image/src/DiscardTracker.h@b8a032363ba2 (annotated)
image/src/DiscardTracker.h
Thu, 22 Jan 2015 13:21:57 +0100
- author
- Michael Schloh von Bennewitz <michael@schloh.com>
- date
- Thu, 22 Jan 2015 13:21:57 +0100
- branch
- TOR_BUG_9701
- changeset 15
- b8a032363ba2
- permissions
- -rw-r--r--
Incorporate requested changes from Mozilla in review:
https://bugzilla.mozilla.org/show_bug.cgi?id=1123480#c6
| michael@0 | 1 | /* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */ |
| michael@0 | 2 | /* This Source Code Form is subject to the terms of the Mozilla Public |
| michael@0 | 3 | * License, v. 2.0. If a copy of the MPL was not distributed with this file, |
| michael@0 | 4 | * You can obtain one at http://mozilla.org/MPL/2.0/. */ |
| michael@0 | 5 | |
| michael@0 | 6 | #ifndef mozilla_imagelib_DiscardTracker_h_ |
| michael@0 | 7 | #define mozilla_imagelib_DiscardTracker_h_ |
| michael@0 | 8 | |
| michael@0 | 9 | #include "mozilla/Atomics.h" |
| michael@0 | 10 | #include "mozilla/LinkedList.h" |
| michael@0 | 11 | #include "mozilla/Mutex.h" |
| michael@0 | 12 | #include "mozilla/TimeStamp.h" |
| michael@0 | 13 | #include "prlock.h" |
| michael@0 | 14 | #include "nsThreadUtils.h" |
| michael@0 | 15 | #include "nsAutoPtr.h" |
| michael@0 | 16 | |
| michael@0 | 17 | class nsITimer; |
| michael@0 | 18 | |
| michael@0 | 19 | namespace mozilla { |
| michael@0 | 20 | namespace image { |
| michael@0 | 21 | |
| michael@0 | 22 | class RasterImage; |
| michael@0 | 23 | |
| michael@0 | 24 | /** |
| michael@0 | 25 | * This static class maintains a linked list of RasterImage objects which are |
| michael@0 | 26 | * eligible for discarding. |
| michael@0 | 27 | * |
| michael@0 | 28 | * When Reset() is called, the node is removed from its position in the list |
| michael@0 | 29 | * (if it was there before) and appended to the beginnings of the list. |
| michael@0 | 30 | * |
| michael@0 | 31 | * Periodically (on a timer and when we notice that we're using more memory |
| michael@0 | 32 | * than we'd like for decoded images), we go through the list and discard |
| michael@0 | 33 | * decoded data from images at the end of the list. |
| michael@0 | 34 | */ |
| michael@0 | 35 | class DiscardTracker |
| michael@0 | 36 | { |
| michael@0 | 37 | public: |
| michael@0 | 38 | /** |
| michael@0 | 39 | * The DiscardTracker keeps a linked list of Node objects. Each object |
| michael@0 | 40 | * points to a RasterImage and contains a timestamp indicating when the |
| michael@0 | 41 | * node was inserted into the tracker. |
| michael@0 | 42 | * |
| michael@0 | 43 | * This structure is embedded within each RasterImage object, and we do |
| michael@0 | 44 | * |mDiscardTrackerNode.img = this| on RasterImage construction. Thus, a |
| michael@0 | 45 | * RasterImage must always call DiscardTracker::Remove() in its destructor |
| michael@0 | 46 | * to avoid having the tracker point to bogus memory. |
| michael@0 | 47 | */ |
| michael@0 | 48 | struct Node : public LinkedListElement<Node> |
| michael@0 | 49 | { |
| michael@0 | 50 | RasterImage *img; |
| michael@0 | 51 | TimeStamp timestamp; |
| michael@0 | 52 | }; |
| michael@0 | 53 | |
| michael@0 | 54 | /** |
| michael@0 | 55 | * Add an image to the front of the tracker's list, or move it to the front |
| michael@0 | 56 | * if it's already in the list. This function is main thread only. |
| michael@0 | 57 | */ |
| michael@0 | 58 | static nsresult Reset(struct Node* node); |
| michael@0 | 59 | |
| michael@0 | 60 | /** |
| michael@0 | 61 | * Remove a node from the tracker; do nothing if the node is currently |
| michael@0 | 62 | * untracked. This function is main thread only. |
| michael@0 | 63 | */ |
| michael@0 | 64 | static void Remove(struct Node* node); |
| michael@0 | 65 | |
| michael@0 | 66 | /** |
