1 files changed, 209 insertions, 0 deletions
diff --git a/image/DecodedSurfaceProvider.cpp b/image/DecodedSurfaceProvider.cpp
new file mode 100644
index 0000000000..d91a17a58c
--- /dev/null
+++ b/image/DecodedSurfaceProvider.cpp
@@ -0,0 +1,209 @@
+/* -*- 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 "DecodedSurfaceProvider.h"
+
+#include "mozilla/StaticPrefs_image.h"
+#include "nsProxyRelease.h"
+
+#include "Decoder.h"
+
+using namespace mozilla::gfx;
+
+namespace mozilla {
+namespace image {
+
+DecodedSurfaceProvider::DecodedSurfaceProvider(NotNull<RasterImage*> aImage,
+                                               const SurfaceKey& aSurfaceKey,
+                                               NotNull<Decoder*> aDecoder)
+    : ISurfaceProvider(ImageKey(aImage.get()), aSurfaceKey,
+                       AvailabilityState::StartAsPlaceholder()),
+      mImage(aImage.get()),
+      mMutex("mozilla::image::DecodedSurfaceProvider"),
+      mDecoder(aDecoder.get()) {
+  MOZ_ASSERT(!mDecoder->IsMetadataDecode(),
+             "Use MetadataDecodingTask for metadata decodes");
+  MOZ_ASSERT(mDecoder->IsFirstFrameDecode(),
+             "Use AnimationSurfaceProvider for animation decodes");
+}
+
+DecodedSurfaceProvider::~DecodedSurfaceProvider() { DropImageReference(); }
+
+void DecodedSurfaceProvider::DropImageReference() {
+  if (!mImage) {
+    return;  // Nothing to do.
+  }
+
+  // RasterImage objects need to be destroyed on the main thread. We also need
+  // to destroy them asynchronously, because if our surface cache entry is
+  // destroyed and we were the only thing keeping |mImage| alive, RasterImage's
+  // destructor may call into the surface cache while whatever code caused us to
+  // get evicted is holding the surface cache lock, causing deadlock.
+  RefPtr<RasterImage> image = mImage;
+  mImage = nullptr;
+  SurfaceCache::ReleaseImageOnMainThread(image.forget(),
+                                         /* aAlwaysProxy = */ true);
+}
+
+DrawableFrameRef DecodedSurfaceProvider::DrawableRef(size_t aFrame) {
+  MOZ_ASSERT(aFrame == 0,
+             "Requesting an animation frame from a DecodedSurfaceProvider?");
+
+  // We depend on SurfaceCache::SurfaceAvailable() to provide synchronization
+  // for methods that touch |mSurface|; after SurfaceAvailable() is called,
+  // |mSurface| should be non-null and shouldn't be mutated further until we get
+  // destroyed. That means that the assertions below are very important; we'll
+  // end up with data races if these assumptions are violated.
+  if (Availability().IsPlaceholder()) {
+    MOZ_ASSERT_UNREACHABLE("Calling DrawableRef() on a placeholder");
+    return DrawableFrameRef();
+  }
+
+  if (!mSurface) {
+    MOZ_ASSERT_UNREACHABLE("Calling DrawableRef() when we have no surface");
+    return DrawableFrameRef();
+  }
+
+  return mSurface->DrawableRef();
+}
+
+bool DecodedSurfaceProvider::IsFinished() const {
+  // See DrawableRef() for commentary on these assertions.
+  if (Availability().IsPlaceholder()) {
+    MOZ_ASSERT_UNREACHABLE("Calling IsFinished() on a placeholder");
+    return false;
+  }
+
+  if (!mSurface) {
+    MOZ_ASSERT_UNREACHABLE("Calling IsFinished() when we have no surface");
+    return false;
+  }
+
+  return mSurface->IsFinished();
+}
+
+void DecodedSurfaceProvider::SetLocked(bool aLocked) {
+  // See DrawableRef() for commentary on these assertions.
+  if (Availability().IsPlaceholder()) {
+    MOZ_ASSERT_UNREACHABLE("Calling SetLocked() on a placeholder");
+    return;
+  }
+
+  if (!mSurface) {
+    MOZ_ASSERT_UNREACHABLE("Calling SetLocked() when we have no surface");
+    return;
+  }
+
+  if (aLocked == IsLocked()) {
+    return;  // Nothing to do.
