*** empty log message ***

[software/libev.git] / ev.3

diff --git a/ev.3 b/ev.3
index 6c36997c8f6933d9fe531e2b85f2aca4e47c7227..9aefdffc7a17287c6fb3d41789f8b37e63c438f3 100644 (file)
--- a/ev.3
+++ b/ev.3
@@ -129,18 +129,21 @@
 .\" ========================================================================
 .\"
 .IX Title ""<STANDARD INPUT>" 1"
 .\" ========================================================================
 .\"
 .IX Title ""<STANDARD INPUT>" 1"

-.TH "<STANDARD INPUT>" 1 "2007-11-27" "perl v5.8.8" "User Contributed Perl Documentation"
+.TH "<STANDARD INPUT>" 1 "2007-11-28" "perl v5.8.8" "User Contributed Perl Documentation"

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

-.Vb 2
-\&  /* this is the only header you need */
+.Vb 1
+\&  #include <ev.h>
+.Ve
+.SH "EXAMPLE PROGRAM"
+.IX Header "EXAMPLE PROGRAM"
+.Vb 1

 \&  #include <ev.h>
 .Ve
 .PP
 \&  #include <ev.h>
 .Ve
 .PP

-.Vb 3
-\&  /* what follows is a fully working example program */
+.Vb 2

 \&  ev_io stdin_watcher;
 \&  ev_timer timeout_watcher;
 .Ve
 \&  ev_io stdin_watcher;
 \&  ev_timer timeout_watcher;
 .Ve


@@ -209,22 +212,28 @@ 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 select, poll, the linux-specific epoll and the bsd-specific
-kqueue mechanisms for file descriptor events, relative timers, absolute
-timers with customised rescheduling, signal events, process status change
-events (related to \s-1SIGCHLD\s0), and event watchers dealing with the event
-loop mechanism itself (idle, prepare and check watchers). It also is quite
-fast (see this benchmark comparing
-it to libevent for example).
+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).
+.PP
+It also is quite fast (see this
+benchmark comparing it to libevent
+for example).

 .SH "CONVENTIONS"
 .IX Header "CONVENTIONS"
 .SH "CONVENTIONS"
 .IX Header "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 the file
-\&\fI\s-1README\s0.embed\fR in the libev distribution. 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.
+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"
 Libev represents time as a single floating point number, representing the
 .SH "TIME REPRESENTATION"
 .IX Header "TIME REPRESENTATION"
 Libev represents time as a single floating point number, representing the


@@ -259,8 +268,8 @@ 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

-Example: make sure we haven't accidentally been linked against the wrong
-version:
+Example: Make sure we haven't accidentally been linked against the wrong
+version.

 .Sp
 .Vb 3
 \&  assert (("libev version mismatch",
 .Sp
 .Vb 3
 \&  assert (("libev version mismatch",


@@ -310,8 +319,8 @@ You could override this function in high-availability programs to, say,
 free some memory if it cannot allocate memory, to use a special allocator,
 or even to sleep a while and retry until some memory is available.
 .Sp
 free some memory if it cannot allocate memory, to use a special allocator,
 or even to sleep a while and retry until some memory is available.
 .Sp

-Example: replace the libev allocator with one that waits a bit and then
-retries: better than mine).
+Example: Replace the libev allocator with one that waits a bit and then
+retries).

 .Sp
 .Vb 6
 \&   static void *
 .Sp
 .Vb 6
 \&   static void *


@@ -347,7 +356,7 @@ matter what, when it returns. That is, libev will generally retry the
 requested operation, or, if the condition doesn't go away, do bad stuff
 (such as abort).
 .Sp
 requested operation, or, if the condition doesn't go away, do bad stuff
 (such as abort).
 .Sp

-Example: do the same thing as libev does internally:
+Example: This is basically the same thing that libev does internally, too.

 .Sp
 .Vb 6
 \&   static void
 .Sp
 .Vb 6
 \&   static void


@@ -506,7 +515,7 @@ always distinct from the default loop. Unlike the default loop, it cannot
 handle signal and child watchers, and attempts to do so will be greeted by
 undefined behaviour (or a failed assertion if assertions are enabled).
 .Sp
 handle signal and child watchers, and attempts to do so will be greeted by
 undefined behaviour (or a failed assertion if assertions are enabled).
 .Sp

-Example: try to create a event loop that uses epoll and nothing else.
+Example: Try to create a event loop that uses epoll and nothing else.

