1.1 --- /dev/null Thu Jan 01 00:00:00 1970 +0000
1.2 +++ b/media/mtransport/simpletokenbucket.cpp Wed Dec 31 06:09:35 2014 +0100
1.3 @@ -0,0 +1,62 @@
1.4 +/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
1.5 +/* vim: set ts=2 et sw=2 tw=80: */
1.6 +/* This Source Code Form is subject to the terms of the Mozilla Public
1.7 + * License, v. 2.0. If a copy of the MPL was not distributed with this file,
1.8 + * You can obtain one at http://mozilla.org/MPL/2.0/. */
1.9 +
1.10 +/* Original author: bcampen@mozilla.com */
1.11 +
1.12 +#include "simpletokenbucket.h"
1.13 +
1.14 +#include <stdint.h>
1.15 +
1.16 +#include "prinrval.h"
1.17 +
1.18 +namespace mozilla {
1.19 +
1.20 +SimpleTokenBucket::SimpleTokenBucket(size_t bucket_size,
1.21 + size_t tokens_per_second) :
1.22 + max_tokens_(bucket_size),
1.23 + num_tokens_(bucket_size),
1.24 + tokens_per_second_(tokens_per_second),
1.25 + last_time_tokens_added_(PR_IntervalNow()) {
1.26 +}
1.27 +
1.28 +size_t SimpleTokenBucket::getTokens(size_t num_requested_tokens) {
1.29 + // Only fill if there isn't enough to satisfy the request.
1.30 + // If we get tokens so seldomly that we are able to roll the timer all
1.31 + // the way around its range, then we lose that entire range of time
1.32 + // for token accumulation. Probably not the end of the world.
1.33 + if (num_requested_tokens > num_tokens_) {
1.34 + PRIntervalTime now = PR_IntervalNow();
1.35 +
1.36 + // If we roll over the max, since everything in this calculation is the same
1.37 + // unsigned type, this will still yield the elapsed time (unless we've
1.38 + // wrapped more than once).
1.39 + PRIntervalTime elapsed_ticks = now - last_time_tokens_added_;
1.40 +
1.41 + uint32_t elapsed_milli_sec = PR_IntervalToMilliseconds(elapsed_ticks);
1.42 + size_t tokens_to_add = (elapsed_milli_sec * tokens_per_second_)/1000;
1.43 +
1.44 + // Only update our timestamp if we added some tokens
1.45 + // TODO:(bcampen@mozilla.com) Should we attempt to "save" leftover time?
1.46 + if (tokens_to_add) {
1.47 + num_tokens_ += tokens_to_add;
1.48 + if (num_tokens_ > max_tokens_) {
1.49 + num_tokens_ = max_tokens_;
1.50 + }
1.51 +
1.52 + last_time_tokens_added_ = now;
1.53 + }
1.54 +
1.55 + if (num_requested_tokens > num_tokens_) {
1.56 + return num_tokens_;
1.57 + }
1.58 + }
1.59 +
1.60 + num_tokens_ -= num_requested_tokens;
1.61 + return num_requested_tokens;
1.62 +}
1.63 +
1.64 +} // namespace mozilla
1.65 +
