MeiliSearch/milli/src/update/word_prefix_docids.rs

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4.5 KiB
Rust
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use std::collections::HashMap;
use fst::IntoStreamer;
use grenad::{CompressionType, MergerBuilder};
use slice_group_by::GroupBy;
use crate::update::index_documents::{
create_sorter, fst_stream_into_hashset, merge_roaring_bitmaps, sorter_into_lmdb_database,
CursorClonableMmap, MergeFn, WriteMethod,
};
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use crate::{Index, Result};
pub struct WordPrefixDocids<'t, 'u, 'i> {
wtxn: &'t mut heed::RwTxn<'i, 'u>,
index: &'i Index,
pub(crate) chunk_compression_type: CompressionType,
pub(crate) chunk_compression_level: Option<u32>,
pub(crate) max_nb_chunks: Option<usize>,
pub(crate) max_memory: Option<usize>,
}
impl<'t, 'u, 'i> WordPrefixDocids<'t, 'u, 'i> {
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pub fn new(
wtxn: &'t mut heed::RwTxn<'i, 'u>,
index: &'i Index,
) -> WordPrefixDocids<'t, 'u, 'i> {
WordPrefixDocids {
wtxn,
index,
chunk_compression_type: CompressionType::None,
chunk_compression_level: None,
max_nb_chunks: None,
max_memory: None,
}
}
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#[logging_timer::time("WordPrefixDocids::{}")]
pub fn execute<A: AsRef<[u8]>>(
self,
new_word_docids: Vec<grenad::Reader<CursorClonableMmap>>,
old_prefix_fst: &fst::Set<A>,
) -> Result<()> {
let prefix_fst = self.index.words_prefixes_fst(self.wtxn)?;
let prefix_fst_keys = prefix_fst.into_stream().into_strs()?;
let prefix_fst_keys: Vec<_> =
prefix_fst_keys.as_slice().linear_group_by_key(|x| x.chars().nth(0).unwrap()).collect();
// We compute the set of prefixes that are no more part of the prefix fst.
let suppr_pw = fst_stream_into_hashset(old_prefix_fst.op().add(&prefix_fst).difference());
// It is forbidden to keep a mutable reference into the database
// and write into it at the same time, therefore we write into another file.
let mut prefix_docids_sorter = create_sorter(
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merge_roaring_bitmaps,
self.chunk_compression_type,
self.chunk_compression_level,
self.max_nb_chunks,
self.max_memory,
);
let mut word_docids_merger = MergerBuilder::new(merge_roaring_bitmaps);
word_docids_merger.extend(new_word_docids);
let mut word_docids_iter = word_docids_merger.build().into_merger_iter()?;
let mut current_prefixes: Option<&&[String]> = None;
let mut prefixes_cache = HashMap::new();
while let Some((word, data)) = word_docids_iter.next()? {
current_prefixes = match current_prefixes.take() {
Some(prefixes) if word.starts_with(&prefixes[0].as_bytes()) => Some(prefixes),
_otherwise => {
write_prefixes_in_sorter(&mut prefixes_cache, &mut prefix_docids_sorter)?;
prefix_fst_keys
.iter()
.find(|prefixes| word.starts_with(&prefixes[0].as_bytes()))
}
};
if let Some(prefixes) = current_prefixes {
for prefix in prefixes.iter() {
if word.starts_with(prefix.as_bytes()) {
match prefixes_cache.get_mut(prefix.as_bytes()) {
Some(value) => value.push(data.to_owned()),
None => {
prefixes_cache.insert(prefix.clone().into(), vec![data.to_owned()]);
}
}
}
}
}
}
// We remove all the entries that are no more required in this word prefix docids database.
let mut iter = self.index.word_prefix_docids.iter_mut(self.wtxn)?.lazily_decode_data();
while let Some((prefix, _)) = iter.next().transpose()? {
if suppr_pw.contains(prefix.as_bytes()) {
unsafe { iter.del_current()? };
}
}
drop(iter);
// We finally write the word prefix docids into the LMDB database.
sorter_into_lmdb_database(
self.wtxn,
*self.index.word_prefix_docids.as_polymorph(),
prefix_docids_sorter,
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merge_roaring_bitmaps,
WriteMethod::GetMergePut,
)?;
Ok(())
}
}
fn write_prefixes_in_sorter(
prefixes: &mut HashMap<Vec<u8>, Vec<Vec<u8>>>,
sorter: &mut grenad::Sorter<MergeFn>,
) -> Result<()> {
for (key, data_slices) in prefixes.drain() {
for data in data_slices {
sorter.insert(&key, data)?;
}
}
Ok(())
}