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perf(lsp): replace file polling on linux with per dir watcher (#26108)

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Should help with https://github.com/neovim/neovim/issues/23291

On linux `new_fs_event` doesn't support recursive watching, but we can
still use it to watch folders.

The downside of this approach is that we may end up sending some false
`Deleted` events. For example, if you save a file named `foo` there will
be a intermediate `foo~` due to the save mechanism of neovim.

The events we get from vim.uv in that case are:

- rename: foo~
- rename: foo~
- rename: foo
- rename: foo
- change: foo
- change: foo

The mechanism in this PR uses a debounce to reduce this to:

- deleted: foo~
- changed: foo

`foo~` will be the false positive.
I suspect that for the LSP case this is good enough. If not, we may need
to follow up on this and keep a table in memory that tracks available
files.
This commit is contained in:
Mathias Fußenegger 2023-11-19 14:25:32 +01:00 committed by GitHub
parent a84b454ebe
commit de28a0f84c
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GPG Key ID: 4AEE18F83AFDEB23
2 changed files with 128 additions and 145 deletions
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204
runtime/lua/vim/_watch.lua
View File

@ -1,11 +1,15 @@
local M = {}
local uv = vim.uv
--- Enumeration describing the types of events watchers will emit.
M.FileChangeType = vim.tbl_add_reverse_lookup({
---@enum vim._watch.FileChangeType
local FileChangeType = {
Created = 1,
Changed = 2,
Deleted = 3,
})
}
--- Enumeration describing the types of events watchers will emit.
M.FileChangeType = vim.tbl_add_reverse_lookup(FileChangeType)
--- Joins filepath elements by static '/' separator
---
@ -72,120 +76,120 @@ function M.watch(path, opts, callback)
end
end
local default_poll_interval_ms = 2000
--- @class watch.Watches
--- @field is_dir boolean
--- @field children? table<string,watch.Watches>
--- @field cancel? fun()
--- @field started? boolean
--- @field handle? uv.uv_fs_poll_t
--- @class watch.PollOpts
--- @field interval? integer
--- @field include_pattern? userdata
--- @field exclude_pattern? userdata
--- @field debounce? integer
--- @field include_pattern? vim.lpeg.Pattern
--- @field exclude_pattern? vim.lpeg.Pattern
--- Implementation for poll, hiding internally-used parameters.
---
---@param path string
---@param opts watch.PollOpts
---@param callback fun(patch: string, filechangetype: integer)
---@param watches (watch.Watches|nil) A tree structure to maintain state for recursive watches.
--- - handle (uv_fs_poll_t)
--- The libuv handle
--- - cancel (function)
--- A function that cancels the handle and all children's handles
--- - is_dir (boolean)
--- Indicates whether the path is a directory (and the poll should
--- be invoked recursively)
--- - children (table|nil)
--- A mapping of directory entry name to its recursive watches
--- - started (boolean|nil)
--- Whether or not the watcher has first been initialized. Used
--- to prevent a flood of Created events on startup.
---@return fun() Cancel function
local function poll_internal(path, opts, callback, watches)
path = vim.fs.normalize(path)
local interval = opts and opts.interval or default_poll_interval_ms
watches = watches or {
is_dir = true,
}
watches.cancel = function()
if watches.children then
for _, w in pairs(watches.children) do
w.cancel()
end
end
if watches.handle then
stop(watches.handle)
---@param callback function Called on new events
---@return function cancel stops the watcher
local function recurse_watch(path, opts, callback)
opts = opts or {}
local debounce = opts.debounce or 500
local uvflags = {}
---@type table<string, uv.uv_fs_event_t> handle by fullpath
local handles = {}
local timer = assert(uv.new_timer())
---@type table[]
local changesets = {}
local function is_included(filepath)
return opts.include_pattern and opts.include_pattern:match(filepath)
end
local function is_excluded(filepath)
return opts.exclude_pattern and opts.exclude_pattern:match(filepath)
end
local function incl_match()
return not opts.include_pattern or opts.include_pattern:match(path) ~= nil
end
local function excl_match()
return opts.exclude_pattern and opts.exclude_pattern:match(path) ~= nil
end
