1 files changed, 397 insertions, 0 deletions
diff --git a/dom/canvas/CanvasImageCache.cpp b/dom/canvas/CanvasImageCache.cpp
new file mode 100644
index 0000000000..96a1505a40
--- /dev/null
+++ b/dom/canvas/CanvasImageCache.cpp
@@ -0,0 +1,397 @@
+/* -*- 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/. */
+
+#include "CanvasImageCache.h"
+#include "nsIImageLoadingContent.h"
+#include "nsExpirationTracker.h"
+#include "imgIRequest.h"
+#include "mozilla/dom/Element.h"
+#include "nsTHashtable.h"
+#include "mozilla/dom/HTMLCanvasElement.h"
+#include "nsContentUtils.h"
+#include "mozilla/Preferences.h"
+#include "mozilla/StaticPrefs_canvas.h"
+#include "mozilla/UniquePtr.h"
+#include "mozilla/gfx/2D.h"
+#include "gfx2DGlue.h"
+
+namespace mozilla {
+
+using namespace dom;
+using namespace gfx;
+
+/**
+ * Used for images specific to this one canvas. Required
+ * due to CORS security.
+ */
+struct ImageCacheKey {
+  ImageCacheKey(imgIContainer* aImage, HTMLCanvasElement* aCanvas,
+                BackendType aBackendType)
+      : mImage(aImage), mCanvas(aCanvas), mBackendType(aBackendType) {}
+  nsCOMPtr<imgIContainer> mImage;
+  HTMLCanvasElement* mCanvas;
+  BackendType mBackendType;
+};
+
+/**
+ * Cache data needs to be separate from the entry
+ * for nsExpirationTracker.
+ */
+struct ImageCacheEntryData {
+  ImageCacheEntryData(const ImageCacheEntryData& aOther)
+      : mImage(aOther.mImage),
+        mCanvas(aOther.mCanvas),
+        mBackendType(aOther.mBackendType),
+        mSourceSurface(aOther.mSourceSurface),
+        mSize(aOther.mSize),
+        mIntrinsicSize(aOther.mIntrinsicSize) {}
+  explicit ImageCacheEntryData(const ImageCacheKey& aKey)
+      : mImage(aKey.mImage),
+        mCanvas(aKey.mCanvas),
+        mBackendType(aKey.mBackendType) {}
+
+  nsExpirationState* GetExpirationState() { return &mState; }
+  size_t SizeInBytes() { return mSize.width * mSize.height * 4; }
+
+  // Key
+  nsCOMPtr<imgIContainer> mImage;
+  HTMLCanvasElement* mCanvas;
+  BackendType mBackendType;
+  // Value
+  RefPtr<SourceSurface> mSourceSurface;
+  IntSize mSize;
+  IntSize mIntrinsicSize;
+  nsExpirationState mState;
+};
+
+class ImageCacheEntry : public PLDHashEntryHdr {
+ public:
+  using KeyType = ImageCacheKey;
+  using KeyTypePointer = const ImageCacheKey*;
+
+  explicit ImageCacheEntry(const KeyType* aKey)
+      : mData(new ImageCacheEntryData(*aKey)) {}
+  ImageCacheEntry(const ImageCacheEntry& toCopy)
+      : mData(new ImageCacheEntryData(*toCopy.mData)) {}
+  ~ImageCacheEntry() = default;
+
+  bool KeyEquals(KeyTypePointer key) const {
+    return mData->mImage == key->mImage && mData->mCanvas == key->mCanvas &&
+           mData->mBackendType == key->mBackendType;
+  }
+
+  static KeyTypePointer KeyToPointer(KeyType& key) { return &key; }
+  static PLDHashNumber HashKey(KeyTypePointer key) {
+    return HashGeneric(key->mImage.get(), key->mCanvas, key->mBackendType);
+  }
+  enum { ALLOW_MEMMOVE = true };
+
+  UniquePtr<ImageCacheEntryData> mData;
+};
+
+/**
+ * Used for all images across all canvases.
