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SurfaceCache.cpp
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/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* 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/. */
/**
* SurfaceCache is a service for caching temporary surfaces in imagelib.
*/
#include "SurfaceCache.h"
#include <algorithm>
#include <utility>
#include "ISurfaceProvider.h"
#include "Image.h"
#include "LookupResult.h"
#include "ShutdownTracker.h"
#include "gfx2DGlue.h"
#include "gfxPlatform.h"
#include "imgFrame.h"
#include "mozilla/Assertions.h"
#include "mozilla/Attributes.h"
#include "mozilla/CheckedInt.h"
#include "mozilla/DebugOnly.h"
#include "mozilla/Likely.h"
#include "mozilla/RefPtr.h"
#include "mozilla/StaticMutex.h"
#include "mozilla/StaticPrefs_image.h"
#include "mozilla/StaticPtr.h"
#include "mozilla/Tuple.h"
#include "nsExpirationTracker.h"
#include "nsHashKeys.h"
#include "nsIMemoryReporter.h"
#include "nsRefPtrHashtable.h"
#include "nsSize.h"
#include "nsTArray.h"
#include "prsystem.h"
using std::max;
using std::min;
namespace mozilla {
using namespace gfx;
namespace image {
MOZ_DEFINE_MALLOC_SIZE_OF(SurfaceCacheMallocSizeOf)
class CachedSurface;
class SurfaceCacheImpl;
///////////////////////////////////////////////////////////////////////////////
// Static Data
///////////////////////////////////////////////////////////////////////////////
// The single surface cache instance.
static StaticRefPtr<SurfaceCacheImpl> sInstance;
// The mutex protecting the surface cache.
static StaticMutex sInstanceMutex;
///////////////////////////////////////////////////////////////////////////////
// SurfaceCache Implementation
///////////////////////////////////////////////////////////////////////////////
/**
* Cost models the cost of storing a surface in the cache. Right now, this is
* simply an estimate of the size of the surface in bytes, but in the future it
* may be worth taking into account the cost of rematerializing the surface as
* well.
*/
typedef size_t Cost;
static Cost ComputeCost(const IntSize& aSize, uint32_t aBytesPerPixel) {
MOZ_ASSERT(aBytesPerPixel == 1 || aBytesPerPixel == 4);
return aSize.width * aSize.height * aBytesPerPixel;
}
/**
* Since we want to be able to make eviction decisions based on cost, we need to
* be able to look up the CachedSurface which has a certain cost as well as the
* cost associated with a certain CachedSurface. To make this possible, in data
* structures we actually store a CostEntry, which contains a weak pointer to
* its associated surface.
*
* To make usage of the weak pointer safe, SurfaceCacheImpl always calls
* StartTracking after a surface is stored in the cache and StopTracking before
* it is removed.
*/
class CostEntry {
public:
CostEntry(NotNull<CachedSurface*> aSurface, Cost aCost)
: mSurface(aSurface), mCost(aCost) {}
NotNull<CachedSurface*> Surface() const { return mSurface; }
Cost GetCost() const { return mCost; }
bool operator==(const CostEntry& aOther) const {
return mSurface == aOther.mSurface && mCost == aOther.mCost;
}
bool operator<(const CostEntry& aOther) const {
return mCost < aOther.mCost ||
(mCost == aOther.mCost && mSurface < aOther.mSurface);
}
private:
NotNull<CachedSurface*> mSurface;
Cost mCost;
};
/**
* A CachedSurface associates a surface with a key that uniquely identifies that
* surface.
*/
class CachedSurface {
~CachedSurface() {}
public:
MOZ_DECLARE_REFCOUNTED_TYPENAME(CachedSurface)
NS_INLINE_DECL_THREADSAFE_REFCOUNTING(CachedSurface)
explicit CachedSurface(NotNull<ISurfaceProvider*> aProvider)
: mProvider(aProvider), mIsLocked(false) {}
DrawableSurface GetDrawableSurface() const {
if (MOZ_UNLIKELY(IsPlaceholder())) {
MOZ_ASSERT_UNREACHABLE("Called GetDrawableSurface() on a placeholder");
return DrawableSurface();
}
return mProvider->Surface();
}
void SetLocked(bool aLocked) {
if (IsPlaceholder()) {
return; // Can't lock a placeholder.
