LibCore: Simplify Core::Notifier by only allowing one event type

Not a single client of this API actually used the event mask feature to
listen for readability AND writability.

Let's simplify the API and have only one hook: on_activation.

Ladybird/WebContent/main.cpp

@@ -51,7 +51,7 @@ static void proxy_socket_through_notifier(ClientType& client, QSocketNotifier& n
     notifier.setEnabled(true);
 
     QObject::connect(&notifier, &QSocketNotifier::activated, [&client]() mutable {
-        client.socket().notifier()->on_ready_to_read();
+        client.socket().notifier()->on_activation();
     });
 
     client.set_deferred_invoker(make<DeferredInvokerQt>());

Ladybird/WebContentView.cpp

@@ -610,7 +610,7 @@ void WebContentView::create_client(WebView::EnableCallgrindProfiling enable_call
 
     QObject::connect(&m_web_content_notifier, &QSocketNotifier::activated, [new_client = new_client.ptr()] {
         if (auto notifier = new_client->socket().notifier())
-            notifier->on_ready_to_read();
+            notifier->on_activation();
     });
 
     struct DeferredInvokerQt final : IPC::DeferredInvoker {

Userland/Applications/FileManager/FileOperationProgressWidget.cpp

@@ -69,8 +69,8 @@ FileOperationProgressWidget::FileOperationProgressWidget(FileOperation operation
         VERIFY_NOT_REACHED();
     }
 
-    m_notifier = Core::Notifier::construct(helper_pipe_fd, Core::Notifier::Read);
+    m_notifier = Core::Notifier::construct(helper_pipe_fd, Core::Notifier::Type::Read);
-    m_notifier->on_ready_to_read = [this] {
+    m_notifier->on_activation = [this] {
         auto line_buffer_or_error = ByteBuffer::create_zeroed(1 * KiB);
         if (line_buffer_or_error.is_error()) {
             did_error("Failed to allocate ByteBuffer for reading data."sv);
@@ -211,7 +211,7 @@ void FileOperationProgressWidget::close_pipe()
     m_helper_pipe = nullptr;
     if (m_notifier) {
         m_notifier->set_enabled(false);
-        m_notifier->on_ready_to_read = nullptr;
+        m_notifier->on_activation = nullptr;
     }
     m_notifier = nullptr;
 }

Userland/Libraries/LibChess/UCIEndpoint.cpp

@@ -15,7 +15,7 @@ namespace Chess::UCI {
 Endpoint::Endpoint(NonnullRefPtr<Core::IODevice> in, NonnullRefPtr<Core::IODevice> out)
     : m_in(in)
     , m_out(out)
-    , m_in_notifier(Core::Notifier::construct(in->fd(), Core::Notifier::Read))
+    , m_in_notifier(Core::Notifier::construct(in->fd(), Core::Notifier::Type::Read))
 {
     set_in_notifier();
 }
@@ -70,8 +70,8 @@ void Endpoint::custom_event(Core::CustomEvent& custom_event)
 
 void Endpoint::set_in_notifier()
 {
-    m_in_notifier = Core::Notifier::construct(m_in->fd(), Core::Notifier::Read);
+    m_in_notifier = Core::Notifier::construct(m_in->fd(), Core::Notifier::Type::Read);
-    m_in_notifier->on_ready_to_read = [this] {
+    m_in_notifier->on_activation = [this] {
         if (!m_in->can_read_line()) {
             Core::EventLoop::current().post_event(*this, make<Core::CustomEvent>(EndpointEventType::UnexpectedEof));
             m_in_notifier->set_enabled(false);

Userland/Libraries/LibCore/Event.h

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2018-2020, Andreas Kling <kling@serenityos.org>
+ * Copyright (c) 2018-2023, Andreas Kling <kling@serenityos.org>
  * Copyright (c) 2022, the SerenityOS developers.
  *
  * SPDX-License-Identifier: BSD-2-Clause
@@ -21,8 +21,7 @@ public:
         Invalid = 0,
         Quit,
         Timer,
-        NotifierRead,
+        NotifierActivation,
-        NotifierWrite,
         DeferredInvoke,
         ChildAdded,
         ChildRemoved,
@@ -79,29 +78,14 @@ private:
     int m_timer_id;
 };
 
