.\" ========================================================================
.\"
.IX Title ""<STANDARD INPUT>" 1"
-.TH "<STANDARD INPUT>" 1 "2007-11-26" "perl v5.8.8" "User Contributed Perl Documentation"
+.TH "<STANDARD INPUT>" 1 "2007-11-27" "perl v5.8.8" "User Contributed Perl Documentation"
.SH "NAME"
libev \- a high performance full\-featured event loop written in C
.SH "SYNOPSIS"
.el .IP "\f(CWEV_CHILD\fR" 4
.IX Item "EV_CHILD"
The pid specified in the \f(CW\*(C`ev_child\*(C'\fR watcher has received a status change.
+.ie n .IP """EV_STAT""" 4
+.el .IP "\f(CWEV_STAT\fR" 4
+.IX Item "EV_STAT"
+The path specified in the \f(CW\*(C`ev_stat\*(C'\fR watcher changed its attributes somehow.
.ie n .IP """EV_IDLE""" 4
.el .IP "\f(CWEV_IDLE\fR" 4
.IX Item "EV_IDLE"
.SH "WATCHER TYPES"
.IX Header "WATCHER TYPES"
This section describes each watcher in detail, but will not repeat
-information given in the last section.
+information given in the last section. Any initialisation/set macros,
+functions and members specific to the watcher type are explained.
+.PP
+Members are additionally marked with either \fI[read\-only]\fR, meaning that,
+while the watcher is active, you can look at the member and expect some
+sensible content, but you must not modify it (you can modify it while the
+watcher is stopped to your hearts content), or \fI[read\-write]\fR, which
+means you can expect it to have some sensible content while the watcher
+is active, but you can also modify it. Modifying it may not do something
+sensible or take immediate effect (or do anything at all), but libev will
+not crash or malfunction in any way.
.ie n .Sh """ev_io"" \- is this file descriptor readable or writable?"
.el .Sh "\f(CWev_io\fP \- is this file descriptor readable or writable?"
.IX Subsection "ev_io - is this file descriptor readable or writable?"
Configures an \f(CW\*(C`ev_io\*(C'\fR watcher. The \f(CW\*(C`fd\*(C'\fR is the file descriptor to
rceeive events for and events is either \f(CW\*(C`EV_READ\*(C'\fR, \f(CW\*(C`EV_WRITE\*(C'\fR or
\&\f(CW\*(C`EV_READ | EV_WRITE\*(C'\fR to receive the given events.
+.IP "int fd [read\-only]" 4
+.IX Item "int fd [read-only]"
+The file descriptor being watched.
+.IP "int events [read\-only]" 4
+.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
readable, but only once. Since it is likely line\-buffered, you could
value), or reset the running timer to the repeat value.
.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 after=repeat=60 and calling ev_timer_again 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.
+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
+\&\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.
+.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:
+.Sp
+.Vb 8
+\& ev_timer_init (timer, callback, 0., 5.);
+\& ev_timer_again (loop, timer);
+\& ...
+\& timer->again = 17.;
+\& ev_timer_again (loop, timer);
+\& ...
+\& timer->again = 10.;
+\& 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.
+.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
+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.
.PP
when you changed some parameters or the reschedule callback would return
a different time than the last time it was called (e.g. in a crond like
program when the crontabs have changed).
+.IP "ev_tstamp interval [read\-write]" 4
+.IX Item "ev_tstamp interval [read-write]"
+The current interval value. Can be modified any time, but changes only
+take effect when the periodic timer fires or \f(CW\*(C`ev_periodic_again\*(C'\fR is being
+called.
+.IP "ev_tstamp (*reschedule_cb)(struct ev_periodic *w, ev_tstamp now) [read\-write]" 4
+.IX Item "ev_tstamp (*reschedule_cb)(struct ev_periodic *w, ev_tstamp now) [read-write]"
+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
Example: call a callback every hour, or, more precisely, whenever the
system clock is divisible by 3600. The callback invocation times have
.PD
Configures the watcher to trigger on the given signal number (usually one
of the \f(CW\*(C`SIGxxx\*(C'\fR constants).
+.IP "int signum [read\-only]" 4
+.IX Item "int signum [read-only]"
+The signal the watcher watches out for.
.ie n .Sh """ev_child"" \- watch out for process status changes"
.el .Sh "\f(CWev_child\fP \- watch out for process status changes"
.IX Subsection "ev_child - watch out for process status changes"
the status word (use the macros from \f(CW\*(C`sys/wait.h\*(C'\fR and see your systems
\&\f(CW\*(C`waitpid\*(C'\fR documentation). The \f(CW\*(C`rpid\*(C'\fR member contains the pid of the
process causing the status change.
+.IP "int pid [read\-only]" 4
+.IX Item "int pid [read-only]"
+The process id this watcher watches out for, or \f(CW0\fR, meaning any process id.
+.IP "int rpid [read\-write]" 4
+.IX Item "int rpid [read-write]"
+The process id that detected a status change.
+.IP "int rstatus [read\-write]" 4
+.IX Item "int rstatus [read-write]"
+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.
.PP
\& ev_signal_init (&signal_watcher, sigint_cb, SIGINT);
\& ev_signal_start (loop, &sigint_cb);
.Ve
+.ie n .Sh """ev_stat"" \- did the file attributes just change?"
+.el .Sh "\f(CWev_stat\fP \- did the file attributes just change?"
+.IX Subsection "ev_stat - did the file attributes just change?"
+This watches a filesystem path for attribute changes. That is, it calls
+\&\f(CW\*(C`stat\*(C'\fR regularly (or when the \s-1OS\s0 says it changed) and sees if it changed
+compared to the last time, invoking the callback if it did.
