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master rel-2.01
Marc Alexander Lehmann 14 years ago
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  1. 1
      Changes
  2. 4
      Makefile.am
  3. 2
      configure.ac
  4. 151
      ev.3
  5. 2
      import_libevent

1
Changes

@ -1,6 +1,7 @@
Revision history for libev, a high-performance and full-featured event loop
2.01 Tue Dec 25 08:04:41 CET 2007
- separate Changes file.
- fix ev_path_set => ev_stat_set typo.
- remove event_compat.h from the libev tarball.
- change how include files are found.

4
Makefile.am

@ -3,13 +3,13 @@ AUTOMAKE_OPTIONS = foreign no-dependencies
VERSION_INFO = 2:0
EXTRA_DIST = LICENSE Changes libev.m4 autogen.sh \
ev.h ev_vars.h ev_wrap.h ev++.h event.h \
ev_vars.h ev_wrap.h \
ev_epoll.c ev_select.c ev_poll.c ev_kqueue.c ev_port.c ev_win32.c \
ev.3 ev.pod
man_MANS = ev.3
include_HEADERS = ev.h event_compat.h ev++.h event.h
include_HEADERS = ev.h ev++.h event.h
lib_LTLIBRARIES = libev.la

2
configure.ac

@ -1,7 +1,7 @@
AC_INIT
AC_CONFIG_SRCDIR([ev_epoll.c])
AM_INIT_AUTOMAKE(libev,2.0)
AM_INIT_AUTOMAKE(libev,2.01)
AC_CONFIG_HEADERS([config.h])
AM_MAINTAINER_MODE