-class NotifierReadEvent final : public Event {
+class NotifierActivationEvent final : public Event {
 public:
-    explicit NotifierReadEvent(int fd)
+    explicit NotifierActivationEvent(int fd)
-        : Event(Event::NotifierRead)
+        : Event(Event::NotifierActivation)
         , m_fd(fd)
     {
     }
-    ~NotifierReadEvent() = default;
+    ~NotifierActivationEvent() = default;
-
-    int fd() const { return m_fd; }
-
-private:
-    int m_fd;
-};
-
-class NotifierWriteEvent final : public Event {
-public:
-    explicit NotifierWriteEvent(int fd)
-        : Event(Event::NotifierWrite)
-        , m_fd(fd)
-    {
-    }
-    ~NotifierWriteEvent() = default;
 
     int fd() const { return m_fd; }
 

Userland/Libraries/LibCore/EventLoop.cpp

@@ -651,11 +651,11 @@ retry:
     max_fd = max(max_fd, max_fd_added);
 
     for (auto& notifier : *s_notifiers) {
-        if (notifier->event_mask() & Notifier::Read)
+        if (notifier->type() == Notifier::Type::Read)
             add_fd_to_set(notifier->fd(), rfds);
-        if (notifier->event_mask() & Notifier::Write)
+        if (notifier->type() == Notifier::Type::Write)
             add_fd_to_set(notifier->fd(), wfds);
-        if (notifier->event_mask() & Notifier::Exceptional)
+        if (notifier->type() == Notifier::Type::Exceptional)
             VERIFY_NOT_REACHED();
     }
 
@@ -757,13 +757,11 @@ try_select_again:
 
     // Handle file system notifiers by making them normal events.
     for (auto& notifier : *s_notifiers) {
-        if (FD_ISSET(notifier->fd(), &rfds)) {
+        if (notifier->type() == Notifier::Type::Read && FD_ISSET(notifier->fd(), &rfds)) {
-            if (notifier->event_mask() & Notifier::Event::Read)
+            post_event(*notifier, make<NotifierActivationEvent>(notifier->fd()));
-                post_event(*notifier, make<NotifierReadEvent>(notifier->fd()));
         }
-        if (FD_ISSET(notifier->fd(), &wfds)) {
+        if (notifier->type() == Notifier::Type::Write && FD_ISSET(notifier->fd(), &wfds)) {
-            if (notifier->event_mask() & Notifier::Event::Write)
+            post_event(*notifier, make<NotifierActivationEvent>(notifier->fd()));
-                post_event(*notifier, make<NotifierWriteEvent>(notifier->fd()));
         }
     }
 }

Userland/Libraries/LibCore/FileWatcherLinux.cpp

@@ -97,7 +97,7 @@ ErrorOr<NonnullRefPtr<FileWatcher>> FileWatcher::create(FileWatcherFlags flags)
     if (watcher_fd < 0)
         return Error::from_errno(errno);
 
-    auto notifier = TRY(Notifier::try_create(watcher_fd, Notifier::Event::Read));
+    auto notifier = TRY(Notifier::try_create(watcher_fd, Notifier::Type::Read));
     return adopt_nonnull_ref_or_enomem(new (nothrow) FileWatcher(watcher_fd, move(notifier)));
 }
 
@@ -105,7 +105,7 @@ FileWatcher::FileWatcher(int watcher_fd, NonnullRefPtr<Notifier> notifier)
     : FileWatcherBase(watcher_fd)
     , m_notifier(move(notifier))
 {
-    m_notifier->on_ready_to_read = [this] {
+    m_notifier->on_activation = [this] {
         auto maybe_event = get_event_from_fd(m_notifier->fd(), m_wd_to_path);
         if (maybe_event.has_value()) {
             auto event = maybe_event.value();

Userland/Libraries/LibCore/FileWatcherMacOS.mm

@@ -59,7 +59,7 @@ public:
 
