File BlockInvertedLists.h

namespace faiss

Implementation of k-means clustering with many variants.

Copyright (c) Facebook, Inc. and its affiliates.

This source code is licensed under the MIT license found in the LICENSE file in the root directory of this source tree.

IDSelector is intended to define a subset of vectors to handle (for removal or as subset to search)

PQ4 SIMD packing and accumulation functions

The basic kernel accumulates nq query vectors with bbs = nb * 2 * 16 vectors and produces an output matrix for that. It is interesting for nq * nb <= 4, otherwise register spilling becomes too large.

The implementation of these functions is spread over 3 cpp files to reduce parallel compile times. Templates are instantiated explicitly.

This file contains callbacks for kernels that compute distances.

Throughout the library, vectors are provided as float * pointers. Most algorithms can be optimized when several vectors are processed (added/searched) together in a batch. In this case, they are passed in as a matrix. When n vectors of size d are provided as float * x, component j of vector i is

x[ i * d + j ]

where 0 <= i < n and 0 <= j < d. In other words, matrices are always compact. When specifying the size of the matrix, we call it an n*d matrix, which implies a row-major storage.

I/O functions can read/write to a filename, a file handle or to an object that abstracts the medium.

The read functions return objects that should be deallocated with delete. All references within these objectes are owned by the object.

Definition of inverted lists + a few common classes that implement the interface.

Since IVF (inverted file) indexes are of so much use for large-scale use cases, we group a few functions related to them in this small library. Most functions work both on IndexIVFs and IndexIVFs embedded within an IndexPreTransform.

In this file are the implementations of extra metrics beyond L2 and inner product

Implements a few neural net layers, mainly to support QINCo

Defines a few objects that apply transformations to a set of vectors Often these are pre-processing steps.

struct BlockInvertedLists : public faiss::InvertedLists
#include <BlockInvertedLists.h>

Inverted Lists that are organized by blocks.

Different from the regular inverted lists, the codes are organized by blocks of size block_size bytes that reprsent a set of n_per_block. Therefore, code allocations are always rounded up to block_size bytes. The codes are also aligned on 32-byte boundaries for use with SIMD.

To avoid misinterpretations, the code_size is set to (size_t)(-1), even if arguably the amount of memory consumed by code is block_size / n_per_block.

The writing functions add_entries and update_entries operate on block-aligned data.

Public Functions

BlockInvertedLists(size_t nlist, size_t vec_per_block, size_t block_size)
BlockInvertedLists(size_t nlist, const CodePacker *packer)
BlockInvertedLists()
virtual size_t list_size(size_t list_no) const override

get the size of a list

virtual const uint8_t *get_codes(size_t list_no) const override

get the codes for an inverted list must be released by release_codes

Returns:

codes size list_size * code_size

virtual const idx_t *get_ids(size_t list_no) const override

get the ids for an inverted list must be released by release_ids

Returns:

ids size list_size

size_t remove_ids(const IDSelector &sel)

remove ids from the InvertedLists

virtual size_t add_entries(size_t list_no, size_t n_entry, const idx_t *ids, const uint8_t *code) override
virtual void update_entries(size_t list_no, size_t offset, size_t n_entry, const idx_t *ids, const uint8_t *code) override

not implemented

virtual void resize(size_t list_no, size_t new_size) override
~BlockInvertedLists() override

Public Members

size_t n_per_block = 0
size_t block_size = 0
const CodePacker *packer = nullptr
std::vector<AlignedTable<uint8_t>> codes
std::vector<std::vector<idx_t>> ids
struct BlockInvertedListsIOHook : public faiss::InvertedListsIOHook

Public Functions

BlockInvertedListsIOHook()
virtual void write(const InvertedLists *ils, IOWriter *f) const override

write the index to the IOWriter (including the fourcc)

virtual InvertedLists *read(IOReader *f, int io_flags) const override

called when the fourcc matches this class’s fourcc