Method: Tros::DataFile::Writer#initialize

Defined in:
lib/tros/data_file.rb

#initialize(writer, datum_writer, writers_schema = nil, codec = nil) ⇒ Writer

Returns a new instance of Writer.


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# File 'lib/tros/data_file.rb', line 95

def initialize(writer, datum_writer, writers_schema=nil, codec=nil)
  # If writers_schema is not present, presume we're appending
  @writer = writer
  @encoder = IO::BinaryEncoder.new(@writer)
  @datum_writer = datum_writer
  @buffer_writer = StringIO.new('', 'w')
  @buffer_encoder = IO::BinaryEncoder.new(@buffer_writer)
  @block_count = 0

  @meta = {}

  if writers_schema
    @sync_marker = Writer.generate_sync_marker
    @codec = DataFile.get_codec(codec)
    meta['tros.codec'] = @codec.codec_name.to_s
    meta['tros.schema'] = writers_schema.to_s
    datum_writer.writers_schema = writers_schema
    write_header
  else
    # open writer for reading to collect metadata
    dfr = Reader.new(writer, Tros::IO::DatumReader.new)

    # FIXME(jmhodges): collect arbitrary metadata
    # collect metadata
    @sync_marker = dfr.sync_marker
    meta['tros.codec'] = dfr.meta['tros.codec']
    @codec = DataFile.get_codec(meta['tros.codec'])

    # get schema used to write existing file
    schema_from_file = dfr.meta['tros.schema']
    meta['tros.schema'] = schema_from_file
    datum_writer.writers_schema = Schema.parse(schema_from_file)

    # seek to the end of the file and prepare for writing
    writer.seek(0,2)
  end
end