/* -*- 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_ReleaseOnMainThreadSystemGroup(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(gfxPrefs::ImageMemDecodeBytesAtATime());

}

} // namespace image

} // namespace mozilla