From 6b378da5b7b1d43a0af1c8761b1a035e3929efdd Mon Sep 17 00:00:00 2001
From: Lukasz Samson <lukaszsamson@gmail.com>
Date: Tue, 2 Jan 2024 19:44:23 +0100
Subject: [PATCH] cache module completion results

avoid reading docs chunks
---
 lib/elixir_sense/core/introspection.ex        |  4 +-
 .../providers/suggestion/complete.ex          | 78 +++++++++++++------
 2 files changed, 58 insertions(+), 24 deletions(-)

diff --git a/lib/elixir_sense/core/introspection.ex b/lib/elixir_sense/core/introspection.ex
index 705cb256..df51493e 100644
--- a/lib/elixir_sense/core/introspection.ex
+++ b/lib/elixir_sense/core/introspection.ex
@@ -602,8 +602,8 @@ defmodule ElixirSense.Core.Introspection do
   defp to_var(atom, _) when is_atom(atom), do: {:atom, [], nil}
   defp to_var(_, position), do: {:"arg#{position}", [], nil}
 
-  def get_module_docs_summary(module) do
-    case NormalizedCode.get_docs(module, :moduledoc) do
+  def get_module_docs_summary(module, docs \\ nil) do
+    case docs || NormalizedCode.get_docs(module, :moduledoc) do
       {_, doc, metadata} ->
         {extract_summary_from_docs(doc), metadata}
 
diff --git a/lib/elixir_sense/providers/suggestion/complete.ex b/lib/elixir_sense/providers/suggestion/complete.ex
index 6493172a..9aca8cf8 100644
--- a/lib/elixir_sense/providers/suggestion/complete.ex
+++ b/lib/elixir_sense/providers/suggestion/complete.ex
@@ -55,6 +55,9 @@ defmodule ElixirSense.Providers.Suggestion.Complete do
 
   alias ElixirSense.Providers.Suggestion.Matcher
   alias ElixirSense.Providers.Suggestion.Reducers
+  require Logger
+
+  @module_results_cache_key :"#{__MODULE__}_module_results_cache"
 
   @erlang_module_builtin_functions [{:module_info, 0}, {:module_info, 1}]
   @elixir_module_builtin_functions [{:__info__, 1}]
@@ -510,22 +513,37 @@ defmodule ElixirSense.Providers.Suggestion.Complete do
     for mod <- match_modules(hint, true, env, metadata),
         usable_as_unquoted_module?(mod) do
       mod_as_atom = String.to_atom(mod)
-      subtype = Introspection.get_module_subtype(mod_as_atom)
-
-      desc =
-        if hint != "" do
-          Introspection.get_module_docs_summary(mod_as_atom)
-        else
-          # performance optimization
-          # TODO is it still needed on OTP 23+?
-          {"", %{}}
-        end
 
-      name = ":" <> mod
-      %{kind: :module, name: name, full_name: name, type: :erlang, desc: desc, subtype: subtype}
+      case :persistent_term.get({@module_results_cache_key, mod_as_atom}, nil) do
+        nil -> get_erlang_module_result(mod_as_atom)
+        result -> result
+      end
     end
   end
 
+  def fill_erlang_module_cache(module, docs) do
+    get_erlang_module_result(module, docs)
+  end
+
+  defp get_erlang_module_result(module, docs \\ nil) do
+    subtype = Introspection.get_module_subtype(module)
+    desc = Introspection.get_module_docs_summary(module, docs)
+
+    name = inspect(module)
+
+    result = %{
+      kind: :module,
+      name: name,
+      full_name: name,
+      type: :erlang,
+      desc: desc,
+      subtype: subtype
+    }
+
+    :persistent_term.put({@module_results_cache_key, module}, result)
+    result
+  end
+
   defp struct_module_filter(true, %State.Env{} = _env, %Metadata{} = metadata) do
     fn module -> Struct.is_struct(module, metadata.structs) end
   end
@@ -715,17 +733,13 @@ defmodule ElixirSense.Providers.Suggestion.Complete do
     end)
     |> Enum.uniq_by(&elem(&1, 1))
     |> Enum.map(fn {name, module, required_alias?} ->
-      {desc, meta} = Introspection.get_module_docs_summary(module)
-      subtype = Introspection.get_module_subtype(module)
+      result =
+        case :persistent_term.get({@module_results_cache_key, module}, nil) do
+          nil -> get_elixir_module_result(module)
+          result -> result
+        end
 
-      result = %{
-        kind: :module,
-        type: :elixir,
-        name: name,
-        full_name: inspect(module),
-        desc: {desc, meta},
-        subtype: subtype
-      }
+      result = Map.put(result, :name, name)
 
       if required_alias? do
         Map.put(result, :required_alias, module)
@@ -735,6 +749,26 @@ defmodule ElixirSense.Providers.Suggestion.Complete do
     end)
   end
 
+  def fill_elixir_module_cache(module, docs) do
+    get_elixir_module_result(module, docs)
+  end
+
+  defp get_elixir_module_result(module, docs \\ nil) do
+    {desc, meta} = Introspection.get_module_docs_summary(module, docs)
+    subtype = Introspection.get_module_subtype(module)
+
+    result = %{
+      kind: :module,
+      type: :elixir,
+      full_name: inspect(module),
+      desc: {desc, meta},
+      subtype: subtype
+    }
+
+    :persistent_term.put({@module_results_cache_key, module}, result)
+    result
+  end
+
   defp valid_alias_piece?(<<?., char, rest::binary>>) when char in ?A..?Z,
     do: valid_alias_rest?(rest)