\*(C`ev_prepare_set\*(C'\fR and \f(CW\*(C`ev_check_set\*(C'\fR
 macros, but using them is utterly, utterly and completely pointless.
 .PP

-Example: To include a library such as adns, you would add \s-1IO\s0 watchers
-and a timeout watcher in a prepare handler, as required by libadns, and
-in a check watcher, destroy them and call into libadns. What follows is
-pseudo-code only of course:
+There are a number of principal ways to embed other event loops or modules
+into libev. Here are some ideas on how to include libadns into libev
+(there is a Perl module named \f(CW\*(C`EV::ADNS\*(C'\fR that does this, which you could
+use for an actually working example. Another Perl module named \f(CW\*(C`EV::Glib\*(C'\fR
+embeds a Glib main context into libev, and finally, \f(CW\*(C`Glib::EV\*(C'\fR embeds \s-1EV\s0
+into the Glib event loop).
+.PP
+Method 1: Add \s-1IO\s0 watchers and a timeout watcher in a prepare handler,
+and in a check watcher, destroy them and call into libadns. What follows
+is pseudo-code only of course. This requires you to either use a low
+priority for the check watcher or use \f(CW\*(C`ev_clear_pending\*(C'\fR explicitly, as
+the callbacks for the IO/timeout watchers might not have been called yet.

 .PP
 .Vb 2
 \&  static ev_io iow [nfd];
 \&  static ev_timer tw;
 .Ve
 .PP
 .PP
 .Vb 2
 \&  static ev_io iow [nfd];
 \&  static ev_timer tw;
 .Ve
 .PP

-.Vb 9
+.Vb 4

 \&  static void
 \&  io_cb (ev_loop *loop, ev_io *w, int revents)
 \&  {
 \&  static void
 \&  io_cb (ev_loop *loop, ev_io *w, int revents)
 \&  {

-\&    // set the relevant poll flags
-\&    // could also call adns_processreadable etc. here
-\&    struct pollfd *fd = (struct pollfd *)w->data;
-\&    if (revents & EV_READ ) fd->revents |= fd->events & POLLIN;
-\&    if (revents & EV_WRITE) fd->revents |= fd->events & POLLOUT;

 \&  }
 .Ve
 .PP
 \&  }
 .Ve
 .PP

-.Vb 7
+.Vb 8

 \&  // create io watchers for each fd and a timer before blocking
 \&  static void
 \&  adns_prepare_cb (ev_loop *loop, ev_prepare *w, int revents)
 \&  {
 \&  // create io watchers for each fd and a timer before blocking
 \&  static void
 \&  adns_prepare_cb (ev_loop *loop, ev_prepare *w, int revents)
 \&  {

-\&    int timeout = 3600000;truct pollfd fds [nfd];
+\&    int timeout = 3600000;
+\&    struct pollfd fds [nfd];

 \&    // actual code will need to loop here and realloc etc.
 \&    adns_beforepoll (ads, fds, &nfd, &timeout, timeval_from (ev_time ()));
 .Ve
 \&    // actual code will need to loop here and realloc etc.
 \&    adns_beforepoll (ads, fds, &nfd, &timeout, timeval_from (ev_time ()));
 .Ve


@@ -1607,7 +1714,7 @@ pseudo-code only of course:
 .Ve
 .PP
 .Vb 6
 .Ve
 .PP
 .Vb 6

-\&    // create on ev_io per pollfd
+\&    // create one ev_io per pollfd

 \&    for (int i = 0; i < nfd; ++i)
 \&      {
 \&        ev_io_init (iow + i, io_cb, fds [i].fd,
 \&    for (int i = 0; i < nfd; ++i)
 \&      {
 \&        ev_io_init (iow + i, io_cb, fds [i].fd,


@@ -1615,9 +1722,8 @@ pseudo-code only of course:
 \&           | (fds [i].events & POLLOUT ? EV_WRITE : 0)));
 .Ve
 .PP
 \&           | (fds [i].events & POLLOUT ? EV_WRITE : 0)));
 .Ve
 .PP

-.Vb 5
+.Vb 4

 \&        fds [i].revents = 0;
 \&        fds [i].revents = 0;

