Module: Rubadoop::MapReduce::Reducable

Extended by:
ActiveSupport::Concern
Included in:
Reducer
Defined in:
lib/rubadoop/map_reduce/reducable.rb

Instance Method Summary collapse

Instance Method Details

#reducer(&block) ⇒ Object 



10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
 
# File 'lib/rubadoop/map_reduce/reducable.rb', line 10

def reducer(&block)
  # Use blocks for memory efficiency, the alternative is for testing only
  # Entries come in per line: key\tvalue1 \n key\tvalue2 \n etc..
  # This will pivot that to: key [values1, value2] etc..

  lines = []
  last_key = nil
  enum = nil

  line = MapReduce.io_in.gets
  if line.nil?
    return lines unless block_given?
    return nil
  end
  line.chomp!
  key, value = key_value_split(line)

  last_key ||= key
  loop do
    if enum && !enum.flushed
      enum.each { |v| }
      break if (line == nil)
    end

    enum = TrackingEnumerator.new { |y|
      y << value
      loop do
        line = MapReduce.io_in.gets
        if line.nil?
          enum.flushed = true
          break
        end
        line.chomp!

        key, value = key_value_split(line)
        if key != last_key
          enum.flushed = true
          break
        end
        y << value
      end
      last_key = key
    }

    enum.flushed = false
    if block_given?
      block.call(last_key, enum)
    else
      lines << {key: last_key, values: enum.to_a} # must execute enum immediately here
    end
    break if (line == nil)
  end

  lines unless block_given?
end