using sendmsg_nonblock instead of #send for udp writes

lib/httpx/io/udp.rb

@@ -39,16 +39,20 @@ module HTTPX
       end
     end
 
-    def write(buffer)
-      siz = @io.send(buffer.to_s, 0, @host, @port)
-      log { "WRITE: #{siz} bytes..." }
-      buffer.shift!(siz)
-      siz
-    end
-
     # :nocov:
     if (RUBY_ENGINE == "truffleruby" && RUBY_ENGINE_VERSION < "21.1.0") ||
        RUBY_VERSION < "2.3"
+      def write(buffer)
+        siz = @io.sendmsg_nonblock(buffer.to_s, 0, Socket.sockaddr_in(@port, @host.to_s))
+        log { "WRITE: #{siz} bytes..." }
+        buffer.shift!(siz)
+        siz
+      rescue ::IO::WaitWritable
+        0
+      rescue EOFError
+        nil
+      end
+
       def read(size, buffer)
         data, _ = @io.recvfrom_nonblock(size)
         buffer.replace(data)
@@ -59,6 +63,18 @@ module HTTPX
       rescue IOError
       end
     else
+
+      def write(buffer)
+        siz = @io.sendmsg_nonblock(buffer.to_s, 0, Socket.sockaddr_in(@port, @host.to_s), exception: false)
+        return 0 if siz == :wait_writable
+        return if siz.nil?
+
+        log { "WRITE: #{siz} bytes..." }
+
+        buffer.shift!(siz)
+        siz
+      end
+
       def read(size, buffer)
         ret = @io.recvfrom_nonblock(size, 0, buffer, exception: false)
         return 0 if ret == :wait_readable