151
ev.3

@ -129,7 +129,7 @@
.\" ========================================================================
.\"
.IX Title "EV 1"
.TH EV 1 "2007-12-22" "perl v5.8.8" "User Contributed Perl Documentation"
.TH EV 1 "2007-12-25" "perl v5.8.8" "User Contributed Perl Documentation"
.SH "NAME"
libev \- a high performance full\-featured event loop written in C
.SH "SYNOPSIS"
@ -137,8 +137,8 @@ libev \- a high performance full\-featured event loop written in C
.Vb 1
\& #include <ev.h>
.Ve
.SH "EXAMPLE PROGRAM"
.IX Header "EXAMPLE PROGRAM"
.Sh "\s-1EXAMPLE\s0 \s-1PROGRAM\s0"
.IX Subsection "EXAMPLE PROGRAM"
.Vb 1
\& #include <ev.h>
.Ve
@ -214,8 +214,8 @@ You register interest in certain events by registering so-called \fIevent
watchers\fR, which are relatively small C structures you initialise with the
details of the event, and then hand it over to libev by \fIstarting\fR the
watcher.
.SH "FEATURES"
.IX Header "FEATURES"
.Sh "\s-1FEATURES\s0"
.IX Subsection "FEATURES"
Libev supports \f(CW\*(C`select\*(C'\fR, \f(CW\*(C`poll\*(C'\fR, the Linux-specific \f(CW\*(C`epoll\*(C'\fR, the
BSD-specific \f(CW\*(C`kqueue\*(C'\fR and the Solaris-specific event port mechanisms
for file descriptor events (\f(CW\*(C`ev_io\*(C'\fR), the Linux \f(CW\*(C`inotify\*(C'\fR interface
@ -230,16 +230,16 @@ file watchers (\f(CW\*(C`ev_stat\*(C'\fR) and even limited support for fork even
It also is quite fast (see this
benchmark comparing it to libevent
for example).
.SH "CONVENTIONS"
.IX Header "CONVENTIONS"
.Sh "\s-1CONVENTIONS\s0"
.IX Subsection "CONVENTIONS"
Libev is very configurable. In this manual the default configuration will
be described, which supports multiple event loops. For more info about
various configuration options please have a look at \fB\s-1EMBED\s0\fR section in
this manual. If libev was configured without support for multiple event
loops, then all functions taking an initial argument of name \f(CW\*(C`loop\*(C'\fR
(which is always of type \f(CW\*(C`struct ev_loop *\*(C'\fR) will not have this argument.
.SH "TIME REPRESENTATION"
.IX Header "TIME REPRESENTATION"
.Sh "\s-1TIME\s0 \s-1REPRESENTATION\s0"
.IX Subsection "TIME REPRESENTATION"
Libev represents time as a single floating point number, representing the
(fractional) number of seconds since the (\s-1POSIX\s0) epoch (somewhere near
the beginning of 1970, details are complicated, don't ask). This type is
@ -1140,12 +1140,6 @@ fd as you want (as long as you don't confuse yourself). Setting all file
descriptors to non-blocking mode is also usually a good idea (but not
required if you know what you are doing).
.PP
You have to be careful with dup'ed file descriptors, though. Some backends
(the linux epoll backend is a notable example) cannot handle dup'ed file
descriptors correctly if you register interest in two or more fds pointing
to the same underlying file/socket/etc. description (that is, they share
the same underlying \*(L"file open\*(R").
.PP
If you must do this, then force the use of a known-to-be-good backend
(at the time of this writing, this includes only \f(CW\*(C`EVBACKEND_SELECT\*(C'\fR and
\&\f(CW\*(C`EVBACKEND_POLL\*(C'\fR).
@ -1191,12 +1185,12 @@ optimisations to libev.
.IX Subsection "The special problem of dup'ed file descriptors"
.PP
Some backends (e.g. epoll), cannot register events for file descriptors,
but only events for the underlying file descriptions. That menas when you
have \f(CW\*(C`dup ()\*(C'\fR'ed file descriptors and register events for them, only one
file descriptor might actually receive events.
but only events for the underlying file descriptions. That means when you
have \f(CW\*(C`dup ()\*(C'\fR'ed file descriptors or weirder constellations, and register
events for them, only one file descriptor might actually receive events.
.PP
There is no workaorund possible except not registering events
for potentially \f(CW\*(C`dup ()\*(C'\fR'ed file descriptors or to resort to
There is no workaround possible except not registering events
for potentially \f(CW\*(C`dup ()\*(C'\fR'ed file descriptors, or to resort to
\&\f(CW\*(C`EVBACKEND_SELECT\*(C'\fR or \f(CW\*(C`EVBACKEND_POLL\*(C'\fR.
.PP
\fIThe special problem of fork\fR
@ -1662,6 +1656,41 @@ to fall back to regular polling again even with inotify, but changes are
usually detected immediately, and if the file exists there will be no
polling.
.PP
\fIInotify\fR
.IX Subsection "Inotify"
.PP
When \f(CW\*(C`inotify (7)\*(C'\fR support has been compiled into libev (generally only
available on Linux) and present at runtime, it will be used to speed up
change detection where possible. The inotify descriptor will be created lazily
when the first \f(CW\*(C`ev_stat\*(C'\fR watcher is being started.
.PP
Inotify presense does not change the semantics of \f(CW\*(C`ev_stat\*(C'\fR watchers
except that changes might be detected earlier, and in some cases, to avoid
making regular \f(CW\*(C`stat\*(C'\fR calls. Even in the presense of inotify support
there are many cases where libev has to resort to regular \f(CW\*(C`stat\*(C'\fR polling.
.PP
(There is no support for kqueue, as apparently it cannot be used to
implement this functionality, due to the requirement of having a file
descriptor open on the object at all times).
.PP
\fIThe special problem of stat time resolution\fR
.IX Subsection "The special problem of stat time resolution"
.PP
The \f(CW\*(C`stat ()\*(C'\fR syscall only supports full-second resolution portably, and
even on systems where the resolution is higher, many filesystems still
only support whole seconds.
.PP
That means that, if the time is the only thing that changes, you might
miss updates: on the first update, \f(CW\*(C`ev_stat\*(C'\fR detects a change and calls
your callback, which does something. When there is another update within
