add performance.filtering_context_budget

fixes #2060

doc/cmp.txt

@@ -456,6 +456,12 @@ performance.fetching_timeout~
     Sets the timeout of candidate fetching process.
     The nvim-cmp will wait to display the most prioritized source.
 
+                                *cmp-config.performance.filtering_context_budget*
+performance.filtering_context_budget~
+    `number`
+    Sets the filtering context budget in ms.
+    If filtering takes longer than this, it will be deferred.
+
                                  *cmp-config.performance.confirm_resolve_timeout*
 performance.confirm_resolve_timeout~
     `number`

lua/cmp/config/default.lua

@@ -19,6 +19,7 @@ return function()
       debounce = 60,
       throttle = 30,
       fetching_timeout = 500,
+      filtering_context_budget = 3,
       confirm_resolve_timeout = 80,
       async_budget = 1,
       max_view_entries = 200,

lua/cmp/source.lua

@@ -61,7 +61,8 @@ source.reset = function(self)
   self.request_offset = -1
   self.completion_context = nil
   self.status = source.SourceStatus.WAITING
-  self.complete_dedup(function() end)
+  self.complete_dedup(function()
+  end)
 end
 
 ---Return source config
@@ -111,6 +112,9 @@ source.get_entries = function(self, ctx)
   ---@type cmp.Entry[]
   local entries = {}
   local matching_config = self:get_matching_config()
+  local filtering_context_budget = config.get().performance.filtering_context_budget / 1000
+
+  local s = os.clock()
   for _, e in ipairs(target_entries) do
     local o = e.offset
     if not inputs[o] then
@@ -128,10 +132,14 @@ source.get_entries = function(self, ctx)
         entries[#entries + 1] = e
       end
     end
+
+    if os.clock() - s > filtering_context_budget then
       async.yield()
       if ctx.aborted then
         async.abort()
       end
+      s = os.clock()
+    end
   end
 
   if not self.incomplete then

lua/cmp/types/cmp.lua

@@ -103,6 +103,7 @@ cmp.ItemField = {
 ---@field public debounce integer
 ---@field public throttle integer
 ---@field public fetching_timeout integer
+---@field public filtering_context_budget integer
 ---@field public confirm_resolve_timeout integer
 ---@field public async_budget integer Maximum time (in ms) an async function is allowed to run during one step of the event loop.
 ---@field public max_view_entries integer