The Tor Browser / file comparison
comparison: image/src/DiscardTracker.h
image/src/DiscardTracker.h
- branch
- TOR_BUG_9701
- changeset 15
- b8a032363ba2
equal
deleted
inserted
replaced
| -1:000000000000 | 0:e5c0d1be4425 |
|---|---|
| 1 /* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */ | |
| 2 /* This Source Code Form is subject to the terms of the Mozilla Public | |
| 3 * License, v. 2.0. If a copy of the MPL was not distributed with this file, | |
| 4 * You can obtain one at http://mozilla.org/MPL/2.0/. */ | |
| 5 | |
| 6 #ifndef mozilla_imagelib_DiscardTracker_h_ | |
| 7 #define mozilla_imagelib_DiscardTracker_h_ | |
| 8 | |
| 9 #include "mozilla/Atomics.h" | |
| 10 #include "mozilla/LinkedList.h" | |
| 11 #include "mozilla/Mutex.h" | |
| 12 #include "mozilla/TimeStamp.h" | |
| 13 #include "prlock.h" | |
| 14 #include "nsThreadUtils.h" | |
| 15 #include "nsAutoPtr.h" | |
| 16 | |
| 17 class nsITimer; | |
| 18 | |
| 19 namespace mozilla { | |
| 20 namespace image { | |
| 21 | |
| 22 class RasterImage; | |
| 23 | |
| 24 /** | |
| 25 * This static class maintains a linked list of RasterImage objects which are | |
| 26 * eligible for discarding. | |
| 27 * | |
| 28 * When Reset() is called, the node is removed from its position in the list | |
| 29 * (if it was there before) and appended to the beginnings of the list. | |
| 30 * | |
| 31 * Periodically (on a timer and when we notice that we're using more memory | |
| 32 * than we'd like for decoded images), we go through the list and discard | |
| 33 * decoded data from images at the end of the list. | |
| 34 */ | |
| 35 class DiscardTracker | |
| 36 { | |
| 37 public: | |
| 38 /** | |
| 39 * The DiscardTracker keeps a linked list of Node objects. Each object | |
| 40 * points to a RasterImage and contains a timestamp indicating when the | |
| 41 * node was inserted into the tracker. | |
| 42 * | |
| 43 * This structure is embedded within each RasterImage object, and we do | |
| 44 * |mDiscardTrackerNode.img = this| on RasterImage construction. Thus, a | |
| 45 * RasterImage must always call DiscardTracker::Remove() in its destructor | |
| 46 * to avoid having the tracker point to bogus memory. | |
| 47 */ | |
| 48 struct Node : public LinkedListElement<Node> | |
| 49 { | |
| 50 RasterImage *img; | |
| 51 TimeStamp timestamp; | |
| 52 }; | |
| 53 | |
| 54 /** | |
| 55 * Add an image to the front of the tracker's list, or move it to the front | |
| 56 * if it's already in the list. This function is main thread only. | |
| 57 */ | |
| 58 static nsresult Reset(struct Node* node); | |
| 59 | |
| 60 /** | |
| 61 * Remove a node from the tracker; do nothing if the node is currently | |
| 62 * untracked. This function is main thread only. | |
| 63 */ | |
| 64 static void Remove(struct Node* node); | |
| 65 | |
| 66 /** | |
| 67 * Initializes the discard tracker. This function is main thread only. | |
| 68 */ | |
| 69 static nsresult Initialize(); | |
| 70 | |
| 71 /** | |
| 72 * Shut the discard tracker down. This should be called on XPCOM shutdown | |
| 73 * so we destroy the discard timer's nsITimer. This function is main thread | |
| 74 * only. | |
| 75 */ | |
| 76 static void Shutdown(); | |
| 77 | |
| 78 /** | |
| 79 * Discard the decoded image data for all images tracked by the discard | |
| 80 * tracker. This function is main thread only. | |
| 81 */ | |
| 82 static void DiscardAll(); | |
| 83 | |
| 84 /** | |
| 85 * Inform the discard tracker that we are going to allocate some memory | |
| 86 * for a decoded image. We use this to determine when we've allocated | |
| 87 * too much memory and should discard some images. This function can be | |
| 88 * called from any thread and is thread-safe. If this function succeeds, the | |
| 89 * caller is now responsible for ensuring that InformDeallocation is called. | |
| 90 */ | |
| 91 static bool TryAllocation(uint64_t aBytes); | |
| 92 | |
| 93 /** | |
| 94 * Inform the discard tracker that we've deallocated some memory for a | |
| 95 * decoded image. This function can be called from any thread and is | |
| 96 * thread-safe. | |
| 97 */ | |
| 98 static void InformDeallocation(uint64_t aBytes); | |
| 99 | |
| 100 private: | |
| 101 /** | |
| 102 * This is called when the discard timer fires; it calls into DiscardNow(). | |
| 103 */ | |
| 104 friend void DiscardTimeoutChangedCallback(const char* aPref, void *aClosure); | |
| 105 | |
| 106 /** | |
| 107 * When run, this runnable sets sDiscardRunnablePending to false and calls | |
| 108 * DiscardNow(). | |
| 109 */ | |
| 110 class DiscardRunnable : public nsRunnable | |
| 111 { | |
| 112 NS_IMETHOD Run(); | |
| 113 }; | |
| 114 | |
| 115 static void ReloadTimeout(); | |
| 116 static nsresult EnableTimer(); | |
| 117 static void DisableTimer(); | |
| 118 static void MaybeDiscardSoon(); | |
| 119 static void TimerCallback(nsITimer *aTimer, void *aClosure); | |
| 120 static void DiscardNow(); | |
| 121 | |
| 122 static LinkedList<Node> sDiscardableImages; | |
| 123 static nsCOMPtr<nsITimer> sTimer; | |
| 124 static bool sInitialized; | |
| 125 static bool sTimerOn; | |
| 126 static mozilla::Atomic<bool> sDiscardRunnablePending; | |
| 127 static uint64_t sCurrentDecodedImageBytes; | |
| 128 static uint32_t sMinDiscardTimeoutMs; | |
| 129 static uint32_t sMaxDecodedImageKB; | |
| 130 static uint32_t sHardLimitDecodedImageKB; | |
| 131 // Lock for safegarding the 64-bit sCurrentDecodedImageBytes | |
| 132 static PRLock *sAllocationLock; | |
| 133 static mozilla::Mutex* sNodeListMutex; | |
| 134 static Atomic<bool> sShutdown; | |
| 135 }; | |
| 136 | |
| 137 } // namespace image | |
| 138 } // namespace mozilla | |
| 139 | |
| 140 #endif /* mozilla_imagelib_DiscardTracker_h_ */ |
