NAME
    RenameLock - Simple exclusive lock by renaming lockfile.

SYNOPSIS
      ### Simple One ###
      use RenameLock;
      my $lock = RenameLock->new(basename   => "lockfile",
                                 lockdir    => "./lock",
                                 timeout    => 10,
                                 expiretime => 600);
      $lock->lock or die "busy!;
      my $fh = IO::File->new(">file");
      # blash, blash, blash...
      undef $fh;       # close
      $lock->unlock;

      ### Sample for using auto unlock when DESTROY ###
      use RenameLock;

      my @datafiles;
      foreach (qw(file_a file_b file_c)) {
        my $lock = RenameLock->new(basename => "$_.lock");
        $lock->lock or die "busy!";
        my $fh = IO::File->new(">$_");
        push @datafiles, { fh => $fh, lock => $lock};
      }
      # blash, blash, blash...
      my $selected_fh = $datafiles[1]->{fh};
      print $selected_fh "moge\n";
      # blash, blash, blash...
      delete $datafiles[1];    # auto close & unlock for "file_b"

DESCRIPTION
    Simple exclusive lock by renaming lockfile.

  METHODS
    * new
        Create new object.

        - lockdir
            Assign directory for create lockfile. default is ".".

            This directory MUST be writable. (But, should NOT assign world
            writable directory. To avoid symlink attack.)

        - basename
            Lockfile's basename. You should create empty file before
            processing.

        - timeout
            Timeout(sec) for lock. default is 30(sec).

        - expiretime
            Timeout(sec) for force purge lock. Default is undef(=never).

        - nowarn
            If it is true, suppress non-serious warning message.

    * lock
        Do lock. return filename if success.

    * unlock
        Do unlock. return true for success.

    * is_locked
        Detects lockstatus. return true for locked.

        Notice: this method can NOT detect lock by other process or
        instance. only affects locked by self.

  EXPORT
    * default
    None.

    * all:
    lock, unlock.

LICENSE
    Same as perl itself.

AUTHOR
    Tatsuki Sugiura <sugi@nemui.org>

THANKS
    HZAKI Hiroki! (http://www.din.or.jp/~ohzaki/perl.htm#File_Lock)

SEE ALSO
    perl.