Ref T184 Moved CTokenBucket from BlackCore to BlackMisc.

src/blackmisc/tokenbucket.cpp

@@ -0,0 +1,61 @@
+/* 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 "blackmisc/tokenbucket.h"
+#include "blackmisc/pq/units.h"
+
+#include <QtGlobal>
+
+using namespace BlackMisc::PhysicalQuantities;
+
+namespace BlackMisc
+{
+    CTokenBucket::CTokenBucket(int capacity, const CTime &interval, int numTokensToRefill)
+        : m_capacity(capacity), m_interval(interval), m_numTokensToRefill(numTokensToRefill) {}
+
+    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;
+    }
+
+    void CTokenBucket::setNumberOfTokensToRefill(int noTokens)
+    {
+        m_numTokensToRefill = noTokens;
+    }
+
+    void CTokenBucket::setCapacity(int capacity)
+    {
+        m_capacity = capacity;
+    }
+
+    int CTokenBucket::getTokens()
+    {
+        const auto now = QDateTime::currentDateTime();
+        const auto deltaSeconds = m_lastReplenishmentTime.secsTo(now);
+        const int numberOfTokens = static_cast<int>(m_numTokensToRefill * deltaSeconds / m_interval.value(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

src/blackmisc/tokenbucket.h

@@ -0,0 +1,56 @@
+/* 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.
+ */
+
+#ifndef BLACKMISC_TOKENBUCKET_H
+#define BLACKMISC_TOKENBUCKET_H
+
+#include "blackmisc/blackmiscexport.h"
+#include "blackmisc/pq/time.h"
+#include <QDateTime>
+
+namespace BlackMisc
+{
+    /*!
+     * \brief Token bucket algorithm
+     * \details This class implements the token bucket algorithm. Tokens as arbitrary unit are added to the bucket at a defined rate.
+     *   Token can be consumsed as long as there are enough available. This class can be used to throttle traffic and packet
+     *   generation. Each time a packet needs to be generated and sent a token is consumed. If no token is available, consumption
+     *   will fail the the packet cannot be sent.
+     */
+    class BLACKMISC_EXPORT CTokenBucket
+    {
+    public:
+        //! Constructor for given replenishment policy
+        CTokenBucket(int capacity, const PhysicalQuantities::CTime &interval, int numTokensToRefill);
+
+        //! Try to consume a number of tokens
+        bool tryConsume(int numTokens = 1);
+
+        //! Number of tokens to refill
+        void setNumberOfTokensToRefill(int noTokens);
+
+        //! Set the capacity
+        void setCapacity(int capacity);
+
+    private:
+        //! Get available tokens since last replenishment.
+        //! \note Note that replenishment is implemented lazy.
+        //!    This means, tokens will not replenished on regular basis via a running timer,
+        //!    but they will be replenished while trying to consume them.
+        int getTokens();
+
+        int m_capacity = 10;        //!< Maximum capacity of tokens
+        int m_availableTokens = 10; //!< Currently available tokens. The initial value is 10
+        PhysicalQuantities::CTime m_interval; //!< Refill interval, e.g. every 5 secs
+        int m_numTokensToRefill;    //!< Number of tokens to be refilled each interval
+        QDateTime m_lastReplenishmentTime = QDateTime::currentDateTime(); //!< Last time
+    };
+} // ns
+
+#endif