}
// Update both our state and our provider's state. Some surface providers
// are permanently locked; maintaining our own locking state enables us to
// respect SetLocked() even when it's meaningless from the provider's
// perspective.
mIsLocked = aLocked;
mProvider->SetLocked(aLocked);
}
bool IsLocked() const {
return !IsPlaceholder() && mIsLocked && mProvider->IsLocked();
}
void SetCannotSubstitute() {
mProvider->Availability().SetCannotSubstitute();
}
bool CannotSubstitute() const {
return mProvider->Availability().CannotSubstitute();
}
bool IsPlaceholder() const {
return mProvider->Availability().IsPlaceholder();
}
bool IsDecoded() const { return !IsPlaceholder() && mProvider->IsFinished(); }
ImageKey GetImageKey() const { return mProvider->GetImageKey(); }
const SurfaceKey& GetSurfaceKey() const { return mProvider->GetSurfaceKey(); }
nsExpirationState* GetExpirationState() { return &mExpirationState; }
CostEntry GetCostEntry() {
return image::CostEntry(WrapNotNull(this), mProvider->LogicalSizeInBytes());
}
size_t ShallowSizeOfIncludingThis(MallocSizeOf aMallocSizeOf) const {
return aMallocSizeOf(this) + aMallocSizeOf(mProvider.get());
}
// A helper type used by SurfaceCacheImpl::CollectSizeOfSurfaces.
struct MOZ_STACK_CLASS SurfaceMemoryReport {
SurfaceMemoryReport(nsTArray<SurfaceMemoryCounter>& aCounters,
MallocSizeOf aMallocSizeOf)
: mCounters(aCounters), mMallocSizeOf(aMallocSizeOf) {}
void Add(NotNull<CachedSurface*> aCachedSurface, bool aIsFactor2) {
if (aCachedSurface->IsPlaceholder()) {
return;
}
// Record the memory used by the ISurfaceProvider. This may not have a
// straightforward relationship to the size of the surface that
// DrawableRef() returns if the surface is generated dynamically. (i.e.,
// for surfaces with PlaybackType::eAnimated.)
aCachedSurface->mProvider->AddSizeOfExcludingThis(
mMallocSizeOf, [&](ISurfaceProvider::AddSizeOfCbData& aMetadata) {
SurfaceMemoryCounter counter(aCachedSurface->GetSurfaceKey(),
aCachedSurface->IsLocked(),
aCachedSurface->CannotSubstitute(),
aIsFactor2, aMetadata.mFinished);
counter.Values().SetDecodedHeap(aMetadata.mHeapBytes);
counter.Values().SetDecodedNonHeap(aMetadata.mNonHeapBytes);
counter.Values().SetDecodedUnknown(aMetadata.mUnknownBytes);
counter.Values().SetExternalHandles(aMetadata.mExternalHandles);
counter.Values().SetFrameIndex(aMetadata.mIndex);
counter.Values().SetExternalId(aMetadata.mExternalId);
counter.Values().SetSurfaceTypes(aMetadata.mTypes);
mCounters.AppendElement(counter);
});
}
private:
nsTArray<SurfaceMemoryCounter>& mCounters;
MallocSizeOf mMallocSizeOf;
};
private:
nsExpirationState mExpirationState;
NotNull<RefPtr<ISurfaceProvider>> mProvider;
bool mIsLocked;
};
static int64_t AreaOfIntSize(const IntSize& aSize) {
return static_cast<int64_t>(aSize.width) * static_cast<int64_t>(aSize.height);
}
/**
* An ImageSurfaceCache is a per-image surface cache. For correctness we must be
* able to remove all surfaces associated with an image when the image is
* destroyed or invalidated. Since this will happen frequently, it makes sense
* to make it cheap by storing the surfaces for each image separately.
*
* ImageSurfaceCache also keeps track of whether its associated image is locked
* or unlocked.
*
* The cache may also enter "factor of 2" mode which occurs when the number of
* surfaces in the cache exceeds the "image.cache.factor2.threshold-surfaces"
* pref plus the number of native sizes of the image. When in "factor of 2"
* mode, the cache will strongly favour sizes which are a factor of 2 of the
* largest native size. It accomplishes this by suggesting a factor of 2 size
* when lookups fail and substituting the nearest factor of 2 surface to the
* ideal size as the "best" available (as opposed to substitution but not
* found). This allows us to minimize memory consumption and CPU time spent
* decoding when a website requires many variants of the same surface.
