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use Result;
use DocId;
use std::io;
use schema::Schema;
use schema::Term;
use core::Segment;
use core::SerializableSegment;
use fastfield::FastFieldsWriter;
use schema::Field;
use schema::FieldValue;
use schema::FieldType;
use indexer::segment_serializer::SegmentSerializer;
use datastruct::stacker::Heap;
use indexer::index_writer::MARGIN_IN_BYTES;
use super::operation::AddOperation;
use postings::MultiFieldPostingsWriter;
/// A `SegmentWriter` is in charge of creating segment index from a
/// documents.
///
/// They creates the postings list in anonymous memory.
/// The segment is layed on disk when the segment gets `finalized`.
pub struct SegmentWriter<'a> {
heap: &'a Heap,
max_doc: DocId,
multifield_postings: MultiFieldPostingsWriter<'a>,
segment_serializer: SegmentSerializer,
fast_field_writers: FastFieldsWriter,
fieldnorms_writer: FastFieldsWriter,
doc_opstamps: Vec<u64>,
}
fn create_fieldnorms_writer(schema: &Schema) -> FastFieldsWriter {
let u64_fields: Vec<Field> = schema
.fields()
.iter()
.enumerate()
.filter(|&(_, field_entry)| field_entry.is_indexed())
.map(|(field_id, _)| Field(field_id as u32))
.collect();
FastFieldsWriter::new(u64_fields)
}
impl<'a> SegmentWriter<'a> {
/// Creates a new `SegmentWriter`
///
/// The arguments are defined as follows
///
/// - heap: most of the segment writer data (terms, and postings lists recorders)
/// is stored in a user-defined heap object. This makes it possible for the user to define
/// the flushing behavior as a buffer limit
/// - segment: The segment being written
/// - schema
pub fn for_segment(heap: &'a Heap,
mut segment: Segment,
schema: &Schema)
-> Result<SegmentWriter<'a>> {
let segment_serializer = try!(SegmentSerializer::for_segment(&mut segment));
let multifield_postings = MultiFieldPostingsWriter::new(schema, heap);
Ok(SegmentWriter {
heap: heap,
max_doc: 0,
multifield_postings: multifield_postings,
fieldnorms_writer: create_fieldnorms_writer(schema),
segment_serializer: segment_serializer,
fast_field_writers: FastFieldsWriter::from_schema(schema),
doc_opstamps: Vec::with_capacity(1_000),
})
}
/// Lay on disk the current content of the `SegmentWriter`
///
/// Finalize consumes the `SegmentWriter`, so that it cannot
/// be used afterwards.
pub fn finalize(self) -> Result<Vec<u64>> {
write(&self.multifield_postings,
&self.fast_field_writers,
&self.fieldnorms_writer,
self.segment_serializer)?;
Ok(self.doc_opstamps)
}
/// Returns true iff the segment writer's buffer has reached capacity.
///
/// The limit is defined as `the user defined heap size - an arbitrary margin of 10MB`
/// The `Segment` is `finalize`d when the buffer gets full.
///
/// Because, we cannot cut through a document, the margin is there to ensure that we rarely
/// exceeds the heap size.
pub fn is_buffer_full(&self) -> bool {
self.heap.num_free_bytes() <= MARGIN_IN_BYTES
}
/// Return true if the term dictionary hashmap is reaching capacity.
/// It is one of the condition that triggers a `SegmentWriter` to
/// be finalized.
pub(crate) fn is_term_saturated(&self) -> bool {
self.multifield_postings.is_term_saturated()
}
/// Indexes a new document
///
/// As a user, you should rather use `IndexWriter`'s add_document.
pub fn add_document(&mut self,
add_operation: &AddOperation,
schema: &Schema)
-> io::Result<()> {
let doc_id = self.max_doc;
let doc = &add_operation.document;
self.doc_opstamps.push(add_operation.opstamp);
for (field, field_values) in doc.get_sorted_field_values() {
let field_options = schema.get_field_entry(field);
match *field_options.field_type() {
FieldType::Str(ref text_options) => {
let num_tokens: u32 = if text_options.get_indexing_options().is_tokenized() {
self.multifield_postings
.index_text(doc_id, field, &field_values)
} else {
let num_field_values = field_values.len() as u32;
for field_value in field_values {
let term = Term::from_field_text(field, field_value.value().text());
self.multifield_postings.suscribe(doc_id, &term);
}
num_field_values
};
self.fieldnorms_writer
.get_field_writer(field)
.map(|field_norms_writer| field_norms_writer.add_val(num_tokens as u64));
}
FieldType::U64(ref int_option) => {
if int_option.is_indexed() {
for field_value in field_values {
let term = Term::from_field_u64(field_value.field(),
field_value.value().u64_value());
self.multifield_postings.suscribe(doc_id, &term);
}
}
}
FieldType::I64(ref int_option) => {
if int_option.is_indexed() {
for field_value in field_values {
let term = Term::from_field_i64(field_value.field(),
field_value.value().i64_value());
self.multifield_postings.suscribe(doc_id, &term);
}
}
}
}
}
self.fieldnorms_writer.fill_val_up_to(doc_id);
self.fast_field_writers.add_document(doc);
let stored_fieldvalues: Vec<&FieldValue> = doc.field_values()
.iter()
.filter(|field_value| schema.get_field_entry(field_value.field()).is_stored())
.collect();
let doc_writer = self.segment_serializer.get_store_writer();
try!(doc_writer.store(&stored_fieldvalues));
self.max_doc += 1;
Ok(())
}
/// Max doc is
/// - the number of documents in the segment assuming there is no deletes
/// - the maximum document id (including deleted documents) + 1
///
/// Currently, **tantivy** does not handle deletes anyway,
/// so `max_doc == num_docs`
pub fn max_doc(&self) -> u32 {
self.max_doc
}
/// Number of documents in the index.
/// Deleted documents are not counted.
///
/// Currently, **tantivy** does not handle deletes anyway,
/// so `max_doc == num_docs`
#[allow(dead_code)]
pub fn num_docs(&self) -> u32 {
self.max_doc
}
}
// This method is used as a trick to workaround the borrow checker
fn write(multifield_postings: &MultiFieldPostingsWriter,
fast_field_writers: &FastFieldsWriter,
fieldnorms_writer: &FastFieldsWriter,
mut serializer: SegmentSerializer)
-> Result<()> {
try!(multifield_postings.serialize(serializer.get_postings_serializer()));
try!(fast_field_writers.serialize(serializer.get_fast_field_serializer()));
try!(fieldnorms_writer.serialize(serializer.get_fieldnorms_serializer()));
try!(serializer.close());
Ok(())
}
impl<'a> SerializableSegment for SegmentWriter<'a> {
fn write(&self, serializer: SegmentSerializer) -> Result<u32> {
let max_doc = self.max_doc;
write(&self.multifield_postings,
&self.fast_field_writers,
&self.fieldnorms_writer,
serializer)?;
Ok(max_doc)
}
}
|
