[ViewVC] Diff of: cvs/EV/README

Comparing EV/README (file contents):
Revision 1.6 by root, Thu Nov 1 17:32:39 2007 UTC vs.
Revision 1.9 by root, Mon Nov 12 01:23:21 2007 UTC

       my $w = EV::timer 2, 0, sub {
          warn "is called after 2s";
       };
-      my $w = EV::timer 2, 1, sub {
+      my $w = EV::timer 2, 2, sub {
-         warn "is called roughly every 2s (repeat = 1)";
+         warn "is called roughly every 2s (repeat = 2)";
       };
       undef $w; # destroy event watcher again
-      my $w = EV::periodic 0, 60, sub {
+      my $w = EV::periodic 0, 60, 0, sub {
          warn "is called every minute, on the minute, exactly";
       };
       # IO
       my $w = EV::io *STDIN, EV::READ, sub {
-         my ($w, $revents) = @_; # all callbacks get the watcher object and event mask
+         my ($w, $revents) = @_; # all callbacks receive the watcher and event mask
          warn "stdin is readable, you entered: ", <STDIN>;
       };
       # SIGNALS
       my $w = EV::signal 'QUIT', sub {
          warn "sigquit received\n";
       };
-      my $w = EV::signal 3, sub {
-         warn "sigquit received (this is GNU/Linux, right?)\n";
-      };
       # CHILD/PID STATUS CHANGES
       my $w = EV::child 666, sub {
-         my ($w, $revents, $status) = @_;
+         my ($w, $revents) = @_;
+         my $status = $w->rstatus;
       };
       # MAINLOOP
-      EV::loop;                   # loop until EV::loop_done is called
+      EV::loop;           # loop until EV::loop_done is called or all watchers stop
       EV::loop EV::LOOP_ONESHOT;  # block until at least one event could be handled
       EV::loop EV::LOOP_NONBLOCK; # try to handle same events, but do not block
 DESCRIPTION
     This module provides an interface to libev
     In the rare case where one wants to create a watcher but not start it at
     the same time, each constructor has a variant with a trailing "_ns" in
     its name, e.g. EV::io has a non-starting variant EV::io_ns and so on.
     Please note that a watcher will automatically be stopped when the
-    watcher object is returned, so you *need* to keep the watcher objects
+    watcher object is destroyed, so you *need* to keep the watcher objects
     returned by the constructors.
+    Also, all methods changing some aspect of a watcher (->set, ->priority,
+    ->fh and so on) automatically stop and start it again if it is active,
+    which means pending events get lost.
   WATCHER TYPES
     Now lets move to the existing watcher types and asociated methods.
     The following methods are available for all watchers. Then followes a
         not.
     $bool = $w->is_active
         Returns true if the watcher is active, false otherwise.
+    $current_data = $w->data
+    $old_data = $w->data ($new_data)
+        Queries a freely usable data scalar on the watcher and optionally
+        changes it. This is a way to associate custom data with a watcher:
+           my $w = EV::timer 60, 0, sub {
+              warn $_[0]->data;
+           };
+           $w->data ("print me!");
     $current_cb = $w->cb
     $old_cb = $w->cb ($new_cb)
         Queries the callback on the watcher and optionally changes it. You
-        cna do this at any time.
+        can do this at any time without the watcher restarting.
+    $current_priority = $w->priority
+    $old_priority = $w->priority ($new_priority)
+        Queries the priority on the watcher and optionally changes it.
+        Pending watchers with higher priority will be invoked first. The
+        valid range of priorities lies between EV::MAXPRI (default 2) and
+        EV::MINPRI (default -2). If the priority is outside this range it
+        will automatically be normalised to the nearest valid priority.
+        The default priority of any newly-created weatcher is 0.
     $w->trigger ($revents)
         Call the callback *now* with the given event mask.
     $w = EV::io $fileno_or_fh, $eventmask, $callback
         This behaviour is useful when you have a timeout for some IO
         operation. You create a timer object with the same value for $after
         and $repeat, and then, in the read/write watcher, run the "again"
         method on the timeout.
-    $w = EV::periodic $at, $interval, $callback
+    $w = EV::periodic $at, $interval, $reschedule_cb, $callback
-    $w = EV::periodic_ns $at, $interval, $callback
+    $w = EV::periodic_ns $at, $interval, $reschedule_cb, $callback
-        Similar to EV::timer, but the time is given as an absolute point in
+        Similar to EV::timer, but is not based on relative timeouts but on
-        time ($at), plus an optional $interval.
+        absolute times. Apart from creating "simple" timers that trigger
+        "at" the specified time, it can also be used for non-drifting
+        absolute timers and more complex, cron-like, setups that are not
+        adversely affected by time jumps (i.e. when the system clock is
+        changed by explicit date -s or other means such as ntpd). It is also
+        the most complex watcher type in EV.
-        If the $interval is zero, then the callback will be called at the
+        It has three distinct "modes":
-        time $at if that is in the future, or as soon as possible if it is
-        in the past. It will not automatically repeat.
-        If the $interval is nonzero, then the watcher will always be
+        * absolute timer ($interval = $reschedule_cb = 0)
-        scheduled to time out at the next "$at + N * $interval" time.
+            This time simply fires at the wallclock time $at and doesn't
+            repeat. It will not adjust when a time jump occurs, that is, if
+            it is to be run at January 1st 2011 then it will run when the
+            system time reaches or surpasses this time.
-        This can be used to schedule a callback to run at very regular
+        * non-repeating interval timer ($interval > 0, $reschedule_cb = 0)
