test.p6

# http://sprunge.us/Yqnpg9
# http://sprunge.us/a425r1

sub tree-watch ( IO() $root ) {
  supply {
    # make sure there is only one tap for each file/dir
    my %taps;
    # make sure that only one thread is changing %taps
    my Lock $lock .= new;
    
    sub add ( IO $path ) {
      # make sure there isn't some form of race
      return if $lock.protect: { %taps{$path} };
      
      if $path.d {
        # add the existing files in the directory in parrallel.
        # that way we don't have to wait for them all to be added initially
        start { add $_ for $path.dir }
        
        # the lock.protect is only needed to add the tap
        $lock.protect:
        {
          %taps{$path} = do whenever $path.watch
          {
            say 'dir tap fired';
          
            # a file might have been added
            start { add $_ for $path.dir }
          
            .emit;
            LAST $lock.protect: { %taps{$path}:delete };
          }
        }
      } else {
        # the lock.protect is only needed to add the tap
        $lock.protect:
        {
          %taps{$path} = do whenever $path.watch
          {
            .emit;
            LAST $lock.protect: { %taps{$path}:delete };
          }
        }
      }
    }
    
    add( $root );
  } 
}