-\&        iow [i].data = fds + i;

 \&        ev_io_start (loop, iow + i);
 \&      }
 \&  }
 \&        ev_io_start (loop, iow + i);
 \&      }
 \&  }


@@ -1631,15 +1737,110 @@ pseudo-code only of course:
 \&    ev_timer_stop (loop, &tw);
 .Ve
 .PP
 \&    ev_timer_stop (loop, &tw);
 .Ve
 .PP

-.Vb 2
+.Vb 8

 \&    for (int i = 0; i < nfd; ++i)
 \&    for (int i = 0; i < nfd; ++i)

-\&      ev_io_stop (loop, iow + i);
+\&      {
+\&        // set the relevant poll flags
+\&        // could also call adns_processreadable etc. here
+\&        struct pollfd *fd = fds + i;
+\&        int revents = ev_clear_pending (iow + i);
+\&        if (revents & EV_READ ) fd->revents |= fd->events & POLLIN;
+\&        if (revents & EV_WRITE) fd->revents |= fd->events & POLLOUT;
+.Ve
+.PP
+.Vb 3
+\&        // now stop the watcher
+\&        ev_io_stop (loop, iow + i);
+\&      }

 .Ve
 .PP
 .Vb 2
 \&    adns_afterpoll (adns, fds, nfd, timeval_from (ev_now (loop));
 \&  }
 .Ve
 .Ve
 .PP
 .Vb 2
 \&    adns_afterpoll (adns, fds, nfd, timeval_from (ev_now (loop));
 \&  }
 .Ve

+.PP
+Method 2: This would be just like method 1, but you run \f(CW\*(C`adns_afterpoll\*(C'\fR
+in the prepare watcher and would dispose of the check watcher.
+.PP
+Method 3: If the module to be embedded supports explicit event
+notification (adns does), you can also make use of the actual watcher
+callbacks, and only destroy/create the watchers in the prepare watcher.
+.PP
+.Vb 5
+\&  static void
+\&  timer_cb (EV_P_ ev_timer *w, int revents)
+\&  {
+\&    adns_state ads = (adns_state)w->data;
+\&    update_now (EV_A);
+.Ve
+.PP
+.Vb 2
+\&    adns_processtimeouts (ads, &tv_now);
+\&  }
+.Ve
+.PP
+.Vb 5
+\&  static void
+\&  io_cb (EV_P_ ev_io *w, int revents)
+\&  {
+\&    adns_state ads = (adns_state)w->data;
+\&    update_now (EV_A);
+.Ve
+.PP
+.Vb 3
+\&    if (revents & EV_READ ) adns_processreadable  (ads, w->fd, &tv_now);
+\&    if (revents & EV_WRITE) adns_processwriteable (ads, w->fd, &tv_now);
+\&  }
+.Ve
+.PP
+.Vb 1
+\&  // do not ever call adns_afterpoll
+.Ve
+.PP
+Method 4: Do not use a prepare or check watcher because the module you
+want to embed is too inflexible to support it. Instead, youc na override
+their poll function.  The drawback with this solution is that the main
+loop is now no longer controllable by \s-1EV\s0. The \f(CW\*(C`Glib::EV\*(C'\fR module does
+this.
+.PP
+.Vb 4
+\&  static gint
+\&  event_poll_func (GPollFD *fds, guint nfds, gint timeout)
+\&  {
+\&    int got_events = 0;
+.Ve
+.PP
+.Vb 2
+\&    for (n = 0; n < nfds; ++n)
+\&      // create/start io watcher that sets the relevant bits in fds[n] and increment got_events
+.Ve
+.PP
+.Vb 2
+\&    if (timeout >= 0)
+\&      // create/start timer
+.Ve
+.PP
+.Vb 2
+\&    // poll
+\&    ev_loop (EV_A_ 0);
+.Ve
+.PP
+.Vb 3
+\&    // stop timer again
+\&    if (timeout >= 0)
+\&      ev_timer_stop (EV_A_ &to);
+.Ve
+.PP
+.Vb 3
+\&    // stop io watchers again - their callbacks should have set
+\&    for (n = 0; n < nfds; ++n)
+\&      ev_io_stop (EV_A_ iow [n]);
+.Ve
+.PP
+.Vb 2
+\&    return got_events;
+\&  }
+.Ve

