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.

12 files changed, 51 insertions, 70 deletions

diff --git a/Userland/Libraries/LibCore/Event.h b/Userland/Libraries/LibCore/Event.h
index f3da4419e4..a539ee5943 100644
--- a/Userland/Libraries/LibCore/Event.h
+++ b/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,
-        NotifierWrite,
+        NotifierActivation,
         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)
-        : Event(Event::NotifierRead)
+    explicit NotifierActivationEvent(int fd)
+        : Event(Event::NotifierActivation)
         , m_fd(fd)
     {
     }
-    ~NotifierReadEvent() = 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;
+    ~NotifierActivationEvent() = default;
 
     int fd() const { return m_fd; }
 
diff --git a/Userland/Libraries/LibCore/EventLoop.cpp b/Userland/Libraries/LibCore/EventLoop.cpp
index 979e551047..c8f48c6ebf 100644
--- a/Userland/Libraries/LibCore/EventLoop.cpp
+++ b/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->event_mask() & Notifier::Event::Read)
-                post_event(*notifier, make<NotifierReadEvent>(notifier->fd()));
+        if (notifier->type() == Notifier::Type::Read && FD_ISSET(notifier->fd(), &rfds)) {
+            post_event(*notifier, make<NotifierActivationEvent>(notifier->fd()));
         }
-        if (FD_ISSET(notifier->fd(), &wfds)) {
-            if (notifier->event_mask() & Notifier::Event::Write)
-                post_event(*notifier, make<NotifierWriteEvent>(notifier->fd()));
+        if (notifier->type() == Notifier::Type::Write && FD_ISSET(notifier->fd(), &wfds)) {
+            post_event(*notifier, make<NotifierActivationEvent>(notifier->fd()));
         }
     }
 }
diff --git a/Userland/Libraries/LibCore/FileWatcherLinux.cpp b/Userland/Libraries/LibCore/FileWatcherLinux.cpp
index 963e809e73..4c0ccdc969 100644
--- a/Userland/Libraries/LibCore/FileWatcherLinux.cpp
+++ b/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();
diff --git a/Userland/Libraries/LibCore/FileWatcherMacOS.mm b/Userland/Libraries/LibCore/FileWatcherMacOS.mm
index 760fe6dc51..c546698273 100644
--- a/Userland/Libraries/LibCore/FileWatcherMacOS.mm
+++ b/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)));
     }
diff --git a/Userland/Libraries/LibCore/FileWatcherSerenity.cpp b/Userland/Libraries/LibCore/FileWatcherSerenity.cpp
index fbf3344729..946826981e 100644
--- a/Userland/Libraries/LibCore/FileWatcherSerenity.cpp
+++ b/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());
 }
diff --git a/Userland/Libraries/LibCore/LocalServer.cpp b/Userland/Libraries/LibCore/LocalServer.cpp
index 88a614fc8b..49f78c37fa 100644
--- a/Userland/Libraries/LibCore/LocalServer.cpp
+++ b/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->on_ready_to_read = [this] {
+    m_notifier = Notifier::construct(m_fd, Notifier::Type::Read, this);
+    m_notifier->on_activation = [this] {
         if (on_accept) {
             auto maybe_client_socket = accept();
             if (maybe_client_socket.is_error()) {
diff --git a/Userland/Libraries/LibCore/Notifier.cpp b/Userland/Libraries/LibCore/Notifier.cpp
index 17d55cfa7b..04e620f1be 100644
--- a/Userland/Libraries/LibCore/Notifier.cpp
+++ b/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) {
-        on_ready_to_read();
-    } else if (event.type() == Core::Event::NotifierWrite && on_ready_to_write) {
-        on_ready_to_write();
-    } else {
-        Object::event(event);
+    if (event.type() == Core::Event::NotifierActivation) {
+        if (on_activation)
+            on_activation();
+        return;
     }
+    Object::event(event);
 }
 
 }
diff --git a/Userland/Libraries/LibCore/Notifier.h b/Userland/Libraries/LibCore/Notifier.h
index ff7d0eb8c8..1815ad0b2c 100644
--- a/Userland/Libraries/LibCore/Notifier.h
+++ b/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 {
-    C_OBJECT(Notifier)
+class Notifier final : public Object {
+    C_OBJECT(Notifier);
+
 public:
-    enum Event {
-        None = 0,
-        Read = 1,
-        Write = 2,
-        Exceptional = 4,
+    enum class Type {
+        None,
+        Read,
+        Write,
+        Exceptional,
     };
 
     virtual ~Notifier() override;
 
     void set_enabled(bool);
 
-    Function<void()> on_ready_to_read;
-    Function<void()> on_ready_to_write;
+    Function<void()> on_activation;
 
     void close();
 
     int fd() const { return m_fd; }
-    unsigned event_mask() const { return m_event_mask; }
-    void set_event_mask(unsigned event_mask) { m_event_mask = event_mask; }
+    Type type() const { return m_type; }
+    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 };
 };
 
 }
diff --git a/Userland/Libraries/LibCore/Socket.cpp b/Userland/Libraries/LibCore/Socket.cpp
index dfc400322f..639837ae0b 100644
--- a/Userland/Libraries/LibCore/Socket.cpp
+++ b/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)
diff --git a/Userland/Libraries/LibCore/Socket.h b/Userland/Libraries/LibCore/Socket.h
index 0906b02116..f005fa2074 100644
--- a/Userland/Libraries/LibCore/Socket.h
+++ b/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();
         };
diff --git a/Userland/Libraries/LibCore/TCPServer.cpp b/Userland/Libraries/LibCore/TCPServer.cpp
index d5ab99f241..0a5a42963e 100644
--- a/Userland/Libraries/LibCore/TCPServer.cpp
+++ b/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->on_ready_to_read = [this] {
+    m_notifier = Notifier::construct(m_fd, Notifier::Type::Read, this);
+    m_notifier->on_activation = [this] {
         if (on_ready_to_accept)
             on_ready_to_accept();
     };
diff --git a/Userland/Libraries/LibCore/UDPServer.cpp b/Userland/Libraries/LibCore/UDPServer.cpp
index da46081c19..70249b623a 100644
--- a/Userland/Libraries/LibCore/UDPServer.cpp
+++ b/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->on_ready_to_read = [this] {
+    m_notifier = Notifier::construct(m_fd, Notifier::Type::Read, this);
+    m_notifier->on_activation = [this] {
         if (on_ready_to_receive)
             on_ready_to_receive();
     };