[ViewVC] Diff of: cvs/EV/README

Comparing EV/README (file contents):
Revision 1.14 by root, Wed Nov 28 19:22:16 2007 UTC vs.
Revision 1.20 by root, Sat Dec 22 12:05:42 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.
+EVENT LOOPS
+    EV supports multiple event loops: There is a single "default event loop"
+    that can handle everything including signals and child watchers, and any
+    number of "dynamic event loops" that can use different backends (with
+    various limitations), but no child and signal watchers.
+    You do not have to do anything to create the default event loop: When
+    the module is loaded a suitable backend is selected on the premise of
+    selecting a working backend (which for example rules out kqueue on most
+    BSDs). Modules should, unless they have "special needs" always use the
+    default loop as this is fastest (perl-wise), best supported by other
+    modules (e.g. AnyEvent or Coro) and most portable event loop.
+    For specific programs you cna create additional event loops dynamically.
+    $loop = new EV::loop [$flags]
+        Create a new event loop as per the specified flags. Please refer to
+        the "ev_loop_new ()" function description in the libev documentation
+        (<http://pod.tst.eu/http://cvs.schmorp.de/libev/ev.pod#GLOBAL_FUNCTI
+        ONS>) for more info.
+        The loop will automatically be destroyed when it is no longer
+        referenced by any watcher and the loop object goes out of scope.
+        Using "EV::FLAG_FORKCHECK" is recommended, as only the default event
+        loop is protected by this module.
+    $loop->loop_fork
+        Must be called after a fork in the child, before entering or
+        continuing the event loop. An alternative is to use
+        "EV::FLAG_FORKCHECK" which calls this fucntion automatically, at
+        some performance loss (refer to the libev documentation).
 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
+        callback throws an exception (with $@ containing the error). The
         default prints an informative message and continues.
         If this callback throws an exception it will be silently ignored.
     $time = EV::time
         Returns the current time in (fractional) seconds since the epoch.
     $time = EV::now
+    $time = $loop->now
         Returns the time the last event loop iteration has been started.
         This is the time that (relative) timers are based on, and refering
         to it is usually faster then calling EV::time.
-    $method = EV::method
+    $backend = EV::backend
+    $backend = $loop->backend
         Returns an integer describing the backend used by libev
         (EV::METHOD_SELECT or EV::METHOD_EPOLL).
     EV::loop [$flags]
+    $loop->loop ([$flags])
         Begin checking for events and calling callbacks. It returns when a
         callback calls EV::unloop.
         The $flags argument can be one of the following:
            0                  as above
            EV::LOOP_ONESHOT   block at most once (wait, but do not loop)
            EV::LOOP_NONBLOCK  do not block at all (fetch/handle events but do not wait)
     EV::unloop [$how]
+    $loop->unloop ([$how])
         When called with no arguments or an argument of EV::UNLOOP_ONE,
         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
+    $count = $loop->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)
+    $loop->once ($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 $events
         must be a bitset containing either "EV::READ", "EV::WRITE" or
         If timeout is "undef" or negative, then there will be no timeout.
         Otherwise a EV::timer with this value will be started.
         When an error occurs or either the timeout or I/O watcher triggers,
         then the callback will be called with the received event set (in
-        general you can expect it to be a combination of "EV:ERROR",
+        general you can expect it to be a combination of "EV::ERROR",
         "EV::READ", "EV::WRITE" and "EV::TIMEOUT").
         EV::once doesn't return anything: the watchers stay active till
         either of them triggers, then they will be stopped and freed, and
         the callback invoked.
+    EV::feed_fd_event ($fd, $revents)
+    $loop->feed_fd_event ($fd, $revents)
+        Feed an event on a file descriptor into EV. EV will react to this
+        call as if the readyness notifications specified by $revents (a
+        combination of "EV::READ" and "EV::WRITE") happened on the file
+        descriptor $fd.
+    EV::feed_signal_event ($signal)
+        Feed a signal event into EV. EV will react to this call as if the
+        signal specified by $signal had occured.
-  WATCHER OBJECTS
+WATCHER OBJECTS
     A watcher is an object that gets created to record your interest in some
     event. For instance, if you want to wait for STDIN to become readable,
     you would create an EV::io watcher for that:
       my $watcher = EV::io *STDIN, EV::READ, sub {
          my ($watcher, $revents) = @_;
-         warn "yeah, STDIN should not be readable without blocking!\n"
+         warn "yeah, STDIN should now be readable without blocking!\n"
       };
     All watchers can be active (waiting for events) or inactive (paused).
     Only active watchers will have their callbacks invoked. All callbacks
     will be called with at least two arguments: the watcher and a bitmask of
     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
         The default priority of any newly-created watcher is 0.
         Note that the priority semantics have not yet been fleshed out and
         are subject to almost certain change.
-    $w->trigger ($revents)
+    $w->invoke ($revents)
         Call the callback *now* with the given event mask.
+    $w->feed_event ($revents)
+        Feed some events on this watcher into EV. EV will react to this call
+        as if the watcher had received the given $revents mask.
