Add support for a keep-alive ping/pong (default to at most 10 seconds).

lib/live/page.rb

@@ -113,22 +113,47 @@ def process_message(message)
 
 		# Run the event handling loop with the given websocket connection.
 		# @parameter connection [Async::WebSocket::Connection]
-		def run(connection)
+		def run(connection, keep_alive: 10)
 			Sync do |task|
+				last_update = Async::Clock.now
+
 				queue_task = task.async do
 					while update = @updates.dequeue
-						::Protocol::WebSocket::TextMessage.generate(update).send(connection)
+						if update == :ping
+							connection.send_ping
+						else
+							::Protocol::WebSocket::TextMessage.generate(update).send(connection)
+						end
 
 						# Flush the output if there are no more updates:
-						connection.flush if @updates.empty?
+						if @updates.empty?
+							connection.flush
+						end
+					end
+				end
+
+				keep_alive_task = task.async do
+					while true
+						sleep(keep_alive)
+
+						duration = Async::Clock.now - last_update
+
+						# We synchronize all writes to the update queue:
+						if duration > keep_alive
+							@updates.enqueue(:ping)
+						end
 					end
 				end
 
 				while message = connection.read
+					last_update = Async::Clock.now
 					process_message(message.parse)
 				end
 			ensure
+				keep_alive_task&.stop
+
 				self.close
+
 				queue_task&.stop
 			end
 		end

test/live/page.rb

@@ -7,6 +7,10 @@
 require "live/view"
 require "live/resolver"
 
+require "async/websocket/client"
+require "async/websocket/adapters/http"
+require "sus/fixtures/async/http/server_context"
+
 class MyView < Live::View
 end
 
@@ -38,4 +42,26 @@ class MyView < Live::View
 			expect(page.resolve(view.id)).to be_nil
 		end
 	end
+
+	with "a server" do
+		include Sus::Fixtures::Async::HTTP::ServerContext
+
+		let(:app) do
+			::Protocol::HTTP::Middleware.for do |request|
+				Async::WebSocket::Adapters::HTTP.open(request) do |connection|
+					Live::Page.new(resolver).run(connection, keep_alive: 0.001)
+				end
+			end
+		end
+
+		it "can connect to server and receives ping" do
+			Async::WebSocket::Client.connect(client_endpoint) do |connection|
+				expect(connection).to receive(:receive_ping)
+
+				frame = connection.read_frame
+
+				expect(frame).to be_a(Protocol::WebSocket::PingFrame)
+			end
+		end
+	end
 end