ProgressTracker.cpp

/* -*- 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 "ImageLogging.h"
#include "ProgressTracker.h"

#include "imgIContainer.h"
#include "imgINotificationObserver.h"
#include "imgIRequest.h"
#include "Image.h"
#include "nsNetUtil.h"
#include "nsIObserverService.h"

#include "mozilla/Assertions.h"
#include "mozilla/Services.h"
#include "mozilla/SystemGroup.h"

using mozilla::WeakPtr;

namespace mozilla {
namespace image {

static void
CheckProgressConsistency(Progress aOldProgress, Progress aNewProgress, bool aIsMultipart)
{
  // Check preconditions for every progress bit.

  // Error's do not get propagated from the tracker for each image part to the
  // tracker for the multipart image because we don't want one bad part to
  // prevent the remaining parts from showing. So we need to consider whether
  // this is a tracker for a multipart image for these assertions to work.

  if (aNewProgress & FLAG_SIZE_AVAILABLE) {
    // No preconditions.
  }
  if (aNewProgress & FLAG_DECODE_COMPLETE) {
    MOZ_ASSERT(aNewProgress & FLAG_SIZE_AVAILABLE);
    MOZ_ASSERT(aIsMultipart || aNewProgress & (FLAG_FRAME_COMPLETE | FLAG_HAS_ERROR));
  }
  if (aNewProgress & FLAG_FRAME_COMPLETE) {
    MOZ_ASSERT(aNewProgress & FLAG_SIZE_AVAILABLE);
  }
  if (aNewProgress & FLAG_LOAD_COMPLETE) {
    MOZ_ASSERT(aIsMultipart || aNewProgress & (FLAG_SIZE_AVAILABLE | FLAG_HAS_ERROR));
  }
  if (aNewProgress & FLAG_IS_ANIMATED) {
    // No preconditions; like FLAG_HAS_TRANSPARENCY, we should normally never
    // discover this *after* FLAG_SIZE_AVAILABLE, but unfortunately some corrupt
    // GIFs may fool us.
  }
  if (aNewProgress & FLAG_HAS_TRANSPARENCY) {
    // XXX We'd like to assert that transparency is only set during metadata
    // decode but we don't have any way to assert that until bug 1254892 is fixed.
  }
  if (aNewProgress & FLAG_LAST_PART_COMPLETE) {
    MOZ_ASSERT(aNewProgress & FLAG_LOAD_COMPLETE);
  }
  if (aNewProgress & FLAG_HAS_ERROR) {
    // No preconditions.
  }
}

ProgressTracker::ProgressTracker()
  : mMutex("ProgressTracker::mMutex")
  , mImage(nullptr)
  , mEventTarget(WrapNotNull(nsCOMPtr<nsIEventTarget>(SystemGroup::EventTargetFor(TaskCategory::Other))))
  , mObserversWithTargets(0)
  , mObservers(new ObserverTable)
  , mProgress(NoProgress)
  , mIsMultipart(false)
{ }

void
ProgressTracker::SetImage(Image* aImage)
{
  MutexAutoLock lock(mMutex);
  MOZ_ASSERT(aImage, "Setting null image");
  MOZ_ASSERT(!mImage, "Setting image when we already have one");
  mImage = aImage;
}

void
ProgressTracker::ResetImage()
{
  MutexAutoLock lock(mMutex);
  MOZ_ASSERT(mImage, "Resetting image when it's already null!");
  mImage = nullptr;
}

uint32_t
ProgressTracker::GetImageStatus() const
{
  uint32_t status = imgIRequest::STATUS_NONE;

  // Translate our current state to a set of imgIRequest::STATE_* flags.
  if (mProgress & FLAG_SIZE_AVAILABLE) {
    status |= imgIRequest::STATUS_SIZE_AVAILABLE;
  }
  if (mProgress & FLAG_DECODE_COMPLETE) {
    status |= imgIRequest::STATUS_DECODE_COMPLETE;
  }
  if (mProgress & FLAG_FRAME_COMPLETE) {
    status |= imgIRequest::STATUS_FRAME_COMPLETE;
  }
  if (mProgress & FLAG_LOAD_COMPLETE) {
    status |= imgIRequest::STATUS_LOAD_COMPLETE;
  }
  if (mProgress & FLAG_IS_ANIMATED) {
    status |= imgIRequest::STATUS_IS_ANIMATED;
  }
  if (mProgress & FLAG_HAS_TRANSPARENCY) {
    status |= imgIRequest::STATUS_HAS_TRANSPARENCY;
  }
  if (mProgress & FLAG_HAS_ERROR) {
    status |= imgIRequest::STATUS_ERROR;
  }

  return status;
}

// A helper class to allow us to call SyncNotify asynchronously.
class AsyncNotifyRunnable : public Runnable
{
  public:
    AsyncNotifyRunnable(ProgressTracker* aTracker,
                        IProgressObserver* aObserver)
     : Runnable("ProgressTracker::AsyncNotifyRunnable")
     , mTracker(aTracker)
    {
      MOZ_ASSERT(NS_IsMainThread(), "Should be created on the main thread");
      MOZ_ASSERT(aTracker, "aTracker should not be null");
      MOZ_ASSERT(aObserver, "aObserver should not be null");
      mObservers.AppendElement(aObserver);
    }

