+Libev comes with some simplistic wrapper classes for \*(C+ that mainly allow
+you to use some convinience methods to start/stop watchers and also change
+the callback model to a model using method callbacks on objects.
+.PP
+To use it,
+.PP
+.Vb 1
+\& #include <ev++.h>
+.Ve
+.PP
+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
+Care has been taken to keep the overhead low. The only data member added
+to the C\-style watchers is the event loop 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
+.el .IP "\f(CWev::READ\fR, \f(CWev::WRITE\fR etc." 4
+.IX Item "ev::READ, ev::WRITE etc."
+These are just enum values with the same values as the \f(CW\*(C`EV_READ\*(C'\fR etc.
+macros from \fIev.h\fR.
+.ie n .IP """ev::tstamp""\fR, \f(CW""ev::now""" 4
+.el .IP "\f(CWev::tstamp\fR, \f(CWev::now\fR" 4
+.IX Item "ev::tstamp, ev::now"
+Aliases to the same types/functions as with the \f(CW\*(C`ev_\*(C'\fR prefix.
+.ie n .IP """ev::io""\fR, \f(CW""ev::timer""\fR, \f(CW""ev::periodic""\fR, \f(CW""ev::idle""\fR, \f(CW""ev::sig"" etc." 4
+.el .IP "\f(CWev::io\fR, \f(CWev::timer\fR, \f(CWev::periodic\fR, \f(CWev::idle\fR, \f(CWev::sig\fR etc." 4
+.IX Item "ev::io, ev::timer, ev::periodic, ev::idle, ev::sig etc."
+For each \f(CW\*(C`ev_TYPE\*(C'\fR watcher in \fIev.h\fR there is a corresponding class of
+the same name in the \f(CW\*(C`ev\*(C'\fR namespace, with the exception of \f(CW\*(C`ev_signal\*(C'\fR
+which is called \f(CW\*(C`ev::sig\*(C'\fR to avoid clashes with the \f(CW\*(C`signal\*(C'\fR macro
+defines by many implementations.
+.Sp
+All of those classes have these methods:
+.RS 4
+.IP "ev::TYPE::TYPE ()" 4
+.IX Item "ev::TYPE::TYPE ()"
+.PD 0
+.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
+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.
+.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 (void (*function)(watcher &w, int), void *data = 0)" 4
+.IX Item "w->set (void (*function)(watcher &w, int), 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
+See the method\-\f(CW\*(C`set\*(C'\fR above for more details.
+.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
+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
+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 ()"
+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.
+.ie n .IP "w\->again () ""ev::timer""\fR, \f(CW""ev::periodic"" only" 4
+.el .IP "w\->again () \f(CWev::timer\fR, \f(CWev::periodic\fR only" 4
+.IX Item "w->again () ev::timer, ev::periodic only"
+For \f(CW\*(C`ev::timer\*(C'\fR and \f(CW\*(C`ev::periodic\*(C'\fR, this invokes the corresponding
+\&\f(CW\*(C`ev_TYPE_again\*(C'\fR function.
+.ie n .IP "w\->sweep () ""ev::embed"" only" 4
+.el .IP "w\->sweep () \f(CWev::embed\fR only" 4
+.IX Item "w->sweep () ev::embed only"
+Invokes \f(CW\*(C`ev_embed_sweep\*(C'\fR.
+.ie n .IP "w\->update () ""ev::stat"" only" 4
+.el .IP "w\->update () \f(CWev::stat\fR only" 4
+.IX Item "w->update () ev::stat only"
+Invokes \f(CW\*(C`ev_stat_stat\*(C'\fR.
+.RE
+.RS 4
+.RE
+.PP
+Example: Define a class with an \s-1IO\s0 and idle watcher, start one of them in
+the constructor.