         // NOTE: This isn't actually used on macOS, but is needed for FileWatcherBase.
         //       Creating it with an FD of -1 will effectively disable the notifier.
-        auto notifier = TRY(Notifier::try_create(-1, Notifier::Event::None));
+        auto notifier = TRY(Notifier::try_create(-1, Notifier::Type::None));
 
         return adopt_nonnull_ref_or_enomem(new (nothrow) FileWatcherMacOS(move(context), dispatch_queue, move(notifier)));
     }

Userland/Libraries/LibCore/FileWatcherSerenity.cpp

@@ -188,7 +188,7 @@ ErrorOr<NonnullRefPtr<FileWatcher>> FileWatcher::create(FileWatcherFlags flags)
     if (watcher_fd < 0)
         return Error::from_errno(errno);
 
-    auto notifier = Notifier::construct(watcher_fd, Notifier::Event::Read);
+    auto notifier = Notifier::construct(watcher_fd, Notifier::Type::Read);
     return adopt_ref(*new FileWatcher(watcher_fd, move(notifier)));
 }
 
@@ -196,7 +196,7 @@ FileWatcher::FileWatcher(int watcher_fd, NonnullRefPtr<Notifier> notifier)
     : FileWatcherBase(watcher_fd)
     , m_notifier(move(notifier))
 {
-    m_notifier->on_ready_to_read = [this] {
+    m_notifier->on_activation = [this] {
         auto maybe_event = get_event_from_fd(m_notifier->fd(), m_wd_to_path);
         if (maybe_event.has_value()) {
             auto event = maybe_event.value();
@@ -214,7 +214,7 @@ FileWatcher::FileWatcher(int watcher_fd, NonnullRefPtr<Notifier> notifier)
 
 FileWatcher::~FileWatcher()
 {
-    m_notifier->on_ready_to_read = nullptr;
+    m_notifier->on_activation = nullptr;
     close(m_notifier->fd());
     dbgln_if(FILE_WATCHER_DEBUG, "Stopped watcher at fd {}", m_notifier->fd());
 }

Userland/Libraries/LibCore/LocalServer.cpp

@@ -49,8 +49,8 @@ ErrorOr<void> LocalServer::take_over_from_system_server(DeprecatedString const&
 
 void LocalServer::setup_notifier()
 {
-    m_notifier = Notifier::construct(m_fd, Notifier::Event::Read, this);
+    m_notifier = Notifier::construct(m_fd, Notifier::Type::Read, this);
-    m_notifier->on_ready_to_read = [this] {
+    m_notifier->on_activation = [this] {
         if (on_accept) {
             auto maybe_client_socket = accept();
             if (maybe_client_socket.is_error()) {

Userland/Libraries/LibCore/Notifier.cpp

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2018-2020, Andreas Kling <kling@serenityos.org>
+ * Copyright (c) 2018-2023, Andreas Kling <kling@serenityos.org>
  *
  * SPDX-License-Identifier: BSD-2-Clause
  */
@@ -10,10 +10,10 @@
 
 namespace Core {
 
-Notifier::Notifier(int fd, unsigned event_mask, Object* parent)
+Notifier::Notifier(int fd, Type type, Object* parent)
     : Object(parent)
     , m_fd(fd)
-    , m_event_mask(event_mask)
+    , m_type(type)
 {
     set_enabled(true);
 }
@@ -43,13 +43,12 @@ void Notifier::close()
 
 void Notifier::event(Core::Event& event)
 {
-    if (event.type() == Core::Event::NotifierRead && on_ready_to_read) {
+    if (event.type() == Core::Event::NotifierActivation) {
-        on_ready_to_read();
+        if (on_activation)
-    } else if (event.type() == Core::Event::NotifierWrite && on_ready_to_write) {
+            on_activation();
-        on_ready_to_write();
+        return;
-    } else {
-        Object::event(event);
     }
+    Object::event(event);
 }
 
