#!/usr/bin/perl

use strict; use warnings;
sub Log;

die "Usage:     $0 <filename>\n" unless @ARGV == 1;
my $logfile = shift;

# Pass #1 : gather line numbers to be deleted.
my %locks;                      # Hash of currently open locks.
my @unlock_lines;               # lines to rid ourselves of
open(LOGFILE,$logfile) or die "Can't read $logfile - $!\n";
while (<LOGFILE>) {
  Log 2, "Analysing line $.";
  next unless /Mutex\((.*?)\)::(\w+)/;
  my ($address,$action) = ($1,$2);
  if ($action eq 'locking') {
    Log 2, "Address $address locked at line $.";
    if (defined $locks{$address}) {
      Log 0, "ERROR: Address $address locked at line $., but already locked at line $locks{$address}.";
    }
    $locks{$address} = $.;
  }

  if ($action eq 'unlocked') {
    Log 2, "Address $address unlocked at line $.";
    unless (defined $locks{$address}) {
       Log 0, "ERROR: Address $address not locked, but unlocked at line $..";
    } else {
        push @unlock_lines, $., delete $locks{$address};
    }
  }
}
close LOGFILE;

# Sort the lines numbers that we've accumulated because we put them in
# unordered. This allows us to make just one more pass through the file
# to remove the lines.
@unlock_lines = sort { $a <=> $b } @unlock_lines;

# Pass #2: output all but the lines we're not interested in.
my $rmline = shift @unlock_lines;
open(LOGFILE,$logfile) or die "Can't read $logfile - $!\n";
while (<LOGFILE>) {
   if (defined $rmline && $. == $rmline) {
      $rmline = shift @unlock_lines;
      next;
   }
   print;
}
close LOGFILE;