Files
tantivy/src/core/codec.rs
2016-02-23 23:02:40 +09:00

104 lines
3.4 KiB
Rust

use core::serial::*;
use std::io::Write;
use fst::MapBuilder;
use std::io::Error as IOError;
use std::io::ErrorKind as IOErrorKind;
use byteorder::{BigEndian, WriteBytesExt};
use core::directory::Segment;
use core::directory::SegmentComponent;
use core::schema::Term;
use core::schema::DocId;
use core::store::StoreWriter;
use std::fs::File;
use fst;
use core::simdcompression;
use std::convert::From;
use core::schema::FieldValue;
pub struct SimpleCodec;
pub struct SimpleSegmentSerializer {
segment: Segment,
written_bytes_postings: usize,
postings_write: File,
store_writer: StoreWriter,
term_fst_builder: MapBuilder<File>, // TODO find an alternative to work around the "move"
cur_term_num_docs: DocId,
encoder: simdcompression::Encoder,
}
fn convert_fst_error(e: fst::Error) -> IOError {
IOError::new(IOErrorKind::Other, e)
}
impl SimpleSegmentSerializer {
pub fn segment(&self,) -> Segment {
self.segment.clone()
}
}
impl SegmentSerializer<()> for SimpleSegmentSerializer {
fn store_doc(&mut self, field_values_it: &mut Iterator<Item=&FieldValue>) {
let field_values: Vec<&FieldValue> = field_values_it.collect();
self.store_writer.store(&field_values);
}
fn new_term(&mut self, term: &Term, doc_freq: DocId) -> Result<(), IOError> {
self.term_fst_builder.insert(term.as_slice(), self.written_bytes_postings as u64);
self.cur_term_num_docs = doc_freq;
// writing the size of the posting list
try!(self.postings_write.write_u32::<BigEndian>(doc_freq));
self.written_bytes_postings += 4;
Ok(())
}
fn write_docs(&mut self, doc_ids: &[DocId]) -> Result<(), IOError> {
// TODO write_all transmuted [u8]
let docs_data = self.encoder.encode(doc_ids);
try!(self.postings_write.write_u32::<BigEndian>(docs_data.len() as u32));
self.written_bytes_postings += 4;
for num in docs_data {
try!(self.postings_write.write_u32::<BigEndian>(num.clone() as u32));
}
Ok(())
}
fn close(mut self,) -> Result<(), IOError> {
// TODO handle errors on close
try!(self.term_fst_builder
.finish()
.map_err(convert_fst_error));
self.store_writer.close()
}
}
impl SimpleCodec {
// TODO impl packed int
// TODO skip lists
// TODO make that part of the codec API
pub fn serializer(segment: &Segment) -> Result<SimpleSegmentSerializer, IOError> {
let term_write = try!(segment.open_writable(SegmentComponent::TERMS));
let postings_write = try!(segment.open_writable(SegmentComponent::POSTINGS));
let store_write = try!(segment.open_writable(SegmentComponent::STORE));
let term_fst_builder_result = MapBuilder::new(term_write);
let term_fst_builder = term_fst_builder_result.unwrap();
Ok(SimpleSegmentSerializer {
segment: segment.clone(),
written_bytes_postings: 0,
postings_write: postings_write,
store_writer: StoreWriter::new(store_write),
term_fst_builder: term_fst_builder,
cur_term_num_docs: 0,
encoder: simdcompression::Encoder::new(),
})
}
pub fn write<I: SerializableSegment>(index: &I, segment: &Segment) -> Result<(), IOError> {
let mut serializer = try!(SimpleCodec::serializer(segment));
index.write(&mut serializer)
}
}