*** empty log message ***

[software/libev.git] / ev.3

diff --git a/ev.3 b/ev.3
index 439489a6e619a7e648dd908eec90a5625d7b7ed8..1f33e819abcd70e0ec45634a66888759cf955a37 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 "2007-12-07" "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.


@@ -212,12 +216,13 @@ details of the event, and then hand it over to libev by \fIstarting\fR the
 watcher.
 .SH "FEATURES"
 .IX Header "FEATURES"
 watcher.
 .SH "FEATURES"
 .IX Header "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), relative timers (\f(CW\*(C`ev_timer\*(C'\fR),
-absolute timers with customised rescheduling (\f(CW\*(C`ev_periodic\*(C'\fR), synchronous
-signals (\f(CW\*(C`ev_signal\*(C'\fR), process status change events (\f(CW\*(C`ev_child\*(C'\fR), and
-event watchers dealing with the event loop mechanism itself (\f(CW\*(C`ev_idle\*(C'\fR,
+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
+(for \f(CW\*(C`ev_stat\*(C'\fR), relative timers (\f(CW\*(C`ev_timer\*(C'\fR), absolute timers
+with customised rescheduling (\f(CW\*(C`ev_periodic\*(C'\fR), synchronous signals
+(\f(CW\*(C`ev_signal\*(C'\fR), process status change events (\f(CW\*(C`ev_child\*(C'\fR), and event
+watchers dealing with the event loop mechanism itself (\f(CW\*(C`ev_idle\*(C'\fR,

 \&\f(CW\*(C`ev_embed\*(C'\fR, \f(CW\*(C`ev_prepare\*(C'\fR and \f(CW\*(C`ev_check\*(C'\fR watchers) as well as
 file watchers (\f(CW\*(C`ev_stat\*(C'\fR) and even limited support for fork events
 (\f(CW\*(C`ev_fork\*(C'\fR).
 \&\f(CW\*(C`ev_embed\*(C'\fR, \f(CW\*(C`ev_prepare\*(C'\fR and \f(CW\*(C`ev_check\*(C'\fR watchers) as well as
 file watchers (\f(CW\*(C`ev_stat\*(C'\fR) and even limited support for fork events
 (\f(CW\*(C`ev_fork\*(C'\fR).


@@ -306,13 +311,14 @@ might be supported on the current system, you would need to look at
 recommended ones.
 .Sp
 See the description of \f(CW\*(C`ev_embed\*(C'\fR watchers for more info.
 recommended ones.
 .Sp
 See the description of \f(CW\*(C`ev_embed\*(C'\fR watchers for more info.

-.IP "ev_set_allocator (void *(*cb)(void *ptr, size_t size))" 4
-.IX Item "ev_set_allocator (void *(*cb)(void *ptr, size_t size))"
-Sets the allocation function to use (the prototype and semantics are
-identical to the realloc C function). It is used to allocate and free
-memory (no surprises here). If it returns zero when memory needs to be
-allocated, the library might abort or take some potentially destructive
-action. The default is your system realloc function.
+.IP "ev_set_allocator (void *(*cb)(void *ptr, long size))" 4
+.IX Item "ev_set_allocator (void *(*cb)(void *ptr, long size))"
+Sets the allocation function to use (the prototype is similar \- the
+semantics is identical \- to the realloc C function). It is used to
+allocate and free memory (no surprises here). If it returns zero when
+memory needs to be allocated, the library might abort or take some
+potentially destructive action. The default is your system realloc
+function.

 .Sp
 You could override this function in high-availability programs to, say,
 free some memory if it cannot allocate memory, to use a special allocator,
 .Sp
 You could override this function in high-availability programs to, say,
 free some memory if it cannot allocate memory, to use a special allocator,


@@ -411,6 +417,26 @@ 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)"


@@ -561,6 +587,15 @@ 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


@@ -865,6 +900,32 @@ 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
+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.

 .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


@@ -985,7 +1046,7 @@ 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


@@ -1071,23 +1132,25 @@ 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
+If the timer is started but nonrepeating, stop it (as if it timed out).

 .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 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.);


@@ -1100,8 +1163,8 @@ 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


@@ -1384,6 +1447,9 @@ not exist\*(R" is signified by the \f(CW\*(C`st_nlink\*(C'\fR field being zero (
 otherwise always forced to be at least one) and all the other fields of
 the stat buffer having unspecified contents.
 .PP
 otherwise always forced to be at least one) and all the other fields of
 the stat buffer having unspecified contents.
 .PP

+The path \fIshould\fR be absolute and \fImust not\fR end in a slash. If it is
+relative and your working directory changes, the behaviour is undefined.
+.PP

 Since there is no standard to do this, the portable implementation simply
 calls \f(CW\*(C`stat (2)\*(C'\fR regularly on the path to see if it changed somehow. You
 can specify a recommended polling interval for this case. If you specify
 Since there is no standard to do this, the portable implementation simply
 calls \f(CW\*(C`stat (2)\*(C'\fR regularly on the path to see if it changed somehow. You
 can specify a recommended polling interval for this case. If you specify


@@ -1474,13 +1540,16 @@ 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.


@@ -1585,12 +1654,13 @@ pseudo-code only of course:
 \&  }
 .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


@@ -1826,12 +1896,21 @@ 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


@@ -1853,21 +1932,61 @@ 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 (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
 .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


@@ -1875,12 +1994,13 @@ 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.


@@ -1916,18 +2036,21 @@ 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


@@ -1972,8 +2095,9 @@ 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


@@ -2046,7 +2170,7 @@ 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)


@@ -2209,11 +2333,34 @@ 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


@@ -2283,13 +2430,18 @@ 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


@@ -2307,27 +2459,50 @@ 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>.