Imported Upstream version 2.99.6upstream/2.99.6

1 files changed, 84 insertions, 0 deletions

diff --git a/SQLiteStudio3/coreSQLiteStudio/common/objectpool.h b/SQLiteStudio3/coreSQLiteStudio/common/objectpool.h
new file mode 100644
index 0000000..b9f6b9f
--- /dev/null
+++ b/SQLiteStudio3/coreSQLiteStudio/common/objectpool.h
@@ -0,0 +1,84 @@
+#ifndef OBJECTPOOL_H
+#define OBJECTPOOL_H
+
+#include <QHash>
+#include <QHashIterator>
+#include <QMutex>
+#include <QWaitCondition>
+
+template <class T>
+class ObjectPool
+{
+    public:
+        ObjectPool(quint32 min, quint32 max);
+
+        T* reserve();
+        void release(T* obj);
+
+    private:
+        QHash<T*, bool> pool;
+        QMutex mutex;
+        QWaitCondition waitCond;
+        int min;
+        int max;
+};
+
+template <class T>
+ObjectPool::ObjectPool(quint32 min, quint32 max)
+    : min(min), max(max)
+{
+    Q_ASSERT(min > 0);
+    T* obj = nullptr;
+    for (int i = 0; i < min; i++)
+    {
+        obj = new T();
+        pool[obj] = false;
+    }
+}
+
+T* ObjectPool::reserve()
+{
+    mutex.lock();
+
+    forever
+    {
+        QHashIterator<T*, bool> i(pool);
+        while (i.hasNext())
+        {
+            i.next();
+            if (!i.value())
+            {
+                pool[i.key()] = true;
+                T* obj = i.key();
+                mutex.unlock();
+                return obj;
+            }
+        }
+
+        // Check if we can enlarge the pool
+        if (pool.size() < max)
+        {
+            T* obj = new T();
+            pool[i.key()] = true;
+            mutex.unlock();
+            return obj;
+        }
+
+        // Wait for release
+        waitCond.wait(&mutex);
+    }
+
+    // no need to unlock, because the loop will repeat
+    // until the free obj is found and then mutex is unlocked.
+}
+
+template <class T>
+void ObjectPool::release(T* obj)
+{
+    mutex.lock();
+    pool[obj] = false;
+    mutex.unlock();
+    waitCond.wakeOne();
+}
+
+#endif // OBJECTPOOL_H