the same second, \f(CW\*(C`ev_stat\*(C'\fR will be unable to detect it.
.PP
The solution to this is to delay acting on a change for a second (or till
the next second boundary), using a roughly one-second delay \f(CW\*(C`ev_timer\*(C'\fR
(\f(CW\*(C`ev_timer_set (w, 0., 1.01); ev_timer_again (loop, w)\*(C'\fR). The \f(CW.01\fR
is added to work around small timing inconsistencies of some operating
systems.
.PP
\fIWatcher-Specific Functions and Data Members\fR
.IX Subsection "Watcher-Specific Functions and Data Members"
.IP "ev_stat_init (ev_stat *, callback, const char *path, ev_tstamp interval)" 4
@ -1702,6 +1731,9 @@ The specified interval.
.IX Item "const char *path [read-only]"
The filesystem path that is being watched.
.PP
\fIExamples\fR
.IX Subsection "Examples"
.PP
Example: Watch \f(CW\*(C`/etc/passwd\*(C'\fR for attribute changes.
.PP
.Vb 15
@ -1728,9 +1760,47 @@ Example: Watch \f(CW\*(C`/etc/passwd\*(C'\fR for attribute changes.
.Ve
.PP
.Vb 2
\& ev_stat_init (&passwd, passwd_cb, "/etc/passwd");
\& ev_stat_init (&passwd, passwd_cb, "/etc/passwd", 0.);
\& ev_stat_start (loop, &passwd);
.Ve
.PP
Example: Like above, but additionally use a one-second delay so we do not
miss updates (however, frequent updates will delay processing, too, so
one might do the work both on \f(CW\*(C`ev_stat\*(C'\fR callback invocation \fIand\fR on
\&\f(CW\*(C`ev_timer\*(C'\fR callback invocation).
.PP
.Vb 2
\& static ev_stat passwd;
\& static ev_timer timer;
.Ve
.PP
.Vb 4
\& static void
\& timer_cb (EV_P_ ev_timer *w, int revents)
\& {
\& ev_timer_stop (EV_A_ w);
.Ve
.PP
.Vb 2
\& /* now it's one second after the most recent passwd change */
\& }
.Ve
.PP
.Vb 6
\& static void
\& stat_cb (EV_P_ ev_stat *w, int revents)
\& {
\& /* reset the one-second timer */
\& ev_timer_again (EV_A_ &timer);
\& }
.Ve
.PP
.Vb 4
\& ...
\& ev_stat_init (&passwd, stat_cb, "/etc/passwd", 0.);
\& ev_stat_start (loop, &passwd);
\& ev_timer_init (&timer, timer_cb, 0., 1.01);
.Ve
.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..."
@ -2635,8 +2705,8 @@ be detected at runtime.
.IP "\s-1EV_H\s0" 4
.IX Item "EV_H"
The name of the \fIev.h\fR header file used to include it. The default if
undefined is \f(CW\*(C`<ev.h>\*(C'\fR in \fIevent.h\fR and \f(CW"ev.h"\fR in \fIev.c\fR. This
can be used to virtually rename the \fIev.h\fR header file in case of conflicts.
undefined is \f(CW"ev.h"\fR in \fIevent.h\fR and \fIev.c\fR. This can be used to
virtually rename the \fIev.h\fR header file in case of conflicts.
.IP "\s-1EV_CONFIG_H\s0" 4
.IX Item "EV_CONFIG_H"
If \f(CW\*(C`EV_STANDALONE\*(C'\fR isn't \f(CW1\fR, this variable can be used to override
@ -2645,7 +2715,7 @@ If \f(CW\*(C`EV_STANDALONE\*(C'\fR isn't \f(CW1\fR, this variable can be used to
.IP "\s-1EV_EVENT_H\s0" 4
.IX Item "EV_EVENT_H"
Similarly to \f(CW\*(C`EV_H\*(C'\fR, this macro can be used to override \fIevent.c\fR's idea
of how the \fIevent.h\fR header can be found.
of how the \fIevent.h\fR header can be found, the dfeault is \f(CW"event.h"\fR.
.IP "\s-1EV_PROTOTYPES\s0" 4
.IX Item "EV_PROTOTYPES"
If defined to be \f(CW0\fR, then \fIev.h\fR will not define any function
@ -2712,7 +2782,7 @@ than enough. If you need to manage thousands of children you might want to
increase this value (\fImust\fR be a power of two).
.IP "\s-1EV_INOTIFY_HASHSIZE\s0" 4
.IX Item "EV_INOTIFY_HASHSIZE"
\&\f(CW\*(C`ev_staz\*(C'\fR watchers use a small hash table to distribute workload by
\&\f(CW\*(C`ev_stat\*(C'\fR watchers use a small hash table to distribute workload by
inotify watch id. The default size is \f(CW16\fR (or \f(CW1\fR with \f(CW\*(C`EV_MINIMAL\*(C'\fR),
usually more than enough. If you need to manage thousands of \f(CW\*(C`ev_stat\*(C'\fR
watchers you might want to increase this value (\fImust\fR be a power of
@ -2826,37 +2896,42 @@ it is much faster and asymptotically approaches constant time.
.IX Item "Starting and stopping timer/periodic watchers: O(log skipped_other_timers)"
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)"
That means that for changing a timer costs less than removing/adding them
have to skip roughly seven (\f(CW\*(C`ld 100\*(C'\fR) of these watchers.
.IP "Changing timer/periodic watchers (by autorepeat or calling again): O(log skipped_other_timers)" 4
.IX Item "Changing timer/periodic watchers (by autorepeat or calling again): O(log skipped_other_timers)"
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.
.IP "Starting io/check/prepare/idle/signal/child watchers: O(1)" 4
.IX 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)
.IP "Stopping check/prepare/idle watchers: O(1)" 4
.IX Item "Stopping check/prepare/idle watchers: O(1)"
.PD 0
.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))"
.PD
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)"
.PD 0
.IP "Finding the next timer in each loop iteration: O(1)" 4
.IX 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.
.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)"
libev to recalculate its status (and possibly tell the kernel, depending
on backend and wether \f(CW\*(C`ev_io_set\*(C'\fR was used).
.IP "Activating one watcher (putting it into the pending state): O(1)" 4
.IX Item "Activating one watcher (putting it into the pending state): 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.
linearly search all the priorities, but starting/stopping and activating
watchers becomes O(1) w.r.t. prioritiy handling.
.RE
.RS 4
.SH "AUTHOR"

2
import_libevent

@ -108,7 +108,7 @@ perl -ne '
s/-Wall//g;
#s/libevent/libev/g;
#VERSION
s/AM_INIT_AUTOMAKE\s*\(.*,(.*)\)/AM_INIT_AUTOMAKE(libevent-$1+libev,2.0)/;
s/AM_INIT_AUTOMAKE\s*\(.*,(.*)\)/AM_INIT_AUTOMAKE(libevent-$1+libev,2.01)/;
s/AC_LIBOBJ\(select\)/: ;/g;
s/AC_LIBOBJ\(poll\)/: ;/g;
s/AC_LIBOBJ\(kqueue\)/: ;/g;

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