From 6bf0a5cb5034a7e684dcc3500e841785237ce2dd Mon Sep 17 00:00:00 2001 From: Daniel Baumann Date: Sun, 7 Apr 2024 19:32:43 +0200 Subject: Adding upstream version 1:115.7.0. Signed-off-by: Daniel Baumann --- netwerk/base/EventTokenBucket.h | 155 ++++++++++++++++++++++++++++++++++++++++ 1 file changed, 155 insertions(+) create mode 100644 netwerk/base/EventTokenBucket.h (limited to 'netwerk/base/EventTokenBucket.h') diff --git a/netwerk/base/EventTokenBucket.h b/netwerk/base/EventTokenBucket.h new file mode 100644 index 0000000000..4206a622f5 --- /dev/null +++ b/netwerk/base/EventTokenBucket.h @@ -0,0 +1,155 @@ +/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */ +/* vim:set ts=2 sw=2 sts=2 et cindent: */ +/* 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/. */ + +#ifndef NetEventTokenBucket_h__ +#define NetEventTokenBucket_h__ + +#include "ARefBase.h" +#include "nsCOMPtr.h" +#include "nsDeque.h" +#include "nsINamed.h" +#include "nsITimer.h" + +#include "mozilla/TimeStamp.h" + +class nsICancelable; + +namespace mozilla { +namespace net { + +/* A token bucket is used to govern the maximum rate a series of events + can be executed at. For instance if your event was "eat a piece of cake" + then a token bucket configured to allow "1 piece per day" would spread + the eating of a 8 piece cake over 8 days even if you tried to eat the + whole thing up front. In a practical sense it 'costs' 1 token to execute + an event and tokens are 'earned' at a particular rate as time goes by. + + The token bucket can be perfectly smooth or allow a configurable amount of + burstiness. A bursty token bucket allows you to save up unused credits, while + a perfectly smooth one would not. A smooth "1 per day" cake token bucket + would require 9 days to eat that cake if you skipped a slice on day 4 + (use the token or lose it), while a token bucket configured with a burst + of 2 would just let you eat 2 slices on day 5 (the credits for day 4 and day + 5) and finish the cake in the usual 8 days. + + EventTokenBucket(hz=20, burst=5) creates a token bucket with the following + properties: + + + events from an infinite stream will be admitted 20 times per second (i.e. + hz=20 means 1 event per 50 ms). Timers will be used to space things evenly + down to 5ms gaps (i.e. up to 200hz). Token buckets with rates greater than + 200hz will admit multiple events with 5ms gaps between them. 10000hz is the + maximum rate and 1hz is the minimum rate. + + + The burst size controls the limit of 'credits' that a token bucket can + accumulate when idle. For our (20,5) example each event requires 50ms of + credit (again, 20hz = 50ms per event). a burst size of 5 means that the + token bucket can accumulate a maximum of 250ms (5 * 50ms) for this bucket. + If no events have been admitted for the last full second the bucket can + still only accumulate 250ms of credit - but that credit means that 5 events + can be admitted without delay. A burst size of 1 is the minimum. The + EventTokenBucket is created with maximum credits already applied, but they + can be cleared with the ClearCredits() method. The maximum burst size is 15 + minutes worth of events. + + + An event is submitted to the token bucket asynchronously through + SubmitEvent(). The OnTokenBucketAdmitted() method of the submitted event + is used as a callback when the event is ready to run. A cancelable event is + returned to the SubmitEvent() caller for use in the case they do not wish + to wait for the callback. +*/ + +class EventTokenBucket; + +class ATokenBucketEvent { + public: + virtual void OnTokenBucketAdmitted() = 0; +}; + +class TokenBucketCancelable; + +class EventTokenBucket : public nsITimerCallback, + public nsINamed, + public ARefBase { + public: + NS_DECL_THREADSAFE_ISUPPORTS + NS_DECL_NSITIMERCALLBACK + NS_DECL_NSINAMED + + // This should be constructed on the main thread + EventTokenBucket(uint32_t eventsPerSecond, uint32_t burstSize); + + // These public methods are all meant to be called from the socket thread + void ClearCredits(); + uint32_t BurstEventsAvailable(); + uint32_t QueuedEvents(); + + // a paused token bucket will not process any events, but it will accumulate + // credits. ClearCredits can be used before unpausing if desired. + void Pause(); + void UnPause(); + void Stop(); + + // The returned cancelable event can only be canceled from the socket thread + nsresult SubmitEvent(ATokenBucketEvent* event, nsICancelable** cancelable); + + private: + virtual ~EventTokenBucket(); + void CleanupTimers(); + + friend class RunNotifyEvent; + friend class SetTimerEvent; + + bool TryImmediateDispatch(TokenBucketCancelable* cancelable); + void SetRate(uint32_t eventsPerSecond, uint32_t burstSize); + + void DispatchEvents(); + void UpdateTimer(); + void UpdateCredits(); + + const static uint64_t kUsecPerSec = 1000000; + const static uint64_t kUsecPerMsec = 1000; + const static uint64_t kMaxHz = 10000; + + uint64_t + mUnitCost; // usec of credit needed for 1 event (from eventsPerSecond) + uint64_t mMaxCredit; // usec mCredit limit (from busrtSize) + uint64_t mCredit; // usec of accumulated credit. + + bool mPaused; + bool mStopped; + nsRefPtrDeque mEvents; + bool mTimerArmed; + TimeStamp mLastUpdate; + + // The timer is created on the main thread, but is armed and executes Notify() + // callbacks on the socket thread in order to maintain low latency of event + // delivery. + nsCOMPtr mTimer; + +#ifdef XP_WIN + // Windows timers are 15ms granularity by default. When we have active events + // that need to be dispatched at 50ms or less granularity we change the OS + // granularity to 1ms. 90 seconds after that need has elapsed we will change + // it back + const static uint64_t kCostFineGrainThreshold = 50 * kUsecPerMsec; + + void FineGrainTimers(); // get 1ms granularity + void NormalTimers(); // reset to default granularity + void WantNormalTimers(); // reset after 90 seconds if not needed in interim + void FineGrainResetTimerNotify(); // delayed callback to reset + + TimeStamp mLastFineGrainTimerUse; + bool mFineGrainTimerInUse; + bool mFineGrainResetTimerArmed; + nsCOMPtr mFineGrainResetTimer; +#endif +}; + +} // namespace net +} // namespace mozilla + +#endif -- cgit v1.2.3