+.PP
+.Vb 4
+\& class myclass
+\& {
+\& ev_io io; void io_cb (ev::io &w, int revents);
+\& ev_idle idle void idle_cb (ev::idle &w, int revents);
+.Ve
+.PP
+.Vb 2
+\& myclass ();
+\& }
+.Ve
+.PP
+.Vb 4
+\& myclass::myclass (int fd)
+\& {
+\& 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
+\&\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
+following macros are defined:
+.ie n .IP """EV_A""\fR, \f(CW""EV_A_""" 4
+.el .IP "\f(CWEV_A\fR, \f(CWEV_A_\fR" 4
+.IX Item "EV_A, EV_A_"
+This provides the loop \fIargument\fR for functions, if one is required (\*(L"ev
+loop argument\*(R"). The \f(CW\*(C`EV_A\*(C'\fR form is used when this is the sole argument,
+\&\f(CW\*(C`EV_A_\*(C'\fR is used when other arguments are following. Example:
+.Sp
+.Vb 3
+\& ev_unref (EV_A);
+\& ev_timer_add (EV_A_ watcher);
+\& ev_loop (EV_A_ 0);
+.Ve
+.Sp
+It assumes the variable \f(CW\*(C`loop\*(C'\fR of type \f(CW\*(C`struct ev_loop *\*(C'\fR is in scope,
+which is often provided by the following macro.
+.ie n .IP """EV_P""\fR, \f(CW""EV_P_""" 4
+.el .IP "\f(CWEV_P\fR, \f(CWEV_P_\fR" 4
+.IX Item "EV_P, EV_P_"
+This provides the loop \fIparameter\fR for functions, if one is required (\*(L"ev
+loop parameter\*(R"). The \f(CW\*(C`EV_P\*(C'\fR form is used when this is the sole parameter,
+\&\f(CW\*(C`EV_P_\*(C'\fR is used when other parameters are following. Example:
+.Sp
+.Vb 2
+\& // this is how ev_unref is being declared
+\& static void ev_unref (EV_P);
+.Ve
+.Sp
+.Vb 2
+\& // this is how you can declare your typical callback
+\& static void cb (EV_P_ ev_timer *w, int revents)
+.Ve
+.Sp
+It declares a parameter \f(CW\*(C`loop\*(C'\fR of type \f(CW\*(C`struct ev_loop *\*(C'\fR, quite
+suitable for use with \f(CW\*(C`EV_A\*(C'\fR.
+.ie n .IP """EV_DEFAULT""\fR, \f(CW""EV_DEFAULT_""" 4
+.el .IP "\f(CWEV_DEFAULT\fR, \f(CWEV_DEFAULT_\fR" 4
+.IX Item "EV_DEFAULT, EV_DEFAULT_"
+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, utilising the above
+macros so it will work regardless of whether multiple loops are supported
+or not.
+.PP
+.Vb 5
+\& static void
+\& check_cb (EV_P_ ev_timer *w, int revents)
+\& {
+\& ev_check_stop (EV_A_ w);
+\& }
+.Ve
+.PP
+.Vb 4
+\& ev_check check;
+\& ev_check_init (&check, check_cb);
+\& ev_check_start (EV_DEFAULT_ &check);
+\& ev_loop (EV_DEFAULT_ 0);
+.Ve
+.SH "EMBEDDING"
+.IX Header "EMBEDDING"
+Libev can (and often is) directly embedded into host
+applications. Examples of applications that embed it include the Deliantra
+Game Server, the \s-1EV\s0 perl module, the \s-1GNU\s0 Virtual Private Ethernet (gvpe)
+and rxvt\-unicode.
+.PP
+The goal is to enable you to just copy the neecssary files into your
+source directory without having to change even a single line in them, so
+you can easily upgrade by simply copying (or having a checked-out copy of
+libev somewhere in your source tree).
+.Sh "\s-1FILESETS\s0"
+.IX Subsection "FILESETS"
+Depending on what features you need you need to include one or more sets of files
+in your app.
+.PP
+\fI\s-1CORE\s0 \s-1EVENT\s0 \s-1LOOP\s0\fR
+.IX Subsection "CORE EVENT LOOP"
+.PP
+To include only the libev core (all the \f(CW\*(C`ev_*\*(C'\fR functions), with manual
+configuration (no autoconf):
+.PP
+.Vb 2
+\& #define EV_STANDALONE 1
+\& #include "ev.c"
+.Ve
+.PP
+This will automatically include \fIev.h\fR, too, and should be done in a
+single C source file only to provide the function implementations. To use
+it, do the same for \fIev.h\fR in all files wishing to use this \s-1API\s0 (best
+done by writing a wrapper around \fIev.h\fR that you can include instead and
+where you can put other configuration options):
+.PP
+.Vb 2
+\& #define EV_STANDALONE 1
+\& #include "ev.h"
+.Ve
+.PP
+Both header files and implementation files can be compiled with a \*(C+
+compiler (at least, thats a stated goal, and breakage will be treated
+as a bug).
