Module: Ligarb::Inotify

Defined in:
lib/ligarb/inotify.rb

Constant Summary collapse

LIBC = 
Fiddle.dlopen(nil)
InotifyInit1 = 
Fiddle::Function.new(
  LIBC["inotify_init1"],
  [Fiddle::TYPE_INT],
  Fiddle::TYPE_INT
)
InotifyAddWatch = 
Fiddle::Function.new(
  LIBC["inotify_add_watch"],
  [Fiddle::TYPE_INT, Fiddle::TYPE_VOIDP, Fiddle::TYPE_UINT32_T],
  Fiddle::TYPE_INT
)
InotifyRmWatch = 
Fiddle::Function.new(
  LIBC["inotify_rm_watch"],
  [Fiddle::TYPE_INT, Fiddle::TYPE_INT],
  Fiddle::TYPE_INT
)
IN_CLOSE_WRITE =

inotify event masks

0x00000008
IN_CLOEXEC =

O_CLOEXEC on x86_64

0x00080000
EVENT_HEADER_SIZE =

struct inotify_event fixed part: int wd, uint32 mask, uint32 cookie, uint32 len

16

Class Method Summary collapse

Class Method Details

.add_watch(fd, path) ⇒ Object

Raises:

  • (SystemCallError) 


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# File 'lib/ligarb/inotify.rb', line 69

def self.add_watch(fd, path)
  wd = InotifyAddWatch.call(fd, path, IN_CLOSE_WRITE)
  raise SystemCallError.new("inotify_add_watch: #{path}", Fiddle.last_error) if wd < 0
  wd
end

.watch_file(path, &block) ⇒ Object

Watch a file for writes. Yields each time the file is written and closed. Blocks the calling thread. Caller should wrap in Thread.new.



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# File 'lib/ligarb/inotify.rb', line 39

def self.watch_file(path, &block)
  fd = InotifyInit1.call(IN_CLOEXEC)
  raise SystemCallError.new("inotify_init1", Fiddle.last_error) if fd < 0

  io = IO.for_fd(fd, autoclose: true)
  wd = add_watch(fd, path)

  loop do
    # IO.select releases GVL while waiting
    IO.select([io])
    buf = io.read_nonblock(4096, exception: false)
    next if buf == :wait_readable || buf.nil?

    # Parse events — may contain multiple events
    offset = 0
    while offset + EVENT_HEADER_SIZE <= buf.bytesize
      _wd, mask, _cookie, name_len = buf.byteslice(offset, EVENT_HEADER_SIZE).unpack("iIII")
      offset += EVENT_HEADER_SIZE + name_len

      if mask & IN_CLOSE_WRITE != 0
        block.call
      end
    end
  rescue IOError, Errno::EBADF
    break
  end
ensure
  io&.close rescue nil
end