http: add workers to improve the server's concurrent capacity. (#18271)

vlib/net/http/server.v

@@ -6,11 +6,12 @@ module http
 import io
 import net
 import time
-
+import runtime
 // ServerStatus is the current status of the server.
 // .running means that the server is active and serving.
 // .stopped means that the server is not active but still listening.
 // .closed means that the server is completely inactive.
+
 pub enum ServerStatus {
 	running
 	stopped
@@ -27,11 +28,13 @@ mut:
 	state    ServerStatus = .closed
 	listener net.TcpListener
 pub mut:
-	port           int           = 8080
-	handler        Handler       = DebugHandler{}
-	read_timeout   time.Duration = 30 * time.second
-	write_timeout  time.Duration = 30 * time.second
-	accept_timeout time.Duration = 30 * time.second
+	port               int           = 8080
+	handler            Handler       = DebugHandler{}
+	read_timeout       time.Duration = 30 * time.second
+	write_timeout      time.Duration = 30 * time.second
+	accept_timeout     time.Duration = 30 * time.second
+	pool_channel_slots int = 1024
+	worker_num         int = runtime.nr_jobs()
 }
 
 // listen_and_serve listens on the server port `s.port` over TCP network and
@@ -45,6 +48,16 @@ pub fn (mut s Server) listen_and_serve() {
 		return
 	}
 	s.listener.set_accept_timeout(s.accept_timeout)
+
+	// Create tcp connection channel
+	ch := chan &net.TcpConn{cap: s.pool_channel_slots}
+
+	// Create workers
+	mut ws := []thread{cap: s.worker_num}
+	for wid in 0 .. s.worker_num {
+		ws << new_handler_worker(wid, ch, s.handler)
+	}
+
 	eprintln('Listening on :${s.port}')
 	s.state = .running
 	for {
@@ -62,8 +75,7 @@ pub fn (mut s Server) listen_and_serve() {
 		}
 		conn.set_read_timeout(s.read_timeout)
 		conn.set_write_timeout(s.write_timeout)
-		// TODO: make concurrent
-		s.parse_and_respond(mut conn)
+		ch <- conn
 	}
 	if s.state == .stopped {
 		s.close()
@@ -89,7 +101,30 @@ pub fn (s &Server) status() ServerStatus {
 	return s.state
 }
 
-fn (mut s Server) parse_and_respond(mut conn net.TcpConn) {
+struct HandlerWorker {
+	id int
+	ch chan &net.TcpConn
+pub mut:
+	handler Handler
+}
+
+fn new_handler_worker(wid int, ch chan &net.TcpConn, handler Handler) thread {
+	mut w := &HandlerWorker{
+		id: wid
+		ch: ch
+		handler: handler
+	}
+	return spawn w.process_requests()
+}
+
+fn (mut w HandlerWorker) process_requests() {
+	for {
+		mut conn := <-w.ch or { break }
+		w.handle_conn(mut conn)
+	}
+}
+
+fn (mut w HandlerWorker) handle_conn(mut conn net.TcpConn) {
 	defer {
 		conn.close() or { eprintln('close() failed: ${err}') }
 	}
@@ -111,10 +146,16 @@ fn (mut s Server) parse_and_respond(mut conn net.TcpConn) {
 	remote_ip := conn.peer_ip() or { '' }
 	req.header.add_custom('Remote-Addr', remote_ip) or {}
 
-	mut resp := s.handler.handle(req)
+	mut resp := w.handler.handle(req)
 	if resp.version() == .unknown {
 		resp.set_version(req.version)
 	}
+
+	// Implemented by developers?
+	if !resp.header.contains(.content_length) {
+		resp.header.set(.content_length, '${resp.body.len}')
+	}
+
 	conn.write(resp.bytes()) or { eprintln('error sending response: ${err}') }
 }