 }

Userland/Libraries/LibCore/Notifier.h

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2018-2020, Andreas Kling <kling@serenityos.org>
+ * Copyright (c) 2018-2023, Andreas Kling <kling@serenityos.org>
  *
  * SPDX-License-Identifier: BSD-2-Clause
  */
@@ -11,36 +11,36 @@
 
 namespace Core {
 
-class Notifier : public Object {
+class Notifier final : public Object {
-    C_OBJECT(Notifier)
+    C_OBJECT(Notifier);
+
 public:
-    enum Event {
+    enum class Type {
-        None = 0,
+        None,
-        Read = 1,
+        Read,
-        Write = 2,
+        Write,
-        Exceptional = 4,
+        Exceptional,
     };
 
     virtual ~Notifier() override;
 
     void set_enabled(bool);
 
-    Function<void()> on_ready_to_read;
+    Function<void()> on_activation;
-    Function<void()> on_ready_to_write;
 
     void close();
 
     int fd() const { return m_fd; }
-    unsigned event_mask() const { return m_event_mask; }
+    Type type() const { return m_type; }
-    void set_event_mask(unsigned event_mask) { m_event_mask = event_mask; }
+    void set_type(Type type) { m_type = type; }
 
     void event(Core::Event&) override;
 
 private:
-    Notifier(int fd, unsigned event_mask, Object* parent = nullptr);
+    Notifier(int fd, Type type, Object* parent = nullptr);
 
     int m_fd { -1 };
-    unsigned m_event_mask { 0 };
+    Type m_type { Type::None };
 };
 
 }

Userland/Libraries/LibCore/Socket.cpp

@@ -186,7 +186,7 @@ ErrorOr<void> PosixSocketHelper::set_receive_timeout(Time timeout)
 void PosixSocketHelper::setup_notifier()
 {
     if (!m_notifier)
-        m_notifier = Core::Notifier::construct(m_fd, Core::Notifier::Read);
+        m_notifier = Core::Notifier::construct(m_fd, Core::Notifier::Type::Read);
 }
 
 ErrorOr<NonnullOwnPtr<TCPSocket>> TCPSocket::connect(DeprecatedString const& host, u16 port)

Userland/Libraries/LibCore/Socket.h

@@ -204,7 +204,7 @@ private:
         VERIFY(is_open());
 
         m_helper.setup_notifier();
-        m_helper.notifier()->on_ready_to_read = [this] {
+        m_helper.notifier()->on_activation = [this] {
             if (on_ready_to_read)
                 on_ready_to_read();
         };
@@ -278,7 +278,7 @@ private:
         VERIFY(is_open());
 
         m_helper.setup_notifier();
-        m_helper.notifier()->on_ready_to_read = [this] {
+        m_helper.notifier()->on_activation = [this] {
             if (on_ready_to_read)
                 on_ready_to_read();
         };
@@ -352,7 +352,7 @@ private:
         VERIFY(is_open());
 
         m_helper.setup_notifier();
-        m_helper.notifier()->on_ready_to_read = [this] {
+        m_helper.notifier()->on_activation = [this] {
             if (on_ready_to_read)
                 on_ready_to_read();
         };

Userland/Libraries/LibCore/TCPServer.cpp

@@ -57,8 +57,8 @@ ErrorOr<void> TCPServer::listen(IPv4Address const& address, u16 port, AllowAddre
     TRY(Core::System::listen(m_fd, 5));
     m_listening = true;
 
-    m_notifier = Notifier::construct(m_fd, Notifier::Event::Read, this);
+    m_notifier = Notifier::construct(m_fd, Notifier::Type::Read, this);
-    m_notifier->on_ready_to_read = [this] {
+    m_notifier->on_activation = [this] {
         if (on_ready_to_accept)
             on_ready_to_accept();
     };

Userland/Libraries/LibCore/UDPServer.cpp

@@ -55,8 +55,8 @@ bool UDPServer::bind(IPv4Address const& address, u16 port)
 
     m_bound = true;
 
-    m_notifier = Notifier::construct(m_fd, Notifier::Event::Read, this);
+    m_notifier = Notifier::construct(m_fd, Notifier::Type::Read, this);
-    m_notifier->on_ready_to_read = [this] {
+    m_notifier->on_activation = [this] {
         if (on_ready_to_receive)
             on_ready_to_receive();
     };

