Queue signals while connecting to application

Otherwise we can end up with a situation where the user issues a ^C
after the application has started running the command, but before we've
got the worker pid. Thus the client process exits but the worker process
carries on running, and output appears on the user's terminal.

Author: jonleighton

lib/spring/client/run.rb

@@ -5,6 +5,12 @@ module Spring
   module Client
     class Run < Command
       FORWARDED_SIGNALS = %w(INT QUIT USR1 USR2 INFO) & Signal.list.keys
+      TIMEOUT = 1
+
+      def initialize(args)
+        super
+        @signal_queue = []
+      end
 
       def log(message)
         env.log "[client] #{message}"
@@ -20,6 +26,7 @@ def call
 
         application, client = UNIXSocket.pair
 
+        queue_signals
         connect_to_application(client)
         run_command(client, application)
       rescue Errno::ECONNRESET
@@ -59,7 +66,12 @@ def verify_server_version
       def connect_to_application(client)
         server.send_io client
         send_json server, "args" => args, "default_rails_env" => default_rails_env
-        server.gets or raise CommandNotFound
+
+        if IO.select([server], [], [], TIMEOUT)
+          server.gets or raise CommandNotFound
+        else
+          raise "Error connecting to Spring server"
+        end
       end
 
       def run_command(client, application)
@@ -96,21 +108,34 @@ def run_command(client, application)
         application.close
       end
 
+      def queue_signals
+        FORWARDED_SIGNALS.each do |sig|
+          trap(sig) { @signal_queue << sig }
+        end
+      end
+
       def forward_signals(pid)
+        @signal_queue.each { |sig| kill sig, pid }
+
         FORWARDED_SIGNALS.each do |sig|
           trap(sig) { forward_signal sig, pid }
         end
+      rescue Errno::ESRCH
       end
 
       def forward_signal(sig, pid)
-        Process.kill(sig, -Process.getpgid(pid))
+        kill(sig, pid)
       rescue Errno::ESRCH
         # If the application process is gone, then don't block the
         # signal on this process.
         trap(sig, 'DEFAULT')
         Process.kill(sig, Process.pid)
       end
 
+      def kill(sig, pid)
+        Process.kill(sig, -Process.getpgid(pid))
+      end
+
       def send_json(socket, data)
         data = JSON.dump(data)