Class: GeoTreeModule::PtBuffer

Inherits:
Object
  • Object
show all
Includes:
ExternalSortModule
Defined in:
lib/geotree/ptbuffer.rb

Overview

Support for buffering new points to a file, then shuffling the points before adding them to (one or more) geotrees.

Constant Summary collapse

PT_SHUFFLER_ = 
Proc.new do |x,y|
  rand(2) == 0 ? -1 : 1
end

Constants included from ExternalSortModule

ExternalSortModule::MAX_CHUNK_SIZE_

Instance Method Summary collapse

Constructor Details

#initialize(tree) ⇒ PtBuffer

Construct an inactive buffer

Parameters:

  • tree —

    tree to receive the points; calls its add_buffered_point() method when the buffer is being closed



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# File 'lib/geotree/ptbuffer.rb', line 52

def initialize(tree)
  @tree = tree
  @buffering = false
  @buff_file = nil
  @buffered_count = 0
end

Instance Method Details

#active ⇒ Object

Return true if buffer is active



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# File 'lib/geotree/ptbuffer.rb', line 60

def active
  @buffering
end

#active=(val) ⇒ Object

Change buffer’s active state



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# File 'lib/geotree/ptbuffer.rb', line 65

def active=(val)
  db = false

  if @buffering != val

    @buffering = val

    # If we were buffering the points, then close the file,
    # shuffle the points, and send them to the receiving tree(s).
    if @buff_file
      @buff_file.close

      # Sort the buffered points into a random order
      so = Sorter.new(@buff_file.path,DATAPOINT_BYTES, PT_SHUFFLER_)
      so.sort

      !db || pr(" opening chunk reader for #@buffered_count points\n")

      @buff_file.open
      @buff_file.binmode

      r = ChunkReader.new(@buff_file, 0, DATAPOINT_BYTES * @buffered_count, DATAPOINT_BYTES)
      while !r.done
        by,off = r.peek
        dp = GeoTree.read_data_point_from(by,off / INT_BYTES)
        r.read
        !db||  pr("adding data point: #{dp}\n")
        @tree.add_buffered_point(dp)
      end
      @buff_file.close
    end
    @buff_file = nil
    @buffered_count = 0
  end

end

#add(data_point) ⇒ Object

Add point to buffer



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# File 'lib/geotree/ptbuffer.rb', line 103

def add(data_point)
  if !active
    @tree.add_buffered_point(data_point)
  else
    if @buffered_count == 0
      @buff_file = Tempfile.new('_geotree_')
      @buff_file.binmode
    end

    by = zero_bytes(DATAPOINT_BYTES)
    GeoTree.write_data_point(data_point, by, 0)
    nw = @buff_file.write(by)
    raise IOError if nw != by.size
    @buffered_count += 1
  end
end