[core] stream response to client (#949)

This replaces buffering entire response prior to sending data to client

x-ref:
  "fastcgi, cgi, flush, php5 problem."
  https://redmine.lighttpd.net/issues/949

src/connections.c

@@ -1036,6 +1036,9 @@ int connection_state_machine(server *srv, connection *con) {
 			}
 
 			switch (r = http_response_prepare(srv, con)) {
+			case HANDLER_WAIT_FOR_EVENT:
+				if (!con->file_started) break; /* come back here */
+				/* response headers received from backend; fall through to start response */
 			case HANDLER_FINISHED:
 				if (con->error_handler_saved_status > 0) {
 					con->request.http_method = con->error_handler_saved_method;
@@ -1126,9 +1129,6 @@ int connection_state_machine(server *srv, connection *con) {
 				break;
 			case HANDLER_COMEBACK:
 				done = -1;
-				/* fallthrough */
-			case HANDLER_WAIT_FOR_EVENT:
-				/* come back here */
 				break;
 			case HANDLER_ERROR:
 				/* something went wrong */
@@ -1278,19 +1278,44 @@ int connection_state_machine(server *srv, connection *con) {
 						"state for fd", con->fd, connection_get_state(con->state));
 			}
 
-			/* only try to write if we have something in the queue */
-			if (!chunkqueue_is_empty(con->write_queue)) {
-				if (con->is_writable) {
-					if (-1 == connection_handle_write(srv, con)) {
-						log_error_write(srv, __FILE__, __LINE__, "ds",
-								con->fd,
-								"handle write failed.");
+			do {
+				/* only try to write if we have something in the queue */
+				if (!chunkqueue_is_empty(con->write_queue)) {
+					if (con->is_writable) {
+						if (-1 == connection_handle_write(srv, con)) {
+							log_error_write(srv, __FILE__, __LINE__, "ds",
+									con->fd,
+									"handle write failed.");
+							connection_set_state(srv, con, CON_STATE_ERROR);
+							break;
+						}
+						if (con->state != CON_STATE_WRITE) break;
+					}
+				} else if (con->file_finished) {
+					connection_set_state(srv, con, CON_STATE_RESPONSE_END);
+					break;
+				}
+
+				if (con->mode != DIRECT && !con->file_finished) {
+					switch(r = plugins_call_handle_subrequest(srv, con)) {
+					case HANDLER_WAIT_FOR_EVENT:
+					case HANDLER_FINISHED:
+					case HANDLER_GO_ON:
+						break;
+					case HANDLER_WAIT_FOR_FD:
+						srv->want_fds++;
+						fdwaitqueue_append(srv, con);
+						break;
+					case HANDLER_COMEBACK:
+					default:
+						log_error_write(srv, __FILE__, __LINE__, "sdd", "unexpected subrequest handler ret-value: ", con->fd, r);
+						/* fall through */
+					case HANDLER_ERROR:
 						connection_set_state(srv, con, CON_STATE_ERROR);
+						break;
 					}
 				}
-			} else if (con->file_finished) {
-				connection_set_state(srv, con, CON_STATE_RESPONSE_END);
-			}
+			} while (con->state == CON_STATE_WRITE && (!chunkqueue_is_empty(con->write_queue) ? con->is_writable : con->file_finished));
 
 			break;
 		case CON_STATE_ERROR: /* transient */

src/http-header-glue.c

@@ -726,3 +726,26 @@ void http_response_xsendfile (server *srv, connection *con, buffer *path, const
 		con->http_status = status;
 	}
 }
+
+void http_response_backend_done (server *srv, connection *con) {
+	/* (not CON_STATE_ERROR and not CON_STATE_RESPONSE_END,
+	 *  i.e. not called from handle_connection_close or connection_reset
+	 *  hooks, except maybe from errdoc handler, which later resets state)*/
+	switch (con->state) {
+	case CON_STATE_HANDLE_REQUEST:
+	case CON_STATE_READ_POST:
+		if (!con->file_started) {
+			/* Send an error if we haven't sent any data yet */
+			con->http_status = 500;
+			con->mode = DIRECT;
+			break;
+		} /* else fall through */
+	case CON_STATE_WRITE:
+		if (!con->file_finished) {
+			http_chunk_close(srv, con);
+			con->file_finished = 1;
+		}
+	default:
+		break;
+	}
+}

src/mod_cgi.c

@@ -662,20 +662,9 @@ static void cgi_connection_close(server *srv, handler_ctx *hctx) {
 	}
 #endif
 
