while(my $s1 = <LOG>){
  next unless $s1 =~ m#^(\d+/\d+/\d+) (\d+:\d+:\d+) user=(\S+) func\(#;
  my ($date, $time, $user) = ($1, $2, $3);
  ...  # above variables are available
  while(my $s2 = <LOG>){
    last if $s2 =~ /^\) #end trans#/;
    ...   # $s2 is log data
  }
}