*/
class ImageSurfaceCache {
~ImageSurfaceCache() {}
public:
explicit ImageSurfaceCache(const ImageKey aImageKey)
: mLocked(false),
mFactor2Mode(false),
mFactor2Pruned(false),
mIsVectorImage(aImageKey->GetType() == imgIContainer::TYPE_VECTOR) {}
MOZ_DECLARE_REFCOUNTED_TYPENAME(ImageSurfaceCache)
NS_INLINE_DECL_THREADSAFE_REFCOUNTING(ImageSurfaceCache)
typedef nsRefPtrHashtable<nsGenericHashKey<SurfaceKey>, CachedSurface>
SurfaceTable;
bool IsEmpty() const { return mSurfaces.Count() == 0; }
size_t ShallowSizeOfIncludingThis(MallocSizeOf aMallocSizeOf) const {
size_t bytes = aMallocSizeOf(this) +
mSurfaces.ShallowSizeOfExcludingThis(aMallocSizeOf);
for (auto iter = ConstIter(); !iter.Done(); iter.Next()) {
bytes += iter.UserData()->ShallowSizeOfIncludingThis(aMallocSizeOf);
}
return bytes;
}
[[nodiscard]] bool Insert(NotNull<CachedSurface*> aSurface) {
MOZ_ASSERT(!mLocked || aSurface->IsPlaceholder() || aSurface->IsLocked(),
"Inserting an unlocked surface for a locked image");
return mSurfaces.Put(aSurface->GetSurfaceKey(),
RefPtr<CachedSurface>{aSurface}, fallible);
}
already_AddRefed<CachedSurface> Remove(NotNull<CachedSurface*> aSurface) {
MOZ_ASSERT(mSurfaces.GetWeak(aSurface->GetSurfaceKey()),
"Should not be removing a surface we don't have");
RefPtr<CachedSurface> surface;
mSurfaces.Remove(aSurface->GetSurfaceKey(), getter_AddRefs(surface));
AfterMaybeRemove();
return surface.forget();
}
already_AddRefed<CachedSurface> Lookup(const SurfaceKey& aSurfaceKey,
bool aForAccess) {
RefPtr<CachedSurface> surface;
mSurfaces.Get(aSurfaceKey, getter_AddRefs(surface));
if (aForAccess) {
if (surface) {
// We don't want to allow factor of 2 mode pruning to release surfaces
// for which the callers will accept no substitute.
surface->SetCannotSubstitute();
} else if (!mFactor2Mode) {
// If no exact match is found, and this is for use rather than internal
// accounting (i.e. insert and removal), we know this will trigger a
// decode. Make sure we switch now to factor of 2 mode if necessary.
MaybeSetFactor2Mode();
}
}
return surface.forget();
}
/**
* @returns A tuple containing the best matching CachedSurface if available,
* a MatchType describing how the CachedSurface was selected, and
* an IntSize which is the size the caller should choose to decode
* at should it attempt to do so.
*/
Tuple<already_AddRefed<CachedSurface>, MatchType, IntSize> LookupBestMatch(
const SurfaceKey& aIdealKey) {
// Try for an exact match first.
RefPtr<CachedSurface> exactMatch;
mSurfaces.Get(aIdealKey, getter_AddRefs(exactMatch));
if (exactMatch) {
if (exactMatch->IsDecoded()) {
return MakeTuple(exactMatch.forget(), MatchType::EXACT, IntSize());
}
} else if (!mFactor2Mode) {
// If no exact match is found, and we are not in factor of 2 mode, then
// we know that we will trigger a decode because at best we will provide
// a substitute. Make sure we switch now to factor of 2 mode if necessary.
MaybeSetFactor2Mode();
}
// Try for a best match second, if using compact.
IntSize suggestedSize = SuggestedSize(aIdealKey.Size());
if (suggestedSize != aIdealKey.Size()) {
if (!exactMatch) {
SurfaceKey compactKey = aIdealKey.CloneWithSize(suggestedSize);
mSurfaces.Get(compactKey, getter_AddRefs(exactMatch));
if (exactMatch && exactMatch->IsDecoded()) {
MOZ_ASSERT(suggestedSize != aIdealKey.Size());
return MakeTuple(exactMatch.forget(),
MatchType::SUBSTITUTE_BECAUSE_BEST, suggestedSize);
}
}
}
// There's no perfect match, so find the best match we can.
RefPtr<CachedSurface> bestMatch;
for (auto iter = ConstIter(); !iter.Done(); iter.Next()) {
NotNull<CachedSurface*> current = WrapNotNull(iter.UserData());
const SurfaceKey& currentKey = current->GetSurfaceKey();
// We never match a placeholder.
if (current->IsPlaceholder()) {
continue;
}
// Matching the playback type and SVG context is required.
if (currentKey.Playback() != aIdealKey.Playback() ||
currentKey.SVGContext() != aIdealKey.SVGContext()) {
continue;
}
// Matching the flags is required.
if (currentKey.Flags() != aIdealKey.Flags()) {
continue;
}
// Anything is better than nothing! (Within the constraints we just
// checked, of course.)
if (!bestMatch) {
bestMatch = current;
continue;
}
MOZ_ASSERT(bestMatch, "Should have a current best match");
// Always prefer completely decoded surfaces.
bool bestMatchIsDecoded = bestMatch->IsDecoded();
if (bestMatchIsDecoded && !current->IsDecoded()) {
continue;
}
if (!bestMatchIsDecoded && current->IsDecoded()) {
bestMatch = current;
continue;
}
SurfaceKey bestMatchKey = bestMatch->GetSurfaceKey();
if (CompareArea(aIdealKey.Size(), bestMatchKey.Size(),
currentKey.Size())) {
bestMatch = current;
}
}
MatchType matchType;
if (bestMatch) {
if (!exactMatch) {
// No exact match, neither ideal nor factor of 2.
