perf(source): only filter up to 200 entries and dont use the cache (#1574)

lua/cmp/source.lua

@@ -18,6 +18,7 @@ local char = require('cmp.utils.char')
 ---@field public incomplete boolean
 ---@field public is_triggered_by_symbol boolean
 ---@field public entries cmp.Entry[]
+---@field public filtered {entries: cmp.Entry[], ctx: cmp.Context}
 ---@field public offset integer
 ---@field public request_offset integer
 ---@field public context cmp.Context
@@ -53,6 +54,7 @@ source.reset = function(self)
   self.is_triggered_by_symbol = false
   self.incomplete = false
   self.entries = {}
+  self.filtered = {}
   self.offset = -1
   self.request_offset = -1
   self.completion_context = nil
@@ -88,6 +90,10 @@ source.get_entries = function(self, ctx)
     return {}
   end
 
+  if self.filtered.ctx and self.filtered.ctx.id == ctx.id then
+    return self.filtered.entries
+  end
+
   local target_entries = (function()
     local key = { 'get_entries', self.revision }
     for i = ctx.cursor.col, self.offset, -1 do
@@ -103,7 +109,9 @@ source.get_entries = function(self, ctx)
   local entry_filter = self:get_entry_filter()
 
   local inputs = {}
+  ---@type cmp.Entry[]
   local entries = {}
+  local max_item_count = self:get_source_config().max_item_count or 200
   local matching_config = self:get_matching_config()
   for _, e in ipairs(target_entries) do
     local o = e:get_offset()
@@ -119,21 +127,22 @@ source.get_entries = function(self, ctx)
       e.exact = e:get_filter_text() == inputs[o] or e:get_word() == inputs[o]
 
       if entry_filter(e, ctx) then
-        table.insert(entries, e)
+        entries[#entries + 1] = e
+        if max_item_count and #entries >= max_item_count then
+          break
+        end
       end
     end
   end
-  self.cache:set({ 'get_entries', tostring(self.revision), ctx.cursor_before_line }, entries)
 
-  local max_item_count = self:get_source_config().max_item_count or 200
-  local limited_entries = {}
-  for _, e in ipairs(entries) do
-    table.insert(limited_entries, e)
-    if max_item_count and #limited_entries >= max_item_count then
-      break
-    end
+  -- only save to cache, when there are no additional entries that could match the filter
+  -- This also prevents too much memory usage
+  if #entries < max_item_count then
+    self.cache:set({ 'get_entries', tostring(self.revision), ctx.cursor_before_line }, entries)
   end
-  return limited_entries
+
+  self.filtered = { entries = entries, ctx = ctx }
+  return entries
 end
 
 ---Get default insert range (UTF8 byte index).