+ */
+struct AllCanvasImageCacheKey {
+  explicit AllCanvasImageCacheKey(imgIContainer* aImage,
+                                  BackendType aBackendType)
+      : mImage(aImage), mBackendType(aBackendType) {}
+
+  nsCOMPtr<imgIContainer> mImage;
+  BackendType mBackendType;
+};
+
+class AllCanvasImageCacheEntry : public PLDHashEntryHdr {
+ public:
+  using KeyType = AllCanvasImageCacheKey;
+  using KeyTypePointer = const AllCanvasImageCacheKey*;
+
+  explicit AllCanvasImageCacheEntry(const KeyType* aKey)
+      : mImage(aKey->mImage), mBackendType(aKey->mBackendType) {}
+
+  AllCanvasImageCacheEntry(const AllCanvasImageCacheEntry& toCopy)
+      : mImage(toCopy.mImage),
+        mSourceSurface(toCopy.mSourceSurface),
+        mBackendType(toCopy.mBackendType) {}
+
+  ~AllCanvasImageCacheEntry() = default;
+
+  bool KeyEquals(KeyTypePointer key) const {
+    return mImage == key->mImage && mBackendType == key->mBackendType;
+  }
+
+  static KeyTypePointer KeyToPointer(KeyType& key) { return &key; }
+  static PLDHashNumber HashKey(KeyTypePointer key) {
+    return HashGeneric(key->mImage.get(), key->mBackendType);
+  }
+  enum { ALLOW_MEMMOVE = true };
+
+  nsCOMPtr<imgIContainer> mImage;
+  RefPtr<SourceSurface> mSourceSurface;
+  BackendType mBackendType;
+};
+
+class ImageCacheObserver;
+
+class ImageCache final : public nsExpirationTracker<ImageCacheEntryData, 4> {
+ public:
+  // We use 3 generations of 1 second each to get a 2-3 seconds timeout.
+  enum { GENERATION_MS = 1000 };
+  ImageCache();
+  ~ImageCache();
+
+  virtual void NotifyExpired(ImageCacheEntryData* aObject) override {
+    mTotal -= aObject->SizeInBytes();
+    RemoveObject(aObject);
+
+    // Remove from the all canvas cache entry first since nsExpirationTracker
+    // will delete aObject.
+    mAllCanvasCache.RemoveEntry(
+        AllCanvasImageCacheKey(aObject->mImage, aObject->mBackendType));
+
+    // Deleting the entry will delete aObject since the entry owns aObject.
+    mCache.RemoveEntry(ImageCacheKey(aObject->mImage, aObject->mCanvas,
+                                     aObject->mBackendType));
+  }
+
+  nsTHashtable<ImageCacheEntry> mCache;
+  nsTHashtable<AllCanvasImageCacheEntry> mAllCanvasCache;
+  size_t mTotal;
+  RefPtr<ImageCacheObserver> mImageCacheObserver;
+};
+
+static ImageCache* gImageCache = nullptr;
+
+// Listen memory-pressure event for image cache purge.