 .Sp
 .Vb 3
 \&  struct ev_loop *epoller = ev_loop_new (EVBACKEND_EPOLL | EVFLAG_NOENV);
 .Sp
 .Vb 3
 \&  struct ev_loop *epoller = ev_loop_new (EVBACKEND_EPOLL | EVFLAG_NOENV);


@@ -614,7 +623,7 @@ Here are the gory details of what \f(CW\*(C`ev_loop\*(C'\fR does:
 \&     were used, return, otherwise continue with step *.
 .Ve
 .Sp
 \&     were used, return, otherwise continue with step *.
 .Ve
 .Sp

-Example: queue some jobs and then loop until no events are outsanding
+Example: Queue some jobs and then loop until no events are outsanding

 anymore.
 .Sp
 .Vb 4
 anymore.
 .Sp
 .Vb 4


@@ -646,21 +655,21 @@ no event watchers registered by it are active. It is also an excellent
 way to do this for generic recurring timers or from within third-party
 libraries. Just remember to \fIunref after start\fR and \fIref before stop\fR.
 .Sp
 way to do this for generic recurring timers or from within third-party
 libraries. Just remember to \fIunref after start\fR and \fIref before stop\fR.
 .Sp

-Example: create a signal watcher, but keep it from keeping \f(CW\*(C`ev_loop\*(C'\fR
+Example: Create a signal watcher, but keep it from keeping \f(CW\*(C`ev_loop\*(C'\fR

 running when nothing else is active.
 .Sp
 .Vb 4
 running when nothing else is active.
 .Sp
 .Vb 4

-\&  struct dv_signal exitsig;
+\&  struct ev_signal exitsig;

 \&  ev_signal_init (&exitsig, sig_cb, SIGINT);
 \&  ev_signal_init (&exitsig, sig_cb, SIGINT);

-\&  ev_signal_start (myloop, &exitsig);
-\&  evf_unref (myloop);
+\&  ev_signal_start (loop, &exitsig);
+\&  evf_unref (loop);

 .Ve
 .Sp
 .Ve
 .Sp

-Example: for some weird reason, unregister the above signal handler again.
+Example: For some weird reason, unregister the above signal handler again.

 .Sp
 .Vb 2
 .Sp
 .Vb 2

-\&  ev_ref (myloop);
-\&  ev_signal_stop (myloop, &exitsig);
+\&  ev_ref (loop);
+\&  ev_signal_stop (loop, &exitsig);

 .Ve
 .SH "ANATOMY OF A WATCHER"
 .IX Header "ANATOMY OF A WATCHER"
 .Ve
 .SH "ANATOMY OF A WATCHER"
 .IX Header "ANATOMY OF A WATCHER"


@@ -850,8 +859,8 @@ 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).
 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).

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


@@ -887,8 +896,45 @@ can cast it back to your own type:
 \&  }
 .Ve
 .PP
 \&  }
 .Ve
 .PP

-More interesting and less C\-conformant ways of catsing your callback type
-have been omitted....
+More interesting and less C\-conformant ways of casting your callback type
+instead have been omitted.
+.PP
+Another common scenario is having some data structure with multiple
+watchers:
+.PP
+.Vb 6
+\&  struct my_biggy
+\&  {
+\&    int some_data;
+\&    ev_timer t1;
+\&    ev_timer t2;
+\&  }
+.Ve
+.PP
+In this case getting the pointer to \f(CW\*(C`my_biggy\*(C'\fR is a bit more complicated,
+you need to use \f(CW\*(C`offsetof\*(C'\fR:
+.PP
+.Vb 1
+\&  #include <stddef.h>
+.Ve
+.PP
+.Vb 6
+\&  static void
+\&  t1_cb (EV_P_ struct ev_timer *w, int revents)
+\&  {
+\&    struct my_biggy big = (struct my_biggy *
+\&      (((char *)w) - offsetof (struct my_biggy, t1));
+\&  }
+.Ve
+.PP
+.Vb 6
+\&  static void
+\&  t2_cb (EV_P_ struct ev_timer *w, int revents)
+\&  {
+\&    struct my_biggy big = (struct my_biggy *
+\&      (((char *)w) - offsetof (struct my_biggy, t2));
+\&  }
+.Ve