+    $revents = $w->clear_pending
+        If the watcher is pending, this function clears its pending status
+        and returns its $revents bitset (as if its callback was invoked). If
+        the watcher isn't pending it does nothing and returns 0.
     $previous_state = $w->keepalive ($bool)
         Normally, "EV::loop" will return when there are no active watchers
         (which is a "deadlock" because no progress can be made anymore).
         This is convinient because it allows you to start your watchers (and
         your jobs), call "EV::loop" once and when it returns you know that
         all your jobs are finished (or they forgot to register some watchers
         for their task :).
-        Sometimes, however, this gets in your way, for example when you the
+        Sometimes, however, this gets in your way, for example when the
         module that calls "EV::loop" (usually the main program) is not the
         same module as a long-living watcher (for example a DNS client
         module written by somebody else even). Then you might want any
         outstanding requests to be handled, but you would not want to keep
         "EV::loop" from returning just because you happen to have this
         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);
+           $1000udp_watcher->keepalive (0);
+    $loop = $w->loop
+        Return the loop that this watcher is attached to.
-  WATCHER TYPES
+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
+    $w = $loop->io ($fileno_or_fh, $eventmask, $callback)
+    $w = $loop->io_ns ($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.
         The $eventmask can be one or more of these constants ORed together:
         Returns the previously set event mask and optionally set a new one.
    TIMER WATCHERS - relative and optionally repeating timeouts
     $w = EV::timer $after, $repeat, $callback
     $w = EV::timer_ns $after, $repeat, $callback
+    $w = $loop->timer ($after, $repeat, $callback)
+    $w = $loop->timer_ns ($after, $repeat, $callback)
         Calls the callback after $after seconds (which may be fractional).
         If $repeat is non-zero, the timer will be restarted (with the
         $repeat value as $after) after the callback returns.
         This means that the callback would be called roughly after $after
         method on the timeout.
    PERIODIC WATCHERS - to cron or not to cron?
     $w = EV::periodic $at, $interval, $reschedule_cb, $callback
     $w = EV::periodic_ns $at, $interval, $reschedule_cb, $callback
+    $w = $loop->periodic ($at, $interval, $reschedule_cb, $callback)
+    $w = $loop->periodic_ns ($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
         be called at any time.
     $w->again
         Simply stops and starts the watcher again.
+    $time = $w->at
+        Return the time that the watcher is expected to trigger next.
    SIGNAL WATCHERS - signal me when a signal gets signalled!
     $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).
         optionally set a new one.
    CHILD WATCHERS - watch out for process status changes
     $w = EV::child $pid, $callback
     $w = EV::child_ns $pid, $callback
+    $w = $loop->child ($pid, $callback)
+    $w = $loop->child_ns ($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.
         a watcher for all pids).
    STAT WATCHERS - did the file attributes just change?
     $w = EV::stat $path, $interval, $callback
     $w = EV::stat_ns $path, $interval, $callback
+    $w = $loop->stat ($path, $interval, $callback)
+    $w = $loop->stat_ns ($path, $interval, $callback)
         Call the callback when a file status change has been detected on
         $path. The $path does not need to exist, changing from "path exists"
         to "path does not exist" is a status change like any other.
         The $interval is a recommended polling interval for systems where
         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
+    $w = $loop->idle ($callback)
+    $w = $loop->idle_ns ($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!
     $w = EV::prepare $callback
     $w = EV::prepare_ns $callback
+    $w = $loop->prepare ($callback)
+    $w = $loop->prepare_ns ($callback)
         Call the callback just before the process would block. You can still
         create/modify any watchers at this point.
         See the EV::check watcher, below, for explanations and an example.
         watcher.
    CHECK WATCHERS - customise your event loop even more!
     $w = EV::check $callback
     $w = EV::check_ns $callback
+    $w = $loop->check ($callback)
+    $w = $loop->check_ns ($callback)
         Call the callback just after the process wakes up again (after it
         has gathered events), but before any other callbacks have been
         invoked.
         This is used to integrate other event-based software into the EV
                  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]
     is done before the event loop blocks next and before "check" watchers
     are being called, and only in the child after the fork.
     $w = EV::fork $callback
     $w = EV::fork_ns $callback
+    $w = $loop->fork ($callback)
+    $w = $loop->fork_ns ($callback)
         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 gets into control for a short time to handle any
+    pending signals, and also ensures (slightly) 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), EV::Glib (embed Glib into EV), Coro::EV (efficient coroutines
+    with EV), Net::SNMP::EV (asynchronous SNMP).
 AUTHOR
      Marc Lehmann <schmorp@schmorp.de>
      http://home.schmorp.de/

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Comparing EV/README (file contents): Revision 1.14 by root, Wed Nov 28 19:22:16 2007 UTC vs. Revision 1.20 by root, Sat Dec 22 12:05:42 2007 UTC

Diff Legend

Comparing EV/README (file contents):
Revision 1.14 by root, Wed Nov 28 19:22:16 2007 UTC vs.
Revision 1.20 by root, Sat Dec 22 12:05:42 2007 UTC