Log::Log4perl::Appender::Socket - Log to a socket


Log-Log4perl documentation Contained in the Log-Log4perl distribution.

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NAME

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Log::Log4perl::Appender::Socket - Log to a socket

SYNOPSIS

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    use Log::Log4perl::Appender::Socket;

    my $appender = Log::Log4perl::Appender::Socket->new(
      PeerAddr => "server.foo.com",
      PeerPort => 1234,
    );

    $appender->log(message => "Log me\n");

DESCRIPTION

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This is a simple appender for writing to a socket. It relies on IO::Socket::INET and offers all parameters this module offers.

Upon destruction of the object, pending messages will be flushed and the socket will be closed.

If the appender cannot contact the server during the initialization phase (while running the constructor new), it will die().

If the appender fails to log a message because the socket's send() method fails (most likely because the server went down), it will try to reconnect once. If it succeeds, the message will be sent. If the reconnect fails, a warning is sent to STDERR and the log() method returns, discarding the message.

If the option silent_recovery is given to the constructor and set to a true value, the behaviour is different: If the socket connection can't be established at initialization time, a single warning is issued. Every log attempt will then try to establish the connection and discard the message silently if it fails. If you don't even want the warning, set the no_warning option to a true value.

Connecting at initialization time may not be the best option when running under Apache1 Apache2/prefork, because the parent process creates the socket and the connections are shared among the forked children--all the children writing to the same socket could intermingle messages. So instead of that, you can use defer_connection which will put off making the connection until the first log message is sent.

EXAMPLE

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Write a server quickly using the IO::Socket::INET module:

    use IO::Socket::INET;

    my $sock = IO::Socket::INET->new(
        Listen    => 5,
        LocalAddr => 'localhost',
        LocalPort => 12345,
        Proto     => 'tcp');

    while(my $client = $sock->accept()) {
        print "Client connected\n";
        while(<$client>) {
            print "$_\n";
        }
    }

Start it and then run the following script as a client:

    use Log::Log4perl qw(:easy);

    my $conf = q{
        log4perl.category                  = WARN, Socket
        log4perl.appender.Socket           = Log::Log4perl::Appender::Socket
        log4perl.appender.Socket.PeerAddr  = localhost
        log4perl.appender.Socket.PeerPort  = 12345
        log4perl.appender.Socket.layout    = SimpleLayout
    };

    Log::Log4perl->init(\$conf);

    sleep(2);

    for(1..10) {
        ERROR("Quack!");
        sleep(5);
    }

COPYRIGHT AND LICENSE

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Log-Log4perl documentation Contained in the Log-Log4perl distribution.

##################################################
package Log::Log4perl::Appender::Socket;
##################################################
our @ISA = qw(Log::Log4perl::Appender);

use warnings;
use strict;

use IO::Socket::INET;

##################################################
sub new {
##################################################
    my($class, @options) = @_;

    my $self = {
        name            => "unknown name",
        silent_recovery => 0,
        no_warning      => 0,
        PeerAddr        => "localhost",
        Proto           => 'tcp',
        Timeout         => 5,
        @options,
    };

    bless $self, $class;

    unless ($self->{defer_connection}){
        unless($self->connect(@options)) {
            if($self->{silent_recovery}) {
                if( ! $self->{no_warning}) {
                    warn "Connect to $self->{PeerAddr}:$self->{PeerPort} failed: $!";
                }
               return $self;
            }
            die "Connect to $self->{PeerAddr}:$self->{PeerPort} failed: $!";
        }

        $self->{socket}->autoflush(1); 
        #autoflush has been the default behavior since 1997
    }

    return $self;
}
    
##################################################
sub connect {
##################################################
    my($self, @options) = @_;

    $self->{socket} = IO::Socket::INET->new(@options);

    return $self->{socket};
}

##################################################
sub log {
##################################################
    my($self, %params) = @_;


    {
            # If we were never able to establish
            # a connection, try to establish one 
            # here. If it fails, return.
        if(($self->{silent_recovery} or $self->{defer_connection}) and 
           !defined $self->{socket}) {
            if(! $self->connect(%$self)) {
                return undef;
            }
        }
  
            # Try to send the message across
        eval { $self->{socket}->send($params{message}); 
             };

        if($@) {
            warn "Send to " . ref($self) . " failed ($@), retrying once...";
            if($self->connect(%$self)) {
                redo;
            }
            if($self->{silent_recovery}) {
                return undef;
            }
            warn "Reconnect to $self->{PeerAddr}:$self->{PeerPort} " .
                 "failed: $!";
            return undef;
        }
    };

    return 1;
}

##################################################
sub DESTROY {
##################################################
    my($self) = @_;

    undef $self->{socket};
}

1;

__END__