 .SH "WATCHER TYPES"
 .IX Header "WATCHER TYPES"
 This section describes each watcher in detail, but will not repeat
 .SH "WATCHER TYPES"
 .IX Header "WATCHER TYPES"
 This section describes each watcher in detail, but will not repeat


@@ -959,9 +1005,9 @@ The file descriptor being watched.
 .IX Item "int events [read-only]"
 The events being watched.
 .PP
 .IX Item "int events [read-only]"
 The events being watched.
 .PP

-Example: call \f(CW\*(C`stdin_readable_cb\*(C'\fR when \s-1STDIN_FILENO\s0 has become, well
+Example: Call \f(CW\*(C`stdin_readable_cb\*(C'\fR when \s-1STDIN_FILENO\s0 has become, well

 readable, but only once. Since it is likely line\-buffered, you could
 readable, but only once. Since it is likely line\-buffered, you could

-attempt to read a whole line in the callback:
+attempt to read a whole line in the callback.

 .PP
 .Vb 6
 \&  static void
 .PP
 .Vb 6
 \&  static void


@@ -1063,7 +1109,7 @@ The current \f(CW\*(C`repeat\*(C'\fR value. Will be used each time the watcher t
 or \f(CW\*(C`ev_timer_again\*(C'\fR is called and determines the next timeout (if any),
 which is also when any modifications are taken into account.
 .PP
 or \f(CW\*(C`ev_timer_again\*(C'\fR is called and determines the next timeout (if any),
 which is also when any modifications are taken into account.
 .PP

-Example: create a timer that fires after 60 seconds.
+Example: Create a timer that fires after 60 seconds.

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


@@ -1079,7 +1125,7 @@ Example: create a timer that fires after 60 seconds.
 \&  ev_timer_start (loop, &mytimer);
 .Ve
 .PP
 \&  ev_timer_start (loop, &mytimer);
 .Ve
 .PP

-Example: create a timeout timer that times out after 10 seconds of
+Example: Create a timeout timer that times out after 10 seconds of

 inactivity.
 .PP
 .Vb 5
 inactivity.
 .PP
 .Vb 5


@@ -1214,7 +1260,7 @@ The current reschedule callback, or \f(CW0\fR, if this functionality is
 switched off. Can be changed any time, but changes only take effect when
 the periodic timer fires or \f(CW\*(C`ev_periodic_again\*(C'\fR is being called.
 .PP
 switched off. Can be changed any time, but changes only take effect when
 the periodic timer fires or \f(CW\*(C`ev_periodic_again\*(C'\fR is being called.
 .PP

-Example: call a callback every hour, or, more precisely, whenever the
+Example: Call a callback every hour, or, more precisely, whenever the

 system clock is divisible by 3600. The callback invocation times have
 potentially a lot of jittering, but good long-term stability.
 .PP
 system clock is divisible by 3600. The callback invocation times have
 potentially a lot of jittering, but good long-term stability.
 .PP


@@ -1232,7 +1278,7 @@ potentially a lot of jittering, but good long-term stability.
 \&  ev_periodic_start (loop, &hourly_tick);
 .Ve
 .PP
 \&  ev_periodic_start (loop, &hourly_tick);
 .Ve
 .PP

-Example: the same as above, but use a reschedule callback to do it:
+Example: The same as above, but use a reschedule callback to do it:

 .PP
 .Vb 1
 \&  #include <math.h>
 .PP
 .Vb 1
 \&  #include <math.h>


@@ -1250,7 +1296,7 @@ Example: the same as above, but use a reschedule callback to do it:
 \&  ev_periodic_init (&hourly_tick, clock_cb, 0., 0., my_scheduler_cb);
 .Ve
 .PP
 \&  ev_periodic_init (&hourly_tick, clock_cb, 0., 0., my_scheduler_cb);
 .Ve
 .PP

-Example: call a callback every hour, starting now:
+Example: Call a callback every hour, starting now:

 .PP
 .Vb 4
 \&  struct ev_periodic hourly_tick;
 .PP
 .Vb 4
 \&  struct ev_periodic hourly_tick;


@@ -1311,7 +1357,7 @@ The process id that detected a status change.
 The process exit/trace status caused by \f(CW\*(C`rpid\*(C'\fR (see your systems
 \&\f(CW\*(C`waitpid\*(C'\fR and \f(CW\*(C`sys/wait.h\*(C'\fR documentation for details).
 .PP
 The process exit/trace status caused by \f(CW\*(C`rpid\*(C'\fR (see your systems
 \&\f(CW\*(C`waitpid\*(C'\fR and \f(CW\*(C`sys/wait.h\*(C'\fR documentation for details).
 .PP

-Example: try to exit cleanly on \s-1SIGINT\s0 and \s-1SIGTERM\s0.
+Example: Try to exit cleanly on \s-1SIGINT\s0 and \s-1SIGTERM\s0.

