NAME
    SNMP::Parallel - An effective SNMP-information-gathering module

VERSION
    0.02

DISCLAIMER
    THIS MODULE HAS NOT BEEN TESTED EXTENSIVELY AND ITS API IS SUBJECT TO
    CHANGE.

    Please post any feedback and bug reports to "bug-snmp-parallel at
    rt.cpan.org".

SYNOPSIS
     use SNMP::Parallel;
 
     my $snmp = SNMP::Parallel->new(
         max_sessions   => $NUM_POLLERS,
         master_timeout => $TIMEOUT_SECONDS,
     );

     $snmp->add(
         dest_host => $ip,
         callback  => sub { store_data() },
         get       => [ '1.3.6.1.2.1.1.3.0', 'sysDescr' ],
     );

     # lather, rinse, repeat
     # retrieve data from all hosts

     $snmp->execute;

DESCRIPTION
    This module collects information, over SNMP, from many hosts and many
    OIDs, really fast.

    It is a wrapper around the facilities of "SNMP.pm", which is the Perl
    interface to the C libraries in the "SNMP" package. Advantages of using
    this module include:

    Simple configuration
        The data structures required by "SNMP" are complex to set up before
        polling, and parse for results afterwards. This module provides a
        simpler interface to that configuration by accepting just a list of
        SNMP OIDs or leaf names.

    Parallel execution
        Many users are not aware that "SNMP" can poll devices asynchronously
        using a callback system. By specifying your callback routine as in
        the "SYNOPSIS" section above, many network devices can be polled in
        parallel, making operations far quicker. Note that this does not use
        threads.

    It's fast
        To give one example, "SNMP::Parallel" can walk, say, eight indexed
        OIDs (port status, errors, traffic, etc) for around 300 devices
        (that's 8500 ports) in under 30 seconds. Storage of that data might
        take an additional 10 seconds (depending on whether it's to RAM or
        disk). This makes polling/monitoring your network every five minutes
        (or less) no problem at all.

    The interface to this module is simple, with few options. The sections
    below detail everything you need to know.

METHODS ARGUMENTS
    The method arguments are very flexible. Any of the below acts as the
    same:

     $obj->method(MyKey   => $value);
     $obj->method(my_key  => $value);
     $obj->method(My_Key  => $value);
     $obj->method(mYK__EY => $value);

SEE ALSO
    This module does SNMP::Parallel::Role and SNMP::Parallel::Lock.

    It is a fork of SNMP::Effective. This is built on Moose and has a
    slightly better interface. Unfortunatly it's not 100% compatible with
    SNMP::Effective so it had to get a new name.

OBJECT ATTRIBUTES
  master_timeout
     $seconds = $self->master_timeout;

    Maximum seconds for execute() to run. Default is undef, which means
    forever.

  max_sessions
     $int = $self->max_sessions;

    How many concurrent hosts to retrieve data from.

  sessions
     $int = $self->sessions;

    Returns the number of active sessions.

METHODS
  BUILDARGS
     $hash_ref = $self->BUILDARGS(%args);
     $hash_ref = $self->BUILDARGS({ foo => bar });

    See "METHODS ARGUMENTS".

  add
     $self->add(%arguments);

    Adding information about what SNMP data to get and where to get it.

   Arguments
    "dest_host"
        Either a single host, or an array-ref that holds a list of hosts.
        The format is whatever "SNMP" can handle.

    "arg"
        A hash-ref of options, passed on to SNMP::Session.

    "callback"
        A reference to a sub which is called after each time a request is
        finished.

    "heap"
        This can hold anything you want. By default it's an empty hash-ref.

    "get" / "getnext" / "walk"
        Either "oid object", "numeric oid", SNMP::Varbind SNMP::VarList or
        an array-ref containing any combination of the above.

    "set"
        Either a single SNMP::Varbind or a SNMP::VarList or an array-ref of
        any of the above.

    This can be called with many different combinations, such as:

    "dest_host" / any other argument
        This will make changes per dest_host specified. You can use this to
        change arg, callback or add OIDs on a per-host basis.

    "get" / "getnext" / "walk" / "set"
        The OID list submitted to "add()" will be added to all dest_host, if
        no dest_host is specified.

    "arg" / "callback"
        This can be used to alter all hosts' SNMP arguments or callback
        method.

  execute
     $bool = $self->execute;

    This method starts setting and/or getting data. It will run as long as
    necessary, or until master_timeout seconds has passed. Every time some
    data is set and/or retrieved, it will call the callback-method, as
    defined globally or per host.

    Return true on success, and false if "master_timeout" is reached before
    all data is collected.

  add_snmp_callback
     $class->add_snmp_callback($name, $snmp_method, sub {});
     $self->add_snmp_callback($name, $snmp_method, sub {});

    Will add a callback for SNMP::Parallel.

    $name is what you refere to in SNMP::Parallel::add():

     $self->add( $name => ['sysDescr'] );

    $snmp_method is the method which should be called on the SNMP::Session
    object.

    See SNMP::Parallel::Callbacks for default callbacks.

  get_host
     $host_obj = $self->get_host($hostname);

  delete_host
     $host_obj = $self->delete_host($hostname);

  hosts
     @hostnames = $self->hosts;

The callback method
    When "SNMP" is done collecting data from a host, it calls a callback
    method, provided by the "Callback => sub{}" argument. Here is an example
    of a callback method:

     sub my_callback {
       my $host = shift;

       if(my $error = $host->error) {
          warn "$host failed with this error: $error";
          return;
       }

       printf '%s returned data:\n', $host;

       for my $obj (@{ $host->results }) {
         printf "%s => %s", $obj->name, "$obj";
       }
     }

DEBUGGING
    Debugging is enabled through Log::Log4perl. If nothing else is
    spesified, it will default to "error" level, and print to STDERR. The
    component-name you want to change is "SNMP::Parallel", inless this
    module ins inherited.

BUGS
    Please report any bugs or feature requests to "bug-snmp-parallel at
    rt.cpan.org", or through the web interface at
    <http://rt.cpan.org/NoAuth/ReportBug.html?Queue=SNMP-Parallel>. I will
    be notified, and then you'll automatically be notified of progress on
    your bug as I make changes.

ACKNOWLEDGEMENTS
    Various contributions by Oliver Gorwits.

    Sigurd Weisteen Larsen contributed with a better locking mechanism.

COPYRIGHT & LICENSE
    Copyright 2007 Jan Henning Thorsen, all rights reserved.

    This program is free software; you can redistribute it and/or modify it
    under the same terms as Perl itself.

AUTHOR
    Jan Henning Thorsen, "<jhthorse at cpan.org>"

POD ERRORS
    Hey! The above document had some coding errors, which are explained
    below:

    Around line 572:
        =cut found outside a pod block. Skipping to next block.