From 066876d4910b73362dea74f8760df390f0b3c83a Mon Sep 17 00:00:00 2001
From: Sean McBride <spmcbride1201@gmail.com>
Date: Thu, 18 Aug 2022 13:36:54 -0400
Subject: [PATCH] fix: HTTP session state machine

---
 runtime/include/http_session.h | 23 ++++++++++++++++++++---
 runtime/src/listener_thread.c  | 13 ++++++++-----
 2 files changed, 28 insertions(+), 8 deletions(-)

diff --git a/runtime/include/http_session.h b/runtime/include/http_session.h
index 2252f64..8ef7f69 100644
--- a/runtime/include/http_session.h
+++ b/runtime/include/http_session.h
@@ -35,9 +35,10 @@ enum http_session_state
 	HTTP_SESSION_EXECUTION_COMPLETE,
 	HTTP_SESSION_SENDING_RESPONSE_HEADER,
 	HTTP_SESSION_SEND_RESPONSE_HEADER_BLOCKED,
-	HTTP_SESSION_SENDING_RESPONSE,
-	HTTP_SESSION_SEND_RESPONSE_BLOCKED,
-	HTTP_SESSION_SENT_RESPONSE
+	HTTP_SESSION_SENT_RESPONSE_HEADER,
+	HTTP_SESSION_SENDING_RESPONSE_BODY,
+	HTTP_SESSION_SEND_RESPONSE_BODY_BLOCKED,
+	HTTP_SESSION_SENT_RESPONSE_BODY
 };
 
 struct http_session {
@@ -209,6 +210,9 @@ static inline int
 http_session_send_response_header(struct http_session *session, void_star_cb on_eagain)
 {
 	assert(session != NULL);
+	assert(session->state == HTTP_SESSION_EXECUTION_COMPLETE
+	       || session->state == HTTP_SESSION_SEND_RESPONSE_HEADER_BLOCKED);
+	session->state = HTTP_SESSION_SENDING_RESPONSE_HEADER;
 
 	while (session->response_header_length > session->response_header_written) {
 		ssize_t sent =
@@ -223,6 +227,8 @@ http_session_send_response_header(struct http_session *session, void_star_cb on_
 		}
 	}
 
+	session->state = HTTP_SESSION_SENT_RESPONSE_HEADER;
+
 	return 0;
 }
 
@@ -237,6 +243,10 @@ http_session_send_response_body(struct http_session *session, void_star_cb on_ea
 {
 	assert(session != NULL);
 
+	assert(session->state == HTTP_SESSION_SENT_RESPONSE_HEADER
+	       || session->state == HTTP_SESSION_SEND_RESPONSE_BODY_BLOCKED);
+	session->state = HTTP_SESSION_SENDING_RESPONSE_BODY;
+
 	while (session->response_buffer_written < session->response_buffer.length) {
 		ssize_t sent =
 		  tcp_session_send(session->socket,
@@ -250,6 +260,7 @@ http_session_send_response_body(struct http_session *session, void_star_cb on_ea
 		}
 	}
 
+	session->state = HTTP_SESSION_SENT_RESPONSE_BODY;
 	return 0;
 }
 
@@ -458,6 +469,8 @@ DONE:
 static inline void
 http_session_send_response(struct http_session *session, void_star_cb on_eagain)
 {
+	assert(session->state == HTTP_SESSION_EXECUTION_COMPLETE);
+
 	int rc = http_session_send_response_header(session, on_eagain);
 	/* session blocked and registered to epoll so continue to next handle */
 	if (unlikely(rc == -EAGAIN)) {
@@ -466,6 +479,8 @@ http_session_send_response(struct http_session *session, void_star_cb on_eagain)
 		goto CLOSE;
 	}
 
+	assert(session->state == HTTP_SESSION_SENT_RESPONSE_HEADER);
+
 	rc = http_session_send_response_body(session, on_eagain);
 	/* session blocked and registered to epoll so continue to next handle */
 	if (unlikely(rc == -EAGAIN)) {
@@ -474,6 +489,8 @@ http_session_send_response(struct http_session *session, void_star_cb on_eagain)
 		goto CLOSE;
 	}
 
+	assert(session->state == HTTP_SESSION_SENT_RESPONSE_BODY);
+
 	/* Terminal State Logging for Http Session */
 	session->response_sent_timestamp = __getcycles();
 	http_session_perf_log_print_entry(session);
diff --git a/runtime/src/listener_thread.c b/runtime/src/listener_thread.c
index f615db8..221814e 100644
--- a/runtime/src/listener_thread.c
+++ b/runtime/src/listener_thread.c
@@ -84,9 +84,9 @@ listener_thread_register_http_session(struct http_session *http)
 		accept_evt.events = EPOLLOUT;
 		http->state       = HTTP_SESSION_SEND_RESPONSE_HEADER_BLOCKED;
 		break;
-	case HTTP_SESSION_SENDING_RESPONSE:
+	case HTTP_SESSION_SENDING_RESPONSE_BODY:
 		accept_evt.events = EPOLLOUT;
-		http->state       = HTTP_SESSION_SEND_RESPONSE_BLOCKED;
+		http->state       = HTTP_SESSION_SEND_RESPONSE_BODY_BLOCKED;
 		break;
 	default:
 		panic("Invalid HTTP Session State: %d\n", http->state);
@@ -252,8 +252,7 @@ on_client_request_received(struct http_session *session)
 static void
 on_client_response_header_sending(struct http_session *session)
 {
-	assert(session->state = HTTP_SESSION_EXECUTION_COMPLETE);
-	session->state = HTTP_SESSION_SENDING_RESPONSE_HEADER;
+	assert(session->state = HTTP_SESSION_SEND_RESPONSE_HEADER_BLOCKED);
 
 	int rc = http_session_send_response_header(session, (void_star_cb)listener_thread_register_http_session);
 	if (likely(rc == 0)) {
@@ -272,6 +271,8 @@ on_client_response_header_sending(struct http_session *session)
 static void
 on_client_response_body_sending(struct http_session *session)
 {
+	assert(session->state = HTTP_SESSION_SEND_RESPONSE_BODY_BLOCKED);
+
 	/* Read HTTP request */
 	int rc = http_session_send_response_body(session, (void_star_cb)listener_thread_register_http_session);
 	if (likely(rc == 0)) {
@@ -290,6 +291,8 @@ on_client_response_body_sending(struct http_session *session)
 static void
 on_client_response_sent(struct http_session *session)
 {
+	assert(session->state = HTTP_SESSION_SENT_RESPONSE_BODY);
+
 	/* Terminal State Logging for Http Session */
 	session->response_sent_timestamp = __getcycles();
 	http_session_perf_log_print_entry(session);
@@ -344,7 +347,7 @@ on_client_socket_epoll_event(struct epoll_event *evt)
 		assert((evt->events & EPOLLOUT) == EPOLLOUT);
 		on_client_response_header_sending(session);
 		break;
-	case HTTP_SESSION_SEND_RESPONSE_BLOCKED:
+	case HTTP_SESSION_SEND_RESPONSE_BODY_BLOCKED:
 		assert((evt->events & EPOLLOUT) == EPOLLOUT);
 		on_client_response_body_sending(session);
 		break;