+.PP
+The path does not need to exist: changing from \*(L"path exists\*(R" to \*(L"path does
+not exist\*(R" is a status change like any other. The condition \*(L"path does
+not exist\*(R" is signified by the \f(CW\*(C`st_nlink\*(C'\fR field being zero (which is
+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
+calls \f(CW\*(C`stat (2)\*(C'\fR regulalry 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
+five seconds, although this might change dynamically). Libev will also
+impose a minimum interval which is currently around \f(CW0.1\fR, but thats
+usually overkill.
+.PP
+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
+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.
+.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_set (ev_stat *, const char *path, ev_tstamp interval)" 4
+.IX Item "ev_stat_set (ev_stat *, const char *path, ev_tstamp interval)"
+.PD
+Configures the watcher to wait for status changes of the given
+\&\f(CW\*(C`path\*(C'\fR. The \f(CW\*(C`interval\*(C'\fR is a hint on how quickly a change is expected to
+be detected and should normally be specified as \f(CW0\fR to let libev choose
+a suitable value. The memory pointed to by \f(CW\*(C`path\*(C'\fR must point to the same
+path for as long as the watcher is active.
+.Sp
+The callback will be receive \f(CW\*(C`EV_STAT\*(C'\fR when a change was detected,
+relative to the attributes at the time the watcher was started (or the
+last change was detected).
+.IP "ev_stat_stat (ev_stat *)" 4
+.IX Item "ev_stat_stat (ev_stat *)"
+Updates the stat buffer immediately with new values. If you change the
+watched path in your callback, you could call this fucntion to avoid
+detecting this change (while introducing a race condition). Can also be
+useful simply to find out the new values.
+.IP "ev_statdata attr [read\-only]" 4
+.IX Item "ev_statdata attr [read-only]"
+The most-recently detected attributes of the file. Although the type is of
+\&\f(CW\*(C`ev_statdata\*(C'\fR, this is usually the (or one of the) \f(CW\*(C`struct stat\*(C'\fR types
+suitable for your system. If the \f(CW\*(C`st_nlink\*(C'\fR member is \f(CW0\fR, then there
+was some error while \f(CW\*(C`stat\*(C'\fRing the file.
+.IP "ev_statdata prev [read\-only]" 4
+.IX Item "ev_statdata prev [read-only]"
+The previous attributes of the file. The callback gets invoked whenever
+\&\f(CW\*(C`prev\*(C'\fR != \f(CW\*(C`attr\*(C'\fR.
+.IP "ev_tstamp interval [read\-only]" 4
+.IX Item "ev_tstamp interval [read-only]"
+The specified interval.
+.IP "const char *path [read\-only]" 4
+.IX Item "const char *path [read-only]"
+The filesystem path that is being watched.
+.PP
+Example: Watch \f(CW\*(C`/etc/passwd\*(C'\fR for attribute changes.
+.PP
+.Vb 15
+\& static void
+\& passwd_cb (struct ev_loop *loop, ev_stat *w, int revents)
+\& {
+\& /* /etc/passwd changed in some way */
+\& if (w->attr.st_nlink)
+\& {
+\& printf ("passwd current size %ld\en", (long)w->attr.st_size);
+\& printf ("passwd current atime %ld\en", (long)w->attr.st_mtime);
+\& printf ("passwd current mtime %ld\en", (long)w->attr.st_mtime);
+\& }
+\& else
+\& /* you shalt not abuse printf for puts */
+\& puts ("wow, /etc/passwd is not there, expect problems. "
+\& "if this is windows, they already arrived\en");
+\& }
+.Ve
+.PP
+.Vb 2
+\& ...
+\& ev_stat passwd;
+.Ve
+.PP
+.Vb 2
+\& ev_stat_init (&passwd, passwd_cb, "/etc/passwd");
+\& ev_stat_start (loop, &passwd);
+.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..."
Make a single, non-blocking sweep over the embedded loop. This works
similarly to \f(CW\*(C`ev_loop (embedded_loop, EVLOOP_NONBLOCK)\*(C'\fR, but in the most
apropriate way for embedded loops.
+.IP "struct ev_loop *loop [read\-only]" 4
+.IX Item "struct ev_loop *loop [read-only]"
+The embedded event loop.
.SH "OTHER FUNCTIONS"
.IX Header "OTHER FUNCTIONS"
There are some other functions of possible interest. Described. Here. Now.
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_PERIODICS\s0" 4
-.IX Item "EV_PERIODICS"
-If undefined or defined to be \f(CW1\fR, then periodic timers are supported,
-otherwise not. This 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_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_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_COMMON\s0" 4
.IX Item "EV_COMMON"
By default, all watchers have a \f(CW\*(C`void *data\*(C'\fR member. By redefining
}
#endif
-void
-ev_idle_start (EV_P_ ev_idle *w)
-{
- if (expect_false (ev_is_active (w)))
- return;
-
- ev_start (EV_A_ (W)w, ++idlecnt);
- array_needsize (ev_idle *, idles, idlemax, idlecnt, EMPTY2);
- idles [idlecnt - 1] = w;
-}
-
-void
-ev_idle_stop (EV_P_ ev_idle *w)
-{
- ev_clear_pending (EV_A_ (W)w);
- if (expect_false (!ev_is_active (w)))
- return;
-
- {
- int active = ((W)w)->active;
- idles [active - 1] = idles [--idlecnt];
- ((W)idles [active - 1])->active = active;
- }
-
- ev_stop (EV_A_ (W)w);
-}
-
-void
-ev_prepare_start (EV_P_ ev_prepare *w)
-{
- if (expect_false (ev_is_active (w)))
- return;
-
- ev_start (EV_A_ (W)w, ++preparecnt);
- array_needsize (ev_prepare *, prepares, preparemax, preparecnt, EMPTY2);
