gecko-dev/image/DecodedSurfaceProvider.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/. */
#include "DecodedSurfaceProvider.h"
#include "gfxPrefs.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;
NS_ReleaseOnMainThread(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.width * 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));
// 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(gfxPrefs::ImageMemDecodeBytesAtATime());
}
} // namespace image
} // namespace mozilla