+.PP
+You need the following files in your source tree, or in a directory
+in your include path (e.g. in libev/ when using \-Ilibev):
+.PP
+.Vb 4
+\& ev.h
+\& ev.c
+\& ev_vars.h
+\& ev_wrap.h
+.Ve
+.PP
+.Vb 1
+\& ev_win32.c required on win32 platforms only
+.Ve
+.PP
+.Vb 5
+\& 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_port.c only when the solaris port backend is enabled (disabled by default)
+.Ve
+.PP
+\&\fIev.c\fR includes the backend files directly when enabled, so you only need
+to compile this single file.
+.PP
+\fI\s-1LIBEVENT\s0 \s-1COMPATIBILITY\s0 \s-1API\s0\fR
+.IX Subsection "LIBEVENT COMPATIBILITY API"
+.PP
+To include the libevent compatibility \s-1API\s0, also include:
+.PP
+.Vb 1
+\& #include "event.c"
+.Ve
+.PP
+in the file including \fIev.c\fR, and:
+.PP
+.Vb 1
+\& #include "event.h"
+.Ve
+.PP
+in the files that want to use the libevent \s-1API\s0. This also includes \fIev.h\fR.
+.PP
+You need the following additional files for this:
+.PP
+.Vb 2
+\& event.h
+\& event.c
+.Ve
+.PP
+\fI\s-1AUTOCONF\s0 \s-1SUPPORT\s0\fR
+.IX Subsection "AUTOCONF SUPPORT"
+.PP
+Instead of using \f(CW\*(C`EV_STANDALONE=1\*(C'\fR and providing your config in
+whatever way you want, you can also \f(CW\*(C`m4_include([libev.m4])\*(C'\fR in your
+\&\fIconfigure.ac\fR and leave \f(CW\*(C`EV_STANDALONE\*(C'\fR undefined. \fIev.c\fR will then
+include \fIconfig.h\fR and configure itself accordingly.
+.PP
+For this of course you need the m4 file:
+.PP
+.Vb 1
+\& libev.m4
+.Ve
+.Sh "\s-1PREPROCESSOR\s0 \s-1SYMBOLS/MACROS\s0"
+.IX Subsection "PREPROCESSOR SYMBOLS/MACROS"
+Libev can be configured via a variety of preprocessor symbols you have to define
+before including any of its files. The default is not to build for multiplicity
+and only include the select backend.
+.IP "\s-1EV_STANDALONE\s0" 4
+.IX Item "EV_STANDALONE"
+Must always be \f(CW1\fR if you do not use autoconf configuration, which
+keeps libev from including \fIconfig.h\fR, and it also defines dummy
+implementations for some libevent functions (such as logging, which is not
+supported). It will also not define any of the structs usually found in
+\&\fIevent.h\fR that are not directly supported by the libev core alone.
+.IP "\s-1EV_USE_MONOTONIC\s0" 4
+.IX Item "EV_USE_MONOTONIC"
+If defined to be \f(CW1\fR, libev will try to detect the availability of the
+monotonic clock option at both compiletime and runtime. Otherwise no use
+of the monotonic clock option will be attempted. If you enable this, you
+usually have to link against librt or something similar. Enabling it when
+the functionality isn't available is safe, though, althoguh you have
+to make sure you link against any libraries where the \f(CW\*(C`clock_gettime\*(C'\fR
+function is hiding in (often \fI\-lrt\fR).
+.IP "\s-1EV_USE_REALTIME\s0" 4
+.IX Item "EV_USE_REALTIME"
+If defined to be \f(CW1\fR, libev will try to detect the availability of the
+realtime clock option at compiletime (and assume its availability at
+runtime if successful). Otherwise no use of the realtime clock option will
+be attempted. This effectively replaces \f(CW\*(C`gettimeofday\*(C'\fR by \f(CW\*(C`clock_get
+(CLOCK_REALTIME, ...)\*(C'\fR and will not normally affect correctness. See tzhe note about libraries
+in the description of \f(CW\*(C`EV_USE_MONOTONIC\*(C'\fR, though.
+.IP "\s-1EV_USE_SELECT\s0" 4
+.IX Item "EV_USE_SELECT"
+If undefined or defined to be \f(CW1\fR, libev will compile in support for the
+\&\f(CW\*(C`select\*(C'\fR(2) backend. No attempt at autodetection will be done: if no
+other method takes over, select will be it. Otherwise the select backend
+will not be compiled in.
