feat(Core/Database): port TrinityCore database API (#5611)

src/common/Threading/ProducerConsumerQueue.h

@@ -0,0 +1,100 @@
+/*
+ * Copyright (C) 2016+ AzerothCore <www.azerothcore.org>, released under GNU AGPL v3 license: https://github.com/azerothcore/azerothcore-wotlk/blob/master/LICENSE-AGPL3
+ * Copyright (C) 2021+ WarheadCore <https://github.com/WarheadCore>
+ */
+
+#ifndef _PCQ_H
+#define _PCQ_H
+
+#include <condition_variable>
+#include <mutex>
+#include <queue>
+#include <atomic>
+#include <type_traits>
+
+template <typename T>
+class ProducerConsumerQueue
+{
+private:
+    std::mutex _queueLock;
+    std::queue<T> _queue;
+    std::condition_variable _condition;
+    std::atomic<bool> _shutdown;
+
+public:
+
+    ProducerConsumerQueue<T>() : _shutdown(false) { }
+
+    void Push(const T& value)
+    {
+        std::lock_guard<std::mutex> lock(_queueLock);
+        _queue.push(std::move(value));
+
+        _condition.notify_one();
+    }
+
+    bool Empty()
+    {
+        std::lock_guard<std::mutex> lock(_queueLock);
+
+        return _queue.empty();
+    }
+
+    bool Pop(T& value)
+    {
+        std::lock_guard<std::mutex> lock(_queueLock);
+
+        if (_queue.empty() || _shutdown)
+            return false;
+
+        value = _queue.front();
+
+        _queue.pop();
+
+        return true;
+    }
+
+    void WaitAndPop(T& value)
+    {
+        std::unique_lock<std::mutex> lock(_queueLock);
+
+        // we could be using .wait(lock, predicate) overload here but it is broken
+        // https://connect.microsoft.com/VisualStudio/feedback/details/1098841
+        while (_queue.empty() && !_shutdown)
+            _condition.wait(lock);
+
+        if (_queue.empty() || _shutdown)
+            return;
+
+        value = _queue.front();
+
+        _queue.pop();
+    }
+
+    void Cancel()
+    {
+        std::unique_lock<std::mutex> lock(_queueLock);
+
+        while (!_queue.empty())
+        {
+            T& value = _queue.front();
+
+            DeleteQueuedObject(value);
+
+            _queue.pop();
+        }
+
+        _shutdown = true;
+
+        _condition.notify_all();
+    }
+
+private:
+    template<typename E = T>
+    typename std::enable_if<std::is_pointer<E>::value>::type DeleteQueuedObject(E& obj) { delete obj; }
+
+    template<typename E = T>
+    typename std::enable_if<!std::is_pointer<E>::value>::type DeleteQueuedObject(E const& /*packet*/) { }
+};
+
+#endif

src/common/Utilities/AsyncCallbackProcessor.h

@@ -0,0 +1,51 @@
+/*
+ * Copyright (C) 2016+ AzerothCore <www.azerothcore.org>, released under GNU AGPL v3 license: https://github.com/azerothcore/azerothcore-wotlk/blob/master/LICENSE-AGPL3
+ * Copyright (C) 2021+ WarheadCore <https://github.com/WarheadCore>
+ */
+
+#ifndef AsyncCallbackProcessor_h__
+#define AsyncCallbackProcessor_h__
+
+#include "Define.h"
+#include <algorithm>
+#include <vector>
+
+//template <class T>
+//concept AsyncCallback = requires(T t) { { t.InvokeIfReady() } -> std::convertible_to<bool> };
+
+template<typename T> // requires AsyncCallback<T>
+class AsyncCallbackProcessor
+{
+public:
+    AsyncCallbackProcessor() = default;
+    ~AsyncCallbackProcessor() = default;
+
+    T& AddCallback(T&& query)
+    {
+        _callbacks.emplace_back(std::move(query));
+        return _callbacks.back();
+    }
+
+    void ProcessReadyCallbacks()
+    {
+        if (_callbacks.empty())
+            return;
+
+        std::vector<T> updateCallbacks{ std::move(_callbacks) };
+
+        updateCallbacks.erase(std::remove_if(updateCallbacks.begin(), updateCallbacks.end(), [](T& callback)
+        {
+            return callback.InvokeIfReady();
+        }), updateCallbacks.end());
+
+        _callbacks.insert(_callbacks.end(), std::make_move_iterator(updateCallbacks.begin()), std::make_move_iterator(updateCallbacks.end()));
+    }
+
+private:
+    AsyncCallbackProcessor(AsyncCallbackProcessor const&) = delete;
+    AsyncCallbackProcessor& operator=(AsyncCallbackProcessor const&) = delete;
+
+    std::vector<T> _callbacks;
+};
+
+#endif // AsyncCallbackProcessor_h__