class INotify::Notifier

Notifier wraps a single instance of inotify. It's possible to have more than one instance, but usually unnecessary.

@example

# Create the notifier
notifier = INotify::Notifier.new

# Run this callback whenever the file path/to/foo.txt is read
notifier.watch("path/to/foo.txt", :access) do
  puts "Foo.txt was accessed!"
end

# Watch for any file in the directory being deleted
# or moved out of the directory.
notifier.watch("path/to/directory", :delete, :moved_from) do |event|
  # The #name field of the event object contains the name of the affected file
  puts "#{event.name} is no longer in the directory!"
end

# Nothing happens until you run the notifier!
notifier.run

Constants

RECURSIVE_BLACKLIST

A list of directories that should never be recursively watched.

  • Files in `/dev/fd` sometimes register as directories, but are not enumerable.

Attributes

fd[R]

The underlying file descriptor for this notifier. This is a valid OS file descriptor, and can be used as such (except under JRuby -- see {#to_io}).

@return [Fixnum]

watchers[R]

A hash from {Watcher} ids to the instances themselves.

@private @return [{Fixnum => Watcher}]

Public Class Methods

new() click to toggle source

Creates a new {Notifier}.

@return [Notifier] @raise [SystemCallError] if inotify failed to initialize for some reason

# File lib/rb-inotify/notifier.rb, line 53
def initialize
  @fd = Native.inotify_init
  @watchers = {}
  return unless @fd < 0

  raise SystemCallError.new(
    "Failed to initialize inotify" +
    case FFI.errno
    when Errno::EMFILE::Errno; ": the user limit on the total number of inotify instances has been reached."
    when Errno::ENFILE::Errno; ": the system limit on the total number of file descriptors has been reached."
    when Errno::ENOMEM::Errno; ": insufficient kernel memory is available."
    else; ""
    end,
    FFI.errno)
end
supports_ruby_io?() click to toggle source

@return [Boolean] Whether or not this Ruby implementation supports

wrapping the native file descriptor in a Ruby IO wrapper.
# File lib/rb-inotify/notifier.rb, line 45
def self.supports_ruby_io?
  RUBY_PLATFORM !~ %rjava/
end

Public Instance Methods

close() click to toggle source

Close the notifier.

@raise [SystemCallError] if closing the underlying file descriptor fails.

# File lib/rb-inotify/notifier.rb, line 239
def close
  return if Native.close(@fd) == 0

  raise SystemCallError.new("Failed to properly close inotify socket" +
   case FFI.errno
   when Errno::EBADF::Errno; ": invalid or closed file descriptior"
   when Errno::EIO::Errno; ": an I/O error occured"
   end,
   FFI.errno)
end
process() click to toggle source

Blocks until there are one or more filesystem events that this notifier has watchers registered for. Once there are events, the appropriate callbacks are called and this function returns.

@see run

# File lib/rb-inotify/notifier.rb, line 232
def process
  read_events.each {|event| event.callback!}
end
run() click to toggle source

Starts the notifier watching for filesystem events. Blocks until {#stop} is called.

@see process

# File lib/rb-inotify/notifier.rb, line 214
def run
  @stop = false
  process until @stop
end
stop() click to toggle source

Stop watching for filesystem events. That is, if we're in a {#run} loop, exit out as soon as we finish handling the events.

# File lib/rb-inotify/notifier.rb, line 222
def stop
  @stop = true
end
to_io() click to toggle source

Returns a Ruby IO object wrapping the underlying file descriptor. Since this file descriptor is fully functional (except under JRuby), this IO object can be used in any way a Ruby-created IO object can. This includes passing it to functions like `select`.

Note that this always returns the same IO object. Creating lots of IO objects for the same file descriptor can cause some odd problems.

**This is not supported under JRuby**. JRuby currently doesn't use native file descriptors for the IO object, so we can't use this file descriptor as a stand-in.

@return [IO] An IO object wrapping the file descriptor @raise [NotImplementedError] if this is being called in JRuby

# File lib/rb-inotify/notifier.rb, line 84
def to_io
  unless self.class.supports_ruby_io?
    raise NotImplementedError.new("INotify::Notifier#to_io is not supported under JRuby")
  end
  @io ||= IO.new(@fd)
end
watch(path, *flags, &callback) click to toggle source

Watches a file or directory for changes, calling the callback when there are. This is only activated once {#process} or {#run} is called.

**Note that by default, this does not recursively watch subdirectories of the watched directory**. To do so, use the `:recursive` flag.

## Flags

`:access` : A file is accessed (that is, read).

`:attrib` : A file's metadata is changed (e.g. permissions, timestamps, etc).

`:close_write` : A file that was opened for writing is closed.

`:close_nowrite` : A file that was not opened for writing is closed.

`:modify` : A file is modified.

`:open` : A file is opened.

### Directory-Specific Flags

These flags only apply when a directory is being watched.

`:moved_from` : A file is moved out of the watched directory.

`:moved_to` : A file is moved into the watched directory.

`:create` : A file is created in the watched directory.

`:delete` : A file is deleted in the watched directory.

`:delete_self` : The watched file or directory itself is deleted.

`:move_self` : The watched file or directory itself is moved.

### Helper Flags

These flags are just combinations of the flags above.

`:close` : Either `:close_write` or `:close_nowrite` is activated.

`:move` : Either `:moved_from` or `:moved_to` is activated.

`:all_events` : Any event above is activated.

### Options Flags

These flags don't actually specify events. Instead, they specify options for the watcher.

`:onlydir` : Only watch the path if it's a directory.

`:dont_follow` : Don't follow symlinks.

`:mask_add` : Add these flags to the pre-existing flags for this path.

`:oneshot` : Only send the event once, then shut down the watcher.

`:recursive` : Recursively watch any subdirectories that are created.

Note that this is a feature of rb-inotify,
rather than of inotify itself, which can only watch one level of a directory.
This means that the {Event#name} field
will contain only the basename of the modified file.
When using `:recursive`, {Event#absolute_name} should always be used.

@param path [String] The path to the file or directory @param flags [Array<Symbol>] Which events to watch for @yield [event] A block that will be called

whenever one of the specified events occur

@yieldparam event [Event] The Event object containing information

about the event that occured

@return [Watcher] A Watcher set up to watch this path for these events @raise [SystemCallError] if the file or directory can't be watched,

e.g. if the file isn't found, read access is denied,
or the flags don't contain any events
# File lib/rb-inotify/notifier.rb, line 189
def watch(path, *flags, &callback)
  return Watcher.new(self, path, *flags, &callback) unless flags.include?(:recursive)

  Dir.glob(File.join(path, '*'), File::FNM_DOTMATCH).each do |d|
    binary_d = d.respond_to?(:force_encoding) ? d.dup.force_encoding('BINARY') : d
    next if binary_d =~ %r\/\.\.?$/ # Current or parent directory
    watch(d, *flags, &callback) if !RECURSIVE_BLACKLIST.include?(d) && File.directory?(d)
  end

  rec_flags = [:create, :moved_to]
  return watch(path, *((flags - [:recursive]) | rec_flags)) do |event|
    callback.call(event) if flags.include?(:all_events) || !(flags & event.flags).empty?
    next if (rec_flags & event.flags).empty? || !event.flags.include?(:isdir)
    begin
      watch(event.absolute_name, *flags, &callback)
    rescue Errno::ENOENT
      # If the file has been deleted since the glob was run, we don't want to error out.
    end
  end
end