MOZ_ASSERT(suggestedSize != bestMatch->GetSurfaceKey().Size(),
"No exact match despite the fact the sizes match!");
matchType = MatchType::SUBSTITUTE_BECAUSE_NOT_FOUND;
} else if (exactMatch != bestMatch) {
// The exact match is still decoding, but we found a substitute.
matchType = MatchType::SUBSTITUTE_BECAUSE_PENDING;
} else if (aIdealKey.Size() != bestMatch->GetSurfaceKey().Size()) {
// The best factor of 2 match is still decoding, but the best we've got.
MOZ_ASSERT(suggestedSize != aIdealKey.Size());
MOZ_ASSERT(mFactor2Mode || mIsVectorImage);
matchType = MatchType::SUBSTITUTE_BECAUSE_BEST;
} else {
// The exact match is still decoding, but it's the best we've got.
matchType = MatchType::EXACT;
}
} else {
if (exactMatch) {
// We found an "exact match"; it must have been a placeholder.
MOZ_ASSERT(exactMatch->IsPlaceholder());
matchType = MatchType::PENDING;
} else {
// We couldn't find an exact match *or* a substitute.
matchType = MatchType::NOT_FOUND;
}
}
return MakeTuple(bestMatch.forget(), matchType, suggestedSize);
}
void MaybeSetFactor2Mode() {
MOZ_ASSERT(!mFactor2Mode);
// Typically an image cache will not have too many size-varying surfaces, so
// if we exceed the given threshold, we should consider using a subset.
int32_t thresholdSurfaces =
StaticPrefs::image_cache_factor2_threshold_surfaces();
if (thresholdSurfaces < 0 ||
mSurfaces.Count() <= static_cast<uint32_t>(thresholdSurfaces)) {
return;
}
// Determine how many native surfaces this image has. If it is zero, and it
// is a vector image, then we should impute a single native size. Otherwise,
// it may be zero because we don't know yet, or the image has an error, or
// it isn't supported.
auto first = ConstIter();
NotNull<CachedSurface*> current = WrapNotNull(first.UserData());
Image* image = static_cast<Image*>(current->GetImageKey());
size_t nativeSizes = image->GetNativeSizesLength();
if (mIsVectorImage) {
MOZ_ASSERT(nativeSizes == 0);
nativeSizes = 1;
} else if (nativeSizes == 0) {
return;
}
// Increase the threshold by the number of native sizes. This ensures that
// we do not prevent decoding of the image at all its native sizes. It does
// not guarantee we will provide a surface at that size however (i.e. many
// other sized surfaces are requested, in addition to the native sizes).
thresholdSurfaces += nativeSizes;
if (mSurfaces.Count() <= static_cast<uint32_t>(thresholdSurfaces)) {
return;
}
// Get our native size. While we know the image should be fully decoded,
// if it is an SVG, it is valid to have a zero size. We can't do compacting
// in that case because we need to know the width/height ratio to define a
// candidate set.
IntSize nativeSize;
if (NS_FAILED(image->GetWidth(&nativeSize.width)) ||
NS_FAILED(image->GetHeight(&nativeSize.height)) ||
nativeSize.IsEmpty()) {
return;
}
// We have a valid size, we can change modes.
mFactor2Mode = true;
}
template <typename Function>
void Prune(Function&& aRemoveCallback) {
if (!mFactor2Mode || mFactor2Pruned) {
return;
}
// Attempt to discard any surfaces which are not factor of 2 and the best
// factor of 2 match exists.
bool hasNotFactorSize = false;
for (auto iter = mSurfaces.Iter(); !iter.Done(); iter.Next()) {
NotNull<CachedSurface*> current = WrapNotNull(iter.UserData());
const SurfaceKey& currentKey = current->GetSurfaceKey();
const IntSize& currentSize = currentKey.Size();
// First we check if someone requested this size and would not accept
// an alternatively sized surface.
if (current->CannotSubstitute()) {
continue;
}
// Next we find the best factor of 2 size for this surface. If this
// surface is a factor of 2 size, then we want to keep it.
