mapped_struct.py 文件源码

def build(cls, initializer, destfile = None, tempdir = None, idmap = None):
        if destfile is None:
            destfile = tempfile.NamedTemporaryFile(dir = tempdir)

        initial_pos = destfile.tell()
        write = destfile.write
        write(cls._Header.pack(0, 0, 0))
        write(cls._NewHeader.pack(cls._CURRENT_VERSION, cls._CURRENT_MINIMUM_READER_VERSION, 0, 0))
        destfile.flush()
        data_pos = destfile.tell()
        schema = cls.schema
        _index = []
        index_parts = []
        for item in initializer:
            current_pos = data_pos - initial_pos
            _index.append(current_pos)
            buf = schema.pack(item, idmap, None, None, current_pos)
            write(buf)
            data_pos += len(buf)
            if len(_index) >= 100000:
                index_parts.append(numpy.array(_index, dtype = numpy.uint64))
                del _index[:]
        destfile.flush()
        index_pos = destfile.tell()
        if _index:
            index_parts.append(numpy.array(_index, dtype = numpy.uint64))
            del _index
        if len(index_parts) > 1:
            index = numpy.concatenate(index_parts)
        elif index_parts:
            index = index_parts[0]
        else:
            index = numpy.array([], dtype = numpy.uint64)
        del index_parts
        write(buffer(index))
        destfile.flush()

        schema_pos = destfile.tell()
        cPickle.dump(schema, destfile, 2)
        destfile.flush()

        final_pos = destfile.tell()
        destfile.seek(initial_pos)
        write(cls._Header.pack(final_pos - initial_pos, index_pos - initial_pos, len(index)))
        write(cls._NewHeader.pack(
            cls._CURRENT_VERSION, cls._CURRENT_MINIMUM_READER_VERSION,
            schema_pos - initial_pos, final_pos - schema_pos))
        destfile.flush()
        destfile.seek(final_pos)
        return cls.map_file(destfile, initial_pos)