-	/* finish response (if not already finished) */
-	if (con->mode == p->id
-	    && (con->state == CON_STATE_HANDLE_REQUEST || con->state == CON_STATE_READ_POST)) {
-		/* (not CON_STATE_ERROR and not CON_STATE_RESPONSE_END,
-		 * i.e. not called from cgi_connection_close_callback()) */
-
-		/* Send an error if we haven't sent any data yet */
-		if (0 == con->file_started) {
-			con->http_status = 500;
-			con->mode = DIRECT;
-		} else if (0 == con->file_finished) {
-			http_chunk_close(srv, con);
-			con->file_finished = 1;
-		}
+	/* finish response (if not already con->file_started, con->file_finished) */
+	if (con->mode == p->id) {
+		http_response_backend_done(srv, con);
 	}
 }
 

src/mod_fastcgi.c

@@ -1585,21 +1585,9 @@ static void fcgi_connection_close(server *srv, handler_ctx *hctx) {
 	handler_ctx_free(srv, hctx);
 	con->plugin_ctx[p->id] = NULL;
 
-	/* finish response (if not already finished) */
-	if (con->mode == p->id
-	    && (con->state == CON_STATE_HANDLE_REQUEST || con->state == CON_STATE_READ_POST)) {
-		/* (not CON_STATE_ERROR and not CON_STATE_RESPONSE_END,
-		 *  i.e. not called from fcgi_connection_reset()) */
-
-		/* Send an error if we haven't sent any data yet */
-		if (0 == con->file_started) {
-			con->http_status = 500;
-			con->mode = DIRECT;
-		}
-		else if (!con->file_finished) {
-			http_chunk_close(srv, con);
-			con->file_finished = 1;
-		}
+	/* finish response (if not already con->file_started, con->file_finished) */
+	if (con->mode == p->id) {
+		http_response_backend_done(srv, con);
 	}
 }
 

src/mod_proxy.c

@@ -351,21 +351,9 @@ static void proxy_connection_close(server *srv, handler_ctx *hctx) {
 	handler_ctx_free(hctx);
 	con->plugin_ctx[p->id] = NULL;
 
-	/* finish response (if not already finished) */
-	if (con->mode == p->id
-	    && (con->state == CON_STATE_HANDLE_REQUEST || con->state == CON_STATE_READ_POST)) {
-		/* (not CON_STATE_ERROR and not CON_STATE_RESPONSE_END,
-		 *  i.e. not called from proxy_connection_reset()) */
-
-		/* Send an error if we haven't sent any data yet */
-		if (0 == con->file_started) {
-			con->http_status = 500;
-			con->mode = DIRECT;
-		}
-		else if (!con->file_finished) {
-			http_chunk_close(srv, con);
-			con->file_finished = 1;
-		}
+	/* finish response (if not already con->file_started, con->file_finished) */
+	if (con->mode == p->id) {
+		http_response_backend_done(srv, con);
 	}
 }
 

src/mod_scgi.c

@@ -1336,21 +1336,9 @@ static void scgi_connection_close(server *srv, handler_ctx *hctx) {
 	handler_ctx_free(hctx);
 	con->plugin_ctx[p->id] = NULL;
 
-	/* finish response (if not already finished) */
-	if (con->mode == p->id
-	    && (con->state == CON_STATE_HANDLE_REQUEST || con->state == CON_STATE_READ_POST)) {
-		/* (not CON_STATE_ERROR and not CON_STATE_RESPONSE_END,
-		 *  i.e. not called from scgi_connection_reset()) */
-
-		/* Send an error if we haven't sent any data yet */
-		if (0 == con->file_started) {
-			con->http_status = 500;
-			con->mode = DIRECT;
-		}
-		else if (!con->file_finished) {
-			http_chunk_close(srv, con);
-			con->file_finished = 1;
-		}
+	/* finish response (if not already con->file_started, con->file_finished) */
+	if (con->mode == p->id) {
+		http_response_backend_done(srv, con);
 	}
 }
 

src/response.h

@@ -18,6 +18,7 @@ int http_response_redirect_to_directory(server *srv, connection *con);
 int http_response_handle_cachable(server *srv, connection *con, buffer * mtime);
 void http_response_send_file (server *srv, connection *con, buffer *path);
 void http_response_xsendfile (server *srv, connection *con, buffer *path, const array *xdocroot);
+void http_response_backend_done (server *srv, connection *con);
 
 buffer * strftime_cache_get(server *srv, time_t last_mod);
 #endif