refs #806, minor adjustments of token bucket

This commit is contained in:
Klaus Basan
2016-11-16 03:07:03 +01:00
parent 6a66ab84c2
commit 291474b96f
2 changed files with 43 additions and 38 deletions

View File

@@ -14,6 +14,9 @@
namespace BlackCore
{
CTokenBucket::CTokenBucket(int capacity, BlackMisc::PhysicalQuantities::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);
@@ -33,15 +36,24 @@ namespace BlackCore
return false;
}
int CTokenBucket::getTokens()
void CTokenBucket::setNumberOfTokensToRefill(int noTokens)
{
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;
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(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

View File

@@ -12,52 +12,45 @@
#include "blackcore/blackcoreexport.h"
#include "blackmisc/pq/time.h"
#include <QDateTime>
namespace BlackCore
{
/*!
* Token bucket algorithm
*
* 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.
* \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 BLACKCORE_EXPORT CTokenBucket
{
public:
//! Constructor
//! \tparam Replenishment policy
CTokenBucket(int capacity, BlackMisc::PhysicalQuantities::CTime interval, int numTokensToRefill)
: m_capacity(capacity), m_interval(interval), m_numTokensToRefill(numTokensToRefill) {}
//! Try to consume a token
bool tryConsume()
{
return tryConsume(1);
}
//! Constructor for given replenishment policy
CTokenBucket(int capacity, BlackMisc::PhysicalQuantities::CTime interval, int numTokensToRefill);
//! Try to consume a number of tokens
bool tryConsume(int numTokens);
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 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.
//! \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
BlackMisc::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
int m_capacity = 10; //!< Maximum capacity of tokens
int m_availableTokens = 10; //!< Currently available tokens. The initial value is 10
BlackMisc::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