+class ImageCacheObserver final : public nsIObserver {
+ public:
+  NS_DECL_ISUPPORTS
+
+  explicit ImageCacheObserver(ImageCache* aImageCache)
+      : mImageCache(aImageCache) {
+    RegisterObserverEvents();
+  }
+
+  void Destroy() {
+    UnregisterObserverEvents();
+    mImageCache = nullptr;
+  }
+
+  NS_IMETHOD Observe(nsISupports* aSubject, const char* aTopic,
+                     const char16_t* aSomeData) override {
+    if (!mImageCache || (strcmp(aTopic, "memory-pressure") != 0 &&
+                         strcmp(aTopic, "canvas-device-reset") != 0)) {
+      return NS_OK;
+    }
+
+    mImageCache->AgeAllGenerations();
+    return NS_OK;
+  }
+
+ private:
+  virtual ~ImageCacheObserver() = default;
+
+  void RegisterObserverEvents() {
+    nsCOMPtr<nsIObserverService> observerService =
+        mozilla::services::GetObserverService();
+
+    MOZ_ASSERT(observerService);
+
+    if (observerService) {
+      observerService->AddObserver(this, "memory-pressure", false);
+      observerService->AddObserver(this, "canvas-device-reset", false);
+    }
+  }
+
+  void UnregisterObserverEvents() {
+    nsCOMPtr<nsIObserverService> observerService =
+        mozilla::services::GetObserverService();
+
+    // Do not assert on observerService here. This might be triggered by
+    // the cycle collector at a late enough time, that XPCOM services are
+    // no longer available. See bug 1029504.
+    if (observerService) {
+      observerService->RemoveObserver(this, "memory-pressure");
+      observerService->RemoveObserver(this, "canvas-device-reset");
+    }
+  }
+
+  ImageCache* mImageCache;
+};
+
+NS_IMPL_ISUPPORTS(ImageCacheObserver, nsIObserver)
+
+class CanvasImageCacheShutdownObserver final : public nsIObserver {
+  ~CanvasImageCacheShutdownObserver() = default;
+
+ public:
+  NS_DECL_ISUPPORTS
+  NS_DECL_NSIOBSERVER
+};
+
+ImageCache::ImageCache()
+    : nsExpirationTracker<ImageCacheEntryData, 4>(GENERATION_MS, "ImageCache"),
+      mTotal(0) {
+  mImageCacheObserver = new ImageCacheObserver(this);
+  MOZ_RELEASE_ASSERT(mImageCacheObserver,
+                     "GFX: Can't alloc ImageCacheObserver");
+}
+
+ImageCache::~ImageCache() {
+  AgeAllGenerations();
+  mImageCacheObserver->Destroy();
+}
+
+static already_AddRefed<imgIContainer> GetImageContainer(dom::Element* aImage) {
+  nsCOMPtr<imgIRequest> request;
+  nsCOMPtr<nsIImageLoadingContent> ilc = do_QueryInterface(aImage);
+  if (!ilc) {
+    return nullptr;
+  }
+
+  ilc->GetRequest(nsIImageLoadingContent::CURRENT_REQUEST,
+                  getter_AddRefs(request));
+  if (!request) {
+    return nullptr;
+  }
+
+  nsCOMPtr<imgIContainer> imgContainer;
+  request->GetImage(getter_AddRefs(imgContainer));
+  if (!imgContainer) {
+    return nullptr;
+  }
+
+  return imgContainer.forget();
+}
+
+void CanvasImageCache::NotifyDrawImage(Element* aImage,
+                                       HTMLCanvasElement* aCanvas,
+                                       DrawTarget* aTarget,
+                                       SourceSurface* aSource,
+                                       const IntSize& aSize,
+                                       const IntSize& aIntrinsicSize) {
+  if (!aTarget) {
+    return;
+  }
+
+  if (!gImageCache) {
+    gImageCache = new ImageCache();
+    nsContentUtils::RegisterShutdownObserver(
+        new CanvasImageCacheShutdownObserver());
+  }
+
+  nsCOMPtr<imgIContainer> imgContainer = GetImageContainer(aImage);
+  if (!imgContainer) {
+    return;
+  }
+
+  BackendType backendType = aTarget->GetBackendType();
+  AllCanvasImageCacheKey allCanvasCacheKey(imgContainer, backendType);
+  ImageCacheKey canvasCacheKey(imgContainer, aCanvas, backendType);
+  ImageCacheEntry* entry = gImageCache->mCache.PutEntry(canvasCacheKey);
+
+  if (entry) {
+    if (entry->mData->mSourceSurface) {
+      // We are overwriting an existing entry.
