JFIF$        dd7 

Viewing File: /usr/share/doc/perl-Thread-Queue/examples/callback.pl

#!/usr/bin/perl

# Simplified example illustrating event handling and callback threads

# Callback threads register their queues with the event handler thread.
# Events are passed to the event handler via a queue.
# The event handler then disseminates the event to the appropriately
#   registered thread.

use strict;
use warnings;

use threads;
use Thread::Queue;

MAIN:
{
    # Queue for registering callbacks
    my $regis_q = Thread::Queue->new();

    # Queue for disseminating events
    my $event_q = Thread::Queue->new();

    # Create callback threads
    threads->create('CallBack', 'USR1', $regis_q)->detach();
    threads->create('CallBack', 'USR2', $regis_q)->detach();
    threads->create('CallBack', 'HUP', $regis_q)->detach();
    threads->create('CallBack', 'ALRM', $regis_q)->detach();

    # Create event handler thread
    threads->create('EventHandler', $regis_q, $event_q)->detach();

    # Capture SIGUSR1 events
    $SIG{'USR1'} = sub {
        $event_q->enqueue('USR1');  # Send to event handler
    };

    # Capture SIGUSR1 events
    $SIG{'USR2'} = sub {
        $event_q->enqueue('USR2');  # Send to event handler
    };

    # Capture SIGHUP events
    $SIG{'HUP'} = sub {
        $event_q->enqueue('HUP');  # Send to event handler
    };

    # Capture SIGHUP events
    $SIG{'ALRM'} = sub {
        $event_q->enqueue('ALRM');  # Send to event handler
        alarm(5);                   # Reset alarm
    };

    # Ready
    print(<<_MSG_);
Send signals to PID = $$
  (e.g., 'kill -USR1 $$')
Use ^C (or 'kill -INT $$') to terminate
_MSG_

    # Set initial alarm
    alarm(5);

    # Just hang around
    while (1) {
        sleep(10);
    }
}

### Subroutines ###

sub EventHandler
{
    my ($regis_q, $event_q) = @_;

    my %callbacks;   # Registered callback queues

    while (1) {
        # Check for any registrations
        while (my ($event_type, $q) = $regis_q->dequeue_nb(2)) {
            if ($q) {
                $callbacks{$event_type} = $q;
            } else {
                warn("BUG: Bad callback registration for event type $event_type\n");
            }
        }

        # Wait for event
        if (my $event = $event_q->dequeue()) {
            # Send event to appropriate queue
            if (exists($callbacks{$event})) {
                $callbacks{$event}->enqueue($event);
            } else {
                warn("WARNING: No callback for event type $event\n");
            }
        }
    }
}


sub CallBack
{
    my $event_type = shift;   # The type of event I'm handling
    my $regis_q    = shift;

    # Announce registration
    my $tid = threads->tid();
    print("Callback thread $tid registering for $event_type events\n");

    # Register my queue for my type of event
    my $q = Thread::Queue->new();
    $regis_q->enqueue($event_type, $q);

    # Process loop
    while (1) {
        # Wait for event callback
        my $item = $q->dequeue();
        # Process event
        print("Callback thread $tid notified of $item event\n") if $item;
    }
}

# EOF
Back to Directory  nL+D550H?Mx ,D"v]qv;6*Zqn)ZP0!1 A "#a$2Qr D8 a Ri[f\mIykIw0cuFcRı?lO7к_f˓[C$殷WF<_W ԣsKcëIzyQy/_LKℂ;C",pFA:/]=H  ~,ls/9ć:[=/#f;)x{ٛEQ )~ =𘙲r*2~ a _V=' kumFD}KYYC)({ *g&f`툪ry`=^cJ.I](*`wq1dđ#̩͑0;H]u搂@:~וKL Nsh}OIR*8:2 !lDJVo(3=M(zȰ+i*NAr6KnSl)!JJӁ* %݉?|D}d5:eP0R;{$X'xF@.ÊB {,WJuQɲRI;9QE琯62fT.DUJ;*cP A\ILNj!J۱+O\͔]ޒS߼Jȧc%ANolՎprULZԛerE2=XDXgVQeӓk yP7U*omQIs,K`)6\G3t?pgjrmۛجwluGtfh9uyP0D;Uڽ"OXlif$)&|ML0Zrm1[HXPlPR0'G=i2N+0e2]]9VTPO׮7h(F*癈'=QVZDF,d߬~TX G[`le69CR(!S2!P <0x<!1AQ "Raq02Br#SCTb ?Ζ"]mH5WR7k.ۛ!}Q~+yԏz|@T20S~Kek *zFf^2X*(@8r?CIuI|֓>^ExLgNUY+{.RѪ τV׸YTD I62'8Y27'\TP.6d&˦@Vqi|8-OΕ]ʔ U=TL8=;6c| !qfF3aů&~$l}'NWUs$Uk^SV:U# 6w++s&r+nڐ{@29 gL u"TÙM=6(^"7r}=6YݾlCuhquympǦ GjhsǜNlɻ}o7#S6aw4!OSrD57%|?x>L |/nD6?/8w#[)L7+6〼T ATg!%5MmZ/c-{1_Je"|^$'O&ޱմTrb$w)R$& N1EtdU3Uȉ1pM"N*(DNyd96.(jQ)X 5cQɎMyW?Q*!R>6=7)Xj5`J]e8%t!+'!1Q5 !1 AQaqё#2"0BRb?Gt^## .llQT $v,,m㵜5ubV =sY+@d{N! dnO<.-B;_wJt6;QJd.Qc%p{ 1,sNDdFHI0ГoXшe黅XۢF:)[FGXƹ/w_cMeD,ʡcc.WDtA$j@:) -# u c1<@ۗ9F)KJ-hpP]_x[qBlbpʖw q"LFGdƶ*s+ډ_Zc"?%t[IP 6J]#=ɺVvvCGsGh1 >)6|ey?Lӣm,4GWUi`]uJVoVDG< SB6ϏQ@ TiUlyOU0kfV~~}SZ@*WUUi##; s/[=!7}"WN]'(L! ~y5g9T̅JkbM' +s:S +B)v@Mj e Cf jE 0Y\QnzG1д~Wo{T9?`Rmyhsy3!HAD]mc1~2LSu7xT;j$`}4->L#vzŏILS ֭T{rjGKC;bpU=-`BsK.SFw4Mq]ZdHS0)tLg