-        intervals, as long as the processing time is less then the interval
+            In this mode the watcher will always be scheduled to time out at
-        (otherwise obviously events will be skipped).
+            the next "$at + N * $interval" time (for some integer N) and
+            then repeat, regardless of any time jumps.
+            This can be used to create timers that do not drift with respect
+            to system time:
+               my $hourly = EV::periodic 0, 3600, 0, sub { print "once/hour\n" };
+            That doesn't mean there will always be 3600 seconds in between
+            triggers, but only that the the clalback will be called when the
+            system time shows a full hour (UTC).
-        Another way to think about it (for the mathematically inclined) is
+            Another way to think about it (for the mathematically inclined)
-        that EV::periodic will try to run the callback at the next possible
+            is that EV::periodic will try to run the callback in this mode
-        time where "$time = $at (mod $interval)", regardless of any time
+            at the next possible time where "$time = $at (mod $interval)",
-        jumps.
+            regardless of any time jumps.
-        This periodic timer is based on "wallclock time", that is, if the
+        * manual reschedule mode ($reschedule_cb = coderef)
-        clock changes ("ntp", "date -s" etc.), then the timer will
+            In this mode $interval and $at are both being ignored. Instead,
-        nevertheless run at the specified time. This means it will never
+            each time the periodic watcher gets scheduled, the first
-        drift (it might jitter, but it will not drift).
+            callback ($reschedule_cb) will be called with the watcher as
+            first, and the current time as second argument.
+            *This callback MUST NOT stop or destroy this or any other
+            periodic watcher, ever*. If you need to stop it, return 1e30 and
+            stop it afterwards.
+            It must return the next time to trigger, based on the passed
+            time value (that is, the lowest time value larger than to the
+            second argument). It will usually be called just before the
+            callback will be triggered, but might be called at other times,
+            too.
+            This can be used to create very complex timers, such as a timer
+            that triggers on each midnight, local time (actually 24 hours
+            after the last midnight, to keep the example simple. If you know
+            a way to do it correctly in about the same space (without
+            requiring elaborate modules), drop me a note :):
+               my $daily = EV::periodic 0, 0, sub {
+                  my ($w, $now) = @_;
+                  use Time::Local ();
+                  my (undef, undef, undef, $d, $m, $y) = localtime $now;
+                  86400 + Time::Local::timelocal 0, 0, 0, $d, $m, $y
+               }, sub {
+                  print "it's midnight or likely shortly after, now\n";
+               };
         The "periodic_ns" variant doesn't start (activate) the newly created
         watcher.
-    $w->set ($at, $interval)
+    $w->set ($at, $interval, $reschedule_cb)
         Reconfigures the watcher, see the constructor above for details. Can
         be at any time.
+    $w->again
+        Simply stops and starts the watcher again.
     $w = EV::signal $signal, $callback
     $w = EV::signal_ns $signal, $callback
         Call the callback when $signal is received (the signal can be
         specified by number or by name, just as with kill or %SIG).
         watcher.
     $w->set ($signal)
         Reconfigures the watcher, see the constructor above for details. Can
         be at any time.
+    $current_signum = $w->signal
+    $old_signum = $w->signal ($new_signal)
+        Returns the previously set signal (always as a number not name) and
+        optionally set a new one.
     $w = EV::child $pid, $callback
     $w = EV::child_ns $pid, $callback
         Call the callback when a status change for pid $pid (or any pid if
         $pid is 0) has been received. More precisely: when the process
         receives a SIGCHLD, EV will fetch the outstanding exit/wait status
         for all changed/zombie children and call the callback.
-        Unlike all other callbacks, this callback will be called with an
+        You can access both status and pid by using the "rstatus" and "rpid"
-        additional third argument which is the exit status. See the
+        methods on the watcher object.
-        "waitpid" function for details.
         You can have as many pid watchers per pid as you want.
         The "child_ns" variant doesn't start (activate) the newly created
         watcher.
     $w->set ($pid)
         Reconfigures the watcher, see the constructor above for details. Can
         be at any time.
+    $current_pid = $w->pid
+    $old_pid = $w->pid ($new_pid)
+        Returns the previously set process id and optionally set a new one.
+    $exit_status = $w->rstatus
+        Return the exit/wait status (as returned by waitpid, see the waitpid
+        entry in perlfunc).
+    $pid = $w->rpid
+        Return the pid of the awaited child (useful when you have installed
+        a watcher for all pids).
     $w = EV::idle $callback
     $w = EV::idle_ns $callback
         Call the callback when there are no pending io, timer/periodic,
         signal or child events, i.e. when the process is idle.

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Comparing EV/README (file contents): Revision 1.6 by root, Thu Nov 1 17:32:39 2007 UTC vs. Revision 1.9 by root, Mon Nov 12 01:23:21 2007 UTC

Diff Legend

Comparing EV/README (file contents):
Revision 1.6 by root, Thu Nov 1 17:32:39 2007 UTC vs.
Revision 1.9 by root, Mon Nov 12 01:23:21 2007 UTC