TokenBucket.cpp

/*
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 *
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
 *
 * TokenBucket.cpp
 * Token Bucket implementation.
 * Copyright (C) 2010 Simon Newton
 */

#include <algorithm>
#include "olad/TokenBucket.h"

namespace ola {

/*
 * Check if we have enough tokens for an operation. Assuming there is enough
 * tokens, the count is decremented by one.
 * @param now the current time
 * @returns true if there is enough tokens, false otherwise
 */
bool TokenBucket::GetToken(const TimeStamp &now) {
  Count(now);
  if (m_count > 0) {
    m_count--;
    return true;
  }
  return false;
}


/*
 * Get the number of tokens in the bucket
 */
unsigned int TokenBucket::Count(const TimeStamp &now) {
  int64_t delta = (now - m_last).AsInt();
  uint64_t tokens = delta * m_rate / USECS_IN_SECOND;

  m_count = std::min(static_cast<uint64_t>(m_max), m_count + tokens);
  if (tokens)
    m_last += ola::TimeInterval(tokens * USECS_IN_SECOND / m_rate);
  return m_count;
}
}  // namespace ola