NAME

       "IO::Async::File" - watch a file for changes

SYNOPSIS

        use IO::Async::File;

        use IO::Async::Loop;
        my $loop = IO::Async::Loop->new;

        my $file = IO::Async::File->new(
           filename => "config.ini",
           on_mtime_changed => sub {
              my ( $self ) = @_;
              print STDERR "Config file has changed\n";
              reload_config( $self->handle );
           }
        );

        $loop->add( $file );

        $loop->run;

DESCRIPTION

       This subclass of IO::Async::Notifier watches an open filehandle or named filesystem entity
       for changes in its "stat()" fields. It invokes various events when the values of these
       fields change. It is most often used to watch a file for size changes; for this task see
       also IO::Async::FileStream.

       While called "File", it is not required that the watched filehandle be a regular file. It
       is possible to watch anything that stat(2) may be called on, such as directories or other
       filesystem entities.

EVENTS

       The following events are invoked, either using subclass methods or CODE references in
       parameters.

   on_dev_changed $new_dev, $old_dev
   on_ino_changed $new_ino, $old_ino
   ...
   on_ctime_changed $new_ctime, $old_ctime
       Invoked when each of the individual "stat()" fields have changed. All the "stat()" fields
       are supported apart from "blocks" and "blksize". Each is passed the new and old values of
       the field.

   on_devino_changed $new_stat, $old_stat
       Invoked when either of the "dev" or "ino" fields have changed. It is passed two File::stat
       instances containing the complete old and new "stat()" fields. This can be used to observe
       when a named file is renamed; it will not be observed to happen on opened filehandles.

   on_stat_changed $new_stat, $old_stat
       Invoked when any of the "stat()" fields have changed. It is passed two File::stat
       instances containing the old and new "stat()" fields.

PARAMETERS

       The following named parameters may be passed to "new" or "configure".

       handle => IO
               The opened filehandle to watch for "stat()" changes if "filename" is not supplied.

       filename => STRING
               Optional. If supplied, watches the named file rather than the filehandle given in
               "handle". The file will be opened for reading and then watched for renames. If the
               file is renamed, the new filename is opened and tracked similarly after closing
               the previous file.

       interval => NUM
               Optional. The interval in seconds to poll the filehandle using stat(2) looking for
               size changes. A default of 2 seconds will be applied if not defined.

METHODS

   $handle = $file->handle
       Returns the filehandle currently associated with the instance; either the one passed to
       the "handle" parameter, or opened from the "filename" parameter.

AUTHOR

       Paul Evans <leonerd@leonerd.org.uk>