IntSize bestSize = SuggestedSize(currentSize);
if (bestSize == currentSize) {
continue;
}
// Check the cache for a surface with the same parameters except for the
// size which uses the closest factor of 2 size.
SurfaceKey compactKey = currentKey.CloneWithSize(bestSize);
RefPtr<CachedSurface> compactMatch;
mSurfaces.Get(compactKey, getter_AddRefs(compactMatch));
if (compactMatch && compactMatch->IsDecoded()) {
aRemoveCallback(current);
iter.Remove();
} else {
hasNotFactorSize = true;
}
}
// We have no surfaces that are not factor of 2 sized, so we can stop
// pruning henceforth, because we avoid the insertion of new surfaces that
// don't match our sizing set (unless the caller won't accept a
// substitution.)
if (!hasNotFactorSize) {
mFactor2Pruned = true;
}
// We should never leave factor of 2 mode due to pruning in of itself, but
// if we discarded surfaces due to the volatile buffers getting released,
// it is possible.
AfterMaybeRemove();
}
IntSize SuggestedSize(const IntSize& aSize) const {
IntSize suggestedSize = SuggestedSizeInternal(aSize);
if (mIsVectorImage) {
suggestedSize = SurfaceCache::ClampVectorSize(suggestedSize);
}
return suggestedSize;
}
IntSize SuggestedSizeInternal(const IntSize& aSize) const {
// When not in factor of 2 mode, we can always decode at the given size.
if (!mFactor2Mode) {
return aSize;
}
// We cannot enter factor of 2 mode unless we have a minimum number of
// surfaces, and we should have left it if the cache was emptied.
if (MOZ_UNLIKELY(IsEmpty())) {
MOZ_ASSERT_UNREACHABLE("Should not be empty and in factor of 2 mode!");
return aSize;
}
// This bit of awkwardness gets the largest native size of the image.
auto iter = ConstIter();
NotNull<CachedSurface*> firstSurface = WrapNotNull(iter.UserData());
Image* image = static_cast<Image*>(firstSurface->GetImageKey());
IntSize factorSize;
if (NS_FAILED(image->GetWidth(&factorSize.width)) ||
NS_FAILED(image->GetHeight(&factorSize.height)) ||
factorSize.IsEmpty()) {
// We should not have entered factor of 2 mode without a valid size, and
// several successfully decoded surfaces. Note that valid vector images
// may have a default size of 0x0, and those are not yet supported.
MOZ_ASSERT_UNREACHABLE("Expected valid native size!");
return aSize;
}
if (image->GetOrientation().SwapsWidthAndHeight() &&
image->HandledOrientation()) {
std::swap(factorSize.width, factorSize.height);
}
if (mIsVectorImage) {
// Ensure the aspect ratio matches the native size before forcing the
// caller to accept a factor of 2 size. The difference between the aspect
// ratios is:
//
// delta = nativeWidth/nativeHeight - desiredWidth/desiredHeight
//
// delta*nativeHeight*desiredHeight = nativeWidth*desiredHeight
// - desiredWidth*nativeHeight
//
// Using the maximum accepted delta as a constant, we can avoid the
// floating point division and just compare after some integer ops.
int32_t delta =
factorSize.width * aSize.height - aSize.width * factorSize.height;
int32_t maxDelta = (factorSize.height * aSize.height) >> 4;
if (delta > maxDelta || delta < -maxDelta) {
return aSize;
}
// If the requested size is bigger than the native size, we actually need
// to grow the native size instead of shrinking it.
if (factorSize.width < aSize.width) {
do {
IntSize candidate(factorSize.width * 2, factorSize.height * 2);
if (!SurfaceCache::IsLegalSize(candidate)) {
break;
}
factorSize = candidate;
} while (factorSize.width < aSize.width);
return factorSize;
}
// Otherwise we can find the best fit as normal.
}
// Start with the native size as the best first guess.
IntSize bestSize = factorSize;
factorSize.width /= 2;
factorSize.height /= 2;
while (!factorSize.IsEmpty()) {
if (!CompareArea(aSize, bestSize, factorSize)) {
// This size is not better than the last. Since we proceed from largest
// to smallest, we know that the next size will not be better if the
// previous size was rejected. Break early.
break;
}
// The current factor of 2 size is better than the last selected size.
bestSize = factorSize;
factorSize.width /= 2;
factorSize.height /= 2;
}
return bestSize;
}
bool CompareArea(const IntSize& aIdealSize, const IntSize& aBestSize,
const IntSize& aSize) const {
// Compare sizes. We use an area-based heuristic here instead of computing a
// truly optimal answer, since it seems very unlikely to make a difference
// for realistic sizes.
