Module: Moped::Protocol::Message::ClassMethods

Defined in:
lib/moped/protocol/message.rb

Overview

Provides a DSL for defining struct-like fields for building messages for the Mongo Wire.

Examples:

class Command
  extend Message::ClassMethods

  int32 :length
end

Command.fields # => [:length]
command = Command.new
command.length = 12
command.serialize_length("") # => "\f\x00\x00\x00"

Instance Method Summary collapse

Instance Method Details

#cstring(name) ⇒ Object

Declare a null terminated string field.

Examples:

class Query < Message
  cstring :collection
end

Parameters:

  • name (String) —

    the name of this field



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# File 'lib/moped/protocol/message.rb', line 81

def cstring(name)
  attr_accessor name

  class_eval <<-RUBY, __FILE__, __LINE__ + 1
    def serialize_#{name}(buffer)
      buffer << #{name}
      buffer << 0
    end
  RUBY

  fields << name
end

#document(name, options = {}) ⇒ Object

Declare a BSON Document field.

Examples:

class Update < Message
  document :selector
end

optional document field

class Query < Message
  document :selector
  document :fields, optional: true
end

array of documents

class Reply < Message
  document :documents, type: :array
end

Parameters:

  • name (String) —

    the name of this field

  • options (Hash) (defaults to: {}) —

    the options for this field

Options Hash (options):

  • :type (:array) —

    specify an array of documents

  • :optional (Boolean) —

    specify this field as optional



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# File 'lib/moped/protocol/message.rb', line 116

def document(name, options = {})
  attr_accessor name

  if options[:optional]
    class_eval <<-RUBY, __FILE__, __LINE__ + 1
      def serialize_#{name}(buffer)
        BSON::Document.serialize(#{name}, buffer) if #{name}
      end
    RUBY
  elsif options[:type] == :array
    class_eval <<-RUBY, __FILE__, __LINE__ + 1
      def serialize_#{name}(buffer)
        #{name}.each do |document|
          BSON::Document.serialize(document, buffer)
        end
      end
    RUBY
  else
    class_eval <<-RUBY, __FILE__, __LINE__ + 1
      def serialize_#{name}(buffer)
        BSON::Document.serialize(#{name}, buffer)
      end
    RUBY
  end

  fields << name
end

#fields ⇒ Array

Returns the fields defined for this message.

Returns:

  • (Array) —

    the fields defined for this message



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# File 'lib/moped/protocol/message.rb', line 69

def fields
  @fields ||= []
end

#finalize ⇒ Object

Declares the message class as complete, and defines its serialization method from the declared fields.



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# File 'lib/moped/protocol/message.rb', line 276

def finalize
  class_eval <<-EOS, __FILE__, __LINE__ + 1
    def serialize(buffer = "")
      start = buffer.bytesize

      #{fields.map { |f| "serialize_#{f}(buffer)" }.join("\n")}

      self.length = buffer.bytesize - start
      buffer[start, 4] = serialize_length ""
      buffer
    end
    alias to_s serialize
  EOS
end

#flags(name, flag_map = {}) ⇒ Object

Declare a flag field (32 bit signed integer)

Examples:

class Update < Message
  flags :flags, upsert: 2 ** 0,
                multi:  2 ** 1
end

Parameters:

  • name (String) —

    the name of this field

  • flags (Hash{Symbol => Number}) —

    the flags for this flag field



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# File 'lib/moped/protocol/message.rb', line 154

def flags(name, flag_map = {})
  class_eval <<-RUBY, __FILE__, __LINE__ + 1
    def #{name}
      @#{name} ||= []
    end

    def #{name}=(flags)
      if flags.is_a? Numeric
        @#{name} = #{name}_from_int(flags)
      else
        @#{name} = flags
      end
    end

    def #{name}_as_int
      bits = 0
      flags = self.#{name}
      #{flag_map.map { |flag, value| "bits |= #{value} if flags.include? #{flag.inspect}" }.join "\n"}
      bits
    end

    def #{name}_from_int(bits)
      flags = []
      #{flag_map.map { |flag, value| "flags << #{flag.inspect} if #{value} & bits == #{value}" }.join "\n"}
      flags
    end

    def serialize_#{name}(buffer)
      buffer << [#{name}_as_int].pack('l<')
    end

    def deserialize_#{name}(buffer)
      bits, = buffer.read(4).unpack('l<')

      self.#{name} = bits
    end
  RUBY

  fields << name
end

#int32(name) ⇒ Object

Declare a 32 bit signed integer field.

Examples:

class Query < Message
  int32 :length
end

Parameters:

  • name (String) —

    the name of this field



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# File 'lib/moped/protocol/message.rb', line 203

def int32(name)
  attr_writer name

  class_eval <<-RUBY, __FILE__, __LINE__ + 1
    def #{name}
      @#{name} ||= 0
    end

    def serialize_#{name}(buffer)
      buffer << [#{name}].pack('l<')
    end

    def deserialize_#{name}(buffer)
      self.#{name}, = buffer.read(4).unpack('l<')
    end
  RUBY

  fields << name
end

#int64(name, options = {}) ⇒ Object

Declare a 64 bit signed integer field.

Examples:

class Query < Message
  int64 :cursor_id
end

with array type

class KillCursors < Message
  int64 :cursor_ids, type: :array
end

Parameters:

  • name (String) —

    the name of this field

  • options (Hash) (defaults to: {}) —

    the options for this field

Options Hash (options):

  • :type (:array) —

    specify an array of 64 bit ints



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# File 'lib/moped/protocol/message.rb', line 238

def int64(name, options = {})
  attr_writer name

  if options[:type] == :array
    class_eval <<-RUBY, __FILE__, __LINE__ + 1
      def #{name}
        @#{name} ||= []
      end

      def serialize_#{name}(buffer)
        buffer << #{name}.pack('q<*')
      end

      def deserialize_#{name}(buffer)
        raise NotImplementedError
      end
    RUBY
  else
    class_eval <<-RUBY, __FILE__, __LINE__ + 1
      def #{name}
        @#{name} ||= 0
      end

      def serialize_#{name}(buffer)
        buffer << [#{name}].pack('q<')
      end

      def deserialize_#{name}(buffer)
        self.#{name}, = buffer.read(8).unpack('q<')
      end
    RUBY
  end

  fields << name
end