 .ie n .Sh """ev_embed"" \- when one backend isn't enough..."
 .el .Sh "\f(CWev_embed\fP \- when one backend isn't enough..."
 .IX Subsection "ev_embed - when one backend isn't enough..."
 .ie n .Sh """ev_embed"" \- when one backend isn't enough..."
 .el .Sh "\f(CWev_embed\fP \- when one backend isn't enough..."
 .IX Subsection "ev_embed - when one backend isn't enough..."


@@ -1831,12 +2032,21 @@ To use it,
 \&  #include <ev++.h>
 .Ve
 .PP
 \&  #include <ev++.h>
 .Ve
 .PP

-(it is not installed by default). This automatically includes \fIev.h\fR
-and puts all of its definitions (many of them macros) into the global
-namespace. All \*(C+ specific things are put into the \f(CW\*(C`ev\*(C'\fR namespace.
+This automatically includes \fIev.h\fR and puts all of its definitions (many
+of them macros) into the global namespace. All \*(C+ specific things are
+put into the \f(CW\*(C`ev\*(C'\fR namespace. It should support all the same embedding
+options as \fIev.h\fR, most notably \f(CW\*(C`EV_MULTIPLICITY\*(C'\fR.

 .PP
 .PP

-It should support all the same embedding options as \fIev.h\fR, most notably
-\&\f(CW\*(C`EV_MULTIPLICITY\*(C'\fR.
+Care has been taken to keep the overhead low. The only data member the \*(C+
+classes add (compared to plain C\-style watchers) is the event loop pointer
+that the watcher is associated with (or no additional members at all if
+you disable \f(CW\*(C`EV_MULTIPLICITY\*(C'\fR when embedding libev).
+.PP
+Currently, functions, and static and non-static member functions can be
+used as callbacks. Other types should be easy to add as long as they only
+need one additional pointer for context. If you need support for other
+types of functors please contact the author (preferably after implementing
+it).

 .PP
 Here is a list of things available in the \f(CW\*(C`ev\*(C'\fR namespace:
 .ie n .IP """ev::READ""\fR, \f(CW""ev::WRITE"" etc." 4
 .PP
 Here is a list of things available in the \f(CW\*(C`ev\*(C'\fR namespace:
 .ie n .IP """ev::READ""\fR, \f(CW""ev::WRITE"" etc." 4


@@ -1858,21 +2068,70 @@ defines by many implementations.
 .Sp
 All of those classes have these methods:
 .RS 4
 .Sp
 All of those classes have these methods:
 .RS 4

-.IP "ev::TYPE::TYPE (object *, object::method *)" 4
-.IX Item "ev::TYPE::TYPE (object *, object::method *)"
+.IP "ev::TYPE::TYPE ()" 4
+.IX Item "ev::TYPE::TYPE ()"

 .PD 0
 .PD 0

-.IP "ev::TYPE::TYPE (object *, object::method *, struct ev_loop *)" 4
-.IX Item "ev::TYPE::TYPE (object *, object::method *, struct ev_loop *)"
+.IP "ev::TYPE::TYPE (struct ev_loop *)" 4
+.IX Item "ev::TYPE::TYPE (struct ev_loop *)"

 .IP "ev::TYPE::~TYPE" 4
 .IX Item "ev::TYPE::~TYPE"
 .PD
 .IP "ev::TYPE::~TYPE" 4
 .IX Item "ev::TYPE::~TYPE"
 .PD

-The constructor takes a pointer to an object and a method pointer to
-the event handler callback to call in this class. The constructor calls
-\&\f(CW\*(C`ev_init\*(C'\fR for you, which means you have to call the \f(CW\*(C`set\*(C'\fR method
-before starting it. If you do not specify a loop then the constructor
-automatically associates the default loop with this watcher.
+The constructor (optionally) takes an event loop to associate the watcher
+with. If it is omitted, it will use \f(CW\*(C`EV_DEFAULT\*(C'\fR.
+.Sp
+The constructor calls \f(CW\*(C`ev_init\*(C'\fR for you, which means you have to call the
+\&\f(CW\*(C`set\*(C'\fR method before starting it.
+.Sp
+It will not set a callback, however: You have to call the templated \f(CW\*(C`set\*(C'\fR
+method to set a callback before you can start the watcher.
+.Sp
+(The reason why you have to use a method is a limitation in \*(C+ which does
+not allow explicit template arguments for constructors).