- prepares [preparecnt - 1] = w;
-}
-
-void
-ev_prepare_stop (EV_P_ ev_prepare *w)
-{
- ev_clear_pending (EV_A_ (W)w);
- if (expect_false (!ev_is_active (w)))
- return;
-
- {
- int active = ((W)w)->active;
- prepares [active - 1] = prepares [--preparecnt];
- ((W)prepares [active - 1])->active = active;
- }
-
- ev_stop (EV_A_ (W)w);
-}
-
-void
-ev_check_start (EV_P_ ev_check *w)
-{
- if (expect_false (ev_is_active (w)))
- return;
-
- ev_start (EV_A_ (W)w, ++checkcnt);
- array_needsize (ev_check *, checks, checkmax, checkcnt, EMPTY2);
- checks [checkcnt - 1] = w;
-}
-
-void
-ev_check_stop (EV_P_ ev_check *w)
-{
- ev_clear_pending (EV_A_ (W)w);
- if (expect_false (!ev_is_active (w)))
- return;
-
- {
- int active = ((W)w)->active;
- checks [active - 1] = checks [--checkcnt];
- ((W)checks [active - 1])->active = active;
- }
-
- ev_stop (EV_A_ (W)w);
-}
-
#ifndef SA_RESTART
# define SA_RESTART 0
#endif
ev_stop (EV_A_ (W)w);
}
-#if EV_EMBED_ENABLE
-void noinline
-ev_embed_sweep (EV_P_ ev_embed *w)
-{
- ev_loop (w->loop, EVLOOP_NONBLOCK);
-}
-
-static void
-embed_cb (EV_P_ ev_io *io, int revents)
-{
- ev_embed *w = (ev_embed *)(((char *)io) - offsetof (ev_embed, io));
-
- if (ev_cb (w))
- ev_feed_event (EV_A_ (W)w, EV_EMBED);
- else
- ev_embed_sweep (loop, w);
-}
-
-void
-ev_embed_start (EV_P_ ev_embed *w)
-{
- if (expect_false (ev_is_active (w)))
- return;
-
- {
- struct ev_loop *loop = w->loop;
- assert (("loop to be embedded is not embeddable", backend & ev_embeddable_backends ()));
- ev_io_init (&w->io, embed_cb, backend_fd, EV_READ);
- }
-
- ev_set_priority (&w->io, ev_priority (w));
- ev_io_start (EV_A_ &w->io);
-
- ev_start (EV_A_ (W)w, 1);
-}
-
-void
-ev_embed_stop (EV_P_ ev_embed *w)
-{
- ev_clear_pending (EV_A_ (W)w);
- if (expect_false (!ev_is_active (w)))
- return;
-
- ev_io_stop (EV_A_ &w->io);
-
- ev_stop (EV_A_ (W)w);
-}
-#endif
-
#if EV_STAT_ENABLE
# ifdef _WIN32
}
#endif
+void
+ev_idle_start (EV_P_ ev_idle *w)
+{
+ if (expect_false (ev_is_active (w)))
+ return;
+
+ ev_start (EV_A_ (W)w, ++idlecnt);
+ array_needsize (ev_idle *, idles, idlemax, idlecnt, EMPTY2);
+ idles [idlecnt - 1] = w;
+}
+
+void
+ev_idle_stop (EV_P_ ev_idle *w)
+{
+ ev_clear_pending (EV_A_ (W)w);
+ if (expect_false (!ev_is_active (w)))
+ return;
+
+ {
+ int active = ((W)w)->active;
+ idles [active - 1] = idles [--idlecnt];
+ ((W)idles [active - 1])->active = active;
+ }
+
+ ev_stop (EV_A_ (W)w);
+}
+
+void
+ev_prepare_start (EV_P_ ev_prepare *w)
+{
+ if (expect_false (ev_is_active (w)))
+ return;
+
+ ev_start (EV_A_ (W)w, ++preparecnt);
+ array_needsize (ev_prepare *, prepares, preparemax, preparecnt, EMPTY2);
+ prepares [preparecnt - 1] = w;
+}
+
+void
+ev_prepare_stop (EV_P_ ev_prepare *w)
+{
+ ev_clear_pending (EV_A_ (W)w);
+ if (expect_false (!ev_is_active (w)))
+ return;
+
+ {
+ int active = ((W)w)->active;
+ prepares [active - 1] = prepares [--preparecnt];
+ ((W)prepares [active - 1])->active = active;
+ }
+
+ ev_stop (EV_A_ (W)w);
+}
+
+void
+ev_check_start (EV_P_ ev_check *w)
+{
+ if (expect_false (ev_is_active (w)))
+ return;
+
+ ev_start (EV_A_ (W)w, ++checkcnt);
+ array_needsize (ev_check *, checks, checkmax, checkcnt, EMPTY2);
+ checks [checkcnt - 1] = w;
+}
+
+void
+ev_check_stop (EV_P_ ev_check *w)
+{
+ ev_clear_pending (EV_A_ (W)w);
+ if (expect_false (!ev_is_active (w)))
+ return;
+
+ {
+ int active = ((W)w)->active;
+ checks [active - 1] = checks [--checkcnt];
+ ((W)checks [active - 1])->active = active;
+ }
+
+ ev_stop (EV_A_ (W)w);
+}
+
+#if EV_EMBED_ENABLE
+void noinline
+ev_embed_sweep (EV_P_ ev_embed *w)
+{
+ ev_loop (w->loop, EVLOOP_NONBLOCK);
+}
+
+static void
+embed_cb (EV_P_ ev_io *io, int revents)
+{
+ ev_embed *w = (ev_embed *)(((char *)io) - offsetof (ev_embed, io));
+
+ if (ev_cb (w))
+ ev_feed_event (EV_A_ (W)w, EV_EMBED);
+ else
+ ev_embed_sweep (loop, w);
+}
+
+void
+ev_embed_start (EV_P_ ev_embed *w)
+{
+ if (expect_false (ev_is_active (w)))
+ return;
+
+ {
+ struct ev_loop *loop = w->loop;
+ assert (("loop to be embedded is not embeddable", backend & ev_embeddable_backends ()));
+ ev_io_init (&w->io, embed_cb, backend_fd, EV_READ);
+ }
+
+ ev_set_priority (&w->io, ev_priority (w));
+ ev_io_start (EV_A_ &w->io);
+
+ ev_start (EV_A_ (W)w, 1);
+}
+
+void
+ev_embed_stop (EV_P_ ev_embed *w)
+{
+ ev_clear_pending (EV_A_ (W)w);
+ if (expect_false (!ev_is_active (w)))
+ return;
+
+ ev_io_stop (EV_A_ &w->io);
+
+ ev_stop (EV_A_ (W)w);
+}
+#endif
+
/*****************************************************************************/
struct ev_once
EV_WATCHER_TIME (ev_watcher_time)
} ev_watcher_time;
+/* invoked when fd is either EV_READable or EV_WRITEable */
+/* revent EV_READ, EV_WRITE */
+typedef struct ev_io
+{
+ EV_WATCHER_LIST (ev_io)
+
+ int fd; /* ro */
+ int events; /* ro */
+} ev_io;
+
/* invoked after a specific time, repeatable (based on monotonic clock) */
/* revent EV_TIMEOUT */
typedef struct ev_timer
ev_tstamp (*reschedule_cb)(struct ev_periodic *w, ev_tstamp now); /* rw */
} ev_periodic;
-/* invoked when fd is either EV_READable or EV_WRITEable */
-/* revent EV_READ, EV_WRITE */
