Replace LanguageServer::Protocol::Transport with our own implementation

exe/ruby-lsp

@@ -88,6 +88,13 @@ if ENV["BUNDLE_GEMFILE"].nil?
   exit exec(env, "#{base_command} exec ruby-lsp #{original_args.join(" ")}".strip)
 end
 
+$stdin.sync = true
+$stdout.sync = true
+$stderr.sync = true
+$stdin.binmode
+$stdout.binmode
+$stderr.binmode
+
 $LOAD_PATH.unshift(File.expand_path("../lib", __dir__))
 
 require "ruby_lsp/load_sorbet"
@@ -147,8 +154,10 @@ if options[:doctor]
   return
 end
 
+server = RubyLsp::Server.new
+
 # Ensure all output goes out stderr by default to allow puts/p/pp to work
 # without specifying output device.
 $> = $stderr
 
-RubyLsp::Server.new.start
+server.start

exe/ruby-lsp-launcher

@@ -6,6 +6,13 @@
 # composed bundle
 # !!!!!!!
 
+$stdin.sync = true
+$stdout.sync = true
+$stderr.sync = true
+$stdin.binmode
+$stdout.binmode
+$stderr.binmode
+
 setup_error = nil
 install_error = nil
 reboot = false
@@ -28,7 +35,6 @@ else
   # Read the initialize request before even starting the server. We need to do this to figure out the workspace URI.
   # Editors are not required to spawn the language server process on the same directory as the workspace URI, so we need
   # to ensure that we're setting up the bundle in the right place
-  $stdin.binmode
   headers = $stdin.gets("\r\n\r\n")
   content_length = headers[/Content-Length: (\d+)/i, 1].to_i
   $stdin.read(content_length)
@@ -138,22 +144,28 @@ if ARGV.include?("--debug")
   end
 end
 
-# Ensure all output goes out stderr by default to allow puts/p/pp to work without specifying output device.
-$> = $stderr
-
 initialize_request = JSON.parse(raw_initialize, symbolize_names: true) if raw_initialize
 
 begin
-  RubyLsp::Server.new(
+  server = RubyLsp::Server.new(
     install_error: install_error,
     setup_error: setup_error,
     initialize_request: initialize_request,
-  ).start
+  )
+
+  # Ensure all output goes out stderr by default to allow puts/p/pp to work without specifying output device.
+  $> = $stderr
+
+  server.start
 rescue ArgumentError
   # If the launcher is booting an outdated version of the server, then the initializer doesn't accept a keyword splat
   # and we already read the initialize request from the stdin pipe. In this case, we need to process the initialize
   # request manually and then start the main loop
   server = RubyLsp::Server.new
+
+  # Ensure all output goes out stderr by default to allow puts/p/pp to work without specifying output device.
+  $> = $stderr
+
   server.process_message(initialize_request)
   server.start
 end

lib/ruby_lsp/base_server.rb

@@ -10,11 +10,11 @@ class BaseServer
 
     #: (**untyped options) -> void
     def initialize(**options)
+      @reader = MessageReader.new(options[:reader] || $stdin) #: MessageReader
+      @writer = MessageWriter.new(options[:writer] || $stdout) #: MessageWriter
       @test_mode = options[:test_mode] #: bool?
       @setup_error = options[:setup_error] #: StandardError?
       @install_error = options[:install_error] #: StandardError?
-      @writer = Transport::Stdio::Writer.new #: Transport::Stdio::Writer
-      @reader = Transport::Stdio::Reader.new #: Transport::Stdio::Reader
       @incoming_queue = Thread::Queue.new #: Thread::Queue
       @outgoing_queue = Thread::Queue.new #: Thread::Queue
       @cancelled_requests = [] #: Array[Integer]
@@ -40,7 +40,7 @@ def initialize(**options)
 
     #: -> void
     def start
-      @reader.read do |message|
+      @reader.each_message do |message|
         method = message[:method]
 
         # We must parse the document under a mutex lock or else we might switch threads and accept text edits in the

lib/ruby_lsp/utils.rb

@@ -5,7 +5,6 @@ module RubyLsp
   # rubocop:disable RubyLsp/UseLanguageServerAliases
   Interface = LanguageServer::Protocol::Interface
   Constant = LanguageServer::Protocol::Constant
-  Transport = LanguageServer::Protocol::Transport
   # rubocop:enable RubyLsp/UseLanguageServerAliases
 
   # Used to indicate that a request shouldn't return a response
@@ -302,4 +301,37 @@ def none? = @level == :none
     #: -> bool
     def true_or_higher? = @level == :true || @level == :strict
   end
+
+  # Reads JSON RPC messages from the given IO in a loop
+  class MessageReader
+    #: (IO) -> void
+    def initialize(io)
+      @io = io
+    end
+
+    #: () { (Hash[Symbol, untyped]) -> void } -> void
+    def each_message(&block)
+      while (headers = @io.gets("\r\n\r\n"))
+        raw_message = @io.read(headers[/Content-Length: (\d+)/i, 1].to_i) #: as !nil
+        block.call(JSON.parse(raw_message, symbolize_names: true))
+      end
+    end
+  end
+
+  # Writes JSON RPC messages to the given IO
+  class MessageWriter
+    #: (IO) -> void
+    def initialize(io)
+      @io = io
+    end
+
+    #: (Hash[Symbol, untyped]) -> void
+    def write(message)
+      message[:jsonrpc] = "2.0"
+      json_message = message.to_json
+
+      @io.write("Content-Length: #{json_message.bytesize}\r\n\r\n#{json_message}")
+      @io.flush
+    end
+  end
 end

test/integration_test.rb

@@ -314,6 +314,23 @@ def test_launch_mode_retries_if_setup_failed_after_successful_install
     end
   end
 
+  def test_launching_an_older_server_version
+    in_temp_dir do |dir|
+      File.write(File.join(dir, "Gemfile"), <<~RUBY)
+        source "https://rubygems.org"
+        gem "ruby-lsp", "0.23.0"
+      RUBY
+
+      Bundler.with_unbundled_env do
+        capture_subprocess_io do
+          system("bundle", "install")
+        end
+
+        launch(dir)
+      end
+    end
+  end
+
   private
 
   def launch(workspace_path, exec = "ruby-lsp-launcher", extra_env = {})