/* This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this file,
 * You can obtain one at http://mozilla.org/MPL/2.0/. */

/* Original author: bcampen@mozilla.com */

/*
 *  This file defines a dirt-simple token bucket class.
 */

#ifndef simpletokenbucket_h_
#define simpletokenbucket_h_

#include <stdint.h>

#include "m_cpp_utils.h"
#include "prinrval.h"

namespace mozilla {

class SimpleTokenBucket {
 public:
  /*
   *  Create a SimpleTokenBucket with a given maximum size and
   *  token replenishment rate.
   *  (eg; if you want a maximum rate of 5 per second over a 7 second
   *  period, call SimpleTokenBucket b(5*7, 5);)
   */
  SimpleTokenBucket(size_t bucket_size, size_t tokens_per_second);

  /*
   *  Attempt to acquire a number of tokens. If successful, returns
   *  |num_tokens|, otherwise returns the number of tokens currently
   *  in the bucket.
   *  Note: To get the number of tokens in the bucket, pass something
   *  like UINT32_MAX.
   */
  size_t getTokens(size_t num_tokens);

 protected:  // Allow testing to touch these.
  uint64_t max_tokens_;
  uint64_t num_tokens_;
  size_t tokens_per_second_;
  PRIntervalTime last_time_tokens_added_;

  DISALLOW_COPY_ASSIGN(SimpleTokenBucket);
};

}  // namespace mozilla

#endif  // simpletokenbucket_h_