Optimize Snacks.util.bo with buffer option caching to improve file picker performance

Co-authored-by: spenrose <481185+spenrose@users.noreply.github.com>

lua/snacks/util/init.lua

@@ -11,6 +11,10 @@ local uv = vim.uv or vim.loop
 local key_cache = {} ---@type table<string, string>
 local langs = {} ---@type table<string, boolean>
 
+-- Cache for buffer options to avoid redundant API calls
+local buf_options_cache = {} ---@type table<number, table<string, any>>
+local buf_cache_autocmd_id = nil
+
 ---@alias snacks.util.hl table<string, string|vim.api.keyset.highlight>
 
 local hl_groups = {} ---@type table<string, vim.api.keyset.highlight>
@@ -89,8 +93,49 @@ end
 ---@param buf number
 ---@param bo vim.bo|{}
 function M.bo(buf, bo)
-  for k, v in pairs(bo or {}) do
-    vim.api.nvim_set_option_value(k, v, { buf = buf })
+  if not bo or not next(bo) then
+    return
+  end
+
+  -- Ensure buffer is valid
+  if not vim.api.nvim_buf_is_valid(buf) then
+    -- Clean up cache for invalid buffer
+    buf_options_cache[buf] = nil
+    return
+  end
+
+  -- Initialize cache for this buffer if not exists
+  if not buf_options_cache[buf] then
+    buf_options_cache[buf] = {}
+  end
+
+  local cache = buf_options_cache[buf]
+
+  for k, v in pairs(bo) do
+    -- Only set option if value has changed
+    if cache[k] ~= v then
+      local ok, err = pcall(vim.api.nvim_set_option_value, k, v, { buf = buf })
+      if ok then
+        cache[k] = v
+      else
+        -- If setting option failed, don't cache the value
+        -- This ensures we'll try again next time
+        cache[k] = nil
+      end
+    end
+  end
+
+  -- Setup autocmd to clean up cache when buffers are deleted (only once)
+  if not buf_cache_autocmd_id then
+    buf_cache_autocmd_id = vim.api.nvim_create_autocmd("BufDelete", {
+      group = vim.api.nvim_create_augroup("snacks_util_buf_cache", { clear = true }),
+      callback = function(args)
+        local deleted_buf = args.buf
+        if buf_options_cache[deleted_buf] then
+          buf_options_cache[deleted_buf] = nil
+        end
+      end,
+    })
   end
 end
 

tests/util_spec.lua

@@ -37,3 +37,110 @@ describe("util.normkey", function()
     end)
   end
 end)
+
+describe("util.bo", function()
+  local util = require("snacks.util")
+
+  -- Helper to count actual API calls by mocking vim.api.nvim_set_option_value
+  local api_call_count = 0
+  local original_set_option = vim.api.nvim_set_option_value
+
+  before_each(function()
+    api_call_count = 0
+    vim.api.nvim_set_option_value = function(...)
+      api_call_count = api_call_count + 1
+      return original_set_option(...)
+    end
+  end)
+
+  after_each(function()
+    vim.api.nvim_set_option_value = original_set_option
+  end)
+
+  it("should set buffer options correctly", function()
+    local buf = vim.api.nvim_create_buf(false, true)
+    util.bo(buf, { buftype = "nofile", filetype = "lua" })
+
+    -- Verify options were set
+    assert.are.equal("nofile", vim.api.nvim_get_option_value("buftype", { buf = buf }))
+    assert.are.equal("lua", vim.api.nvim_get_option_value("filetype", { buf = buf }))
+    assert.are.equal(2, api_call_count)
+
+    vim.api.nvim_buf_delete(buf, { force = true })
+  end)
+
+  it("should cache options and avoid redundant API calls", function()
+    local buf = vim.api.nvim_create_buf(false, true)
+
+    -- First call should set options
+    util.bo(buf, { buftype = "nofile", filetype = "lua" })
+    assert.are.equal(2, api_call_count)
+
+    -- Second call with same options should not call API
+    api_call_count = 0
+    util.bo(buf, { buftype = "nofile", filetype = "lua" })
+    assert.are.equal(0, api_call_count)
+
+    vim.api.nvim_buf_delete(buf, { force = true })
+  end)
+
+  it("should detect changes and update only changed options", function()
+    local buf = vim.api.nvim_create_buf(false, true)
+
+    -- Set initial options
+    util.bo(buf, { buftype = "nofile", filetype = "lua" })
+    assert.are.equal(2, api_call_count)
+
+    -- Change only one option
+    api_call_count = 0
+    util.bo(buf, { buftype = "nofile", filetype = "javascript" })
+    assert.are.equal(1, api_call_count) -- Only filetype should be updated
+
+    vim.api.nvim_buf_delete(buf, { force = true })
+  end)
+
+  it("should handle empty or nil options", function()
+    local buf = vim.api.nvim_create_buf(false, true)
+
+    -- Should handle nil options
+    util.bo(buf, nil)
+    assert.are.equal(0, api_call_count)
+
+    -- Should handle empty table
+    util.bo(buf, {})
+    assert.are.equal(0, api_call_count)
+
+    vim.api.nvim_buf_delete(buf, { force = true })
+  end)
+
+  it("should handle invalid buffers gracefully", function()
+    local buf = vim.api.nvim_create_buf(false, true)
+    vim.api.nvim_buf_delete(buf, { force = true })
+
+    -- Should not error with invalid buffer
+    util.bo(buf, { buftype = "nofile" })
+    assert.are.equal(0, api_call_count)
+  end)
+
+  it("should clean up cache when buffer is deleted", function()
+    local buf = vim.api.nvim_create_buf(false, true)
+
+    -- Set options to populate cache
+    util.bo(buf, { buftype = "nofile" })
+    assert.are.equal(1, api_call_count)
+
+    -- Delete buffer (this should trigger cache cleanup via autocmd)
+    vim.api.nvim_buf_delete(buf, { force = true })
+
+    -- Processing autocmds
+    vim.api.nvim_exec_autocmds("BufDelete", { buffer = buf })
+
+    -- Create new buffer with same ID shouldn't use old cache
+    local new_buf = vim.api.nvim_create_buf(false, true)
+    api_call_count = 0
+    util.bo(new_buf, { buftype = "nofile" })
+    assert.are.equal(1, api_call_count) -- Should call API, not use cache
+
+    vim.api.nvim_buf_delete(new_buf, { force = true })
+  end)
+end)