-typedef struct ev_io
-{
- EV_WATCHER_LIST (ev_io)
-
- int fd; /* ro */
- int events; /* ro */
-} ev_io;
-
/* invoked when the given signal has been received */
/* revent EV_SIGNAL */
typedef struct ev_signal
int signum; /* ro */
} ev_signal;
+/* invoked when sigchld is received and waitpid indicates the given pid */
+/* revent EV_CHILD */
+/* does not support priorities */
+typedef struct ev_child
+{
+ EV_WATCHER_LIST (ev_child)
+
+ int pid; /* ro */
+ int rpid; /* rw, holds the received pid */
+ int rstatus; /* rw, holds the exit status, use the macros from sys/wait.h */
+} ev_child;
+
+#if EV_STAT_ENABLE
+/* st_nlink = 0 means missing file or other error */
+typedef struct stat ev_statdata;
+
+/* invoked each time the stat data changes for a given path */
+/* revent EV_STAT */
+typedef struct ev_stat
+{
+ EV_WATCHER (ev_stat)
+
+ ev_timer timer; /* private */
+ ev_tstamp interval; /* ro */
+ const char *path; /* ro */
+ ev_statdata prev; /* ro */
+ ev_statdata attr; /* ro */
+} ev_stat;
+#endif
+
/* invoked when the nothing else needs to be done, keeps the process from blocking */
/* revent EV_IDLE */
typedef struct ev_idle
EV_WATCHER (ev_check)
} ev_check;
-/* invoked when sigchld is received and waitpid indicates the given pid */
-/* revent EV_CHILD */
-/* does not support priorities */
-typedef struct ev_child
-{
- EV_WATCHER_LIST (ev_child)
-
- int pid; /* ro */
- int rpid; /* rw, holds the received pid */
- int rstatus; /* rw, holds the exit status, use the macros from sys/wait.h */
-} ev_child;
-
#if EV_EMBED_ENABLE
/* used to embed an event loop inside another */
/* the callback gets invoked when the event loop has handled events, and can be 0 */
} ev_embed;
#endif
-#if EV_STAT_ENABLE
-/* st_nlink = 0 means missing file or other error */
-typedef struct stat ev_statdata;
-
-/* invoked each time the stat data changes for a given path */
-/* revent EV_STAT */
-typedef struct ev_stat
-{
- EV_WATCHER (ev_stat)
-
- ev_timer timer; /* private */
- ev_tstamp interval; /* rw */
- const char *path; /* ro */
- ev_statdata prev; /* ro */
- ev_statdata attr; /* ro */
-} ev_stat;
-#endif
-
/* the presence of this union forces similar struct layout */
union ev_any_watcher
{
struct ev_io io;
struct ev_timer timer;
struct ev_periodic periodic;
+ struct ev_child child;
+#if EV_STAT_ENABLE
+ struct ev_stat stat;
+#endif
struct ev_idle idle;
struct ev_prepare prepare;
struct ev_check check;
struct ev_signal signal;
- struct ev_child child;
#if EV_EMBED_ENABLE
struct ev_embed embed;
#endif
-#if EV_STAT_ENABLE
- struct ev_stat stat;
-#endif
};
/* bits for ev_default_loop and ev_loop_new */
#define ev_timer_set(ev,after_,repeat_) do { (ev)->at = (after_); (ev)->repeat = (repeat_); } while (0)
#define ev_periodic_set(ev,at_,ival_,res_) do { (ev)->at = (at_); (ev)->interval = (ival_); (ev)->reschedule_cb= (res_); } while (0)
#define ev_signal_set(ev,signum_) do { (ev)->signum = (signum_); } while (0)
+#define ev_child_set(ev,pid_) do { (ev)->pid = (pid_); } while (0)
+#define ev_stat_set(ev,path_,interval_) do { (ev)->path = (path_); (ev)->interval = (interval_); } while (0)
#define ev_idle_set(ev) /* nop, yes, this is a serious in-joke */
#define ev_prepare_set(ev) /* nop, yes, this is a serious in-joke */
#define ev_check_set(ev) /* nop, yes, this is a serious in-joke */
-#define ev_child_set(ev,pid_) do { (ev)->pid = (pid_); } while (0)
#define ev_embed_set(ev,loop_) do { (ev)->loop = (loop_); } while (0)
-#define ev_stat_set(ev,path_,interval_) do { (ev)->path = (path_); (ev)->interval = (interval_); } while (0)
#define ev_io_init(ev,cb,fd,events) do { ev_init ((ev), (cb)); ev_io_set ((ev),(fd),(events)); } while (0)
#define ev_timer_init(ev,cb,after,repeat) do { ev_init ((ev), (cb)); ev_timer_set ((ev),(after),(repeat)); } while (0)
#define ev_periodic_init(ev,cb,at,ival,res) do { ev_init ((ev), (cb)); ev_periodic_set ((ev),(at),(ival),(res)); } while (0)
#define ev_signal_init(ev,cb,signum) do { ev_init ((ev), (cb)); ev_signal_set ((ev), (signum)); } while (0)
+#define ev_child_init(ev,cb,pid) do { ev_init ((ev), (cb)); ev_child_set ((ev),(pid)); } while (0)
+#define ev_stat_init(ev,cb,path,interval) do { ev_init ((ev), (cb)); ev_path_set ((ev),(path),(interval)); } while (0)
#define ev_idle_init(ev,cb) do { ev_init ((ev), (cb)); ev_idle_set ((ev)); } while (0)
#define ev_prepare_init(ev,cb) do { ev_init ((ev), (cb)); ev_prepare_set ((ev)); } while (0)
#define ev_check_init(ev,cb) do { ev_init ((ev), (cb)); ev_check_set ((ev)); } while (0)
-#define ev_child_init(ev,cb,pid) do { ev_init ((ev), (cb)); ev_child_set ((ev),(pid)); } while (0)
#define ev_embed_init(ev,cb,loop) do { ev_init ((ev), (cb)); ev_embed_set ((ev),(loop)); } while (0)
-#define ev_stat_init(ev,cb,path,interval) do { ev_init ((ev), (cb)); ev_path_set ((ev),(path),(interval)); } while (0)
#define ev_is_pending(ev) (0 + ((ev_watcher *)(void *)(ev))->pending) /* ro, true when watcher is waiting for callback invocation */
#define ev_is_active(ev) (0 + ((ev_watcher *)(void *)(ev))->active) /* ro, true when the watcher has been started */