+  }
+
+  // If we're locked, hold a DrawableFrameRef to |mSurface|, which will keep any
+  // volatile buffer it owns in memory.
+  mLockRef = aLocked ? mSurface->DrawableRef() : DrawableFrameRef();
+}
+
+size_t DecodedSurfaceProvider::LogicalSizeInBytes() const {
+  // Single frame images are always 32bpp.
+  IntSize size = GetSurfaceKey().Size();
+  return size_t(size.width) * size_t(size.height) * sizeof(uint32_t);
+}
+
+void DecodedSurfaceProvider::Run() {
+  MutexAutoLock lock(mMutex);
+
+  if (!mDecoder || !mImage) {
+    MOZ_ASSERT_UNREACHABLE("Running after decoding finished?");
+    return;
+  }
+
+  // Run the decoder.
+  LexerResult result = mDecoder->Decode(WrapNotNull(this));
+
+  // If there's a new surface available, announce it to the surface cache.
+  CheckForNewSurface();
+
+  if (result.is<TerminalState>()) {
+    FinishDecoding();
+    return;  // We're done.
+  }
+
+  // Notify for the progress we've made so far.
+  if (mDecoder->HasProgress()) {
+    NotifyProgress(WrapNotNull(mImage), WrapNotNull(mDecoder));
+  }
+
+  MOZ_ASSERT(result.is<Yield>());
+
+  if (result == LexerResult(Yield::NEED_MORE_DATA)) {
+    // We can't make any more progress right now. The decoder itself will ensure
+    // that we get reenqueued when more data is available; just return for now.
+    return;
+  }
+
+  // Single-frame images shouldn't yield for any reason except NEED_MORE_DATA.
+  MOZ_ASSERT_UNREACHABLE("Unexpected yield for single-frame image");
+  mDecoder->TerminateFailure();
+  FinishDecoding();
+}
+
+void DecodedSurfaceProvider::CheckForNewSurface() {
+  mMutex.AssertCurrentThreadOwns();
+  MOZ_ASSERT(mDecoder);
+
+  if (mSurface) {
+    // Single-frame images should produce no more than one surface, so if we
+    // have one, it should be the same one the decoder is working on.
+    MOZ_ASSERT(mSurface.get() == mDecoder->GetCurrentFrameRef().get(),
+               "DecodedSurfaceProvider and Decoder have different surfaces?");
+    return;
+  }
+
+  // We don't have a surface yet; try to get one from the decoder.
+  mSurface = mDecoder->GetCurrentFrameRef().get();
+  if (!mSurface) {
+    return;  // No surface yet.
+  }
+
+  // We just got a surface for the first time; let the surface cache know.
+  MOZ_ASSERT(mImage);
+  SurfaceCache::SurfaceAvailable(WrapNotNull(this));
+}
+
+void DecodedSurfaceProvider::FinishDecoding() {
+  mMutex.AssertCurrentThreadOwns();
+  MOZ_ASSERT(mImage);
+  MOZ_ASSERT(mDecoder);
+
+  // Send notifications.
+  NotifyDecodeComplete(WrapNotNull(mImage), WrapNotNull(mDecoder));
+
+  // If we have a new and complete surface, we can try to prune similarly sized
+  // surfaces if the cache supports it.
+  if (mSurface && mSurface->IsFinished()) {
+    SurfaceCache::PruneImage(ImageKey(mImage));
+  }
+
+  // Destroy our decoder; we don't need it anymore. (And if we don't destroy it,
+  // our surface can never be optimized, because the decoder has a
+  // RawAccessFrameRef to it.)
+  mDecoder = nullptr;
+
+  // We don't need a reference to our image anymore, either, and we don't want
+  // one. We may be stored in the surface cache for a long time after decoding
+  // finishes. If we don't drop our reference to the image, we'll end up
+  // keeping it alive as long as we remain in the surface cache, which could
+  // greatly extend the image's lifetime - in fact, if the image isn't
+  // discardable, it'd result in a leak!
+  DropImageReference();
+}
+
+bool DecodedSurfaceProvider::ShouldPreferSyncRun() const {
+  return mDecoder->ShouldSyncDecode(
+      StaticPrefs::image_mem_decode_bytes_at_a_time_AtStartup());
+}
+
+}  // namespace image
+}  // namespace mozilla