Refactored EventNotifier RAII class

src/CMakeLists.txt

@@ -8,6 +8,7 @@ target_sources(
         ${CMAKE_CURRENT_SOURCE_DIR}/Logger/Logger.cpp
         ${CMAKE_CURRENT_SOURCE_DIR}/Helpers/Paths.cpp
         ${CMAKE_CURRENT_SOURCE_DIR}/Helpers/EpollInstance.cpp
+        ${CMAKE_CURRENT_SOURCE_DIR}/Helpers/EventNotifier.cpp
         ${CMAKE_CURRENT_SOURCE_DIR}/VersionNumber.cpp
         ${CMAKE_CURRENT_SOURCE_DIR}/Generated/resources.cpp
 

src/Helpers/EventNotifier.cpp

@@ -0,0 +1,55 @@
+#include "EventNotifier.hpp"
+
+#include <sys/eventfd.h>
+#include <unistd.h>
+#include <cerrno>
+#include <string>
+
+#include "src/Exceptions/Exception.hpp"
+
+namespace Bloom
+{
+    using Exceptions::Exception;
+
+    EventNotifier::EventNotifier() {
+        this->fileDescriptor = ::eventfd(0, EFD_NONBLOCK);
+
+        if (this->fileDescriptor < 0) {
+            throw Exception(
+                "Failed to create eventfd object - error number " + std::to_string(errno)
+                    + " returned."
+            );
+        }
+    }
+
+    EventNotifier::EventNotifier(EventNotifier&& other) noexcept
+        : fileDescriptor(other.fileDescriptor)
+    {
+        other.fileDescriptor = std::nullopt;
+    }
+
+    EventNotifier::~EventNotifier() noexcept {
+        this->close();
+    }
+
+    void EventNotifier::notify() {
+        if (::eventfd_write(this->fileDescriptor.value(), 1) < 0) {
+            throw Exceptions::Exception("Failed to increment eventfd counter - error number: "
+                + std::to_string(errno));
+        }
+    }
+
+    void EventNotifier::clear() {
+        eventfd_t counter = {};
+        if (::eventfd_read(this->fileDescriptor.value(), &counter) < 0 && errno != EAGAIN) {
+            throw Exceptions::Exception("Failed to clear EventNotifier object - eventfd_read failed - "
+                "error number: " + std::to_string(errno));
+        }
+    }
+
+    void EventNotifier::close() {
+        if (this->fileDescriptor.value_or(-1) >= 0) {
+            ::close(this->fileDescriptor.value());
+        }
+    }
+}

src/Helpers/EventNotifier.hpp

@@ -1,82 +1,45 @@
 #pragma once
 
-#include <sys/eventfd.h>
+#include <optional>
-#include <errno.h>
-#include <fcntl.h>
-#include <unistd.h>
-#include <atomic>
-
-#include "src/Exceptions/Exception.hpp"
 
 namespace Bloom
 {
     /**
-     * The EventNotifier class provides a means to interrupt a thread that is blocked by an IO call.
+     * The EventNotifier class is an RAII wrapper for a Linux eventfd object.
-     *
-     * It's implementation is rather simple: It uses a Linux event file descriptor (sys/eventfd.h), which should be used
-     * along side epoll() to interrupt a blocking call that is waiting on the epoll file descriptor.
      *
      * The EventListener can hold an instance to EventNotifier, where it will invoke EventNotifier::notify() everytime
      * a new event is registered on the listener.
-     *
-     * @TODO: This could do with some cleaning. It's a bit hacky. Also, maybe add the ability to register the event
-     *        file descriptor to an epoll instance within a public method (instead of relying on the caller to do this
-     *        themselves via EventNotifier::getFileDescriptor()).
      */
     class EventNotifier
     {
     public:
-        EventNotifier() {
+        EventNotifier();
-            this->init();
-        };
 
-        ~EventNotifier() {
+        /*
-            if (this->initialised) {
+         * EpollInstance objects should not be copied.
-                this->close();
+         */
-            }
+        EventNotifier(EventNotifier& other) = delete;
+        EventNotifier& operator = (EventNotifier& other) = delete;
+
+        /*
+         * TODO: Implement this. For now, use the move constructor.
+         */
+        EventNotifier& operator = (EventNotifier&& other) = delete;
+
+        EventNotifier(EventNotifier&& other) noexcept;
+        ~EventNotifier() noexcept;
+
+        [[nodiscard]] int getFileDescriptor() const {
+            return this->fileDescriptor.value();
         }
 
-        int getFileDescriptor() const {
+        void notify();
-            return this->fileDescriptor;
-        }
 
-        bool isInitialised() {
+        void clear();
-            return this->initialised;
-        }
-
-        void notify() {
-            if (::eventfd_write(this->fileDescriptor, 1) < 0) {
-                throw Exceptions::Exception("Failed to increment eventfd counter - error number: "
-                    + std::to_string(errno));
-            }
-        }
-
-        void clear() {
-            eventfd_t counter;
-            if (::eventfd_read(this->fileDescriptor, &counter) < 0 && errno != EAGAIN) {
-                throw Exceptions::Exception("Failed to clear EventNotifier object - eventfd_read failed - "
-                    "error number: " + std::to_string(errno));
-            }
-        }
 
     private:
-        int fileDescriptor = -1;
+        std::optional<int> fileDescriptor;
-        std::atomic<bool> initialised = false;
 
-        void init() {
+        void close();
-            this->fileDescriptor = ::eventfd(0, EFD_NONBLOCK);
-
-            if (this->fileDescriptor < -1) {
-                throw Exceptions::Exception("Failed to create new eventfd object - error number: "
-                    + std::to_string(errno));
-            }
-
-            this->initialised = true;
-        }
-
-        void close() {
-            ::close(this->fileDescriptor);
-            this->initialised = false;
-        }
     };
 }