[ViewVC] Diff of: cvs/EV/README

Comparing EV/README (file contents):
Revision 1.13 by root, Tue Nov 27 16:35:47 2007 UTC vs.
Revision 1.16 by root, Fri Dec 7 18:11:23 2007 UTC

     This module provides an interface to libev
     (<http://software.schmorp.de/pkg/libev.html>). While the documentation
     below is comprehensive, one might also consult the documentation of
     libev itself (<http://cvs.schmorp.de/libev/ev.html>) for more subtle
     details on watcher semantics or some discussion on the available
-    backends, or how to force a specific backend with "LIBEV_FLAGS".
+    backends, or how to force a specific backend with "LIBEV_FLAGS", or just
+    about in any case because it has much more detailed information.
 BASIC INTERFACE
     $EV::DIED
         Must contain a reference to a function that is called when a
         callback throws an exception (with $@ containing thr error). The
         makes the innermost call to EV::loop return.
         When called with an argument of EV::UNLOOP_ALL, all calls to
         EV::loop will return as fast as possible.
+    $count = EV::loop_count
+        Return the number of times the event loop has polled for new events.
+        Sometiems useful as a generation counter.
     EV::once $fh_or_undef, $events, $timeout, $cb->($revents)
         This function rolls together an I/O and a timer watcher for a single
         one-shot event without the need for managing a watcher object.
         If $fh_or_undef is a filehandle or file descriptor, then $events
     received events.
     Each watcher type has its associated bit in revents, so you can use the
     same callback for multiple watchers. The event mask is named after the
     type, i..e. EV::child sets EV::CHILD, EV::prepare sets EV::PREPARE,
-    EV::periodic sets EV::PERIODIC and so on, with the exception of IO
+    EV::periodic sets EV::PERIODIC and so on, with the exception of I/O
     events (which can set both EV::READ and EV::WRITE bits), and EV::timer
     (which uses EV::TIMEOUT).
     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
         stopped watchers).
     $w->stop
         Stop a watcher if it is active. Also clear any pending events
         (events that have been received but that didn't yet result in a
-        callback invocation), regardless of wether the watcher was active or
+        callback invocation), regardless of whether the watcher was active
-        not.
+        or not.
     $bool = $w->is_active
         Returns true if the watcher is active, false otherwise.
     $current_data = $w->data
         returning.
         The initial value for keepalive is true (enabled), and you cna
         change it any time.
-        Example: Register an IO watcher for some UDP socket but do not keep
+        Example: Register an I/O watcher for some UDP socket but do not keep
         the event loop from running just because of that watcher.
            my $udp_socket = ...
            my $udp_watcher = EV::io $udp_socket, EV::READ, sub { ... };
            $udp_watcher->keepalive (0);
   WATCHER TYPES
     Each of the following subsections describes a single watcher type.
-   IO WATCHERS - is this file descriptor readable or writable?
+   I/O WATCHERS - is this file descriptor readable or writable?
     $w = EV::io $fileno_or_fh, $eventmask, $callback
     $w = EV::io_ns $fileno_or_fh, $eventmask, $callback
         As long as the returned watcher object is alive, call the $callback
         when at least one of events specified in $eventmask occurs.
         resource-intensive.
         The "stat_ns" variant doesn't start (activate) the newly created
         watcher.
+    ... = $w->stat
+        This call is very similar to the perl "stat" built-in: It stats
+        (using "lstat") the path specified in the watcher and sets perls
+        stat cache (as well as EV's idea of the current stat values) to the
+        values found.
+        In scalar context, a boolean is return indicating success or failure
+        of the stat. In list context, the same 13-value list as with stat is
+        returned (except that the blksize and blocks fields are not
+        reliable).
+        In the case of an error, errno is set to "ENOENT" (regardless of the
+        actual error value) and the "nlink" value is forced to zero (if the
+        stat was successful then nlink is guaranteed to be non-zero).
+        See also the next two entries for more info.
+    ... = $w->attr
+        Just like "$w->stat", but without the initial stat'ing: this returns
+        the values most recently detected by EV. See the next entry for more
+        info.
+    ... = $w->prev
