lib: grpc: fix shutdown code

fixes #9732

Signed-off-by: Christian Hopps <chopps@labn.net>
(cherry picked from commit 83f6fce7d2fece4617bd85e3da0894fc820dab8d)

1 files changed, 80 insertions, 39 deletions

diff --git a/lib/northbound_grpc.cpp b/lib/northbound_grpc.cpp
index 2d9b61483b..ca253031f4 100644
--- a/lib/northbound_grpc.cpp
+++ b/lib/northbound_grpc.cpp
@@ -50,6 +50,8 @@ static struct thread_master *main_master;
 
 static struct frr_pthread *fpt;
 
+static bool grpc_running;
+
 #define grpc_debug(...)                                                        \
 	do {                                                                   \
 		if (nb_dbg_client_grpc)                                        \
@@ -116,9 +118,11 @@ class Candidates
 class RpcStateBase
 {
       public:
+	virtual ~RpcStateBase() = default;
 	virtual CallState doCallback() = 0;
 	virtual void do_request(::frr::Northbound::AsyncService *service,
-				::grpc::ServerCompletionQueue *cq) = 0;
+				::grpc::ServerCompletionQueue *cq,
+				bool no_copy) = 0;
 };
 
 /*
@@ -188,17 +192,22 @@ template <typename Q, typename S> class NewRpcState : RpcStateBase
 	}
 
 	void do_request(::frr::Northbound::AsyncService *service,
-			::grpc::ServerCompletionQueue *cq) override
+			::grpc::ServerCompletionQueue *cq,
+			bool no_copy) override
 	{
 		grpc_debug("%s, posting a request for: %s", __func__, name);
 		if (requestf) {
 			NewRpcState<Q, S> *copy =
-				new NewRpcState(cdb, requestf, callback, name);
+				no_copy ? this
+					: new NewRpcState(cdb, requestf,
+							  callback, name);
 			(service->*requestf)(&copy->ctx, &copy->request,
 					     &copy->responder, cq, cq, copy);
 		} else {
 			NewRpcState<Q, S> *copy =
-				new NewRpcState(cdb, requestsf, callback, name);
+				no_copy ? this
+					: new NewRpcState(cdb, requestsf,
+							  callback, name);
 			(service->*requestsf)(&copy->ctx, &copy->request,
 					      &copy->async_responder, cq, cq,
 					      copy);
@@ -1225,7 +1234,7 @@ void HandleUnaryExecute(
 						 frr::NAME##Response>(         \
 			(cdb), &frr::Northbound::AsyncService::Request##NAME,  \
 			&HandleUnary##NAME, #NAME);                            \
-		_rpcState->do_request(service, s_cq);                          \
+		_rpcState->do_request(&service, cq.get(), true);               \
 	} while (0)
 
 #define REQUEST_NEWRPC_STREAMING(NAME, cdb)                                    \
@@ -1234,7 +1243,7 @@ void HandleUnaryExecute(
 						 frr::NAME##Response>(         \
 			(cdb), &frr::Northbound::AsyncService::Request##NAME,  \
 			&HandleStreaming##NAME, #NAME);                        \
-		_rpcState->do_request(service, s_cq);                          \
+		_rpcState->do_request(&service, cq.get(), true);               \
 	} while (0)
 
 struct grpc_pthread_attr {
@@ -1243,8 +1252,8 @@ struct grpc_pthread_attr {
 };
 
 // Capture these objects so we can try to shut down cleanly
-static std::unique_ptr<grpc::Server> s_server;
-static grpc::ServerCompletionQueue *s_cq;
+static pthread_mutex_t s_server_lock = PTHREAD_MUTEX_INITIALIZER;
+static grpc::Server *s_server;
 
 static void *grpc_pthread_start(void *arg)
 {
@@ -1254,20 +1263,22 @@ static void *grpc_pthread_start(void *arg)
 	Candidates candidates;
 	grpc::ServerBuilder builder;
 	std::stringstream server_address;
-	frr::Northbound::AsyncService *service =
-		new frr::Northbound::AsyncService();
+	frr::Northbound::AsyncService service;
 
 	frr_pthread_set_name(fpt);
 
 	server_address << "0.0.0.0:" << port;
 	builder.AddListeningPort(server_address.str(),
 				 grpc::InsecureServerCredentials());
-	builder.RegisterService(service);
+	builder.RegisterService(&service);
 	builder.AddChannelArgument(
 		GRPC_ARG_HTTP2_MIN_RECV_PING_INTERVAL_WITHOUT_DATA_MS, 5000);
-	auto cq = builder.AddCompletionQueue();
-	s_cq = cq.get();
-	s_server = builder.BuildAndStart();
+	std::unique_ptr<grpc::ServerCompletionQueue> cq =
+		builder.AddCompletionQueue();
+	std::unique_ptr<grpc::Server> server = builder.BuildAndStart();
+	s_server = server.get();
+
+	grpc_running = true;
 
