lwes-perl-journal-listener

   1 #!/usr/bin/env perl
   2
   3 use strict;
   4 use warnings;
   5
   6 use Getopt::Long;
   7 use Pod::Usage;
   8 use LWES::EventParser;
   9 use LWES::Listener;
  10 use POSIX qw(strftime);
  11
  12 my $help_opt         = 0;
  13 my $man_opt          = 0;
  14 my $verbose_opt      = 0;
  15 my $stats_opt        = 0;
  16
  17 Getopt::Long::Configure ("pass_through");
  18
  19 GetOptions
  20   (
  21     'help'           => \$help_opt,
  22     'man'            => \$man_opt,
  23     'stats'          => \$stats_opt,
  24     'verbose'        => \$verbose_opt,
  25   ) or pod2usage (2);
  26
  27 pod2usage (-exitval => -1, -verbose => 0) if $help_opt;
  28 pod2usage (-exitval => -2, -verbose => 2) if $man_opt;
  29
  30 my $listener_or_code;
  31
  32 # if the first argument is a file, we'll assume it s a journal file, and
  33 # use the PrintingListener
  34 if (-f $ARGV[0])
  35   {
  36     $listener_or_code = "LWES::Listeners::EventPrintingListener";
  37   }
  38 else
  39   {
  40     $listener_or_code = shift @ARGV;
  41   }
  42
  43 # determine the callback which will process each event
  44 my $processEventFunc = getProcessEventFunc ($listener_or_code, \@ARGV);
  45
  46 foreach my $journal (@ARGV)
  47   {
  48     my $start      = time();
  49     my $log_date   = strftime ("%a %b %e %H:%M:%S %Y", localtime ($start));
  50     my $num_events = 0;
  51
  52     if ($stats_opt)
  53       {
  54         print "$log_date : $journal ";
  55       }
  56
  57     if (-f $journal)
  58       {
  59         open FH, "zcat $journal |";
  60
  61         # read and parse header
  62         my $header_bytes;
  63         while ( read (FH, $header_bytes, 22) == 22)
  64           {
  65             my $header = bytesToHeader ($header_bytes);
  66
  67             # read and parse bytes
  68             my $event_bytes;
  69             my $n = read (FH, $event_bytes, $header->{'PayloadLength'});
  70             if (defined ($n) && $n == $header->{'PayloadLength'})
  71               {
  72                 my $event = bytesToEvent ($event_bytes);
  73
  74                 # merge header into event
  75                 foreach my $h (keys %{$header})
  76                   {
  77                     unless (exists ($event->{$h}))
  78                       {
  79                         $event->{$h} = $header->{$h};
  80                       }
  81                   }
  82
  83                 # call handler
  84                 $processEventFunc->($event);
  85                 $num_events++;
  86               }
  87             else
  88               {
  89                 die "malformed or truncated journal";
  90               }
  91           }
  92
  93         close FH;
  94       }
  95
  96     if ($stats_opt)
  97       {
  98         my $end = time()-$start;
  99         print "had $num_events events processed in $end seconds\n";
 100       }
 101   }
 102
 103 0;
 104
 105 __END__
 106
 107 =head1 NAME
 108
 109 lwes-perl-journal-listener - listens for events from a journal
 110
 111 =head1 SYNOPSIS
 112
 113 lwes-perl-journal-listener [options] [<listener> [<args>] | <code>] <journal(s)>
 114
 115 Options:
 116   --stats                     Print information about each file processed
 117   -help                       Brief help message
 118   -man                        Full Documentation
 119
 120 <listener> is the name of a perl module which extends the base
 121 listener LWES::Listener and provides an initialize and processEvent
 122 method.  The <args> are passed directly to the listener constructor.
 123
 124 code is perl code which is embedded in a function which takes one
 125 argument, a reference to a perl hash which contains the contents
 126 of the event called $event
 127
 128 =head1 OPTIONS
 129
 130 =over 8
 131
 132 =item B<--stats>
 133
 134 Print information about how many events were processed and how long it took
 135 to process.
 136
 137 =item B<-help>
 138
 139 Print help information
 140
 141 =item B<-man>
 142
 143 Print more verbose help information
 144
 145 =back
 146
 147 =head1 DESCRIPTION
 148
 149 The lwes-perl-journal-listener is a tool for inspecting LWES events that
 150 are in journal files created by the lwes-journaller.
 151
 152 There are several ways to use the tool.  To just print out events as they
 153 are seen it can be invoked as
 154
 155 % lwes-perl-journal-listener <journal>
 156
 157 Alternatively you can provide a LWES::Listener module as outlined in
 158 the lwes-perl-event-listener man page.
 159
 160 =cut