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

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 51
def initialize
  @running = Mutex.new
  @pipe = IO.pipe

  @watchers = {}

  fd = Native.inotify_init
  unless fd < 0
    @handle = IO.new(fd)
    return
  end

  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

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 261
def close
  stop
  @handle.close
  @watchers.clear
end
fd() click to toggle source

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]

# File lib/rb-inotify/notifier.rb, line 43
def fd
  @handle.fileno
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 251
def process
  read_events.each do |event|
    event.callback!
    event.flags.include?(:ignored) && event.notifier.watchers.delete(event.watcher_id)
  end
end
read_events() click to toggle source

Blocks until there are one or more filesystem events that this notifier has watchers registered for. Once there are events, returns their {Event} objects.

This can return an empty list if the watcher was closed elsewhere.

{#run} or {#process} are ususally preferable to calling this directly.

# File lib/rb-inotify/notifier.rb, line 274
def read_events
  size = Native::Event.size + Native.fpathconf(fd, Native::Flags::PC_NAME_MAX) + 1
  tries = 1

  begin
    data = readpartial(size)
  rescue SystemCallError => er
    # EINVAL means that there's more data to be read
    # than will fit in the buffer size
    raise er unless er.errno == Errno::EINVAL::Errno && tries < 5
    size *= 2
    tries += 1
    retry
  end
  return [] if data.nil?

  events = []
  cookies = {}
  while event = Event.consume(data, self)
    events << event
    next if event.cookie == 0
    cookies[event.cookie] ||= []
    cookies[event.cookie] << event
  end
  cookies.each {|c, evs| evs.each {|ev| ev.related.replace(evs - [ev]).freeze}}
  events
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 225
def run
  @running.synchronize do
    @stop = false

    process until @stop
  end
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 236
def stop
  @stop = true
  @pipe.last.write "."

  @running.synchronize do
    # no-op: we just needed to wait until the lock was available
  end
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 89
def to_io
  @handle
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 191
def watch(path, *flags, &callback)
  return Watcher.new(self, path, *flags, &callback) unless flags.include?(:recursive)

  dir = Dir.new(path)

  dir.each do |base|
    d = File.join(path, base)
    binary_d = d.respond_to?(:force_encoding) ? d.dup.force_encoding('BINARY') : d
    next if binary_d =~ /\/\.\.?$/ # Current or parent directory
    next if RECURSIVE_BLACKLIST.include?(d)
    next if flags.include?(:dont_follow) && File.symlink?(d)
    next if !File.directory?(d)

    watch(d, *flags, &callback)
  end

  dir.close

  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

Private Instance Methods

readpartial(size) click to toggle source

Same as IO#readpartial, or as close as we need.

# File lib/rb-inotify/notifier.rb, line 305
def readpartial(size)
  readable, = select([@handle, @pipe.first])
  return nil if readable.include?(@pipe.first)
  @handle.readpartial(size)
rescue Errno::EBADF
  # If the IO has already been closed, reading from it will cause
  # Errno::EBADF.
  nil
end