 .Sp
 The destructor automatically stops the watcher if it is active.
 .Sp
 The destructor automatically stops the watcher if it is active.

+.IP "w\->set<class, &class::method> (object *)" 4
+.IX Item "w->set<class, &class::method> (object *)"
+This method sets the callback method to call. The method has to have a
+signature of \f(CW\*(C`void (*)(ev_TYPE &, int)\*(C'\fR, it receives the watcher as
+first argument and the \f(CW\*(C`revents\*(C'\fR as second. The object must be given as
+parameter and is stored in the \f(CW\*(C`data\*(C'\fR member of the watcher.
+.Sp
+This method synthesizes efficient thunking code to call your method from
+the C callback that libev requires. If your compiler can inline your
+callback (i.e. it is visible to it at the place of the \f(CW\*(C`set\*(C'\fR call and
+your compiler is good :), then the method will be fully inlined into the
+thunking function, making it as fast as a direct C callback.
+.Sp
+Example: simple class declaration and watcher initialisation
+.Sp
+.Vb 4
+\&  struct myclass
+\&  {
+\&    void io_cb (ev::io &w, int revents) { }
+\&  }
+.Ve
+.Sp
+.Vb 3
+\&  myclass obj;
+\&  ev::io iow;
+\&  iow.set <myclass, &myclass::io_cb> (&obj);
+.Ve
+.IP "w\->set<function> (void *data = 0)" 4
+.IX Item "w->set<function> (void *data = 0)"
+Also sets a callback, but uses a static method or plain function as
+callback. The optional \f(CW\*(C`data\*(C'\fR argument will be stored in the watcher's
+\&\f(CW\*(C`data\*(C'\fR member and is free for you to use.
+.Sp
+The prototype of the \f(CW\*(C`function\*(C'\fR must be \f(CW\*(C`void (*)(ev::TYPE &w, int)\*(C'\fR.
+.Sp
+See the method\-\f(CW\*(C`set\*(C'\fR above for more details.
+.Sp
+Example:
+.Sp
+.Vb 2
+\&  static void io_cb (ev::io &w, int revents) { }
+\&  iow.set <io_cb> ();
+.Ve

 .IP "w\->set (struct ev_loop *)" 4
 .IX Item "w->set (struct ev_loop *)"
 Associates a different \f(CW\*(C`struct ev_loop\*(C'\fR with this watcher. You can only
 .IP "w\->set (struct ev_loop *)" 4
 .IX Item "w->set (struct ev_loop *)"
 Associates a different \f(CW\*(C`struct ev_loop\*(C'\fR with this watcher. You can only


@@ -1880,12 +2139,13 @@ do this when the watcher is inactive (and not pending either).
 .IP "w\->set ([args])" 4
 .IX Item "w->set ([args])"
 Basically the same as \f(CW\*(C`ev_TYPE_set\*(C'\fR, with the same args. Must be
 .IP "w\->set ([args])" 4
 .IX Item "w->set ([args])"
 Basically the same as \f(CW\*(C`ev_TYPE_set\*(C'\fR, with the same args. Must be

-called at least once.  Unlike the C counterpart, an active watcher gets
-automatically stopped and restarted.
+called at least once. Unlike the C counterpart, an active watcher gets
+automatically stopped and restarted when reconfiguring it with this
+method.

 .IP "w\->start ()" 4
 .IX Item "w->start ()"
 .IP "w\->start ()" 4
 .IX Item "w->start ()"

-Starts the watcher. Note that there is no \f(CW\*(C`loop\*(C'\fR argument as the
-constructor already takes the loop.
+Starts the watcher. Note that there is no \f(CW\*(C`loop\*(C'\fR argument, as the
+constructor already stores the event loop.