    NS_IMETHOD Run() override
    {
      MOZ_ASSERT(NS_IsMainThread(), "Should be running on the main thread");
      MOZ_ASSERT(mTracker, "mTracker should not be null");
      for (uint32_t i = 0; i < mObservers.Length(); ++i) {
        mObservers[i]->SetNotificationsDeferred(false);
        mTracker->SyncNotify(mObservers[i]);
      }

      mTracker->mRunnable = nullptr;
      return NS_OK;
    }

    void AddObserver(IProgressObserver* aObserver)
    {
      mObservers.AppendElement(aObserver);
    }

    void RemoveObserver(IProgressObserver* aObserver)
    {
      mObservers.RemoveElement(aObserver);
    }

  private:
    friend class ProgressTracker;

    RefPtr<ProgressTracker> mTracker;
    nsTArray<RefPtr<IProgressObserver>> mObservers;
};

void
ProgressTracker::Notify(IProgressObserver* aObserver)
{
  MOZ_ASSERT(NS_IsMainThread());

  if (MOZ_LOG_TEST(gImgLog, LogLevel::Debug)) {
    RefPtr<Image> image = GetImage();
    if (image && image->GetURI()) {
      RefPtr<ImageURL> uri(image->GetURI());
      nsAutoCString spec;
      uri->GetSpec(spec);
      LOG_FUNC_WITH_PARAM(gImgLog,
                          "ProgressTracker::Notify async", "uri", spec.get());
    } else {
      LOG_FUNC_WITH_PARAM(gImgLog,
                          "ProgressTracker::Notify async", "uri", "<unknown>");
    }
  }

  aObserver->SetNotificationsDeferred(true);

  // If we have an existing runnable that we can use, we just append this
  // observer to its list of observers to be notified. This ensures we don't
  // unnecessarily delay onload.
  AsyncNotifyRunnable* runnable =
    static_cast<AsyncNotifyRunnable*>(mRunnable.get());

  if (runnable) {
    runnable->AddObserver(aObserver);
  } else {
    mRunnable = new AsyncNotifyRunnable(this, aObserver);
    mEventTarget->Dispatch(mRunnable, NS_DISPATCH_NORMAL);
  }
}

// A helper class to allow us to call SyncNotify asynchronously for a given,
// fixed, state.
class AsyncNotifyCurrentStateRunnable : public Runnable
{
  public:
    AsyncNotifyCurrentStateRunnable(ProgressTracker* aProgressTracker,
                                    IProgressObserver* aObserver)
      : Runnable("image::AsyncNotifyCurrentStateRunnable")
      , mProgressTracker(aProgressTracker)
      , mObserver(aObserver)
    {
      MOZ_ASSERT(NS_IsMainThread(), "Should be created on the main thread");
      MOZ_ASSERT(mProgressTracker, "mProgressTracker should not be null");
      MOZ_ASSERT(mObserver, "mObserver should not be null");
      mImage = mProgressTracker->GetImage();
    }

    NS_IMETHOD Run() override
    {
      MOZ_ASSERT(NS_IsMainThread(), "Should be running on the main thread");
      mObserver->SetNotificationsDeferred(false);

      mProgressTracker->SyncNotify(mObserver);
      return NS_OK;
    }

  private:
    RefPtr<ProgressTracker> mProgressTracker;
    RefPtr<IProgressObserver> mObserver;

    // We have to hold on to a reference to the tracker's image, just in case
    // it goes away while we're in the event queue.
    RefPtr<Image> mImage;
};

void
ProgressTracker::NotifyCurrentState(IProgressObserver* aObserver)
{
  MOZ_ASSERT(NS_IsMainThread());

  if (MOZ_LOG_TEST(gImgLog, LogLevel::Debug)) {
    RefPtr<Image> image = GetImage();
    nsAutoCString spec;
    if (image && image->GetURI()) {
      image->GetURI()->GetSpec(spec);
    }
    LOG_FUNC_WITH_PARAM(gImgLog,
                        "ProgressTracker::NotifyCurrentState", "uri", spec.get());
  }

  aObserver->SetNotificationsDeferred(true);

  nsCOMPtr<nsIRunnable> ev = new AsyncNotifyCurrentStateRunnable(this,
                                                                 aObserver);
  mEventTarget->Dispatch(ev.forget(), NS_DISPATCH_NORMAL);
}

