refs #321 token bucket algorithm implementation

src/blackcore/token_bucket.cpp

@@ -0,0 +1,44 @@
+/* Copyright (C) 2014
+ * swift project Community / Contributors
+ *
+ * This file is part of swift project. It is subject to the license terms in the LICENSE file found in the top-level
+ * directory of this distribution and at http://www.swift-project.org/license.html. No part of swift project,
+ * including this file, may be copied, modified, propagated, or distributed except according to the terms
+ * contained in the LICENSE file.
+ */
+
+#include "token_bucket.h"
+
+namespace BlackCore
+{
+    bool CTokenBucket::tryConsume(int numTokens)
+    {
+        Q_ASSERT(numTokens > 0 && numTokens < m_capacity);
+
+        // Replenish maximal up to capacity
+        int replenishedTokens = qMin(m_capacity, getTokens());
+
+        // Take care of overflows
+        m_availableTokens = qMin(m_availableTokens + replenishedTokens, m_capacity);
+
+        if (numTokens <= m_availableTokens)
+        {
+            m_availableTokens -= numTokens;
+            return true;
+        }
+
+        return false;
+    }
+
+    int CTokenBucket::getTokens()
+    {
+        auto now = QDateTime::currentDateTime();
+        auto deltaSeconds = m_lastReplenishmentTime.secsTo(now);
+        int numberOfTokens = static_cast<int>( m_numTokensToRefill * deltaSeconds / m_interval.value(BlackMisc::PhysicalQuantities::CTimeUnit::s()));
+
+        // Update the time only when replenishment actually took place. We will end up in a infinite loop otherwise.
+        if (numberOfTokens > 0 ) m_lastReplenishmentTime = now;
+        return numberOfTokens;
+    }
+
+} // namespace