 .IP "w\->stop ()" 4
 .IX Item "w->stop ()"
 Stops the watcher if it is active. Again, no \f(CW\*(C`loop\*(C'\fR argument.
 .IP "w\->stop ()" 4
 .IX Item "w->stop ()"
 Stops the watcher if it is active. Again, no \f(CW\*(C`loop\*(C'\fR argument.


@@ -1921,18 +2181,21 @@ the constructor.
 \&  }
 .Ve
 .PP
 \&  }
 .Ve
 .PP

-.Vb 6
+.Vb 4

 \&  myclass::myclass (int fd)
 \&  myclass::myclass (int fd)

-\&  : io   (this, &myclass::io_cb),
-\&    idle (this, &myclass::idle_cb)

 \&  {
 \&  {

+\&    io  .set <myclass, &myclass::io_cb  > (this);
+\&    idle.set <myclass, &myclass::idle_cb> (this);
+.Ve
+.PP
+.Vb 2

 \&    io.start (fd, ev::READ);
 \&  }
 .Ve
 .SH "MACRO MAGIC"
 .IX Header "MACRO MAGIC"
 Libev can be compiled with a variety of options, the most fundemantal is
 \&    io.start (fd, ev::READ);
 \&  }
 .Ve
 .SH "MACRO MAGIC"
 .IX Header "MACRO MAGIC"
 Libev can be compiled with a variety of options, the most fundemantal is

-\&\f(CW\*(C`EV_MULTIPLICITY\*(C'\fR. This option determines wether (most) functions and
+\&\f(CW\*(C`EV_MULTIPLICITY\*(C'\fR. This option determines whether (most) functions and

 callbacks have an initial \f(CW\*(C`struct ev_loop *\*(C'\fR argument.
 .PP
 To make it easier to write programs that cope with either variant, the
 callbacks have an initial \f(CW\*(C`struct ev_loop *\*(C'\fR argument.
 .PP
 To make it easier to write programs that cope with either variant, the


@@ -1977,8 +2240,9 @@ suitable for use with \f(CW\*(C`EV_A\*(C'\fR.
 Similar to the other two macros, this gives you the value of the default
 loop, if multiple loops are supported (\*(L"ev loop default\*(R").
 .PP
 Similar to the other two macros, this gives you the value of the default
 loop, if multiple loops are supported (\*(L"ev loop default\*(R").
 .PP

-Example: Declare and initialise a check watcher, working regardless of
-wether multiple loops are supported or not.
+Example: Declare and initialise a check watcher, utilising the above
+macros so it will work regardless of whether multiple loops are supported
+or not.

 .PP
 .Vb 5
 \&  static void
 .PP
 .Vb 5
 \&  static void


@@ -2051,7 +2315,7 @@ in your include path (e.g. in libev/ when using \-Ilibev):
 .Ve
 .PP
 .Vb 5
 .Ve
 .PP
 .Vb 5

-\&  ev_select.c     only when select backend is enabled (which is by default)
+\&  ev_select.c     only when select backend is enabled (which is enabled by default)

 \&  ev_poll.c       only when poll backend is enabled (disabled by default)
 \&  ev_epoll.c      only when the epoll backend is enabled (disabled by default)
 \&  ev_kqueue.c     only when the kqueue backend is enabled (disabled by default)
 \&  ev_poll.c       only when poll backend is enabled (disabled by default)
 \&  ev_epoll.c      only when the epoll backend is enabled (disabled by default)
 \&  ev_kqueue.c     only when the kqueue backend is enabled (disabled by default)


@@ -2214,11 +2478,34 @@ will have the \f(CW\*(C`struct ev_loop *\*(C'\fR as first argument, and you can
 additional independent event loops. Otherwise there will be no support
 for multiple event loops and there is no first event loop pointer
 argument. Instead, all functions act on the single default loop.
 additional independent event loops. Otherwise there will be no support
 for multiple event loops and there is no first event loop pointer
 argument. Instead, all functions act on the single default loop.

