210_nb_ex.t   [plain text]

use strict;
use warnings;

# Non-Blocking Exclusive Lock Test

use Test::More tests => 8;
use File::NFSLock;
use Fcntl qw(O_CREAT O_RDWR O_RDONLY O_TRUNC LOCK_EX LOCK_NB);

$| = 1; # Buffer must be autoflushed because of fork() below.

my $datafile = "testfile.dat";

# Create a blank file
sysopen ( my $fh, $datafile, O_CREAT | O_RDWR | O_TRUNC );
close ($fh);
ok (-e $datafile && !-s _);

my ($rd1,$wr1);
ok (pipe($rd1,$wr1)); # Connected pipe for child1
if (!fork) {
  # Child #1 process
  my $lock = new File::NFSLock {
    file => $datafile,
    lock_type => LOCK_EX | LOCK_NB,
  };
  print $wr1 !!$lock; # Send boolean success status down pipe
  close($wr1); # Signal to parent that the Non-Blocking lock is done
  close($rd1);
  if ($lock) {
    sleep 2;  # hold the lock for a moment
    sysopen(my $fh, $datafile, O_RDWR);
    # now put a magic word into the file
    print $fh "child1\n";
    close $fh;
  }
  exit;
}
ok 1; # Fork successful
close ($wr1);
# Waiting for child1 to finish its lock status
my $child1_lock = <$rd1>;
close ($rd1);
# Report status of the child1_lock.
# It should have been successful
ok ($child1_lock);


my ($rd2, $wr2);
ok (pipe($rd2,$wr2)); # Connected pipe for child2
if (!fork) {
  # Child #2 process
  my $lock = new File::NFSLock {
    file => $datafile,
    lock_type => LOCK_EX | LOCK_NB,
  };
  print $wr2 !!$lock; # Send boolean success status down pipe
  close($wr2); # Signal to parent that the Non-Blocking lock is done
  close($rd2);
  if ($lock) {
    sysopen(my $fh, $datafile, O_RDWR);
    # now put a magic word into the file
    print $fh "child2\n";
    close $fh;
  }
  exit;
}
ok 1; # Fork successful
close ($wr2);
# Waiting for child2 to finish its lock status
my $child2_lock = <$rd2>;
close ($rd2);
# Report status of the child2_lock.
# This lock should not have been obtained since
# the child1 lock should still have been established.
ok (!$child2_lock);

# Wait until the children have finished.
wait; wait;

# Load up whatever the file says now
sysopen(my $fh2, $datafile, O_RDONLY);
$_ = <$fh2>;
close $fh2;

# It should be child1 if it was really nonblocking
# since it got the lock first.
ok /child1/;

# Wipe the temporary file
unlink $datafile;