124 lines
3.2 KiB
Ruby
124 lines
3.2 KiB
Ruby
module Polecat
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# handles the writing of new documents to the index.
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#
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# This class is responsible for writing the documents to the index. It takes
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# a path on creation and checks, if it is an empty or a valid index directory.
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#
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# When the documents are getting written to the filesystem, a 'index.lock'
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# file is written as an extra lock. It then writes a new file into the
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# directory, which has all documents.
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class IndexWriter
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attr_reader :path
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# create a new IndexWriter
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#
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# This creates a new IndexWriter set to the given path.
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# @param [String] path the path to the index directory
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def initialize path
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if !File.directory? path
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raise ArgumentError, 'not a directory'
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elsif File.exists? path + '/index.lock'
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raise IOError, 'index is locked'
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else
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@path = path
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@documents = []
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end
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end
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# returns the count of elements not flushed
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#
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# This method returns the count of all elements stored in the Writer, but
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# not yet flushed to a file.
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# @return [Fixnum] count of files
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def count
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@documents.count
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end
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# add a new document to the writer
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#
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# This adds a Document to the temporary storage. Call #write to write them
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# to the filesystem.
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# @param [Document] doc the document to store
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def add doc
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if doc.respond_to? :attributes
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@documents << doc
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else
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raise ArgumentError, 'missing method attributes'
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end
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end
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# write all documents to the disc
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#
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# Write all stored documents to the disc and clear the buffer.
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# @return [Boolean] true when the write was a success
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def write
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return false unless set_lock
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file_name = generate_filename
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File.open file_name, 'w' do |file|
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file.write Marshal.dump(@documents)
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end
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@documents = []
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release_lock
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end
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# creates an index reader with the writers path
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#
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# @returns [Polecat::IndexReader] an IndexReader with the same path
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def create_reader
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Polecat::IndexReader.new @path
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end
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# set the lock on the index
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# @private
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def set_lock
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if File.exists? lock_file_name
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false
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else
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FileUtils.touch lock_file_name
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true
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end
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end
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private :set_lock
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# release the index lock
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# @private
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def release_lock
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if File.exists? lock_file_name
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FileUtils.rm lock_file_name
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true
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else
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false
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end
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end
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private :release_lock
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# get the full path of the lock file
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# @private
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def lock_file_name
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@path + '/index.lock'
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end
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private :lock_file_name
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# generates a new file name for an index file
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# @private
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def generate_filename
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last_file = Dir[@path + '/*.ind'].sort.last
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if last_file.nil?
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file_name = @path + '/ind0.ind'
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else
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number = File.basename(last_file).match(/[0-9]+/)[0].to_i
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# we have to match the complete name, because there can be
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# numbers before the file too
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file_name = last_file.gsub(
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/ind#{number}\.ind/,
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"ind#{(number + 1)}.ind"
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)
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end
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file_name
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end
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private :generate_filename
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end
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end
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