+.IP "\s-1EV_SELECT_USE_FD_SET\s0" 4
+.IX Item "EV_SELECT_USE_FD_SET"
+If defined to \f(CW1\fR, then the select backend will use the system \f(CW\*(C`fd_set\*(C'\fR
+structure. This is useful if libev doesn't compile due to a missing
+\&\f(CW\*(C`NFDBITS\*(C'\fR or \f(CW\*(C`fd_mask\*(C'\fR definition or it misguesses the bitset layout on
+exotic systems. This usually limits the range of file descriptors to some
+low limit such as 1024 or might have other limitations (winsocket only
+allows 64 sockets). The \f(CW\*(C`FD_SETSIZE\*(C'\fR macro, set before compilation, might
+influence the size of the \f(CW\*(C`fd_set\*(C'\fR used.
+.IP "\s-1EV_SELECT_IS_WINSOCKET\s0" 4
+.IX Item "EV_SELECT_IS_WINSOCKET"
+When defined to \f(CW1\fR, the select backend will assume that
+select/socket/connect etc. don't understand file descriptors but
+wants osf handles on win32 (this is the case when the select to
+be used is the winsock select). This means that it will call
+\&\f(CW\*(C`_get_osfhandle\*(C'\fR on the fd to convert it to an \s-1OS\s0 handle. Otherwise,
+it is assumed that all these functions actually work on fds, even
+on win32. Should not be defined on non\-win32 platforms.
+.IP "\s-1EV_USE_POLL\s0" 4
+.IX Item "EV_USE_POLL"
+If defined to be \f(CW1\fR, libev will compile in support for the \f(CW\*(C`poll\*(C'\fR(2)
+backend. Otherwise it will be enabled on non\-win32 platforms. It
+takes precedence over select.
+.IP "\s-1EV_USE_EPOLL\s0" 4
+.IX Item "EV_USE_EPOLL"
+If defined to be \f(CW1\fR, libev will compile in support for the Linux
+\&\f(CW\*(C`epoll\*(C'\fR(7) backend. Its availability will be detected at runtime,
+otherwise another method will be used as fallback. This is the
+preferred backend for GNU/Linux systems.
+.IP "\s-1EV_USE_KQUEUE\s0" 4
+.IX Item "EV_USE_KQUEUE"
+If defined to be \f(CW1\fR, libev will compile in support for the \s-1BSD\s0 style
+\&\f(CW\*(C`kqueue\*(C'\fR(2) backend. Its actual availability will be detected at runtime,
+otherwise another method will be used as fallback. This is the preferred
+backend for \s-1BSD\s0 and BSD-like systems, although on most BSDs kqueue only
+supports some types of fds correctly (the only platform we found that
+supports ptys for example was NetBSD), so kqueue might be compiled in, but
+not be used unless explicitly requested. The best way to use it is to find
+out whether kqueue supports your type of fd properly and use an embedded
+kqueue loop.
+.IP "\s-1EV_USE_PORT\s0" 4
+.IX Item "EV_USE_PORT"
+If defined to be \f(CW1\fR, libev will compile in support for the Solaris
+10 port style backend. Its availability will be detected at runtime,
+otherwise another method will be used as fallback. This is the preferred
+backend for Solaris 10 systems.
+.IP "\s-1EV_USE_DEVPOLL\s0" 4
+.IX Item "EV_USE_DEVPOLL"
+reserved for future expansion, works like the \s-1USE\s0 symbols above.
+.IP "\s-1EV_USE_INOTIFY\s0" 4
+.IX Item "EV_USE_INOTIFY"
+If defined to be \f(CW1\fR, libev will compile in support for the Linux inotify
+interface to speed up \f(CW\*(C`ev_stat\*(C'\fR watchers. Its actual availability will
+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.
+.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
+\&\fIev.c\fR's idea of where to find the \fIconfig.h\fR file, similarly to
+\&\f(CW\*(C`EV_H\*(C'\fR, above.
+.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.
+.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
+prototypes, but still define all the structs and other symbols. This is
+occasionally useful if you want to provide your own wrapper functions
+around libev functions.