void ev_periodic_again (EV_P_ ev_periodic *w);
#endif
+/* only supported in the default loop */
+void ev_signal_start (EV_P_ ev_signal *w);
+void ev_signal_stop (EV_P_ ev_signal *w);
+
+/* only supported in the default loop */
+void ev_child_start (EV_P_ ev_child *w);
+void ev_child_stop (EV_P_ ev_child *w);
+
+# if EV_STAT_ENABLE
+void ev_stat_start (EV_P_ ev_stat *w);
+void ev_stat_stop (EV_P_ ev_stat *w);
+void ev_stat_stat (EV_P_ ev_stat *w);
+# endif
+
void ev_idle_start (EV_P_ ev_idle *w);
void ev_idle_stop (EV_P_ ev_idle *w);
void ev_check_start (EV_P_ ev_check *w);
void ev_check_stop (EV_P_ ev_check *w);
-/* only supported in the default loop */
-void ev_signal_start (EV_P_ ev_signal *w);
-void ev_signal_stop (EV_P_ ev_signal *w);
-
-/* only supported in the default loop */
-void ev_child_start (EV_P_ ev_child *w);
-void ev_child_stop (EV_P_ ev_child *w);
-
# if EV_EMBED_ENABLE
/* only supported when loop to be embedded is in fact embeddable */
void ev_embed_start (EV_P_ ev_embed *w);
void ev_embed_sweep (EV_P_ ev_embed *w);
# endif
-# if EV_STAT_ENABLE
-void ev_stat_start (EV_P_ ev_stat *w);
-void ev_stat_stop (EV_P_ ev_stat *w);
-void ev_stat_stat (EV_P_ ev_stat *w);
-# endif
-
#endif
#ifdef __cplusplus
<meta name="description" content="Pod documentation for libev" />
<meta name="inputfile" content="<standard input>" />
<meta name="outputfile" content="<standard output>" />
- <meta name="created" content="Mon Nov 26 11:20:35 2007" />
+ <meta name="created" content="Tue Nov 27 09:11:42 2007" />
<meta name="generator" content="Pod::Xhtml 1.57" />
<link rel="stylesheet" href="http://res.tst.eu/pod.css"/></head>
<body>
<li><a href="#code_ev_periodic_code_to_cron_or_not"><code>ev_periodic</code> - to cron or not to cron?</a></li>
<li><a href="#code_ev_signal_code_signal_me_when_a"><code>ev_signal</code> - signal me when a signal gets signalled!</a></li>
<li><a href="#code_ev_child_code_watch_out_for_pro"><code>ev_child</code> - watch out for process status changes</a></li>
+<li><a href="#code_ev_stat_code_did_the_file_attri"><code>ev_stat</code> - did the file attributes just change?</a></li>
<li><a href="#code_ev_idle_code_when_you_ve_got_no"><code>ev_idle</code> - when you've got nothing better to do...</a></li>
<li><a href="#code_ev_prepare_code_and_code_ev_che"><code>ev_prepare</code> and <code>ev_check</code> - customise your event loop!</a></li>
<li><a href="#code_ev_embed_code_when_one_backend_"><code>ev_embed</code> - when one backend isn't enough...</a></li>
<dd>
<p>The pid specified in the <code>ev_child</code> watcher has received a status change.</p>
</dd>
+ <dt><code>EV_STAT</code></dt>
+ <dd>
+ <p>The path specified in the <code>ev_stat</code> watcher changed its attributes somehow.</p>
+ </dd>
<dt><code>EV_IDLE</code></dt>
<dd>
<p>The <code>ev_idle</code> watcher has determined that you have nothing better to do.</p>
<h1 id="WATCHER_TYPES">WATCHER TYPES</h1><p><a href="#TOP" class="toplink">Top</a></p>
<div id="WATCHER_TYPES_CONTENT">
<p>This section describes each watcher in detail, but will not repeat
-information given in the last section.</p>
+information given in the last section. Any initialisation/set macros,
+functions and members specific to the watcher type are explained.</p>
+<p>Members are additionally marked with either <i>[read-only]</i>, meaning that,
+while the watcher is active, you can look at the member and expect some
+sensible content, but you must not modify it (you can modify it while the
+watcher is stopped to your hearts content), or <i>[read-write]</i>, which
+means you can expect it to have some sensible content while the watcher
+is active, but you can also modify it. Modifying it may not do something
+sensible or take immediate effect (or do anything at all), but libev will
+not crash or malfunction in any way.</p>
rceeive events for and events is either <code>EV_READ</code>, <code>EV_WRITE</code> or
<code>EV_READ | EV_WRITE</code> to receive the given events.</p>
</dd>
+ <dt>int fd [read-only]</dt>
+ <dd>
+ <p>The file descriptor being watched.</p>
+ </dd>
+ <dt>int events [read-only]</dt>
+ <dd>
+ <p>The events being watched.</p>
+ </dd>
</dl>
<p>Example: call <code>stdin_readable_cb</code> when STDIN_FILENO has become, well
readable, but only once. Since it is likely line-buffered, you could
<p>If the timer is repeating, either start it if necessary (with the repeat
value), or reset the running timer to the repeat value.</p>
<p>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 <code>ev_timer</code> with after=repeat=60 and calling ev_timer_again 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.</p>
+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 <code>ev_timer</code> with <code>after</code>=<code>repeat</code>=<code>60</code> and calling
+<code>ev_timer_again</code> 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.</p>
+ <p>You can also ignore the <code>after</code> value and <code>ev_timer_start</code> altogether
+and only ever use the <code>repeat</code> value:</p>
+<pre> ev_timer_init (timer, callback, 0., 5.);
+ ev_timer_again (loop, timer);
+ ...
