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go/internal
Muir Manders 613a0345a2 internal/lsp/source: optimize enumeration of a type's fields
When searching for deep completions, we can end up enumerating struct
types' fields a lot. Optimize fieldSelections to reduce work:

- Wait until we see an embedded field before we create the "seen"
  map.
- Use a callback style to iterate over the struct's fields rather than
  returning a slice of fields.
- Change "seen" checking strategy back to track struct types rather
  than each individual field.

Struct with 5 non-embedded fields:

name       old time/op    new time/op    delta
Fields-16     293ns ± 1%      20ns ± 2%   -93.13%  (p=0.008 n=5+5)

name       old alloc/op   new alloc/op   delta
Fields-16      120B ± 0%        0B       -100.00%  (p=0.008 n=5+5)

name       old allocs/op  new allocs/op  delta
Fields-16      4.00 ± 0%      0.00       -100.00%  (p=0.008 n=5+5)

Same struct but add an embedded struct with 2 fields:

name       old time/op    new time/op    delta
Fields-16     389ns ± 1%     142ns ± 1%  -63.53%  (p=0.008 n=5+5)

name       old alloc/op   new alloc/op   delta
Fields-16      120B ± 0%      144B ± 0%  +20.00%  (p=0.008 n=5+5)

name       old allocs/op  new allocs/op  delta
Fields-16      4.00 ± 0%      2.00 ± 0%  -50.00%  (p=0.008 n=5+5)

I think the alloc/op went up because the "seen" map is no longer
allocated on the stack. There is more room for more optimization, but
it's probably not worth making things more complicated.

Change-Id: I6f9f2124334a8594ef9d6f9b5ac4b3a8aead5f49
Reviewed-on: https://go-review.googlesource.com/c/tools/+/223419
Run-TryBot: Muir Manders <muir@mnd.rs>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Rebecca Stambler <rstambler@golang.org>
2020-03-18 05:47:12 +00:00
..
apidiff
fastwalk internal/fastwalk: fix checkptr failure on Darwin 2020-02-27 19:33:42 +00:00
gocommand x/tools/gopls: run go generate through CodeLens 2020-03-17 04:34:34 +00:00
gopathwalk internal: rationalize debug logging 2020-03-03 16:59:18 +00:00
imports internal/imports: don't set a logger unless the user has provided it 2020-03-03 21:46:25 +00:00
jsonrpc2 internal/lsp/lsprpc: clean up client session on disconnection 2020-02-24 23:23:05 +00:00
lsp internal/lsp/source: optimize enumeration of a type's fields 2020-03-18 05:47:12 +00:00
memoize internal/lsp/debug: serve cache entry counts 2020-02-03 22:21:18 +00:00
packagesinternal internal/lsp: add module versions from "go list" to pkg.go.dev links 2020-02-19 19:55:21 +00:00
span internal/span: handle URI escaping better 2020-02-18 20:59:02 +00:00
telemetry internal/telemetry: split the ocagent tests from the support functions 2020-03-17 03:16:54 +00:00
testenv internal/testenv: reject the resolved 'go' command if it does not match runtime.GOROOT 2019-11-11 19:22:22 +00:00
tool internal/tool: avoid editorialization 2020-03-05 14:01:59 +00:00
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