afb-stub-ws: Add reconnection of ws-clients on need

This implementation detects deconnections and try to reconnect
lazily on need.

Bug-AGL: SPEC-1668

Change-Id: Ib2a20a4578f2da80afe1564c42de96c4aa250e64
Signed-off-by: José Bollo <jose.bollo@iot.bzh>

3 files changed, 67 insertions, 6 deletions

diff --git a/src/afb-api-ws.c b/src/afb-api-ws.c
index 6d8506c1..8069da22 100644
--- a/src/afb-api-ws.c
+++ b/src/afb-api-ws.c
@@ -50,6 +50,12 @@ struct api_ws_server
 /***       C L I E N T                                                      ***/
 /******************************************************************************/
 
+static struct fdev *reopen_client(void *closure)
+{
+	const char *uri = closure;
+	return afb_socket_open_fdev(uri, 0);
+}
+
 int afb_api_ws_add_client(const char *uri, struct afb_apiset *declare_set, struct afb_apiset *call_set, int strong)
 {
 	struct afb_stub_ws *stubws;
@@ -73,8 +79,16 @@ int afb_api_ws_add_client(const char *uri, struct afb_apiset *declare_set, struc
 			ERROR("can't setup client ws service to %s", uri);
 			fdev_unref(fdev);
 		} else {
-			if (afb_stub_ws_client_add(stubws, declare_set) >= 0)
+			if (afb_stub_ws_client_add(stubws, declare_set) >= 0) {
+#if 1
+				/* it is asserted here that uri is never released */
+				afb_stub_ws_client_robustify(stubws, reopen_client, (void*)uri, NULL);
+#else
+				/* it is asserted here that uri is released, so use a copy */
+				afb_stub_ws_client_robustify(stubws, reopen_client, strdup(uri), free);
+#endif
 				return 0;
+			}
 			ERROR("can't add the client to the apiset for service %s", uri);
 			afb_stub_ws_unref(stubws);
 		}
diff --git a/src/afb-stub-ws.c b/src/afb-stub-ws.c
index 19b9b618..a41a9b02 100644
--- a/src/afb-stub-ws.c
+++ b/src/afb-stub-ws.c
@@ -128,6 +128,13 @@ struct afb_stub_ws
 		struct {
 			/* event replica  */
 			struct client_event *events;
+
+			/* robustify */
+			struct {
+				struct fdev *(*reopen)(void*);
+				void *closure;
+				void (*release)(void*);
+			} robust;
 		};
 	};
 
@@ -141,6 +148,8 @@ struct afb_stub_ws
 	char apiname[1];
 };
 
+static struct afb_proto_ws *afb_stub_ws_create_proto(struct afb_stub_ws *stubws, struct fdev *fdev, uint8_t server);
+
 /******************* ws request part for server *****************/
 
 /* decrement the reference count of the request and free/release it on falling to null */
@@ -229,19 +238,35 @@ static struct client_event *client_event_search(struct afb_stub_ws *stubws, uint
 	return ev;
 }
 
+static struct afb_proto_ws *client_get_proto(struct afb_stub_ws *stubws)
+{
+	struct fdev *fdev;
+	struct afb_proto_ws *proto;
+
+	proto = stubws->proto;
+	if (proto == NULL && stubws->robust.reopen) {
+		fdev = stubws->robust.reopen(stubws->robust.closure);
+		if (fdev != NULL)
+			proto = afb_stub_ws_create_proto(stubws, fdev, 0);
+	}
+	return proto;
+}
+
 /* on call, propagate it to the ws service */
 static void client_api_call_cb(void * closure, struct afb_xreq *xreq)
 {
 	int rc;
 	struct afb_stub_ws *stubws = closure;
+	struct afb_proto_ws *proto;
 
-	if (stubws->proto == NULL) {
+	proto = client_get_proto(stubws);
+	if (proto == NULL) {
 		afb_xreq_reply(xreq, NULL, "disconnected", "server hung up");
 		return;
 	}
 
 	rc = afb_proto_ws_client_call(
-			stubws->proto,
+			proto,
 			xreq->request.called_verb,
 			afb_xreq_json(xreq),
 			afb_session_uuid(xreq->context.session),
@@ -264,12 +289,14 @@ static void client_on_description_cb(void *closure, struct json_object *data)
 static void client_send_describe_cb(int signum, void *closure, struct jobloop *jobloop)
 {
 	struct client_describe *desc = closure;
+	struct afb_proto_ws *proto;
 
-	if (signum || desc->stubws->proto == NULL)
+	proto = client_get_proto(desc->stubws);
+	if (signum || proto == NULL)
 		jobs_leave(jobloop);
 	else {
 		desc->jobloop = jobloop;
-		afb_proto_ws_client_describe(desc->stubws->proto, client_on_description_cb, desc);
+		afb_proto_ws_client_describe(proto, client_on_description_cb, desc);
 	}
 }
 
@@ -685,6 +712,12 @@ void afb_stub_ws_unref(struct afb_stub_ws *stubws)
 {
 	if (stubws && !__atomic_sub_fetch(&stubws->refcount, 1, __ATOMIC_RELAXED)) {
 
+		if (stubws->is_client) {
+			stubws->robust.reopen = NULL;
+			if (stubws->robust.release)
+				stubws->robust.release(stubws->robust.closure);
+		}
+
 		disconnect(stubws);
 		afb_apiset_unref(stubws->apiset);
 		free(stubws);
@@ -713,7 +746,7 @@ struct afb_api_item afb_stub_ws_client_api(struct afb_stub_ws *stubws)
 	assert(stubws->is_client); /* check client */
 	api.closure = stubws;
 	api.itf = &client_api_itf;
-	api.group = NULL;
+	api.group = stubws; /* serialize for reconnections */
 	return api;
 }
 
@@ -721,3 +754,15 @@ int afb_stub_ws_client_add(struct afb_stub_ws *stubws, struct afb_apiset *apiset
 {
 	return afb_apiset_add(apiset, stubws->apiname, afb_stub_ws_client_api(stubws));
 }
+
+void afb_stub_ws_client_robustify(struct afb_stub_ws *stubws, struct fdev *(*reopen)(void*), void *closure, void (*release)(void*))
+{
+	assert(stubws->is_client); /* check client */
+
+	if (stubws->robust.release)
+		stubws->robust.release(stubws->robust.closure);
+
+	stubws->robust.reopen = reopen;
+	stubws->robust.closure = closure;
+	stubws->robust.release = release;
+}
diff --git a/src/afb-stub-ws.h b/src/afb-stub-ws.h
index f236937d..c0877268 100644
--- a/src/afb-stub-ws.h
+++ b/src/afb-stub-ws.h
@@ -39,3 +39,5 @@ extern struct afb_api_item afb_stub_ws_client_api(struct afb_stub_ws *stubws);
 
 extern int afb_stub_ws_client_add(struct afb_stub_ws *stubws, struct afb_apiset *apiset);
 
+extern void afb_stub_ws_client_robustify(struct afb_stub_ws *stubws, struct fdev *(*reopen)(void*), void *closure, void (*release)(void*));
+