This patch is a proof-of-concept Dex index implementation. It has
several flaws, which don't allow replacing static MemIndex yet, such as:
* Not being able to handle queries of small size (less than 3 symbols);
a way to solve this is generating trigrams of smaller size and having
such incomplete trigrams in the index structure.
* Speed measurements: while manually editing files in Vim and requesting
autocompletion gives an impression that the performance is at least
comparable with the current static index, having actual numbers is
important because we don't want to hurt the users and roll out slow
code. Eric (@ioeric) suggested that we should only replace MemIndex as
soon as we have the evidence that this is not a regression in terms of
performance. An approach which is likely to be successful here is to
wait until we have benchmark library in the LLVM core repository, which
is something I have suggested in the LLVM mailing lists, received
positive feedback on and started working on. I will add a dependency as
soon as the suggested patch is out for a review (currently there's at
least one complication which is being addressed by
https://github.com/google/benchmark/pull/649). Key performance
improvements for iterators are sorting by cost and the limit iterator.
* Quality measurements: currently, boosting iterator and two-phase
lookup stage are not implemented, without these the quality is likely to
be worse than the current implementation can yield. Measuring quality is
tricky, but another suggestion in the offline discussion was that the
drop-in replacement should only happen after Boosting iterators
implementation (and subsequent query enhancement).
The proposed changes do not affect Clangd functionality or performance,
`DexIndex` is only used in unit tests and not in production code.
Reviewed by: ioeric
Differential Revision: https://reviews.llvm.org/D50337
llvm-svn: 340175
This patch introduces the core building block of the next-generation
Clangd symbol index - Dex. Search tokens are the keys in the inverted
index and represent a characteristic of a specific symbol: examples of
search token types (Token Namespaces) are
* Trigrams - these are essential for unqualified symbol name fuzzy
search * Scopes for filtering the symbols by the namespace * Paths, e.g.
these can be used to uprank symbols defined close to the edited file
This patch outlines the generic for such token namespaces, but only
implements trigram generation.
The intuition behind trigram generation algorithm is that each extracted
trigram is a valid sequence for Fuzzy Matcher jumps, proposed
implementation utilize existing FuzzyMatcher API for segmentation and
trigram extraction.
However, trigrams generation algorithm for the query string is different
from the previous one: it simply yields sequences of 3 consecutive
lowercased valid characters (letters, digits).
Dex RFC in the mailing list:
http://lists.llvm.org/pipermail/clangd-dev/2018-July/000022.html
The trigram generation techniques are described in detail in the
proposal:
https://docs.google.com/document/d/1C-A6PGT6TynyaX4PXyExNMiGmJ2jL1UwV91Kyx11gOI/edit#heading=h.903u1zon9nkj
Reviewers: sammccall, ioeric, ilya-biryukovA
Subscribers: cfe-commits, klimek, mgorny, MaskRay, jkorous, arphaman
Differential Revision: https://reviews.llvm.org/D49591
llvm-svn: 337901
Kirill Bobyrev