use strict;
use warnings;
use feature 'say';

use Time::HiRes qw( sleep time );
use Net::SNMPTrapd;
use MCE::Flow;
use MCE::Queue;

my $queue = MCE::Queue->new( await => 1, fast => 1 );
my $start = time;  # floating seconds

# from left to right: 1 listener, 30 consumers, and 2 producers

mce_flow { max_workers => [ 1, 30, 2 ] }, \&listener, \&consumer, \&producer;

printf {*STDERR} "duration: %0.3f seconds\n", time() - $start;

exit(0);

# ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
# listener and consumer roles
# ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

sub listener {
    my $snmptrapd = Net::SNMPTrapd->new( ReusePort => 1 );
    my $count = 0;

    while ( 1 ) {
        my $trap = $snmptrapd->get_trap();

        if ( !defined $trap ) {
            printf {*STDERR} "$0: %s\n", Net::SNMPTrapd->error();
            next;
        }
        elsif ( $trap == 0 ) {
            next;
        }

        # important, remove the file handle inside the object
        # so that serialization into the queue succeeds

        delete $trap->{_UDPSERVER_};

        # enqueue the trap for a consumer to process

        $queue->enqueue($trap);

        # await will block if the queue has more than 2000 pending
        # this prevents the queue from consuming memory out of control
        # simply increase the number of consumers to not block
        #
        # $queue->await(2000) if ( ++$count % 4000 == 0 );

        if ( ( ++$count % 4000 == 0 ) && $queue->pending() > 3000 ) {
            say {*STDERR} "$0: WARN: blocking temporarily";
            $queue->await(2000);
        }

        # reset the counter to not overflow

        $count = 0 if ( $count > 2e9 );

        # for benchmarking, leave the loop after 4000 traps

        last if ( $count == 4000 );
    }

    # notify the manager process to stop the producer and queue

    MCE->do('quit_producers');
}

sub consumer {
    while ( defined ( my $trap = $queue->dequeue() ) ) {
        $trap->process_trap();

        # printf "[$$] %s\t%i\t%i\t%s\n",
        #   $trap->remoteaddr, $trap->remoteport,
        #   $trap->version, $trap->community;

        say "[$$] ".$trap->varbinds->[5]->{'1.3.6.1.4.1.50000.1.6'};

        sleep 0.004;
    }
}

# ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
# producer role for generating traps
# ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

my @producer_pids;

sub set_producer_pid {
    push @producer_pids, $_[0];
}

sub quit_producers {
    kill 'QUIT', @producer_pids;
    $queue->end();
}

sub producer {
    require Net::SNMP;

    my ( $run, $i ) = ( 1, 0 );

    $SIG{QUIT} = sub { $run = 0 };

    # notify the manager process my pid

    MCE->do('set_producer_pid', $$);

    my ( $session, $error ) = Net::SNMP->session(
        -hostname  => 'localhost',
        -version   => 2,
        -community => 'public',
        -port      => 162
    );

    if ( !defined $session ) {
        printf "Error: Starting SNMP session (v2c trap) - %s\n", $error;
        return;
    }

    while ( $run ) {
        my $result = $session->snmpv2_trap(
            -varbindlist  => [
                '1.3.6.1.2.1.1.3.0',      0x43, int( time() ),
                '1.3.6.1.6.3.1.1.4.1.0',  0x06, '1.3.6.1.4.1.50000',
                '1.3.6.1.4.1.50000.1.3',  0x02, 1,
                '1.3.6.1.4.1.50000.1.4',  0x04, 'String',
                '1.3.6.1.4.1.50000.1.5',  0x06, '1.2.3.4.5.6.7.8.9',
                '1.3.6.1.4.1.50000.1.6',  0x40, '10.10.10.'.((++$i % 100) + 1),
                '1.3.6.1.4.1.50000.1.7',  0x41, 32323232,
                '1.3.6.1.4.1.50000.1.8',  0x42, 42424242,
                '1.3.6.1.4.1.50000.1.9',  0x43, int( time() ),
                '1.3.6.1.4.1.50000.1.10', 0x44, 'opaque data'
            ]
        );
    }

    $session->close;
}