lib/nfs/Connection: create the nfs_context in the constructor

Another lifetime simplification.

src/lib/nfs/Connection.cxx

@@ -175,12 +175,16 @@ events_to_libnfs(unsigned i) noexcept
 
 NfsConnection::NfsConnection(EventLoop &_loop,
 			     std::string_view _server,
-			     std::string_view _export_name) noexcept
+			     std::string_view _export_name)
 	:socket_event(_loop, BIND_THIS_METHOD(OnSocketReady)),
 	 defer_new_lease(_loop, BIND_THIS_METHOD(RunDeferred)),
 	 mount_timeout_event(_loop, BIND_THIS_METHOD(OnMountTimeout)),
 	 server(_server), export_name(_export_name),
-	 context(nullptr) {}
+	 context(nfs_init_context())
+{
+	if (context == nullptr)
+		throw std::runtime_error{"nfs_init_context() failed"};
+}
 
 NfsConnection::~NfsConnection() noexcept
 {
@@ -189,11 +193,10 @@ NfsConnection::~NfsConnection() noexcept
 	assert(active_leases.empty());
 	assert(callbacks.IsEmpty());
 	assert(deferred_close.empty());
+	assert(context != nullptr);
 
-	if (context != nullptr) {
+	socket_event.ReleaseSocket();
-		PrepareDestroyContext();
+	nfs_destroy_context(context);
-		nfs_destroy_context(context);
-	}
 }
 
 void
@@ -348,7 +351,6 @@ inline void
 NfsConnection::InternalClose(struct nfsfh *fh) noexcept
 {
 	assert(GetEventLoop().IsInside());
-	assert(context != nullptr);
 	assert(fh != nullptr);
 
 	nfs_close_async(context, fh, DummyCallback, nullptr);
@@ -374,7 +376,6 @@ void
 NfsConnection::PrepareDestroyContext() noexcept
 {
 	assert(GetEventLoop().IsInside());
-	assert(context != nullptr);
 
 #ifndef NDEBUG
 	assert(!in_destroy);
@@ -410,7 +411,6 @@ NfsConnection::DeferClose(struct nfsfh *fh) noexcept
 	assert(GetEventLoop().IsInside());
 	assert(in_event);
 	assert(in_service);
-	assert(context != nullptr);
 	assert(fh != nullptr);
 
 	deferred_close.push_front(fh);
@@ -420,7 +420,6 @@ void
 NfsConnection::ScheduleSocket() noexcept
 {
 	assert(GetEventLoop().IsInside());
-	assert(context != nullptr);
 
 	const int which_events = nfs_which_events(context);
 
@@ -449,7 +448,6 @@ inline int
 NfsConnection::Service(unsigned flags) noexcept
 {
 	assert(GetEventLoop().IsInside());
-	assert(context != nullptr);
 
 #ifndef NDEBUG
 	assert(!in_event);
@@ -462,7 +460,6 @@ NfsConnection::Service(unsigned flags) noexcept
 	int result = nfs_service(context, events_to_libnfs(flags));
 
 #ifndef NDEBUG
-	assert(context != nullptr);
 	assert(in_service);
 	in_service = false;
 #endif
@@ -523,7 +520,6 @@ NfsConnection::OnSocketReady(unsigned flags) noexcept
 		return;
 	}
 
-	assert(context != nullptr);
 	assert(nfs_get_fd(context) >= 0);
 
 #ifndef NDEBUG
@@ -531,8 +527,7 @@ NfsConnection::OnSocketReady(unsigned flags) noexcept
 	in_event = false;
 #endif
 
-	if (context != nullptr)
+	ScheduleSocket();
-		ScheduleSocket();
 }
 
 inline void
@@ -568,13 +563,8 @@ inline void
 NfsConnection::MountInternal()
 {
 	assert(GetEventLoop().IsInside());
-	assert(context == nullptr);
 	assert(mount_state == MountState::INITIAL);
 