int64_t idealArea = AreaOfIntSize(aIdealSize);
int64_t currentArea = AreaOfIntSize(aSize);
int64_t bestMatchArea = AreaOfIntSize(aBestSize);
// If the best match is smaller than the ideal size, prefer bigger sizes.
if (bestMatchArea < idealArea) {
if (currentArea > bestMatchArea) {
return true;
}
return false;
}
// Other, prefer sizes closer to the ideal size, but still not smaller.
if (idealArea <= currentArea && currentArea < bestMatchArea) {
return true;
}
// This surface isn't an improvement over the current best match.
return false;
}
template <typename Function>
void CollectSizeOfSurfaces(nsTArray<SurfaceMemoryCounter>& aCounters,
MallocSizeOf aMallocSizeOf,
Function&& aRemoveCallback) {
CachedSurface::SurfaceMemoryReport report(aCounters, aMallocSizeOf);
for (auto iter = mSurfaces.Iter(); !iter.Done(); iter.Next()) {
NotNull<CachedSurface*> surface = WrapNotNull(iter.UserData());
// We don't need the drawable surface for ourselves, but adding a surface
// to the report will trigger this indirectly. If the surface was
// discarded by the OS because it was in volatile memory, we should remove
// it from the cache immediately rather than include it in the report.
DrawableSurface drawableSurface;
if (!surface->IsPlaceholder()) {
drawableSurface = surface->GetDrawableSurface();
if (!drawableSurface) {
aRemoveCallback(surface);
iter.Remove();
continue;
}
}
const IntSize& size = surface->GetSurfaceKey().Size();
bool factor2Size = false;
if (mFactor2Mode) {
factor2Size = (size == SuggestedSize(size));
}
report.Add(surface, factor2Size);
}
AfterMaybeRemove();
}
SurfaceTable::Iterator ConstIter() const { return mSurfaces.ConstIter(); }
uint32_t Count() const { return mSurfaces.Count(); }
void SetLocked(bool aLocked) { mLocked = aLocked; }
bool IsLocked() const { return mLocked; }
private:
void AfterMaybeRemove() {
if (IsEmpty() && mFactor2Mode) {
// The last surface for this cache was removed. This can happen if the
// surface was stored in a volatile buffer and got purged, or the surface
// expired from the cache. If the cache itself lingers for some reason
// (e.g. in the process of performing a lookup, the cache itself is
// locked), then we need to reset the factor of 2 state because it
// requires at least one surface present to get the native size
// information from the image.
mFactor2Mode = mFactor2Pruned = false;
}
}
SurfaceTable mSurfaces;
bool mLocked;
// True in "factor of 2" mode.
bool mFactor2Mode;
// True if all non-factor of 2 surfaces have been removed from the cache. Note
// that this excludes unsubstitutable sizes.
bool mFactor2Pruned;
// True if the surfaces are produced from a vector image. If so, it must match
// the aspect ratio when using factor of 2 mode.
bool mIsVectorImage;
};
/**
* SurfaceCacheImpl is responsible for determining which surfaces will be cached
* and managing the surface cache data structures. Rather than interact with
* SurfaceCacheImpl directly, client code interacts with SurfaceCache, which
* maintains high-level invariants and encapsulates the details of the surface
* cache's implementation.
*/
class SurfaceCacheImpl final : public nsIMemoryReporter {
public:
NS_DECL_ISUPPORTS
SurfaceCacheImpl(uint32_t aSurfaceCacheExpirationTimeMS,
uint32_t aSurfaceCacheDiscardFactor,
uint32_t aSurfaceCacheSize)
: mExpirationTracker(aSurfaceCacheExpirationTimeMS),
mMemoryPressureObserver(new MemoryPressureObserver),
mDiscardFactor(aSurfaceCacheDiscardFactor),
mMaxCost(aSurfaceCacheSize),
mAvailableCost(aSurfaceCacheSize),
mLockedCost(0),
mOverflowCount(0),
mAlreadyPresentCount(0),
mTableFailureCount(0),
mTrackingFailureCount(0) {
nsCOMPtr<nsIObserverService> os = services::GetObserverService();
if (os) {
os->AddObserver(mMemoryPressureObserver, "memory-pressure", false);
}
}
private:
virtual ~SurfaceCacheImpl() {
nsCOMPtr<nsIObserverService> os = services::GetObserverService();
if (os) {
os->RemoveObserver(mMemoryPressureObserver, "memory-pressure");
}
UnregisterWeakMemoryReporter(this);
}
public:
void InitMemoryReporter() { RegisterWeakMemoryReporter(this); }
InsertOutcome Insert(NotNull<ISurfaceProvider*> aProvider, bool aSetAvailable,
const StaticMutexAutoLock& aAutoLock) {
// If this is a duplicate surface, refuse to replace the original.