+      gImageCache->mTotal -= entry->mData->SizeInBytes();
+      gImageCache->RemoveObject(entry->mData.get());
+      gImageCache->mAllCanvasCache.RemoveEntry(allCanvasCacheKey);
+    }
+
+    gImageCache->AddObject(entry->mData.get());
+    entry->mData->mSourceSurface = aSource;
+    entry->mData->mSize = aSize;
+    entry->mData->mIntrinsicSize = aIntrinsicSize;
+    gImageCache->mTotal += entry->mData->SizeInBytes();
+
+    AllCanvasImageCacheEntry* allEntry =
+        gImageCache->mAllCanvasCache.PutEntry(allCanvasCacheKey);
+    if (allEntry) {
+      allEntry->mSourceSurface = aSource;
+    }
+  }
+
+  if (!StaticPrefs::canvas_image_cache_limit()) {
+    return;
+  }
+
+  // Expire the image cache early if its larger than we want it to be.
+  while (gImageCache->mTotal >
+         size_t(StaticPrefs::canvas_image_cache_limit())) {
+    gImageCache->AgeOneGeneration();
+  }
+}
+
+SourceSurface* CanvasImageCache::LookupAllCanvas(Element* aImage,
+                                                 DrawTarget* aTarget) {
+  if (!gImageCache || !aTarget) {
+    return nullptr;
+  }
+
+  nsCOMPtr<imgIContainer> imgContainer = GetImageContainer(aImage);
+  if (!imgContainer) {
+    return nullptr;
+  }
+
+  AllCanvasImageCacheEntry* entry = gImageCache->mAllCanvasCache.GetEntry(
+      AllCanvasImageCacheKey(imgContainer, aTarget->GetBackendType()));
+  if (!entry) {
+    return nullptr;
+  }
+
+  return entry->mSourceSurface;
+}
+
+SourceSurface* CanvasImageCache::LookupCanvas(Element* aImage,
+                                              HTMLCanvasElement* aCanvas,
+                                              DrawTarget* aTarget,
+                                              IntSize* aSizeOut,
+                                              IntSize* aIntrinsicSizeOut) {
+  if (!gImageCache || !aTarget) {
+    return nullptr;
+  }
+
+  nsCOMPtr<imgIContainer> imgContainer = GetImageContainer(aImage);
+  if (!imgContainer) {
+    return nullptr;
+  }
+
+  // We filter based on the backend type because we don't want a surface that
+  // was optimized for one backend to be preferred for another backend, as this
+  // could have performance implications. For example, a Skia optimized surface
+  // given to a D2D backend would cause an upload each time, and similarly a D2D
+  // optimized surface given to a Skia backend would cause a readback. For
+  // details, see bug 1794442.
+  ImageCacheEntry* entry = gImageCache->mCache.GetEntry(
+      ImageCacheKey(imgContainer, aCanvas, aTarget->GetBackendType()));
+  if (!entry) {
+    return nullptr;
+  }
+
+  MOZ_ASSERT(aSizeOut);
+
+  gImageCache->MarkUsed(entry->mData.get());
+  *aSizeOut = entry->mData->mSize;
+  *aIntrinsicSizeOut = entry->mData->mIntrinsicSize;
+  return entry->mData->mSourceSurface;
+}
+
+NS_IMPL_ISUPPORTS(CanvasImageCacheShutdownObserver, nsIObserver)
+
+NS_IMETHODIMP
+CanvasImageCacheShutdownObserver::Observe(nsISupports* aSubject,
+                                          const char* aTopic,
+                                          const char16_t* aData) {
+  if (strcmp(aTopic, NS_XPCOM_SHUTDOWN_OBSERVER_ID) == 0) {
+    delete gImageCache;
+    gImageCache = nullptr;
+
+    nsContentUtils::UnregisterShutdownObserver(this);
+  }
+
+  return NS_OK;
+}
+
+}  // namespace mozilla