Userland/Libraries/LibLine/Editor.cpp

@@ -747,9 +747,9 @@ auto Editor::get_line(DeprecatedString const& prompt) -> Result<DeprecatedString
 
     Core::EventLoop loop;
 
-    m_notifier = Core::Notifier::construct(STDIN_FILENO, Core::Notifier::Read);
+    m_notifier = Core::Notifier::construct(STDIN_FILENO, Core::Notifier::Type::Read);
 
-    m_notifier->on_ready_to_read = [&] {
+    m_notifier->on_activation = [&] {
         if (try_update_once().is_error())
             loop.quit(Exit);
     };

Userland/Libraries/LibProtocol/Request.cpp

@@ -25,7 +25,7 @@ void Request::stream_into(Stream& stream)
     VERIFY(!m_internal_stream_data);
 
     m_internal_stream_data = make<InternalStreamData>(MUST(Core::File::adopt_fd(fd(), Core::File::OpenMode::Read)));
-    m_internal_stream_data->read_notifier = Core::Notifier::construct(fd(), Core::Notifier::Read);
+    m_internal_stream_data->read_notifier = Core::Notifier::construct(fd(), Core::Notifier::Type::Read);
 
     auto user_on_finish = move(on_finish);
     on_finish = [this](auto success, auto total_size) {
@@ -41,7 +41,7 @@ void Request::stream_into(Stream& stream)
             user_on_finish(m_internal_stream_data->success, m_internal_stream_data->total_size);
         }
     };
-    m_internal_stream_data->read_notifier->on_ready_to_read = [this, &stream] {
+    m_internal_stream_data->read_notifier->on_activation = [this, &stream] {
         constexpr size_t buffer_size = 256 * KiB;
         static char buf[buffer_size];
         do {

Userland/Libraries/LibVT/TerminalWidget.cpp

@@ -47,8 +47,8 @@ void TerminalWidget::set_pty_master_fd(int fd)
         m_notifier = nullptr;
         return;
     }
-    m_notifier = Core::Notifier::construct(m_ptm_fd, Core::Notifier::Read);
+    m_notifier = Core::Notifier::construct(m_ptm_fd, Core::Notifier::Type::Read);
-    m_notifier->on_ready_to_read = [this] {
+    m_notifier->on_activation = [this] {
         u8 buffer[BUFSIZ];
         ssize_t nread = read(m_ptm_fd, buffer, sizeof(buffer));
         if (nread < 0) {

Userland/Services/SpiceAgent/SpiceAgent.cpp

@@ -19,8 +19,8 @@ SpiceAgent::SpiceAgent(int fd, ConnectionToClipboardServer& connection)
     : m_fd(fd)
     , m_clipboard_connection(connection)
 {
-    m_notifier = Core::Notifier::construct(fd, Core::Notifier::Read);
+    m_notifier = Core::Notifier::construct(fd, Core::Notifier::Type::Read);
-    m_notifier->on_ready_to_read = [this] {
+    m_notifier->on_activation = [this] {
         on_message_received();
     };
     m_clipboard_connection.on_data_changed = [this] {

Userland/Services/SystemServer/Service.cpp

@@ -82,8 +82,8 @@ void Service::setup_notifier()
     VERIFY(m_sockets.size() == 1);
     VERIFY(!m_socket_notifier);
 
-    m_socket_notifier = Core::Notifier::construct(m_sockets[0].fd, Core::Notifier::Event::Read, this);
+    m_socket_notifier = Core::Notifier::construct(m_sockets[0].fd, Core::Notifier::Type::Read, this);
-    m_socket_notifier->on_ready_to_read = [this] {
+    m_socket_notifier->on_activation = [this] {
         if (auto result = handle_socket_connection(); result.is_error())
             dbgln("{}", result.release_error());
     };

