class INotify::Watcher

Watchers monitor a single path for changes, specified by {INotify::Notifier#watch event flags}. A watcher is usually created via {Notifier#watch}.

One {Notifier} may have many {Watcher}s. The Notifier actually takes care of the checking for events, via {Notifier#run run} or {Notifier#process process}. The main purpose of having Watcher objects is to be able to disable them using {#close}.

Attributes

flags[R]

The {INotify::Notifier#watch flags} specifying the events that this Watcher is watching for, and potentially some options as well.

@return [Array<Symbol>]

id[R]

The id for this Watcher. Used to retrieve this Watcher from {INotify::Notifier#watchers}.

@private @return [Fixnum]

notifier[R]

The {Notifier} that this Watcher belongs to.

@return [Notifier]

path[R]

The path that this Watcher is watching.

@return [String]

Public Class Methods

new(notifier, path, *flags, &callback) click to toggle source

Creates a new {Watcher}.

@private @see INotify::Notifier#watch

# File lib/rb-inotify/watcher.rb, line 56
def initialize(notifier, path, *flags, &callback)
  @notifier = notifier
  @callback = callback || proc {}
  @path = path
  @flags = flags.freeze
  @id = Native.inotify_add_watch(@notifier.fd, path.dup,
    Native::Flags.to_mask(flags))

  unless @id < 0
    @notifier.watchers[@id] = self
    return
  end

  raise SystemCallError.new(
    "Failed to watch #{path.inspect}" +
    case FFI.errno
    when Errno::EACCES::Errno; ": read access to the given file is not permitted."
    when Errno::EBADF::Errno; ": the given file descriptor is not valid."
    when Errno::EFAULT::Errno; ": path points outside of the process's accessible address space."
    when Errno::EINVAL::Errno; ": the given event mask contains no legal events; or fd is not an inotify file descriptor."
    when Errno::ENOMEM::Errno; ": insufficient kernel memory was available."
    when Errno::ENOSPC::Errno; ": The user limit on the total number of inotify watches was reached or the kernel failed to allocate a needed resource."
    else; ""
    end,
    FFI.errno)
end

Public Instance Methods

callback!(event) click to toggle source

Calls this Watcher's callback with the given {Event}.

@private @param event [Event]

# File lib/rb-inotify/watcher.rb, line 40
def callback!(event)
  @callback[event]
end
close() click to toggle source

Disables this Watcher, so that it doesn't fire any more events.

@raise [SystemCallError] if the watch fails to be disabled for some reason

# File lib/rb-inotify/watcher.rb, line 47
def close
  return if Native.inotify_rm_watch(@notifier.fd, @id) == 0
  raise SystemCallError.new("Failed to stop watching #{path.inspect}", FFI.errno)
end