 	/* Schedule all RPC handlers */
 	REQUEST_NEWRPC(GetCapabilities, NULL);
@@ -1288,20 +1299,25 @@ static void *grpc_pthread_start(void *arg)
 		    server_address.str().c_str());
 
 	/* Process inbound RPCs */
-	while (true) {
-		void *tag;
-		bool ok;
-
-		s_cq->Next(&tag, &ok);
-		if (!ok)
+	bool ok;
+	void *tag;
+	while (grpc_running) {
+		if (!cq->Next(&tag, &ok)) {
+			grpc_debug("%s: CQ empty exiting", __func__);
 			break;
+		}
 
-		grpc_debug("%s: Got next from CompletionQueue, %p %d", __func__,
-			   tag, ok);
+		grpc_debug("%s: got next from CQ tag: %p ok: %d", __func__, tag,
+			   ok);
+
+		if (!ok || !grpc_running) {
+			delete static_cast<RpcStateBase *>(tag);
+			break;
+		}
 
 		RpcStateBase *rpc = static_cast<RpcStateBase *>(tag);
 		CallState state = rpc->doCallback();
-		grpc_debug("%s: Callback returned RPC State: %s", __func__,
+		grpc_debug("%s: callback returned RPC State: %s", __func__,
 			   call_states[state]);
 
 		/*
@@ -1311,10 +1327,30 @@ static void *grpc_pthread_start(void *arg)
 		 * to be called back once more in the FINISH state (from the
 		 * user indicating Finish() for cleanup.
 		 */
-		if (state == FINISH)
-			rpc->do_request(service, s_cq);
+		if (state == FINISH && grpc_running)
+			rpc->do_request(&service, cq.get(), false);
 	}
 
+	/* This was probably done for us to get here, but let's be safe */
+	pthread_mutex_lock(&s_server_lock);
+	grpc_running = false;
+	if (s_server) {
+		grpc_debug("%s: shutdown server and CQ", __func__);
+		server->Shutdown();
+		s_server = NULL;
+	}
+	pthread_mutex_unlock(&s_server_lock);
+
+	grpc_debug("%s: shutting down CQ", __func__);
+	cq->Shutdown();
+
+	grpc_debug("%s: draining the CQ", __func__);
+	while (cq->Next(&tag, &ok)) {
+		grpc_debug("%s: drain tag %p", __func__, tag);
+		delete static_cast<RpcStateBase *>(tag);
+	}
+
+	zlog_info("%s: exiting from grpc pthread", __func__);
 	return NULL;
 }
 
@@ -1326,6 +1362,8 @@ static int frr_grpc_init(uint port)
 		.stop = NULL,
 	};
 
+	grpc_debug("%s: entered", __func__);
+
 	fpt = frr_pthread_new(&attr, "frr-grpc", "frr-grpc");
 	fpt->data = reinterpret_cast<void *>((intptr_t)port);
 
@@ -1341,24 +1379,27 @@ static int frr_grpc_init(uint port)
 
 static int frr_grpc_finish(void)
 {
-	// Shutdown the grpc server
-	if (s_server) {
-		s_server->Shutdown();
-		s_cq->Shutdown();
+	grpc_debug("%s: entered", __func__);
 
-		// And drain the queue
-		void *ignore;
-		bool ok;
-
-		while (s_cq->Next(&ignore, &ok))
-			;
-	}
+	if (!fpt)
+		return 0;
 
-	if (fpt) {
-		pthread_join(fpt->thread, NULL);
-		frr_pthread_destroy(fpt);
+	/*
+	 * Shut the server down here in main thread. This will cause the wait on
+	 * the completion queue (cq.Next()) to exit and cleanup everything else.
+	 */
+	pthread_mutex_lock(&s_server_lock);
+	grpc_running = false;
+	if (s_server) {
+		grpc_debug("%s: shutdown server", __func__);
+		s_server->Shutdown();
+		s_server = NULL;
 	}
+	pthread_mutex_unlock(&s_server_lock);
 
+	grpc_debug("%s: joining and destroy grpc thread", __func__);
+	pthread_join(fpt->thread, NULL);
+	frr_pthread_destroy(fpt);
 	return 0;
 }