Userland/Services/TelnetServer/Client.cpp

@@ -21,7 +21,7 @@ Client::Client(int id, NonnullOwnPtr<Core::TCPSocket> socket, int ptm_fd)
     : m_id(id)
     , m_socket(move(socket))
     , m_ptm_fd(ptm_fd)
-    , m_ptm_notifier(Core::Notifier::construct(ptm_fd, Core::Notifier::Read))
+    , m_ptm_notifier(Core::Notifier::construct(ptm_fd, Core::Notifier::Type::Read))
 {
     m_socket->on_ready_to_read = [this] {
         auto result = drain_socket();
@@ -31,7 +31,7 @@ Client::Client(int id, NonnullOwnPtr<Core::TCPSocket> socket, int ptm_fd)
         }
     };
 
-    m_ptm_notifier->on_ready_to_read = [this] {
+    m_ptm_notifier->on_activation = [this] {
         auto result = drain_pty();
         if (result.is_error()) {
             dbgln("Failed to drain the PTY: {}", result.error());

Userland/Services/WindowServer/EventLoop.cpp

@@ -27,15 +27,15 @@ EventLoop::EventLoop()
     m_wm_server = MUST(IPC::MultiServer<WMConnectionFromClient>::try_create("/tmp/portal/wm"));
 
     if (m_keyboard_fd >= 0) {
-        m_keyboard_notifier = Core::Notifier::construct(m_keyboard_fd, Core::Notifier::Read);
+        m_keyboard_notifier = Core::Notifier::construct(m_keyboard_fd, Core::Notifier::Type::Read);
-        m_keyboard_notifier->on_ready_to_read = [this] { drain_keyboard(); };
+        m_keyboard_notifier->on_activation = [this] { drain_keyboard(); };
     } else {
         dbgln("Couldn't open /dev/input/keyboard/0");
     }
 
     if (m_mouse_fd >= 0) {
-        m_mouse_notifier = Core::Notifier::construct(m_mouse_fd, Core::Notifier::Read);
+        m_mouse_notifier = Core::Notifier::construct(m_mouse_fd, Core::Notifier::Type::Read);
-        m_mouse_notifier->on_ready_to_read = [this] { drain_mouse(); };
+        m_mouse_notifier->on_activation = [this] { drain_mouse(); };
     } else {
         dbgln("Couldn't open /dev/input/mouse/0");
     }

Userland/Shell/AST.cpp

@@ -1742,7 +1742,7 @@ ErrorOr<void> Execute::for_each_entry(RefPtr<Shell> shell, Function<ErrorOr<Iter
 
         Core::EventLoop loop;
 
-        auto notifier = Core::Notifier::construct(pipefd[0], Core::Notifier::Read);
+        auto notifier = Core::Notifier::construct(pipefd[0], Core::Notifier::Type::Read);
         AllocatingMemoryStream stream;
 
         enum CheckResult {
@@ -1788,18 +1788,18 @@ ErrorOr<void> Execute::for_each_entry(RefPtr<Shell> shell, Function<ErrorOr<Iter
             return NothingLeft;
         };
 
-        notifier->on_ready_to_read = [&]() -> void {
+        notifier->on_activation = [&]() -> void {
             constexpr static auto buffer_size = 16;
             u8 buffer[buffer_size];
             size_t remaining_size = buffer_size;
 
             for (;;) {
-                notifier->set_event_mask(Core::Notifier::None);
+                notifier->set_type(Core::Notifier::Type::None);
                 bool should_enable_notifier = false;
 
                 ScopeGuard notifier_enabler { [&] {
                     if (should_enable_notifier)
-                        notifier->set_event_mask(Core::Notifier::Read);
+                        notifier->set_type(Core::Notifier::Type::Read);
                 } };
 
                 if (check_and_call().release_value_but_fixme_should_propagate_errors() == Break) {
@@ -1841,7 +1841,7 @@ ErrorOr<void> Execute::for_each_entry(RefPtr<Shell> shell, Function<ErrorOr<Iter
 
         auto exit_reason = loop.exec();
 
-        notifier->on_ready_to_read = nullptr;
+        notifier->on_activation = nullptr;
 
         if (close(pipefd[0]) < 0) {
             dbgln("close() failed: {}", strerror(errno));