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comparison: gfx/layers/apz/src/TaskThrottler.h
gfx/layers/apz/src/TaskThrottler.h
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| -1:000000000000 | 0:be756eaff17f |
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| 1 /* -*- Mode: C++; c-basic-offset: 2; indent-tabs-mode: nil; tab-width: 2; -*- */ | |
| 2 /* vim: set sw=4 ts=8 et 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 | |
| 5 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */ | |
| 6 | |
| 7 #ifndef mozilla_dom_TaskThrottler_h | |
| 8 #define mozilla_dom_TaskThrottler_h | |
| 9 | |
| 10 #include <stdint.h> // for uint32_t | |
| 11 #include "base/task.h" // for CancelableTask | |
| 12 #include "mozilla/TimeStamp.h" // for TimeDuration, TimeStamp | |
| 13 #include "mozilla/RollingMean.h" // for RollingMean | |
| 14 #include "mozilla/mozalloc.h" // for operator delete | |
| 15 #include "nsAutoPtr.h" // for nsAutoPtr | |
| 16 #include "nsTArray.h" // for nsTArray | |
| 17 | |
| 18 namespace tracked_objects { | |
| 19 class Location; | |
| 20 } | |
| 21 | |
| 22 namespace mozilla { | |
| 23 namespace layers { | |
| 24 | |
| 25 /** The TaskThrottler prevents update event overruns. It is used in cases where | |
| 26 * you're sending an async message and waiting for a reply. You need to call | |
| 27 * PostTask to queue a task and TaskComplete when you get a response. | |
| 28 * | |
| 29 * The call to TaskComplete will run the recent task posted since the last | |
| 30 * request was sent, if any. This means that at any time there can be at most 1 | |
| 31 * outstanding request being processed and at most 1 queued behind it. | |
| 32 * | |
| 33 * This is used in the context of repainting a scrollable region. While another | |
| 34 * process is painting you might get several updates from the UI thread but when | |
| 35 * the paint is complete you want to send the most recent. | |
| 36 */ | |
| 37 | |
| 38 class TaskThrottler { | |
| 39 public: | |
| 40 TaskThrottler(const TimeStamp& aTimeStamp); | |
| 41 | |
| 42 /** Post a task to be run as soon as there are no outstanding tasks. | |
| 43 * | |
| 44 * @param aLocation Use the macro FROM_HERE | |
| 45 * @param aTask Ownership of this object is transferred to TaskThrottler | |
| 46 * which will delete it when it is either run or becomes | |
| 47 * obsolete or the TaskThrottler is destructed. | |
| 48 */ | |
| 49 void PostTask(const tracked_objects::Location& aLocation, | |
| 50 CancelableTask* aTask, const TimeStamp& aTimeStamp); | |
| 51 /** | |
| 52 * Mark the task as complete and process the next queued task. | |
| 53 */ | |
| 54 void TaskComplete(const TimeStamp& aTimeStamp); | |
| 55 | |
| 56 /** | |
| 57 * Calculate the average time between processing the posted task and getting | |
| 58 * the TaskComplete() call back. | |
| 59 */ | |
| 60 TimeDuration AverageDuration() | |
| 61 { | |
| 62 return mMean.empty() ? TimeDuration() : mMean.mean(); | |
| 63 } | |
| 64 | |
| 65 /** | |
| 66 * return true if Throttler has an outstanding task | |
| 67 */ | |
| 68 bool IsOutstanding() { return mOutstanding; } | |
| 69 | |
| 70 /** | |
| 71 * Return the time elapsed since the last request was processed | |
| 72 */ | |
| 73 TimeDuration TimeSinceLastRequest(const TimeStamp& aTimeStamp); | |
| 74 | |
| 75 /** | |
| 76 * Clear average history. | |
| 77 */ | |
| 78 void ClearHistory() { mMean.clear(); } | |
| 79 | |
| 80 /** | |
| 81 * @param aMaxDurations The maximum number of durations to measure. | |
| 82 */ | |
| 83 | |
| 84 void SetMaxDurations(uint32_t aMaxDurations) | |
| 85 { | |
| 86 if (aMaxDurations != mMean.maxValues()) { | |
| 87 mMean = RollingMean<TimeDuration, TimeDuration>(aMaxDurations); | |
| 88 } | |
| 89 } | |
| 90 | |
| 91 private: | |
| 92 bool mOutstanding; | |
| 93 nsAutoPtr<CancelableTask> mQueuedTask; | |
| 94 TimeStamp mStartTime; | |
| 95 RollingMean<TimeDuration, TimeDuration> mMean; | |
| 96 }; | |
| 97 | |
| 98 } | |
| 99 } | |
| 100 | |
| 101 #endif // mozilla_dom_TaskThrottler_h |
