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/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* vim: set ts=2 et sw=2 tw=80: */
/* 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 */
#include "simpletokenbucket.h"
#include <stdint.h>
#include "prinrval.h"
namespace mozilla {
SimpleTokenBucket::SimpleTokenBucket(size_t bucket_size,
size_t tokens_per_second) :
max_tokens_(bucket_size),
num_tokens_(bucket_size),
tokens_per_second_(tokens_per_second),
last_time_tokens_added_(PR_IntervalNow()) {
}
size_t SimpleTokenBucket::getTokens(size_t num_requested_tokens) {
// Only fill if there isn't enough to satisfy the request.
// If we get tokens so seldomly that we are able to roll the timer all
// the way around its range, then we lose that entire range of time
// for token accumulation. Probably not the end of the world.
if (num_requested_tokens > num_tokens_) {
PRIntervalTime now = PR_IntervalNow();
// If we roll over the max, since everything in this calculation is the same
// unsigned type, this will still yield the elapsed time (unless we've
// wrapped more than once).
PRIntervalTime elapsed_ticks = now - last_time_tokens_added_;
uint32_t elapsed_milli_sec = PR_IntervalToMilliseconds(elapsed_ticks);
size_t tokens_to_add = (elapsed_milli_sec * tokens_per_second_)/1000;
// Only update our timestamp if we added some tokens
// TODO:(bcampen@mozilla.com) Should we attempt to "save" leftover time?
if (tokens_to_add) {
num_tokens_ += tokens_to_add;
if (num_tokens_ > max_tokens_) {
num_tokens_ = max_tokens_;
}
last_time_tokens_added_ = now;
}
if (num_requested_tokens > num_tokens_) {
return num_tokens_;
}
}
num_tokens_ -= num_requested_tokens;
return num_requested_tokens;
}
} // namespace mozilla
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