From 5e51a3af6f7f17c8f7d4c57762789c037f127bcf Mon Sep 17 00:00:00 2001
From: Alex Rocha <alex.rocha@shopify.com>
Date: Mon, 21 Oct 2024 14:43:03 -0700
Subject: [PATCH] Skip processing if the file hasn't changed

By leveraging file checksums using `Zlib.crc32`, we can avoid triggering
the DSL generation process for files that have not changed.
---
 lib/ruby_lsp/tapioca/addon.rb | 18 ++++++++++++++++++
 1 file changed, 18 insertions(+)

diff --git a/lib/ruby_lsp/tapioca/addon.rb b/lib/ruby_lsp/tapioca/addon.rb
index 720ec5e32..364b3fbcf 100644
--- a/lib/ruby_lsp/tapioca/addon.rb
+++ b/lib/ruby_lsp/tapioca/addon.rb
@@ -12,6 +12,8 @@
   return
 end
 
+require "zlib"
+
 module RubyLsp
   module Tapioca
     class Addon < ::RubyLsp::Addon
@@ -24,6 +26,7 @@ def initialize
         @global_state = T.let(nil, T.nilable(RubyLsp::GlobalState))
         @rails_runner_client = T.let(nil, T.nilable(RubyLsp::Rails::RunnerClient))
         @index = T.let(nil, T.nilable(RubyIndexer::Index))
+        @file_checksums = T.let({}, T::Hash[String, String])
       end
 
       sig { override.params(global_state: RubyLsp::GlobalState, outgoing_queue: Thread::Queue).void }
@@ -71,6 +74,21 @@ def workspace_did_change_watched_files(changes)
           path = URI(change[:uri]).to_standardized_path
           next if path.end_with?("_test.rb", "_spec.rb")
 
+          case change[:type]
+          when Constant::FileChangeType::CREATED, Constant::FileChangeType::CHANGED
+            content = File.read(path)
+            current_checksum = Zlib.crc32(content).to_s
+
+            if change[:type] == Constant::FileChangeType::CHANGED && @file_checksums[path] == current_checksum
+              $stderr.puts "File has not changed. Skipping #{path}"
+              next
+            end
+
+            @file_checksums[path] = current_checksum
+          when Constant::FileChangeType::DELETED
+            @file_checksums.delete(path)
+          end
+
           entries = T.must(@index).entries_for(path)
           next unless entries