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


@@ -1340,7 +1386,7 @@ otherwise always forced to be at least one) and all the other fields of
 the stat buffer having unspecified contents.
 .PP
 Since there is no standard to do this, the portable implementation simply
 the stat buffer having unspecified contents.
 .PP
 Since there is no standard to do this, the portable implementation simply

-calls \f(CW\*(C`stat (2)\*(C'\fR regulalry on the path to see if it changed somehow. You
+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
 a polling interval of \f(CW0\fR (highly recommended!) then a \fIsuitable,
 unspecified default\fR value will be used (which you can expect to be around
 can specify a recommended polling interval for this case. If you specify
 a polling interval of \f(CW0\fR (highly recommended!) then a \fIsuitable,
 unspecified default\fR value will be used (which you can expect to be around


@@ -1352,8 +1398,13 @@ This watcher type is not meant for massive numbers of stat watchers,
 as even with OS-supported change notifications, this can be
 resource\-intensive.
 .PP
 as even with OS-supported change notifications, this can be
 resource\-intensive.
 .PP

-At the time of this writing, no specific \s-1OS\s0 backends are implemented, but
-if demand increases, at least a kqueue and inotify backend will be added.
+At the time of this writing, only the Linux inotify interface is
+implemented (implementing kqueue support is left as an exercise for the
+reader). Inotify will be used to give hints only and should not change the
+semantics of \f(CW\*(C`ev_stat\*(C'\fR watchers, which means that libev sometimes needs
+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.

 .IP "ev_stat_init (ev_stat *, callback, const char *path, ev_tstamp interval)" 4
 .IX Item "ev_stat_init (ev_stat *, callback, const char *path, ev_tstamp interval)"
 .PD 0
 .IP "ev_stat_init (ev_stat *, callback, const char *path, ev_tstamp interval)" 4
 .IX Item "ev_stat_init (ev_stat *, callback, const char *path, ev_tstamp interval)"
 .PD 0


@@ -1445,8 +1496,8 @@ Initialises and configures the idle watcher \- it has no parameters of any
 kind. There is a \f(CW\*(C`ev_idle_set\*(C'\fR macro, but using it is utterly pointless,
 believe me.
 .PP
 kind. There is a \f(CW\*(C`ev_idle_set\*(C'\fR macro, but using it is utterly pointless,
 believe me.
 .PP

-Example: dynamically allocate an \f(CW\*(C`ev_idle\*(C'\fR, start it, and in the
-callback, free it. Alos, use no error checking, as usual.
+Example: Dynamically allocate an \f(CW\*(C`ev_idle\*(C'\fR watcher, start it, and in the
+callback, free it. Also, use no error checking, as usual.

 .PP
 .Vb 7
 \&  static void
 .PP
 .Vb 7
 \&  static void


@@ -2127,6 +2178,11 @@ 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_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
 .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


@@ -2181,7 +2237,14 @@ some inlining decisions, saves roughly 30% codesize of amd64.
 \&\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
 \&\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.
+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
 .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


@@ -2255,8 +2318,8 @@ documentation for \f(CW\*(C`ev_default_init\*(C'\fR.
 .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)"
 .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)"

-.IP "Stopping an io/signal/child watcher: O(number_of_watchers_for_this_(fd/signal/pid % 16))" 4
-.IX Item "Stopping an io/signal/child watcher: O(number_of_watchers_for_this_(fd/signal/pid % 16))"
+.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 "Finding the next timer per loop iteration: O(1)" 4
 .IX Item "Finding the next timer per loop iteration: O(1)"
 .IP "Each change on a file descriptor per loop iteration: O(number_of_watchers_for_this_fd)" 4
 .IP "Finding the next timer per loop iteration: O(1)" 4
 .IX Item "Finding the next timer per loop iteration: O(1)"
 .IP "Each change on a file descriptor per loop iteration: O(number_of_watchers_for_this_fd)" 4