class type record_reader_factory =object..end
method read_file : read_flag list ->
Mapred_fs.filesystem ->
Plasma_shm.shm_manager ->
record_config ->
string -> int64 -> int64 -> record_readerread_file flags fs rc name block len: Reads from name, starting at
block, ending at block+len-1 (plus the following overflow region).
Reading is done in a separate transaction.
Note that len>=1 is a requirement here.
If block=0 (or the `Process_first_record flag is given), the first
record of the selected file
region is returned to the user. If block>0 (or the
`Skip_first_record flag is set),
the first record is skipped, i.e. reading starts after the first
encountered record separator.
Reading continues past the last block if the last record does not
terminate within the block. The maximum record length is the size
of a bigblock (including the separator), so read_file will at most
read the bigblock following the last selected block.
Reading always stops if the real EOF of the file is reached, or
the position given with the `Eof option (whatever comes first).
It is not required that block or len are multiples of bigblocks,
although this is usually the case.