| michael@0 | 67 | * Initializes the discard tracker. This function is main thread only. |
| michael@0 | 68 | */ |
| michael@0 | 69 | static nsresult Initialize(); |
| michael@0 | 70 | |
| michael@0 | 71 | /** |
| michael@0 | 72 | * Shut the discard tracker down. This should be called on XPCOM shutdown |
| michael@0 | 73 | * so we destroy the discard timer's nsITimer. This function is main thread |
| michael@0 | 74 | * only. |
| michael@0 | 75 | */ |
| michael@0 | 76 | static void Shutdown(); |
| michael@0 | 77 | |
| michael@0 | 78 | /** |
| michael@0 | 79 | * Discard the decoded image data for all images tracked by the discard |
| michael@0 | 80 | * tracker. This function is main thread only. |
| michael@0 | 81 | */ |
| michael@0 | 82 | static void DiscardAll(); |
| michael@0 | 83 | |
| michael@0 | 84 | /** |
| michael@0 | 85 | * Inform the discard tracker that we are going to allocate some memory |
| michael@0 | 86 | * for a decoded image. We use this to determine when we've allocated |
| michael@0 | 87 | * too much memory and should discard some images. This function can be |
| michael@0 | 88 | * called from any thread and is thread-safe. If this function succeeds, the |
| michael@0 | 89 | * caller is now responsible for ensuring that InformDeallocation is called. |
| michael@0 | 90 | */ |
| michael@0 | 91 | static bool TryAllocation(uint64_t aBytes); |
| michael@0 | 92 | |
| michael@0 | 93 | /** |
| michael@0 | 94 | * Inform the discard tracker that we've deallocated some memory for a |
| michael@0 | 95 | * decoded image. This function can be called from any thread and is |
| michael@0 | 96 | * thread-safe. |
| michael@0 | 97 | */ |
| michael@0 | 98 | static void InformDeallocation(uint64_t aBytes); |
| michael@0 | 99 | |
| michael@0 | 100 | private: |
| michael@0 | 101 | /** |
| michael@0 | 102 | * This is called when the discard timer fires; it calls into DiscardNow(). |
| michael@0 | 103 | */ |
| michael@0 | 104 | friend void DiscardTimeoutChangedCallback(const char* aPref, void *aClosure); |
| michael@0 | 105 | |
| michael@0 | 106 | /** |
| michael@0 | 107 | * When run, this runnable sets sDiscardRunnablePending to false and calls |
| michael@0 | 108 | * DiscardNow(). |
| michael@0 | 109 | */ |
| michael@0 | 110 | class DiscardRunnable : public nsRunnable |
| michael@0 | 111 | { |
| michael@0 | 112 | NS_IMETHOD Run(); |
| michael@0 | 113 | }; |
| michael@0 | 114 | |
| michael@0 | 115 | static void ReloadTimeout(); |
| michael@0 | 116 | static nsresult EnableTimer(); |
| michael@0 | 117 | static void DisableTimer(); |
| michael@0 | 118 | static void MaybeDiscardSoon(); |
| michael@0 | 119 | static void TimerCallback(nsITimer *aTimer, void *aClosure); |
| michael@0 | 120 | static void DiscardNow(); |
| michael@0 | 121 | |
| michael@0 | 122 | static LinkedList<Node> sDiscardableImages; |
| michael@0 | 123 | static nsCOMPtr<nsITimer> sTimer; |
| michael@0 | 124 | static bool sInitialized; |
| michael@0 | 125 | static bool sTimerOn; |
| michael@0 | 126 | static mozilla::Atomic<bool> sDiscardRunnablePending; |
| michael@0 | 127 | static uint64_t sCurrentDecodedImageBytes; |
| michael@0 | 128 | static uint32_t sMinDiscardTimeoutMs; |
| michael@0 | 129 | static uint32_t sMaxDecodedImageKB; |
| michael@0 | 130 | static uint32_t sHardLimitDecodedImageKB; |
| michael@0 | 131 | // Lock for safegarding the 64-bit sCurrentDecodedImageBytes |
| michael@0 | 132 | static PRLock *sAllocationLock; |
| michael@0 | 133 | static mozilla::Mutex* sNodeListMutex; |
| michael@0 | 134 | static Atomic<bool> sShutdown; |
| michael@0 | 135 | }; |
| michael@0 | 136 | |
| michael@0 | 137 | } // namespace image |
| michael@0 | 138 | } // namespace mozilla |
| michael@0 | 139 | |
| michael@0 | 140 | #endif /* mozilla_imagelib_DiscardTracker_h_ */ |
