class NotifiedTail - notified_tail-0.2.2 Documentation

Public Class Methods

tail(file_path, opts={}, &on_line) click to toggle source

Yields complete lines, one at a time. Works even if file doesn't exist yet. @param file_path [String] The file to tail @option opts [Boolean] seek_end (true)

If true, seeks to the end of the file before reporting lines.
Otherwise, reports all lines starting at the beginning of the file.

@option opts [Boolean] force_poll (false)

Poll even if inotify or kqueue are available

# File lib/notified_tail.rb, line 15
def self.tail(file_path, opts={}, &on_line)
  new.tail(file_path, opts, &on_line)
end

Private Class Methods

get_ruby_platform() click to toggle source

# File lib/notified_tail.rb, line 94
def self.get_ruby_platform
  RUBY_PLATFORM
end

Public Instance Methods

stop() click to toggle source

# File lib/notified_tail.rb, line 36
def stop
  @queue.stop if @queue
  @queue = nil
  @stopped = true
end

tail(file_path, opts={}, &on_line) click to toggle source

# File lib/notified_tail.rb, line 19
def tail(file_path, opts={}, &on_line)
  @file_path = file_path
  @stopped = false
  seek_end = opts.fetch(:seek_end, true)
  @force_poll = opts.fetch(:force_poll, false)
  sleep(0.25) until File.exists?(file_path)
  File.open(file_path) do |file|
    unreported_line = ''
    if seek_end
      file.seek(0, IO::SEEK_END)
    else
      read_and_report_lines(file, unreported_line, &on_line)
    end
    when_modified(file_path) { read_and_report_lines(file, unreported_line, &on_line) }
  end
end

Private Instance Methods

line_ending?(c) click to toggle source

# File lib/notified_tail.rb, line 98
def line_ending?(c)
  c == "\n" || c == "\r"
end

poll(file_path, &block) click to toggle source

# File lib/notified_tail.rb, line 79
def poll(file_path, &block)
  last_mtime = File.mtime(file_path)
  last_notify_time = nil
  until @stopped do
    sleep(0.5)
    mtime = File.mtime(file_path)
    changed = mtime != last_mtime
    if changed || last_notify_time == nil || (Time.now - last_notify_time) > 5
      last_mtime = mtime
      last_notify_time = Time.now
      block.call
    end
  end
end

read_and_report_lines(file, unreported_line, &on_line) click to toggle source

# File lib/notified_tail.rb, line 44
def read_and_report_lines(file, unreported_line, &on_line)
  loop do
    c = file.readchar
    if line_ending?(c)
      on_line.call(unreported_line.dup)
      unreported_line.clear
      while (c = file.readchar) && line_ending?(c) do; end
    end
    unreported_line << c
  end
rescue EOFError
  # done for now
end

when_modified(file_path, &block) click to toggle source

# File lib/notified_tail.rb, line 58
def when_modified(file_path, &block)
  if @force_poll
    poll(file_path, &block)
  else
    case NotifiedTail.get_ruby_platform
    when /bsd/, /darwin/
      require 'rb-kqueue'
      @queue = KQueue::Queue.new
      @queue.watch_file(file_path, :extend) { block.call }
      @queue.run unless @stopped
    when /linux/
      require 'rb-inotify'
      @queue = INotify::Notifier.new
      @queue.watch(file_path, :modify) { block.call }
      @queue.run unless @stopped
    else
      poll(file_path, &block)
    end
  end
end