+ timer->again = 17.;
+ ev_timer_again (loop, timer);
+ ...
+ timer->again = 10.;
+ ev_timer_again (loop, timer);
+
+</pre>
+ <p>This is more efficient then stopping/starting the timer eahc time you want
+to modify its timeout value.</p>
+ </dd>
+ <dt>ev_tstamp repeat [read-write]</dt>
+ <dd>
+ <p>The current <code>repeat</code> value. Will be used each time the watcher times out
+or <code>ev_timer_again</code> is called and determines the next timeout (if any),
+which is also when any modifications are taken into account.</p>
</dd>
</dl>
<p>Example: create a timer that fires after 60 seconds.</p>
a different time than the last time it was called (e.g. in a crond like
program when the crontabs have changed).</p>
</dd>
+ <dt>ev_tstamp interval [read-write]</dt>
+ <dd>
+ <p>The current interval value. Can be modified any time, but changes only
+take effect when the periodic timer fires or <code>ev_periodic_again</code> is being
+called.</p>
+ </dd>
+ <dt>ev_tstamp (*reschedule_cb)(struct ev_periodic *w, ev_tstamp now) [read-write]</dt>
+ <dd>
+ <p>The current reschedule callback, or <code>0</code>, if this functionality is
+switched off. Can be changed any time, but changes only take effect when
+the periodic timer fires or <code>ev_periodic_again</code> is being called.</p>
+ </dd>
</dl>
<p>Example: call a callback every hour, or, more precisely, whenever the
system clock is divisible by 3600. The callback invocation times have
<p>Configures the watcher to trigger on the given signal number (usually one
of the <code>SIGxxx</code> constants).</p>
</dd>
+ <dt>int signum [read-only]</dt>
+ <dd>
+ <p>The signal the watcher watches out for.</p>
+ </dd>
</dl>
<code>waitpid</code> documentation). The <code>rpid</code> member contains the pid of the
process causing the status change.</p>
</dd>
+ <dt>int pid [read-only]</dt>
+ <dd>
+ <p>The process id this watcher watches out for, or <code>0</code>, meaning any process id.</p>
+ </dd>
+ <dt>int rpid [read-write]</dt>
+ <dd>
+ <p>The process id that detected a status change.</p>
+ </dd>
+ <dt>int rstatus [read-write]</dt>
+ <dd>
+ <p>The process exit/trace status caused by <code>rpid</code> (see your systems
+<code>waitpid</code> and <code>sys/wait.h</code> documentation for details).</p>
+ </dd>
</dl>
<p>Example: try to exit cleanly on SIGINT and SIGTERM.</p>
<pre> static void
+</pre>
+
+</div>
+<h2 id="code_ev_stat_code_did_the_file_attri"><code>ev_stat</code> - did the file attributes just change?</h2>
+<div id="code_ev_stat_code_did_the_file_attri-2">
+<p>This watches a filesystem path for attribute changes. That is, it calls
+<code>stat</code> regularly (or when the OS says it changed) and sees if it changed
+compared to the last time, invoking the callback if it did.</p>
+<p>The path does not need to exist: changing from "path exists" to "path does
+not exist" is a status change like any other. The condition "path does
+not exist" is signified by the <code>st_nlink</code> field being zero (which is
+otherwise always forced to be at least one) and all the other fields of
+the stat buffer having unspecified contents.</p>
+<p>Since there is no standard to do this, the portable implementation simply
+calls <code>stat (2)</code> regulalry 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 <code>0</code> (highly recommended!) then a <i>suitable,
+unspecified default</i> value will be used (which you can expect to be around
+five seconds, although this might change dynamically). Libev will also
+impose a minimum interval which is currently around <code>0.1</code>, but thats
+usually overkill.</p>
+<p>This watcher type is not meant for massive numbers of stat watchers,
+as even with OS-supported change notifications, this can be
+resource-intensive.</p>
+<p>At the time of this writing, no specific OS backends are implemented, but
+if demand increases, at least a kqueue and inotify backend will be added.</p>
+<dl>
+ <dt>ev_stat_init (ev_stat *, callback, const char *path, ev_tstamp interval)</dt>
+ <dt>ev_stat_set (ev_stat *, const char *path, ev_tstamp interval)</dt>
+ <dd>
+ <p>Configures the watcher to wait for status changes of the given
+<code>path</code>. The <code>interval</code> is a hint on how quickly a change is expected to
+be detected and should normally be specified as <code>0</code> to let libev choose
+a suitable value. The memory pointed to by <code>path</code> must point to the same
+path for as long as the watcher is active.</p>
+ <p>The callback will be receive <code>EV_STAT</code> when a change was detected,
+relative to the attributes at the time the watcher was started (or the
+last change was detected).</p>
+ </dd>
+ <dt>ev_stat_stat (ev_stat *)</dt>
+ <dd>
+ <p>Updates the stat buffer immediately with new values. If you change the
+watched path in your callback, you could call this fucntion to avoid