+.IP "\s-1EV_MULTIPLICITY\s0" 4
+.IX Item "EV_MULTIPLICITY"
+If undefined or defined to \f(CW1\fR, then all event-loop-specific functions
+will have the \f(CW\*(C`struct ev_loop *\*(C'\fR as first argument, and you can create
+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_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
+defined to be \f(CW0\fR, then they are not.
+.IP "\s-1EV_STAT_ENABLE\s0" 4
+.IX Item "EV_STAT_ENABLE"
+If undefined or defined to be \f(CW1\fR, then stat watchers are supported. If
+defined to be \f(CW0\fR, then they are not.
+.IP "\s-1EV_FORK_ENABLE\s0" 4
+.IX Item "EV_FORK_ENABLE"
+If undefined or defined to be \f(CW1\fR, then fork watchers are supported. If
+defined to be \f(CW0\fR, then they are not.
+.IP "\s-1EV_MINIMAL\s0" 4
+.IX Item "EV_MINIMAL"
+If you need to shave off some kilobytes of code at the expense of some
+speed, define this symbol to \f(CW1\fR. Currently only used for gcc to override
+some inlining decisions, saves roughly 30% codesize of amd64.
+.IP "\s-1EV_PID_HASHSIZE\s0" 4
+.IX Item "EV_PID_HASHSIZE"
+\&\f(CW\*(C`ev_child\*(C'\fR watchers use a small hash table to distribute workload by
+pid. 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 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
+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
+two).
+.IP "\s-1EV_COMMON\s0" 4
+.IX Item "EV_COMMON"
+By default, all watchers have a \f(CW\*(C`void *data\*(C'\fR member. By redefining
+this macro to a something else you can include more and other types of
+members. You have to define it each time you include one of the files,
+though, and it must be identical each time.
+.Sp
+For example, the perl \s-1EV\s0 module uses something like this:
+.Sp
+.Vb 3
+\& #define EV_COMMON \e
+\& SV *self; /* contains this struct */ \e
+\& SV *cb_sv, *fh /* note no trailing ";" */
+.Ve
+.IP "\s-1EV_CB_DECLARE\s0 (type)" 4
+.IX Item "EV_CB_DECLARE (type)"
+.PD 0
+.IP "\s-1EV_CB_INVOKE\s0 (watcher, revents)" 4
+.IX Item "EV_CB_INVOKE (watcher, revents)"
+.IP "ev_set_cb (ev, cb)" 4
+.IX Item "ev_set_cb (ev, cb)"
+.PD
+Can be used to change the callback member declaration in each watcher,
+and the way callbacks are invoked and set. Must expand to a struct member
+definition and a statement, respectively. See the \fIev.v\fR header file for
+their default definitions. One possible use for overriding these is to
+avoid the \f(CW\*(C`struct ev_loop *\*(C'\fR as first argument in all cases, or to use
+method calls instead of plain function calls in \*(C+.
+.Sh "\s-1EXAMPLES\s0"
+.IX Subsection "EXAMPLES"
+For a real-world example of a program the includes libev
+verbatim, you can have a look at the \s-1EV\s0 perl module
+(<http://software.schmorp.de/pkg/EV.html>). It has the libev files in
+the \fIlibev/\fR subdirectory and includes them in the \fI\s-1EV/EVAPI\s0.h\fR (public
+interface) and \fI\s-1EV\s0.xs\fR (implementation) files. Only the \fI\s-1EV\s0.xs\fR file
+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
+that everybody includes and which overrides some configure choices:
+.Sp
+.Vb 9
+\& #define EV_MINIMAL 1
+\& #define EV_USE_POLL 0
+\& #define EV_MULTIPLICITY 0
+\& #define EV_PERIODIC_ENABLE 0
+\& #define EV_STAT_ENABLE 0
+\& #define EV_FORK_ENABLE 0
+\& #define EV_CONFIG_H <config.h>
+\& #define EV_MINPRI 0
+\& #define EV_MAXPRI 0
+.Ve
+.Sp
+.Vb 1
+\& #include "ev++.h"
+.Ve
+.Sp
+And a \fIev_cpp.C\fR implementation file that contains libev proper and is compiled:
+.Sp
+.Vb 2
+\& #include "ev_cpp.h"
+\& #include "ev.c"
+.Ve
+.SH "COMPLEXITIES"
+.IX Header "COMPLEXITIES"
+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)"
+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
+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 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)"
+.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)"
+.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)"
+.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