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go/internal
Muir Manders f0be937dca internal/lsp: speed up deep completion search
Optimize a few things to speed up deep completions:

- item() is slow, so don't call it unless the candidate's name matches
  the input.
- We only end up returning the top 3 deep candidates, so skip deep
  candidates early if they are not in the top 3 scores we have seen so
  far. This greatly reduces calls to item(), but also avoids a
  humongous sort in lsp/completion.go.
- Get rid of error return value from found(). Nothing checked for this
  error, and we spent a lot of time allocating the only possible error
  "this candidate is not accessible", which is not unexpected to begin
  with.
- Cache the call to types.NewMethodSet in methodsAndFields(). This is
  relatively expensive and can be called many times for the same type
  when searching for deep completions.
- Avoid calling deepState.chainString() twice by calling it once and
  storing the result on the candidate.

These optimizations sped up my slow completion from 1.5s to
0.5s. There were around 200k deep candidates examined for this one
completion. The remaining time is dominated by the fuzzy
matcher. Obviously 500ms is still unacceptable under any
circumstances, so there will be subsequent improvements to limit the
deep completion search scope to make sure we always return completions
in a reasonable amount of time.

I also made it so there is always a "matcher" set on the
completer. This makes the matching logic a bit simpler.

Change-Id: Id48ef7031ee1d4ea04515c828277384562b988a8
Reviewed-on: https://go-review.googlesource.com/c/tools/+/190522
Run-TryBot: Rebecca Stambler <rstambler@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Rebecca Stambler <rstambler@golang.org>
2019-08-20 18:51:39 +00:00
..
apidiff apidiff: represent a Report as a list of Changes 2019-04-22 23:39:26 +00:00
fastwalk internal/fastwalk: avoid slice bounds out of range for long file names 2018-11-12 23:16:31 +00:00
gopathwalk internal/gopathwalk: fix typo ("nonexistant" → "nonexistent") 2019-08-02 00:38:18 +00:00
imports internal/imports: get candidate imports 2019-08-16 16:26:37 +00:00
jsonrpc2 internal/lsp: use a background context for the background worker 2019-07-18 19:01:55 +00:00
lsp internal/lsp: speed up deep completion search 2019-08-20 18:51:39 +00:00
memoize internal/lsp: stop making background contexts everywhere 2019-07-11 16:38:52 +00:00
module imports: stop using go/packages for modules 2019-01-22 20:29:12 +00:00
semver go/packages: add name= query 2018-10-16 20:20:09 +00:00
span internal/span: handle character values beyond end of line in FromUTF16Column 2019-07-06 07:08:13 +00:00
telemetry internal/telemetry: change concurrency model 2019-08-20 03:27:56 +00:00
tool internal/tool: add a small package to unify the flag handling across all our tools 2018-12-17 23:08:00 +00:00
txtar imports: stop using go/packages for modules 2019-01-22 20:29:12 +00:00
xcontext internal/lsp: stop making background contexts everywhere 2019-07-11 16:38:52 +00:00