commit 15a2ab852e19848ec9846e071e4ff9e41fe52022
author Muir Manders <muir@mnd.rs> Thu May 27 13:44:56 2021 -0700
committer Rebecca Stambler <rstambler@golang.org> Thu Aug 12 17:14:32 2021 +0000
tree 21a5b8ef1c7b31958bf173a6a708794258c5bbd5
parent 749a5cd4ad9dc3bd0ee058c54ff1632491dc4da9

lsp/completion: reduce garbage searching for candidates

Tweak a few things to reduce garbage:
- Pre-allocate a couple hot error objects in format.go.
- Change methodsAndFields and packageMembers to take a callback
  instead of returning a slice.
- Use two queues for breadth first search. This allows us to alternate
  between and reuse the queues for each search level instead of
  appending to a single queue indefinitely with no reuse.
- Get rid of candidate.names field. This tracked the string name of
  each object in the deep completion path. Unlike with DFS before,
  due to BFS this has to be copied for every candidate we inspect. Now
  we get the object names from each types.Object in candidate.path,
  with the addition of a new bitmask field to remember whether each
  object needs "()" appended to it.

Using TestBenchmarkFuncDeepCompletion as a benchmark:

name        old time/op    new time/op    delta
Statistics    14.2ms ± 7%    10.3ms ± 1%  -27.41%  (p=0.016 n=5+4)

name        old alloc/op   new alloc/op   delta
Statistics    4.31MB ± 1%    3.03MB ± 0%  -29.60%  (p=0.016 n=5+4)

name        old allocs/op  new allocs/op  delta
Statistics     52.7k ± 1%     44.0k ± 5%  -16.52%  (p=0.008 n=5+5)

Change-Id: I52f619d9a2e8553115be91f05cf8cc5cfa89123e
Reviewed-on: https://go-review.googlesource.com/c/tools/+/323252
Reviewed-by: Rebecca Stambler <rstambler@golang.org>
Trust: Rebecca Stambler <rstambler@golang.org>
Trust: Robert Findley <rfindley@google.com>
Run-TryBot: Rebecca Stambler <rstambler@golang.org>
gopls-CI: kokoro <noreply+kokoro@google.com>
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