if not watches.is_dir and not incl_match() or excl_match() then
return watches.cancel
local process_changes = function()
assert(false, "Replaced later. I'm only here as forward reference")
end
if not watches.handle then
local poll, new_err = vim.uv.new_fs_poll()
assert(not new_err, new_err)
watches.handle = poll
local _, start_err = poll:start(
path,
interval,
vim.schedule_wrap(function(err)
if err == 'ENOENT' then
return
end
local function create_on_change(filepath)
return function(err, filename, events)
assert(not err, err)
poll_internal(path, opts, callback, watches)
callback(path, M.FileChangeType.Changed)
end)
)
assert(not start_err, start_err)
if watches.started then
callback(path, M.FileChangeType.Created)
local fullpath = vim.fs.joinpath(filepath, filename)
if is_included(fullpath) and not is_excluded(filepath) then
table.insert(changesets, {
fullpath = fullpath,
events = events,
})
timer:start(debounce, 0, process_changes)
end
end
end
if watches.is_dir then
watches.children = watches.children or {}
local exists = {} --- @type table<string,true>
for name, ftype in vim.fs.dir(path) do
exists[name] = true
if not watches.children[name] then
watches.children[name] = {
is_dir = ftype == 'directory',
started = watches.started,
}
poll_internal(filepath_join(path, name), opts, callback, watches.children[name])
process_changes = function()
---@type table<string, table[]>
local filechanges = vim.defaulttable()
for i, change in ipairs(changesets) do
changesets[i] = nil
if is_included(change.fullpath) and not is_excluded(change.fullpath) then
table.insert(filechanges[change.fullpath], change.events)
end
end
for fullpath, events_list in pairs(filechanges) do
local stat = uv.fs_stat(fullpath)
---@type vim._watch.FileChangeType
local change_type
if stat then
change_type = FileChangeType.Created
for _, event in ipairs(events_list) do
if event.change then
change_type = FileChangeType.Changed
end
end
if stat.type == 'directory' then
local handle = handles[fullpath]
if not handle then
handle = assert(uv.new_fs_event())
handles[fullpath] = handle
handle:start(fullpath, uvflags, create_on_change(fullpath))
end
end
local newchildren = {} ---@type table<string,watch.Watches>
for name, watch in pairs(watches.children) do
if exists[name] then
newchildren[name] = watch
else
watch.cancel()
watches.children[name] = nil
if watch.handle then
callback(path .. '/' .. name, M.FileChangeType.Deleted)
local handle = handles[fullpath]
if handle then
if not handle:is_closing() then
handle:close()
end
handles[fullpath] = nil
end
change_type = FileChangeType.Deleted
end
callback(fullpath, change_type)
end
end
end
watches.children = newchildren
end
local root_handle = assert(uv.new_fs_event())
handles[path] = root_handle
root_handle:start(path, uvflags, create_on_change(path))
watches.started = true
--- "640K ought to be enough for anyone"
--- Who has folders this deep?
local max_depth = 100
return watches.cancel
for name, type in vim.fs.dir(path, { depth = max_depth }) do
local filepath = vim.fs.joinpath(path, name)
if type == 'directory' and not is_excluded(filepath) then
local handle = assert(uv.new_fs_event())
handles[filepath] = handle
handle:start(filepath, uvflags, create_on_change(filepath))
end
end
local function cancel()
for fullpath, handle in pairs(handles) do
if not handle:is_closing() then
handle:close()
end
handles[fullpath] = nil
end
timer:stop()
timer:close()
end
return cancel
end
--- Initializes and starts a |uv_fs_poll_t| recursively watching every file underneath the
@ -193,8 +197,8 @@ end
---
---@param path (string) The path to watch. Must refer to a directory.
---@param opts (table|nil) Additional options
--- - interval (number|nil)
--- Polling interval in ms as passed to |uv.fs_poll_start()|. Defaults to 2000.
--- - debounce (number|nil)
--- Time events are debounced in ms. Defaults to 500
--- - include_pattern (LPeg pattern|nil)
--- An |lpeg| pattern. Only changes to files whose full paths match the pattern
--- will be reported. Only matches against non-directoriess, all directories will
@ -212,7 +216,7 @@ function M.poll(path, opts, callback)
opts = { opts, 'table', true },
callback = { callback, 'function', false },
})
return poll_internal(path, opts, callback, nil)
return recurse_watch(path, opts, callback)
end
return M