+.IP "\s-1EV_MINPRI\s0" 4
+.IX Item "EV_MINPRI"
+.PD 0
+.IP "\s-1EV_MAXPRI\s0" 4
+.IX Item "EV_MAXPRI"
+.PD
+The range of allowed priorities. \f(CW\*(C`EV_MINPRI\*(C'\fR must be smaller or equal to
+\&\f(CW\*(C`EV_MAXPRI\*(C'\fR, but otherwise there are no non-obvious limitations. You can
+provide for more priorities by overriding those symbols (usually defined
+to be \f(CW\*(C`\-2\*(C'\fR and \f(CW2\fR, respectively).
+.Sp
+When doing priority-based operations, libev usually has to linearly search
+all the priorities, so having many of them (hundreds) uses a lot of space
+and time, so using the defaults of five priorities (\-2 .. +2) is usually
+fine.
+.Sp
+If your embedding app does not need any priorities, defining these both to
+\&\f(CW0\fR will save some memory and cpu.

 .IP "\s-1EV_PERIODIC_ENABLE\s0" 4
 .IX Item "EV_PERIODIC_ENABLE"
 If undefined or defined to be \f(CW1\fR, then periodic timers are supported. If
 defined to be \f(CW0\fR, then they are not. Disabling them saves a few kB of
 code.
 .IP "\s-1EV_PERIODIC_ENABLE\s0" 4
 .IX Item "EV_PERIODIC_ENABLE"
 If undefined or defined to be \f(CW1\fR, then periodic timers are supported. If
 defined to be \f(CW0\fR, then they are not. Disabling them saves a few kB of
 code.

+.IP "\s-1EV_IDLE_ENABLE\s0" 4
+.IX Item "EV_IDLE_ENABLE"
+If undefined or defined to be \f(CW1\fR, then idle watchers are supported. If
+defined to be \f(CW0\fR, then they are not. Disabling them saves a few kB of
+code.

 .IP "\s-1EV_EMBED_ENABLE\s0" 4
 .IX Item "EV_EMBED_ENABLE"
 If undefined or defined to be \f(CW1\fR, then embed watchers are supported. If
 .IP "\s-1EV_EMBED_ENABLE\s0" 4
 .IX Item "EV_EMBED_ENABLE"
 If undefined or defined to be \f(CW1\fR, then embed watchers are supported. If


@@ -2288,13 +2575,18 @@ will be compiled. It is pretty complex because it provides its own header
 file.
 .Sp
 The usage in rxvt-unicode is simpler. It has a \fIev_cpp.h\fR header file
 file.
 .Sp
 The usage in rxvt-unicode is simpler. It has a \fIev_cpp.h\fR header file

-that everybody includes and which overrides some autoconf choices:
+that everybody includes and which overrides some configure choices:

 .Sp
 .Sp

-.Vb 4
+.Vb 9
+\&  #define EV_MINIMAL 1

 \&  #define EV_USE_POLL 0
 \&  #define EV_MULTIPLICITY 0
 \&  #define EV_USE_POLL 0
 \&  #define EV_MULTIPLICITY 0

-\&  #define EV_PERIODICS 0
+\&  #define EV_PERIODIC_ENABLE 0
+\&  #define EV_STAT_ENABLE 0
+\&  #define EV_FORK_ENABLE 0

 \&  #define EV_CONFIG_H <config.h>
 \&  #define EV_CONFIG_H <config.h>

+\&  #define EV_MINPRI 0
+\&  #define EV_MAXPRI 0

 .Ve
 .Sp
 .Vb 1
 .Ve
 .Sp
 .Vb 1


@@ -2312,27 +2604,50 @@ And a \fIev_cpp.C\fR implementation file that contains libev proper and is compi
 In this section the complexities of (many of) the algorithms used inside
 libev will be explained. For complexity discussions about backends see the
 documentation for \f(CW\*(C`ev_default_init\*(C'\fR.
 In this section the complexities of (many of) the algorithms used inside
 libev will be explained. For complexity discussions about backends see the
 documentation for \f(CW\*(C`ev_default_init\*(C'\fR.

