media/mtransport/simpletokenbucket.cpp@97036ab72558
media/mtransport/simpletokenbucket.cpp
Tue, 06 Jan 2015 21:39:09 +0100
- author
- Michael Schloh von Bennewitz <michael@schloh.com>
- date
- Tue, 06 Jan 2015 21:39:09 +0100
- branch
- TOR_BUG_9701
- changeset 8
- 97036ab72558
- permissions
- -rw-r--r--
Conditionally force memory storage according to privacy.thirdparty.isolate;
This solves Tor bug #9701, complying with disk avoidance documented in
https://www.torproject.org/projects/torbrowser/design/#disk-avoidance.
1 /* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
2 /* vim: set ts=2 et sw=2 tw=80: */
3 /* This Source Code Form is subject to the terms of the Mozilla Public
4 * License, v. 2.0. If a copy of the MPL was not distributed with this file,
5 * You can obtain one at http://mozilla.org/MPL/2.0/. */
7 /* Original author: bcampen@mozilla.com */
9 #include "simpletokenbucket.h"
11 #include <stdint.h>
13 #include "prinrval.h"
15 namespace mozilla {
17 SimpleTokenBucket::SimpleTokenBucket(size_t bucket_size,
18 size_t tokens_per_second) :
19 max_tokens_(bucket_size),
20 num_tokens_(bucket_size),
21 tokens_per_second_(tokens_per_second),
22 last_time_tokens_added_(PR_IntervalNow()) {
23 }
25 size_t SimpleTokenBucket::getTokens(size_t num_requested_tokens) {
26 // Only fill if there isn't enough to satisfy the request.
27 // If we get tokens so seldomly that we are able to roll the timer all
28 // the way around its range, then we lose that entire range of time
29 // for token accumulation. Probably not the end of the world.
30 if (num_requested_tokens > num_tokens_) {
31 PRIntervalTime now = PR_IntervalNow();
33 // If we roll over the max, since everything in this calculation is the same
34 // unsigned type, this will still yield the elapsed time (unless we've
35 // wrapped more than once).
36 PRIntervalTime elapsed_ticks = now - last_time_tokens_added_;
38 uint32_t elapsed_milli_sec = PR_IntervalToMilliseconds(elapsed_ticks);
39 size_t tokens_to_add = (elapsed_milli_sec * tokens_per_second_)/1000;
41 // Only update our timestamp if we added some tokens
42 // TODO:(bcampen@mozilla.com) Should we attempt to "save" leftover time?
43 if (tokens_to_add) {
44 num_tokens_ += tokens_to_add;
45 if (num_tokens_ > max_tokens_) {
46 num_tokens_ = max_tokens_;
47 }
49 last_time_tokens_added_ = now;
50 }
52 if (num_requested_tokens > num_tokens_) {
53 return num_tokens_;
54 }
55 }
57 num_tokens_ -= num_requested_tokens;
58 return num_requested_tokens;
59 }
61 } // namespace mozilla