+        Just like "$w->stat", but without the initial stat'ing: this returns
+        the previous set of values, before the change.
+        That is, when the watcher callback is invoked, "$w->prev" will be
+        set to the values found *before* a change was detected, while
+        "$w->attr" returns the values found leading to the change detection.
+        The difference (if any) between "prev" and "attr" is what triggered
+        the callback.
+        If you did something to the filesystem object and do not want to
+        trigger yet another change, you can call "stat" to update EV's idea
+        of what the current attributes are.
     $w->set ($path, $interval)
         Reconfigures the watcher, see the constructor above for details. Can
         be called at any time.
     $current_path = $w->path
         Can be used to query the actual interval used.
    IDLE WATCHERS - when you've got nothing better to do...
     $w = EV::idle $callback
     $w = EV::idle_ns $callback
-        Call the callback when there are no pending io, timer/periodic,
+        Call the callback when there are no other pending watchers of the
-        signal or child events, i.e. when the process is idle.
+        same or higher priority (excluding check, prepare and other idle
+        watchers of the same or lower priority, of course). They are called
+        idle watchers because when the watcher is the highest priority
+        pending event in the process, the process is considered to be idle
+        at that priority.
+        If you want a watcher that is only ever called when *no* other
+        events are outstanding you have to set the priority to "EV::MINPRI".
         The process will not block as long as any idle watchers are active,
         and they will be called repeatedly until stopped.
+        For example, if you have idle watchers at priority 0 and 1, and an
+        I/O watcher at priority 0, then the idle watcher at priority 1 and
+        the I/O watcher will always run when ready. Only when the idle
+        watcher at priority 1 is stopped and the I/O watcher at priority 0
+        is not pending with the 0-priority idle watcher be invoked.
         The "idle_ns" variant doesn't start (activate) the newly created
         watcher.
    PREPARE WATCHERS - customise your event loop!
                  or return;
               # make the dispatcher handle any outstanding stuff
               ... not shown
-              # create an IO watcher for each and every socket
+              # create an I/O watcher for each and every socket
               @snmp_watcher = (
                  (map { EV::io $_, EV::READ, sub { } }
                      keys %{ $dispatcher->{_descriptors} }),
                  EV::timer +($event->[Net::SNMP::Dispatcher::_ACTIVE]
         Call the callback before the event loop is resumed in the child
         process after a fork.
         The "fork_ns" variant doesn't start (activate) the newly created
         watcher.
+PERL SIGNALS
+    While Perl signal handling (%SIG) is not affected by EV, the behaviour
+    with EV is as the same as any other C library: Perl-signals will only be
+    handled when Perl runs, which means your signal handler might be invoked
+    only the next time an event callback is invoked.
+    The solution is to use EV signal watchers (see "EV::signal"), which will
+    ensure proper operations with regards to other event watchers.
+    If you cannot do this for whatever reason, you can also force a watcher
+    to be called on every event loop iteration by installing a "EV::check"
+    watcher:
+       my $async_check = EV::check sub { };
+    This ensures that perl shortly gets into control for a short time, and
+    also ensures slower overall operation.
 THREADS
     Threads are not supported by this module in any way. Perl pseudo-threads
     is evil stuff and must die. As soon as Perl gains real threads I will
     work on thread support for it.
     On win32, there is no notion of fork so all this doesn't apply, of
     course.
 SEE ALSO
-    EV::DNS.
+    EV::ADNS (asynchronous dns), Glib::EV (makes Glib/Gtk2 use EV as event
+    loop), Coro::EV (efficient coroutines with EV).
 AUTHOR
      Marc Lehmann <schmorp@schmorp.de>
      http://home.schmorp.de/

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Comparing EV/README (file contents): Revision 1.13 by root, Tue Nov 27 16:35:47 2007 UTC vs. Revision 1.16 by root, Fri Dec 7 18:11:23 2007 UTC

Diff Legend

Comparing EV/README (file contents):
Revision 1.13 by root, Tue Nov 27 16:35:47 2007 UTC vs.
Revision 1.16 by root, Fri Dec 7 18:11:23 2007 UTC