+detecting this change (while introducing a race condition). Can also be
+useful simply to find out the new values.</p>
+ </dd>
+ <dt>ev_statdata attr [read-only]</dt>
+ <dd>
+ <p>The most-recently detected attributes of the file. Although the type is of
+<code>ev_statdata</code>, this is usually the (or one of the) <code>struct stat</code> types
+suitable for your system. If the <code>st_nlink</code> member is <code>0</code>, then there
+was some error while <code>stat</code>ing the file.</p>
+ </dd>
+ <dt>ev_statdata prev [read-only]</dt>
+ <dd>
+ <p>The previous attributes of the file. The callback gets invoked whenever
+<code>prev</code> != <code>attr</code>.</p>
+ </dd>
+ <dt>ev_tstamp interval [read-only]</dt>
+ <dd>
+ <p>The specified interval.</p>
+ </dd>
+ <dt>const char *path [read-only]</dt>
+ <dd>
+ <p>The filesystem path that is being watched.</p>
+ </dd>
+</dl>
+<p>Example: Watch <code>/etc/passwd</code> for attribute changes.</p>
+<pre> static void
+ passwd_cb (struct ev_loop *loop, ev_stat *w, int revents)
+ {
+ /* /etc/passwd changed in some way */
+ if (w->attr.st_nlink)
+ {
+ printf ("passwd current size %ld\n", (long)w->attr.st_size);
+ printf ("passwd current atime %ld\n", (long)w->attr.st_mtime);
+ printf ("passwd current mtime %ld\n", (long)w->attr.st_mtime);
+ }
+ else
+ /* you shalt not abuse printf for puts */
+ puts ("wow, /etc/passwd is not there, expect problems. "
+ "if this is windows, they already arrived\n");
+ }
+
+ ...
+ ev_stat passwd;
+
+ ev_stat_init (&passwd, passwd_cb, "/etc/passwd");
+ ev_stat_start (loop, &passwd);
+
+
+
+
</pre>
</div>
similarly to <code>ev_loop (embedded_loop, EVLOOP_NONBLOCK)</code>, but in the most
apropriate way for embedded loops.</p>
</dd>
+ <dt>struct ev_loop *loop [read-only]</dt>
+ <dd>
+ <p>The embedded event loop.</p>
+ </dd>
</dl>
for multiple event loops and there is no first event loop pointer
argument. Instead, all functions act on the single default loop.</p>
</dd>
- <dt>EV_PERIODICS</dt>
+ <dt>EV_PERIODIC_ENABLE</dt>
+ <dd>
+ <p>If undefined or defined to be <code>1</code>, then periodic timers are supported. If
+defined to be <code>0</code>, then they are not. Disabling them saves a few kB of
+code.</p>
+ </dd>
+ <dt>EV_EMBED_ENABLE</dt>
+ <dd>
+ <p>If undefined or defined to be <code>1</code>, then embed watchers are supported. If
+defined to be <code>0</code>, then they are not.</p>
+ </dd>
+ <dt>EV_STAT_ENABLE</dt>
+ <dd>
+ <p>If undefined or defined to be <code>1</code>, then stat watchers are supported. If
+defined to be <code>0</code>, then they are not.</p>
+ </dd>
+ <dt>EV_MINIMAL</dt>
<dd>
- <p>If undefined or defined to be <code>1</code>, then periodic timers are supported,
-otherwise not. This saves a few kb of code.</p>
+ <p>If you need to shave off some kilobytes of code at the expense of some
+speed, define this symbol to <code>1</code>. Currently only used for gcc to override
+some inlining decisions, saves roughly 30% codesize of amd64.</p>
</dd>
<dt>EV_COMMON</dt>
<dd>
The pid specified in the C<ev_child> watcher has received a status change.
+=item C<EV_STAT>
+
+The path specified in the C<ev_stat> watcher changed its attributes somehow.
+
=item C<EV_IDLE>
The C<ev_idle> watcher has determined that you have nothing better to do.
=head1 WATCHER TYPES
This section describes each watcher in detail, but will not repeat
-information given in the last section.
+information given in the last section. Any initialisation/set macros,
+functions and members specific to the watcher type are explained.
+
+Members are additionally marked with either I<[read-only]>, meaning that,
+while the watcher is active, you can look at the member and expect some
+sensible content, but you must not modify it (you can modify it while the
+watcher is stopped to your hearts content), or I<[read-write]>, which
+means you can expect it to have some sensible content while the watcher
+is active, but you can also modify it. Modifying it may not do something
+sensible or take immediate effect (or do anything at all), but libev will
+not crash or malfunction in any way.
=head2 C<ev_io> - is this file descriptor readable or writable?
rceeive events for and events is either C<EV_READ>, C<EV_WRITE> or
C<EV_READ | EV_WRITE> to receive the given events.
+=item int fd [read-only]
+
+The file descriptor being watched.
+
+=item int events [read-only]
+
+The events being watched.
+
=back
Example: call C<stdin_readable_cb> when STDIN_FILENO has become, well
value), or reset the running timer to the repeat value.
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 C<ev_timer> with after=repeat=60 and calling ev_timer_again 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.
+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 C<ev_timer> with C<after>=C<repeat>=C<60> and calling
+C<ev_timer_again> 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.