// XXX(seth): Calling Lookup() and then RemoveEntry() does the lookup
// twice. We'll make this more efficient in bug 1185137.
LookupResult result =
Lookup(aProvider->GetImageKey(), aProvider->GetSurfaceKey(), aAutoLock,
/* aMarkUsed = */ false);
if (MOZ_UNLIKELY(result)) {
mAlreadyPresentCount++;
return InsertOutcome::FAILURE_ALREADY_PRESENT;
}
if (result.Type() == MatchType::PENDING) {
RemoveEntry(aProvider->GetImageKey(), aProvider->GetSurfaceKey(),
aAutoLock);
}
MOZ_ASSERT(result.Type() == MatchType::NOT_FOUND ||
result.Type() == MatchType::PENDING,
"A LookupResult with no surface should be NOT_FOUND or PENDING");
// If this is bigger than we can hold after discarding everything we can,
// refuse to cache it.
Cost cost = aProvider->LogicalSizeInBytes();
if (MOZ_UNLIKELY(!CanHoldAfterDiscarding(cost))) {
mOverflowCount++;
return InsertOutcome::FAILURE;
}
// Remove elements in order of cost until we can fit this in the cache. Note
// that locked surfaces aren't in mCosts, so we never remove them here.
while (cost > mAvailableCost) {
MOZ_ASSERT(!mCosts.IsEmpty(),
"Removed everything and it still won't fit");
Remove(mCosts.LastElement().Surface(), /* aStopTracking */ true,
aAutoLock);
}
// Locate the appropriate per-image cache. If there's not an existing cache
// for this image, create it.
const ImageKey imageKey = aProvider->GetImageKey();
RefPtr<ImageSurfaceCache> cache = GetImageCache(imageKey);
if (!cache) {
cache = new ImageSurfaceCache(imageKey);
if (!mImageCaches.Put(aProvider->GetImageKey(), RefPtr{cache},
fallible)) {
mTableFailureCount++;
return InsertOutcome::FAILURE;
}
}
// If we were asked to mark the cache entry available, do so.
if (aSetAvailable) {
aProvider->Availability().SetAvailable();
}
auto surface = MakeNotNull<RefPtr<CachedSurface>>(aProvider);
// We require that locking succeed if the image is locked and we're not
// inserting a placeholder; the caller may need to know this to handle
// errors correctly.
bool mustLock = cache->IsLocked() && !surface->IsPlaceholder();
if (mustLock) {
surface->SetLocked(true);
if (!surface->IsLocked()) {
return InsertOutcome::FAILURE;
}
}
// Insert.
MOZ_ASSERT(cost <= mAvailableCost, "Inserting despite too large a cost");
if (!cache->Insert(surface)) {
mTableFailureCount++;
if (mustLock) {
surface->SetLocked(false);
}
return InsertOutcome::FAILURE;
}
if (MOZ_UNLIKELY(!StartTracking(surface, aAutoLock))) {
MOZ_ASSERT(!mustLock);
Remove(surface, /* aStopTracking */ false, aAutoLock);
return InsertOutcome::FAILURE;
}
return InsertOutcome::SUCCESS;
}
void Remove(NotNull<CachedSurface*> aSurface, bool aStopTracking,
const StaticMutexAutoLock& aAutoLock) {
ImageKey imageKey = aSurface->GetImageKey();
RefPtr<ImageSurfaceCache> cache = GetImageCache(imageKey);
MOZ_ASSERT(cache, "Shouldn't try to remove a surface with no image cache");
// If the surface was not a placeholder, tell its image that we discarded
// it.
if (!aSurface->IsPlaceholder()) {
static_cast<Image*>(imageKey)->OnSurfaceDiscarded(
aSurface->GetSurfaceKey());
}
// If we failed during StartTracking, we can skip this step.
if (aStopTracking) {
StopTracking(aSurface, /* aIsTracked */ true, aAutoLock);
}
// Individual surfaces must be freed outside the lock.
mCachedSurfacesDiscard.AppendElement(cache->Remove(aSurface));
MaybeRemoveEmptyCache(imageKey, cache);
}
bool StartTracking(NotNull<CachedSurface*> aSurface,
const StaticMutexAutoLock& aAutoLock) {
CostEntry costEntry = aSurface->GetCostEntry();
MOZ_ASSERT(costEntry.GetCost() <= mAvailableCost,
"Cost too large and the caller didn't catch it");
if (aSurface->IsLocked()) {
mLockedCost += costEntry.GetCost();
MOZ_ASSERT(mLockedCost <= mMaxCost, "Locked more than we can hold?");
} else {
if (NS_WARN_IF(!mCosts.InsertElementSorted(costEntry, fallible))) {
mTrackingFailureCount++;
return false;
}
// This may fail during XPCOM shutdown, so we need to ensure the object is
// tracked before calling RemoveObject in StopTracking.
