--- EV/README	2007/11/03 16:25:49	1.7
+++ EV/README	2007/11/08 17:02:10	1.8
@@ -17,7 +17,7 @@
   
       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";
       };
   
@@ -149,6 +149,16 @@
     $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
@@ -233,39 +243,85 @@
         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_ns $at, $interval, $callback
-        Similar to EV::timer, but the time is given as an absolute point in
-        time ($at), plus an optional $interval.
-
-        If the $interval is zero, then the callback will be called at the
-        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 $interval is nonzero, then the watcher will always be
-        scheduled to time out at the next "$at + N * $interval" time.
-
-        This can be used to schedule a callback to run at very regular
-        intervals, as long as the processing time is less then the interval
-        (otherwise obviously events will be skipped).
-
-        Another way to think about it (for the mathematically inclined) is
-        that EV::periodic will try to run the callback at the next possible
-        time where "$time = $at (mod $interval)", regardless of any time
-        jumps.
-
-        This periodic timer is based on "wallclock time", that is, if the
-        clock changes ("ntp", "date -s" etc.), then the timer will
-        nevertheless run at the specified time. This means it will never
-        drift (it might jitter, but it will not drift).
+    $w = EV::periodic $at, $interval, $reschedule_cb, $callback
+    $w = EV::periodic_ns $at, $interval, $reschedule_cb, $callback
+        Similar to EV::timer, but is not based on relative timeouts but on
+        absolute times. Apart from creating "simple" timers that trigger
+        "at" the specified time, it can also be used for non-drifting
+        absolute timers and more complex, cron-like, setups that are not
+        adversely affected by time jumps (i.e. when the system clock is
+        changed by explicit date -s or other means such as ntpd). It is also
+        the most complex watcher type in EV.
+
+        It has three distinct "modes":
+
+        * absolute timer ($interval = $reschedule_cb = 0)
+            This time simply fires at the wallclock time $at and doesn't
+            repeat. It will not adjust when a time jump occurs, that is, if
+            it is to be run at January 1st 2011 then it will run when the
+            system time reaches or surpasses this time.
+
+        * non-repeating interval timer ($interval > 0, $reschedule_cb = 0)
+            In this mode the watcher will always be scheduled to time out at
+            the next "$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 $hourly = EV::periodic 0, 3600, 0, sub { print "once/hour\n" };
+
+            That doesn't mean there will always be 3600 seconds in between
+            triggers, but only that the the clalback will be called when the
+            system time shows a full hour (UTC).
+
+            Another way to think about it (for the mathematically inclined)
+            is that EV::periodic will try to run the callback in this mode
+            at the next possible time where "$time = $at (mod $interval)",
+            regardless of any time jumps.
+
+        * manual reschedule mode ($reschedule_cb = coderef)
+            In this mode $interval and $at are both being ignored. Instead,
+            each time the periodic watcher gets scheduled, the first
+            callback ($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