+
+You can also ignore the C<after> value and C<ev_timer_start> altogether
+and only ever use the C<repeat> value:
+
+ ev_timer_init (timer, callback, 0., 5.);
+ ev_timer_again (loop, timer);
+ ...
+ timer->again = 17.;
+ ev_timer_again (loop, timer);
+ ...
+ timer->again = 10.;
+ ev_timer_again (loop, timer);
+
+This is more efficient then stopping/starting the timer eahc time you want
+to modify its timeout value.
+
+=item ev_tstamp repeat [read-write]
+
+The current C<repeat> value. Will be used each time the watcher times out
+or C<ev_timer_again> is called and determines the next timeout (if any),
+which is also when any modifications are taken into account.
=back
a different time than the last time it was called (e.g. in a crond like
program when the crontabs have changed).
+=item ev_tstamp interval [read-write]
+
+The current interval value. Can be modified any time, but changes only
+take effect when the periodic timer fires or C<ev_periodic_again> is being
+called.
+
+=item ev_tstamp (*reschedule_cb)(struct ev_periodic *w, ev_tstamp now) [read-write]
+
+The current reschedule callback, or C<0>, if this functionality is
+switched off. Can be changed any time, but changes only take effect when
+the periodic timer fires or C<ev_periodic_again> is being called.
+
=back
Example: call a callback every hour, or, more precisely, whenever the
Configures the watcher to trigger on the given signal number (usually one
of the C<SIGxxx> constants).
+=item int signum [read-only]
+
+The signal the watcher watches out for.
+
=back
C<waitpid> documentation). The C<rpid> member contains the pid of the
process causing the status change.
+=item int pid [read-only]
+
+The process id this watcher watches out for, or C<0>, meaning any process id.
+
+=item int rpid [read-write]
+
+The process id that detected a status change.
+
+=item int rstatus [read-write]
+
+The process exit/trace status caused by C<rpid> (see your systems
+C<waitpid> and C<sys/wait.h> documentation for details).
+
=back
Example: try to exit cleanly on SIGINT and SIGTERM.
ev_signal_start (loop, &sigint_cb);
+=head2 C<ev_stat> - did the file attributes just change?
+
+This watches a filesystem path for attribute changes. That is, it calls
+C<stat> regularly (or when the OS says it changed) and sees if it changed
+compared to the last time, invoking the callback if it did.
+
+The path does not need to exist: changing from "path exists" to "path does
+not exist" is a status change like any other. The condition "path does
+not exist" is signified by the C<st_nlink> field being zero (which is
+otherwise always forced to be at least one) and all the other fields of
+the stat buffer having unspecified contents.
+
+Since there is no standard to do this, the portable implementation simply
+calls C<stat (2)> regulalry 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 C<0> (highly recommended!) then a I<suitable,
+unspecified default> value will be used (which you can expect to be around
+five seconds, although this might change dynamically). Libev will also
+impose a minimum interval which is currently around C<0.1>, but thats
+usually overkill.
+
+This watcher type is not meant for massive numbers of stat watchers,
+as even with OS-supported change notifications, this can be
+resource-intensive.
+
+At the time of this writing, no specific OS backends are implemented, but
+if demand increases, at least a kqueue and inotify backend will be added.
+
+=over 4
+
+=item ev_stat_init (ev_stat *, callback, const char *path, ev_tstamp interval)
+
+=item ev_stat_set (ev_stat *, const char *path, ev_tstamp interval)
+
+Configures the watcher to wait for status changes of the given
+C<path>. The C<interval> is a hint on how quickly a change is expected to
+be detected and should normally be specified as C<0> to let libev choose
+a suitable value. The memory pointed to by C<path> must point to the same
+path for as long as the watcher is active.
+
+The callback will be receive C<EV_STAT> when a change was detected,
+relative to the attributes at the time the watcher was started (or the
+last change was detected).
+
+=item ev_stat_stat (ev_stat *)
+
+Updates the stat buffer immediately with new values. If you change the
+watched path in your callback, you could call this fucntion to avoid
+detecting this change (while introducing a race condition). Can also be
+useful simply to find out the new values.
+
+=item ev_statdata attr [read-only]
+
+The most-recently detected attributes of the file. Although the type is of
+C<ev_statdata>, this is usually the (or one of the) C<struct stat> types
+suitable for your system. If the C<st_nlink> member is C<0>, then there
+was some error while C<stat>ing the file.
+
+=item ev_statdata prev [read-only]
+
+The previous attributes of the file. The callback gets invoked whenever
+C<prev> != C<attr>.
+
+=item ev_tstamp interval [read-only]
+
+The specified interval.
+
+=item const char *path [read-only]
+
+The filesystem path that is being watched.
+
+=back
+
+Example: Watch C</etc/passwd> for attribute changes.
+
+ static void
+ passwd_cb (struct ev_loop *loop, ev_stat *w, int revents)
+ {
+ /* /etc/passwd changed in some way */
+ if (w->attr.st_nlink)
+ {
+ printf ("passwd current size %ld\n", (long)w->attr.st_size);
+ printf ("passwd current atime %ld\n", (long)w->attr.st_mtime);
+ printf ("passwd current mtime %ld\n", (long)w->attr.st_mtime);
+ }
+ else
+ /* you shalt not abuse printf for puts */
+ puts ("wow, /etc/passwd is not there, expect problems. "
+ "if this is windows, they already arrived\n");
+ }
+
+ ...
+ ev_stat passwd;
+
+ ev_stat_init (&passwd, passwd_cb, "/etc/passwd");
+ ev_stat_start (loop, &passwd);
+
+
=head2 C<ev_idle> - when you've got nothing better to do...
Idle watchers trigger events when there are no other events are pending
similarly to C<ev_loop (embedded_loop, EVLOOP_NONBLOCK)>, but in the most
apropriate way for embedded loops.
+=item struct ev_loop *loop [read-only]
+
+The embedded event loop.
+
=back
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