fix(diagnostics): limit amount of diagnostics processed improving performance

[hinell]

bufferline.nvim/lua/bufferline/diagnostics.lua

Lines 80 to 90 in 655133c

	nvim_lsp = function()
	local results = {}
	local diagnostics = vim.diagnostic.get()
	for _, d in pairs(diagnostics) do
	if diagnostic_is_enabled(d) then
	if not results[d.bufnr] then results[d.bufnr] = {} end
	table.insert(results[d.bufnr], d)
	end
	end
	return results
	end,

The above chunk of code gets constantly evaluated in a loop with diagnostics.get(options) fetching multiple times the same array with evergrowing number of diagnostics that get added by LSP over time.
The table diagnostics is evaluated by for _, d in pairs(diagnostics) loop multiple times though diagnostics remain the same. This results in a degraded performance.

Replicate the issue

I've discovered accidentally a massive drop in performance while configuring lua-language-server (LLS) for nvim plugin project.

Checkout a small bash script down below that automatically sets up a project that replicates the issue. It opens commands.lua file which gets over 2500+ diagnostics (to check this out, you can debug the above chunk of code).

Make sure that LLS is installed and configured for your nvim, and
you have the latest bufferline.nvim and the following config setup:

	config = {}
	config.options.diagnostics  = "nvim_lsp"
	config.options.diagnostics_update_on_event = true
	bufferline.setup(config)

REPLICATE.sh

#!/usr/bin/env -S bash 

pushd $(mktemp -d -p /tmp project-XXXXXXXXX)
test -d ./lua/test/ && echo "exists: ${_}" || mkdir -vp $_
test -s ./lua/test/commands.lua || {
cat <<EOL > ./lua/test/commands.lua
vim.api.nvim_del_user_command("string")
vim.api.nvim_create_user_command() 
---@type vim.api.keyset.create_user_command.command_args
local someVar
EOL
}


test -s .luarc.json || {
cat <<EOL > .luarc.json
{
	"\$schema": "https://raw.githubusercontent.com/sumneko/vscode-lua/master/setting/schema.json",
	"runtime": {
		"version": "LuaJIT",
		"path": [
		]
	},
	"workspace": {
		"library": [
		"/usr/local/share/nvim/runtime/lua/vim/_meta.lua",
		"/usr/local/share/nvim/runtime/lua/vim/_meta/api.lua",
		"/usr/local/share/nvim/runtime/lua/vim/_meta/api_keysets.lua",
		"/usr/local/share/nvim/runtime/lua/vim/_meta/api_keysets_extra.lua",
		"/usr/local/share/nvim/runtime/lua/vim/_meta/base64.lua",
		"/usr/local/share/nvim/runtime/lua/vim/_meta/builtin.lua",
		"/usr/local/share/nvim/runtime/lua/vim/_meta/builtin_types.lua",
		"/usr/local/share/nvim/runtime/lua/vim/_meta/diff.lua",
		"/usr/local/share/nvim/runtime/lua/vim/_meta/lpeg.lua",
		"/usr/local/share/nvim/runtime/lua/vim/_meta/regex.lua",
		"/usr/local/share/nvim/runtime/lua/vim/_meta/vimfn.lua",
		"/usr/local/share/nvim/runtime/lua/vim/_meta/vvars.lua",
		"/usr/local/share/nvim/runtime/lua/vim/_meta/vvars_extra.lua",
		"/usr/local/share/nvim/runtime/lua/vim/_options.lua"
		],
		"checkThirdParty": false,
		"userThirdParty": []
	},
	"diagnostics": {
		"globals": [
		"vim"
		],
		"disable": [
		"unused-local",
		"unused-vararg"
		]
	},
	"format.enable": false
}
EOL

}

echo "${0}: running editor ${EDITOR}"
${EDITOR:-nvim} -p ./lua/test/commands.lua /usr/local/share/nvim/runtime/lua/vim/_meta/api_keysets.lua

Workaround

Just disable diagnostics in

	config.options.diagnostics = false
	bufferline.setup(config)

Related

• feat(diag): add diagnostics_update_on_event option #932