Class: Ferret::Index::SegmentInfos

Inherits:
Array
  • Object
show all
Defined in:
lib/ferret/index/segment_infos.rb

Constant Summary collapse

FORMAT =

for compatability with Java Ferret files

-1
SEGMENT_FILENAME = 
"segments"
TEMPORARY_SEGMENT_FILENAME = 
"segments.new"

Instance Attribute Summary collapse

Class Method Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize ⇒ SegmentInfos

Returns a new instance of SegmentInfos.



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# File 'lib/ferret/index/segment_infos.rb', line 59

def initialize()
  @version = Time.now.to_i * 1000
  @counter = 0
end

Instance Attribute Details

#counter ⇒ Object

counts how often the index has been modified by adding or deleting docs



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# File 'lib/ferret/index/segment_infos.rb', line 28

def counter
  @counter
end

#version ⇒ Object (readonly)

Returns the value of attribute version.



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# File 'lib/ferret/index/segment_infos.rb', line 26

def version
  @version
end

Class Method Details

.read_current_version(directory) ⇒ Object

Current version number from segments file.



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# File 'lib/ferret/index/segment_infos.rb', line 31

def SegmentInfos.read_current_version(directory)
  return 0 if not directory.exists?(SEGMENT_FILENAME)
  input = directory.open_input(SEGMENT_FILENAME)
  @format = 0
  @version = 0
  begin
    @format = input.read_int()
    if(@format < 0)
      if (@format < FORMAT) then raise "Unknown format version: " + @format end
      @version = input.read_long() # read version
    end
  ensure
    input.close()
  end
   
  if(@format < 0)
    return @version
  end

  # We cannot be sure about the format of the file.
  # Therefore we have to read the whole file and cannot simply
  # seek to the version entry.

  sis = SegmentInfos.new()
  sis.read(directory)
  return sis.version()
end

Instance Method Details

#initialize_copy(o) ⇒ Object 



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# File 'lib/ferret/index/segment_infos.rb', line 64

def initialize_copy(o)
  super
  o.each_index {|i| self[i] = o[i].clone}
end

#read(directory) ⇒ Object 



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# File 'lib/ferret/index/segment_infos.rb', line 69

def read(directory)
  input = directory.open_input(SEGMENT_FILENAME)
  begin
    @format = input.read_int()
    if(@format < 0) # file contains explicit format info
      # check that it is a format we can understand
      if (@format < FORMAT) then raise "Unknown format version: " + @format end
      @version = input.read_long()
      @counter = input.read_int()
    else  # file is in old format without explicit format info
      @counter = @format
    end
    
    seg_count = input.read_int()
    seg_count.times do
      self << SegmentInfo.new(input.read_string(),
                              input.read_int(),
                              directory)
    end
   
    if(@format >= 0)   
      # in old format the version number may be at the end of the file
      if (input.pos() >= input.length())
        @version = 0 # old file format without version number
      else
        @version = input.read_long() # read version
      end
    end
  ensure
    input.close()
  end
end

#to_s ⇒ Object 



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# File 'lib/ferret/index/segment_infos.rb', line 122

def to_s()
  str = "\nSegmentInfos: <"
  each() { |si| str << "#{si.name}:#{si.doc_count}," }
  str[-1] = ">"
  str
end

#write(directory) ⇒ Object 



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# File 'lib/ferret/index/segment_infos.rb', line 102

def write(directory)
  output = directory.create_output(TEMPORARY_SEGMENT_FILENAME)
  begin
    output.write_int(FORMAT) # write FORMAT
    output.write_long(@version += 1) # every write changes the index
    output.write_int(@counter) # write counter
    output.write_int(size()) # write infos
    each() do |si|
      output.write_string(si.name)
      output.write_int(si.doc_count)
    end         
  
  ensure
    output.close()
  end

  # install new segment info
  directory.rename(TEMPORARY_SEGMENT_FILENAME, SEGMENT_FILENAME)
end