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



116
117
118
119
120
121
122
123
124
125
126
127
 
# File 'lib/moped/protocol/message.rb', line 116

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



151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
 
# File 'lib/moped/protocol/message.rb', line 151

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

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

  fields << name
end

#fields ⇒ Array

Returns the fields defined for this message.

Returns:

  • (Array) —

    the fields defined for this message



104
105
106
 
# File 'lib/moped/protocol/message.rb', line 104

def fields
  @fields ||= []
end

#finalize ⇒ Object

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



311
312
313
314
315
316
317
318
319
320
321
322
 
# File 'lib/moped/protocol/message.rb', line 311

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



189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
 
# File 'lib/moped/protocol/message.rb', line 189

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



238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
 
# File 'lib/moped/protocol/message.rb', line 238

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



273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
 
# File 'lib/moped/protocol/message.rb', line 273

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