Class: LogClient::Tail

Inherits:
Object show all
Defined in:
lib/nfagent/tail.rb

Defined Under Namespace

Classes: BufferError

Class Method Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(filename) ⇒ Tail

Returns a new instance of Tail.



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# File 'lib/nfagent/tail.rb', line 26

def initialize(filename)
  @buffer = ""
  @filename = filename
  reset_buffer_size
  seek_and_setup
end

Class Method Details

.tail(filename) ⇒ Object 



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# File 'lib/nfagent/tail.rb', line 12

def self.tail(filename)
  loop do
    Tail.new(filename).run do |line|
      unless line.nil? || line.empty?
        if block_given?
          yield line
        else
          puts line
        end
      end
    end
  end
end

Instance Method Details

#run ⇒ Object

The real work Start at next start. Read until we get a new line and yield the line If we don’t get a new line then just ignore and try again until we do



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# File 'lib/nfagent/tail.rb', line 36

def run
  begin
    yield @first_line if block_given?
    while (size = File::Stat.new(@filename).size) >= @next_start
      size = @file.stat.size
      reset_buffer_size
      begin
        line = ""
        @file.seek(@next_start, File::SEEK_SET)
        @file.read(@buf_size, @buffer)
        buffer_start = @next_start
        found_new_line = false
        0.upto(@buffer.size - 1) do |index|
          line << @buffer[index]
          if @buffer[index].chr == "\n"
            yield(line) if block_given?
            line = ""
            found_new_line = true
            @next_start = buffer_start + index + 1
          end
        end
        unless found_new_line || @buffer.empty?
          raise BufferError
        end
      rescue BufferError
        increment_buffer_size
        retry
      end
	  sleep 0.01
    end
  rescue Errno::ENOENT
    # Wait until the file is recreated
    while !File.exists?(@filename)
      sleep 0.05
    end
  end
end