-	context = nfs_init_context();
-	if (context == nullptr)
-		throw std::runtime_error("nfs_init_context() failed");
-
 	postponed_mount_error = std::exception_ptr();
 	mount_state = MountState::WAITING;
 

src/lib/nfs/Connection.hxx

@@ -82,7 +82,7 @@ class NfsConnection {
 
 	const std::string server, export_name;
 
-	nfs_context *context;
+	nfs_context *const context;
 
 	using LeaseList = IntrusiveList<NfsLease>;
 	LeaseList new_leases, active_leases;
@@ -126,10 +126,13 @@ class NfsConnection {
 #endif
 
 public:
+	/**
+	 * Throws on error.
+	 */
 	[[gnu::nonnull]]
 	NfsConnection(EventLoop &_loop,
 		      std::string_view _server,
-		      std::string_view _export_name) noexcept;
+		      std::string_view _export_name);
 
 	/**
 	 * Must be run from EventLoop's thread.

src/lib/nfs/FileReader.cxx

@@ -266,8 +266,13 @@ NfsFileReader::OnDeferredOpen() noexcept
 {
 	assert(state == State::DEFER);
 
-	state = State::MOUNT;
+	try {
+		connection = &nfs_get_connection(server, export_name);
+	} catch (...) {
+		OnNfsFileError(std::current_exception());
+		return;
+	}
 
-	connection = &nfs_get_connection(server, export_name);
 	connection->AddLease(*this);
+	state = State::MOUNT;
 }

src/lib/nfs/Glue.cxx

@@ -41,7 +41,7 @@ nfs_get_event_loop() noexcept
 
 NfsConnection &
 nfs_get_connection(std::string_view server,
-		   std::string_view export_name) noexcept
+		   std::string_view export_name)
 {
 	assert(in_use > 0);
 

src/lib/nfs/Glue.hxx

@@ -21,7 +21,10 @@ nfs_finish() noexcept;
 EventLoop &
 nfs_get_event_loop() noexcept;
 
-[[gnu::pure]]
+/**
+ * Throws on error.
+ */
+[[nodiscard]]
 NfsConnection &
 nfs_get_connection(std::string_view server,
-		   std::string_view export_name) noexcept;
+		   std::string_view export_name);

src/lib/nfs/Manager.cxx

@@ -21,7 +21,7 @@ class NfsManager::ManagedConnection final
 public:
 	ManagedConnection(NfsManager &_manager, EventLoop &_loop,
 			  std::string_view _server,
-			  std::string_view _export_name) noexcept
+			  std::string_view _export_name)
 		:NfsConnection(_loop, _server, _export_name),
 		 manager(_manager) {}
 
@@ -55,7 +55,7 @@ NfsManager::~NfsManager() noexcept
 }
 
 NfsConnection &
-NfsManager::GetConnection(std::string_view server, std::string_view export_name) noexcept
+NfsManager::GetConnection(std::string_view server, std::string_view export_name)
 {
 	assert(GetEventLoop().IsInside());
 

src/lib/nfs/Manager.hxx

@@ -41,9 +41,12 @@ public:
 		return idle_event.GetEventLoop();
 	}
 
-	[[gnu::pure]]
+	/**
+	 * Throws on error.
+	 */
+	[[nodiscard]]
 	NfsConnection &GetConnection(std::string_view server,
-				     std::string_view export_name) noexcept;
+				     std::string_view export_name);
 
 private:
 	void ScheduleDelete(ManagedConnection &c) noexcept;

src/storage/plugins/NfsStorage.cxx

@@ -141,7 +141,14 @@ private:
 		assert(state != State::READY);
 		assert(GetEventLoop().IsInside());
 
-		connection = &nfs_get_connection(server, export_name);
+		try {
+			connection = &nfs_get_connection(server, export_name);
+		} catch (...) {
+			SetState(State::DELAY, std::current_exception());
+			reconnect_timer.Schedule(std::chrono::minutes(10));
+			return;
+		}
+
 		connection->AddLease(*this);
 
 		SetState(State::CONNECTING);