Added callback for events.

memqueue.h

@@ -0,0 +1,72 @@
+#ifndef MEMQUEUE_H
+#define MEMQUEUE_H
+
+#include <string>
+#include <mutex>
+
+class MemQueueItem
+{
+public:
+    MemQueueItem *next;
+    std::string _event;
+    int         _wv;
+};
+
+class MemQueue
+{
+private:
+    std::mutex    _mutex;
+    int           _depth;
+    MemQueueItem *_first;
+    MemQueueItem *_last;
+
+public:
+    void enqueue(int w, std::string s) {
+        _mutex.lock();
+        MemQueueItem *item = new MemQueueItem();
+        item->next = nullptr;
+        item->_event = s;
+        item->_wv = w;
+        if (_last == nullptr) {
+            _last = item;
+            _first = item;
+        } else {
+            _last->next = item;
+            _last = item;
+        }
+        _depth += 1;
+        _mutex.unlock();
+    }
+
+    bool dequeue(int &wv, std::string &s) {
+        _mutex.lock();
+        if (_first == nullptr) {
+            _mutex.unlock();
+            return false;
+        }
+        MemQueueItem *item = _first;
+        _first = _first->next;
+        if (_first == nullptr) {
+            _last = nullptr;
+        }
+        s = item->_event;
+        wv = item->_wv;
+        free(item);
+        _depth -= 1;
+        _mutex.unlock();
+        return true;
+    }
+
+    int depth() {
+        return _depth;
+    }
+
+public:
+    MemQueue() {
+        _depth = 0;
+        _first = nullptr;
+        _last = nullptr;
+    }
+};
+
+#endif // MEMQUEUE_H