+.Sp
+All of the following are about amortised time: If an array needs to be
+extended, libev needs to realloc and move the whole array, but this
+happens asymptotically never with higher number of elements, so O(1) might
+mean it might do a lengthy realloc operation in rare cases, but on average
+it is much faster and asymptotically approaches constant time.

 .RS 4
 .IP "Starting and stopping timer/periodic watchers: O(log skipped_other_timers)" 4
 .IX Item "Starting and stopping timer/periodic watchers: O(log skipped_other_timers)"
 .RS 4
 .IP "Starting and stopping timer/periodic watchers: O(log skipped_other_timers)" 4
 .IX Item "Starting and stopping timer/periodic watchers: O(log skipped_other_timers)"

-.PD 0
+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.

 .IP "Changing timer/periodic watchers (by autorepeat, again): O(log skipped_other_timers)" 4
 .IX Item "Changing timer/periodic watchers (by autorepeat, again): O(log skipped_other_timers)"
 .IP "Changing timer/periodic watchers (by autorepeat, again): O(log skipped_other_timers)" 4
 .IX Item "Changing timer/periodic watchers (by autorepeat, again): O(log skipped_other_timers)"

+That means that for changing a timer costs less than removing/adding them
+as only the relative motion in the event queue has to be paid for.

 .IP "Starting io/check/prepare/idle/signal/child watchers: O(1)" 4
 .IX Item "Starting io/check/prepare/idle/signal/child watchers: O(1)"
 .IP "Starting io/check/prepare/idle/signal/child watchers: O(1)" 4
 .IX Item "Starting io/check/prepare/idle/signal/child watchers: O(1)"

-.IP "Stopping check/prepare/idle watchers: O(1)" 4
-.IX Item "Stopping check/prepare/idle 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)

 .IP "Stopping an io/signal/child watcher: O(number_of_watchers_for_this_(fd/signal/pid % \s-1EV_PID_HASHSIZE\s0))" 4
 .IX Item "Stopping an io/signal/child watcher: O(number_of_watchers_for_this_(fd/signal/pid % EV_PID_HASHSIZE))"
 .IP "Stopping an io/signal/child watcher: O(number_of_watchers_for_this_(fd/signal/pid % \s-1EV_PID_HASHSIZE\s0))" 4
 .IX Item "Stopping an io/signal/child watcher: O(number_of_watchers_for_this_(fd/signal/pid % EV_PID_HASHSIZE))"

+These watchers are stored in lists then need to be walked to find the
+correct watcher to remove. The lists are usually short (you don't usually
+have many watchers waiting for the same fd or signal).

 .IP "Finding the next timer per loop iteration: O(1)" 4
 .IX Item "Finding the next timer per loop iteration: O(1)"
 .IP "Finding the next timer per loop iteration: O(1)" 4
 .IX Item "Finding the next timer per loop iteration: O(1)"

+.PD 0

 .IP "Each change on a file descriptor per loop iteration: O(number_of_watchers_for_this_fd)" 4
 .IX Item "Each change on a file descriptor per loop iteration: O(number_of_watchers_for_this_fd)"
 .IP "Each change on a file descriptor per loop iteration: O(number_of_watchers_for_this_fd)" 4
 .IX Item "Each change on a file descriptor per loop iteration: O(number_of_watchers_for_this_fd)"

+.PD
+A change means an I/O watcher gets started or stopped, which requires
+libev to recalculate its status (and possibly tell the kernel).

 .IP "Activating one watcher: O(1)" 4
 .IX Item "Activating one watcher: O(1)"
 .IP "Activating one watcher: O(1)" 4
 .IX Item "Activating one watcher: O(1)"

+.PD 0
+.IP "Priority handling: O(number_of_priorities)" 4
+.IX Item "Priority handling: O(number_of_priorities)"
+.PD
+Priorities are implemented by allocating some space for each
+priority. When doing priority-based operations, libev usually has to
+linearly search all the priorities.

 .RE
 .RS 4
 .RE
 .RS 4

-.PD

 .SH "AUTHOR"
 .IX Header "AUTHOR"
 Marc Lehmann <libev@schmorp.de>.
 .SH "AUTHOR"
 .IX Header "AUTHOR"
 Marc Lehmann <libev@schmorp.de>.