nsresult rv = mExpirationTracker.AddObjectLocked(aSurface, aAutoLock);
if (NS_WARN_IF(NS_FAILED(rv))) {
DebugOnly<bool> foundInCosts = mCosts.RemoveElementSorted(costEntry);
MOZ_ASSERT(foundInCosts, "Lost track of costs for this surface");
mTrackingFailureCount++;
return false;
}
}
mAvailableCost -= costEntry.GetCost();
return true;
}
void StopTracking(NotNull<CachedSurface*> aSurface, bool aIsTracked,
const StaticMutexAutoLock& aAutoLock) {
CostEntry costEntry = aSurface->GetCostEntry();
if (aSurface->IsLocked()) {
MOZ_ASSERT(mLockedCost >= costEntry.GetCost(), "Costs don't balance");
mLockedCost -= costEntry.GetCost();
// XXX(seth): It'd be nice to use an O(log n) lookup here. This is O(n).
MOZ_ASSERT(!mCosts.Contains(costEntry),
"Shouldn't have a cost entry for a locked surface");
} else {
if (MOZ_LIKELY(aSurface->GetExpirationState()->IsTracked())) {
MOZ_ASSERT(aIsTracked, "Expiration-tracking a surface unexpectedly!");
mExpirationTracker.RemoveObjectLocked(aSurface, aAutoLock);
} else {
// Our call to AddObject must have failed in StartTracking; most likely
// we're in XPCOM shutdown right now.
MOZ_ASSERT(!aIsTracked, "Not expiration-tracking an unlocked surface!");
}
DebugOnly<bool> foundInCosts = mCosts.RemoveElementSorted(costEntry);
MOZ_ASSERT(foundInCosts, "Lost track of costs for this surface");
}
mAvailableCost += costEntry.GetCost();
MOZ_ASSERT(mAvailableCost <= mMaxCost,
"More available cost than we started with");
}
LookupResult Lookup(const ImageKey aImageKey, const SurfaceKey& aSurfaceKey,
const StaticMutexAutoLock& aAutoLock, bool aMarkUsed) {
RefPtr<ImageSurfaceCache> cache = GetImageCache(aImageKey);
if (!cache) {
// No cached surfaces for this image.
return LookupResult(MatchType::NOT_FOUND);
}
RefPtr<CachedSurface> surface = cache->Lookup(aSurfaceKey, aMarkUsed);
if (!surface) {
// Lookup in the per-image cache missed.
return LookupResult(MatchType::NOT_FOUND);
}
if (surface->IsPlaceholder()) {
return LookupResult(MatchType::PENDING);
}
DrawableSurface drawableSurface = surface->GetDrawableSurface();
if (!drawableSurface) {
// The surface was released by the operating system. Remove the cache
// entry as well.
Remove(WrapNotNull(surface), /* aStopTracking */ true, aAutoLock);
return LookupResult(MatchType::NOT_FOUND);
}
if (aMarkUsed &&
!MarkUsed(WrapNotNull(surface), WrapNotNull(cache), aAutoLock)) {
Remove(WrapNotNull(surface), /* aStopTracking */ false, aAutoLock);
return LookupResult(MatchType::NOT_FOUND);
}
MOZ_ASSERT(surface->GetSurfaceKey() == aSurfaceKey,
"Lookup() not returning an exact match?");
return LookupResult(std::move(drawableSurface), MatchType::EXACT);
}
LookupResult LookupBestMatch(const ImageKey aImageKey,
const SurfaceKey& aSurfaceKey,
const StaticMutexAutoLock& aAutoLock,
bool aMarkUsed) {
RefPtr<ImageSurfaceCache> cache = GetImageCache(aImageKey);
if (!cache) {
// No cached surfaces for this image.
return LookupResult(
MatchType::NOT_FOUND,
SurfaceCache::ClampSize(aImageKey, aSurfaceKey.Size()));
}
// Repeatedly look up the best match, trying again if the resulting surface
// has been freed by the operating system, until we can either lock a
// surface for drawing or there are no matching surfaces left.
// XXX(seth): This is O(N^2), but N is expected to be very small. If we
// encounter a performance problem here we can revisit this.
RefPtr<CachedSurface> surface;
DrawableSurface drawableSurface;
MatchType matchType = MatchType::NOT_FOUND;
IntSize suggestedSize;
while (true) {
Tie(surface, matchType, suggestedSize) =