59
test/functional/lua/watch_spec.lua
View File

@ -108,26 +108,24 @@ describe('vim._watch', function()
local events = {}
local poll_interval_ms = 1000
local poll_wait_ms = poll_interval_ms+200
local debounce = 100
local wait_ms = debounce + 200
local expected_events = 0
local function wait_for_events()
assert(vim.wait(poll_wait_ms, function() return #events == expected_events end), 'Timed out waiting for expected number of events. Current events seen so far: ' .. vim.inspect(events))
assert(vim.wait(wait_ms, function() return #events == expected_events end), 'Timed out waiting for expected number of events. Current events seen so far: ' .. vim.inspect(events))
end
local incl = lpeg.P(root_dir) * lpeg.P("/file")^-1
local excl = lpeg.P(root_dir..'/file.unwatched')
local stop = vim._watch.poll(root_dir, {
interval = poll_interval_ms,
debounce = debounce,
include_pattern = incl,
exclude_pattern = excl,
}, function(path, change_type)
table.insert(events, { path = path, change_type = change_type })
end)
vim.wait(100)
local watched_path = root_dir .. '/file'
local watched, err = io.open(watched_path, 'w')
assert(not err, err)
@ -135,7 +133,7 @@ describe('vim._watch', function()
local unwatched, err = io.open(unwatched_path, 'w')
assert(not err, err)
expected_events = expected_events + 2
expected_events = expected_events + 1
wait_for_events()
watched:close()
@ -143,7 +141,7 @@ describe('vim._watch', function()
unwatched:close()
os.remove(unwatched_path)
expected_events = expected_events + 2
expected_events = expected_events + 1
wait_for_events()
stop()
@ -153,8 +151,6 @@ describe('vim._watch', function()
local watched, err = io.open(watched_path, 'w')
assert(not err, err)
vim.wait(poll_wait_ms)
watched:close()
os.remove(watched_path)
@ -163,36 +159,19 @@ describe('vim._watch', function()
root_dir
)
eq(4, #result)
eq({
change_type = exec_lua([[return vim._watch.FileChangeType.Created]]),
path = root_dir .. '/file',
}, result[1])
eq({
change_type = exec_lua([[return vim._watch.FileChangeType.Changed]]),
path = root_dir,
}, result[2])
-- The file delete and corresponding directory change events do not happen in any
-- particular order, so allow either
if result[3].path == root_dir then
eq({
change_type = exec_lua([[return vim._watch.FileChangeType.Changed]]),
path = root_dir,
}, result[3])
eq({
change_type = exec_lua([[return vim._watch.FileChangeType.Deleted]]),
path = root_dir .. '/file',
}, result[4])
else
eq({
change_type = exec_lua([[return vim._watch.FileChangeType.Deleted]]),
path = root_dir .. '/file',
}, result[3])
eq({
change_type = exec_lua([[return vim._watch.FileChangeType.Changed]]),
path = root_dir,
}, result[4])
end
local created = exec_lua([[return vim._watch.FileChangeType.Created]])
local deleted = exec_lua([[return vim._watch.FileChangeType.Deleted]])
local expected = {
{
change_type = created,
path = root_dir .. "/file",
},
{
change_type = deleted,
path = root_dir .. "/file",
}
}
eq(expected, result)
end)
end)
end)