Class: Carrot::AMQP::Buffer

Inherits:
Object
  • Object
show all
Defined in:
lib/carrot/amqp/buffer.rb

Overview

:nodoc: all

Defined Under Namespace

Classes: InvalidType, Overflow

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(data = '') ⇒ Buffer

Returns a new instance of Buffer.



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# File 'lib/carrot/amqp/buffer.rb', line 16

def initialize data = ''
  @data = data
  @pos = 0
end

Instance Attribute Details

#pos ⇒ Object (readonly)

Returns the value of attribute pos.



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# File 'lib/carrot/amqp/buffer.rb', line 21

def pos
  @pos
end

Instance Method Details

#<<(data) ⇒ Object 



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# File 'lib/carrot/amqp/buffer.rb', line 29

def << data
  @data << data.to_s
  self
end

#_read(size, pack = nil) ⇒ Object 



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# File 'lib/carrot/amqp/buffer.rb', line 250

def _read(size, pack = nil)
  if @data.is_a?(Server)
    raw = @data.read(size)
    return raw if raw.nil? or pack.nil? 
    return raw.unpack(pack).first
  end

  if @pos + size > length
    raise Overflow
  else
    data = @data[@pos,size]
    @data[@pos,size] = ''
    if pack
      data = data.unpack(pack)
      data = data.pop if data.size == 1
    end
    data
  end
end

#_write(data, pack = nil) ⇒ Object 



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# File 'lib/carrot/amqp/buffer.rb', line 270

def _write data, pack = nil
  data = [*data].pack(pack) if pack
  @data[@pos,0] = data
  @pos += data.length
end

#data ⇒ Object Also known as: contents, to_s 



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# File 'lib/carrot/amqp/buffer.rb', line 23

def data
  @data.clone
end

#empty? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/carrot/amqp/buffer.rb', line 38

def empty?
  pos == length
end

#extract ⇒ Object 



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# File 'lib/carrot/amqp/buffer.rb', line 240

def extract
  begin
    cur_data, cur_pos = @data.clone, @pos
    yield self
  rescue Overflow
    @data, @pos = cur_data, cur_pos
    nil
  end
end

#length ⇒ Object 



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# File 'lib/carrot/amqp/buffer.rb', line 34

def length
  @data.length
end

#read(*types) ⇒ Object 



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# File 'lib/carrot/amqp/buffer.rb', line 83

def read *types
  if types.first == :properties
    return read_properties(*types)
  end

  values = types.map do |type|
    case type
    when :octet
      _read(1, 'C')
    when :short
      _read(2, 'n')
    when :long
      _read(4, 'N')
    when :longlong
      upper, lower = _read(8, 'NN')
      upper << 32 | lower
    when :shortstr
      _read read(:octet)
    when :longstr
      _read read(:long)
    when :timestamp
      Time.at read(:longlong)
    when :table
      t = Hash.new

      table = Buffer.new(read(:longstr))
      until table.empty?
        key, type = table.read(:shortstr, :octet)
        key = key.intern
        t[key] ||= case type
                   when 83 # 'S'
                     table.read(:longstr)
                   when 73 # 'I'
                     table.read(:long)
                   when 68 # 'D'
                     exp = table.read(:octet)
                     num = table.read(:long)
                     num / 10.0**exp
                   when 84 # 'T'
                     table.read(:timestamp)
                   when 70 # 'F'
                     table.read(:table)
                   end
      end

      t
    when :bit
      if (@bits ||= []).empty?
        val = read(:octet)
        @bits = (0..7).map{|i| (val & 1<<i) != 0 }
      end

      @bits.shift
    else
      raise InvalidType, "Cannot read data of type #{type}"
    end
  end
  
  types.size == 1 ? values.first : values
end

#read_properties(*types) ⇒ Object 



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# File 'lib/carrot/amqp/buffer.rb', line 46

def read_properties *types
  types.shift if types.first == :properties
  
  i = 0
  values = []

  while props = read(:short)
    (0..14).each do |n|
      # no more property types
      break unless types[i]
      
      # if flag is set
      if props & (1<<(15-n)) != 0
        if types[i] == :bit
          # bit values exist in flags only
          values << true
        else
          # save type name for later reading
          values << types[i]
        end
      else
        # property not set or is false bit
        values << (types[i] == :bit ? false : nil)
      end

      i+=1
    end

    # bit(0) == 0 means no more property flags
    break unless props & 1 == 1
  end

  values.map do |value|
    value.is_a?(Symbol) ? read(value) : value
  end
end

#rewind ⇒ Object 



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# File 'lib/carrot/amqp/buffer.rb', line 42

def rewind
  @pos = 0
end

#write(type, data) ⇒ Object 



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# File 'lib/carrot/amqp/buffer.rb', line 144

def write type, data
  case type
  when :octet
    _write(data, 'C')
  when :short
    _write(data, 'n')
  when :long
    _write(data, 'N')
  when :longlong
    lower =  data & 0xffffffff
    upper = (data & ~0xffffffff) >> 32
    _write([upper, lower], 'NN')
  when :shortstr
    data = (data || '').to_s
    _write([data.length, data], 'Ca*')
  when :longstr
    if data.is_a? Hash
      write(:table, data)
    else
      data = (data || '').to_s
      _write([data.length, data], 'Na*')
    end
  when :timestamp
    write(:longlong, data.to_i)
  when :table
    data ||= {}
    write :longstr, (data.inject(Buffer.new) do |table, (key, value)|
                      table.write(:shortstr, key.to_s)

                      case value
                      when String
                        table.write(:octet, 83) # 'S'
                        table.write(:longstr, value.to_s)
                      when Fixnum
                        table.write(:octet, 73) # 'I'
                        table.write(:long, value)
                      when Float
                        table.write(:octet, 68) # 'D'
                        # XXX there's gotta be a better way to do this..
                        exp = value.to_s.split('.').last.length
                        num = value * 10**exp
                        table.write(:octet, exp)
                        table.write(:long, num)
                      when Time
                        table.write(:octet, 84) # 'T'
                        table.write(:timestamp, value)
                      when Hash
                        table.write(:octet, 70) # 'F'
                        table.write(:table, value)
                      end

                      table
                    end)
  when :bit
    [*data].to_enum(:each_slice, 8).each{|bits|
      write(:octet, bits.enum_with_index.inject(0){ |byte, (bit, i)|
        byte |= 1<<i if bit
        byte
       })
     }
  when :properties
    values = []
    data.enum_with_index.inject(0) do |short, ((type, value), i)|
      n = i % 15
      last = i+1 == data.size

      if (n == 0 and i != 0) or last
        if data.size > i+1
          short |= 1<<0
        elsif last and value
          values << [type,value]
          short |= 1<<(15-n)
        end

        write(:short, short)
        short = 0
      end

      if value and !last
        values << [type,value] 
        short |= 1<<(15-n)
      end

      short
    end
    
    values.each do |type, value|
      write(type, value) unless type == :bit
    end
  else
    raise InvalidType, "Cannot write data of type #{type}"
  end
  
  self
end