/**
 * ImageObserverNotifier is a helper type that abstracts over the difference
 * between sending notifications to all of the observers in an ObserverTable,
 * and sending them to a single observer. This allows the same notification code
 * to be used for both cases.
 */
template <typename T> struct ImageObserverNotifier;

template <>
struct MOZ_STACK_CLASS ImageObserverNotifier<const ObserverTable*>
{
  explicit ImageObserverNotifier(const ObserverTable* aObservers,
                                 bool aIgnoreDeferral = false)
    : mObservers(aObservers)
    , mIgnoreDeferral(aIgnoreDeferral)
  { }

  template <typename Lambda>
  void operator()(Lambda aFunc)
  {
    for (auto iter = mObservers->ConstIter(); !iter.Done(); iter.Next()) {
      RefPtr<IProgressObserver> observer = iter.Data().get();
      if (observer &&
          (mIgnoreDeferral || !observer->NotificationsDeferred())) {
        aFunc(observer);
      }
    }
  }

private:
  const ObserverTable* mObservers;
  const bool mIgnoreDeferral;
};

template <>
struct MOZ_STACK_CLASS ImageObserverNotifier<IProgressObserver*>
{
  explicit ImageObserverNotifier(IProgressObserver* aObserver)
    : mObserver(aObserver)
  { }

  template <typename Lambda>
  void operator()(Lambda aFunc)
  {
    if (mObserver && !mObserver->NotificationsDeferred()) {
      aFunc(mObserver);
    }
  }

private:
  IProgressObserver* mObserver;
};

template <typename T> void
SyncNotifyInternal(const T& aObservers,
                   bool aHasImage,
                   Progress aProgress,
                   const nsIntRect& aDirtyRect)
{
  MOZ_ASSERT(NS_IsMainThread());

  typedef imgINotificationObserver I;
  ImageObserverNotifier<T> notify(aObservers);

  if (aProgress & FLAG_SIZE_AVAILABLE) {
    notify([](IProgressObserver* aObs) { aObs->Notify(I::SIZE_AVAILABLE); });
  }

  if (aHasImage) {
    // OnFrameUpdate
    // If there's any content in this frame at all (always true for
    // vector images, true for raster images that have decoded at
    // least one frame) then send OnFrameUpdate.
    if (!aDirtyRect.IsEmpty()) {
      notify([&](IProgressObserver* aObs) {
        aObs->Notify(I::FRAME_UPDATE, &aDirtyRect);
      });
    }

    if (aProgress & FLAG_FRAME_COMPLETE) {
      notify([](IProgressObserver* aObs) { aObs->Notify(I::FRAME_COMPLETE); });
    }

    if (aProgress & FLAG_HAS_TRANSPARENCY) {
      notify([](IProgressObserver* aObs) { aObs->Notify(I::HAS_TRANSPARENCY); });
    }

    if (aProgress & FLAG_IS_ANIMATED) {
      notify([](IProgressObserver* aObs) { aObs->Notify(I::IS_ANIMATED); });
    }
  }

  if (aProgress & FLAG_DECODE_COMPLETE) {
    MOZ_ASSERT(aHasImage, "Stopped decoding without ever having an image?");
    notify([](IProgressObserver* aObs) { aObs->Notify(I::DECODE_COMPLETE); });
  }

  if (aProgress & FLAG_LOAD_COMPLETE) {
    notify([=](IProgressObserver* aObs) {
      aObs->OnLoadComplete(aProgress & FLAG_LAST_PART_COMPLETE);
    });
  }
}

void
ProgressTracker::SyncNotifyProgress(Progress aProgress,
                                    const nsIntRect& aInvalidRect
                                                  /* = nsIntRect() */)
{
  MOZ_ASSERT(NS_IsMainThread(), "Use mObservers on main thread only");

  Progress progress = Difference(aProgress);
  CheckProgressConsistency(mProgress, mProgress | progress, mIsMultipart);

  // Apply the changes.
  mProgress |= progress;

  // Send notifications.
  mObservers.Read([&](const ObserverTable* aTable) {
    SyncNotifyInternal(aTable, HasImage(), progress, aInvalidRect);
  });

  if (progress & FLAG_HAS_ERROR) {
    FireFailureNotification();
  }
}

void
ProgressTracker::SyncNotify(IProgressObserver* aObserver)
{
  MOZ_ASSERT(NS_IsMainThread());

  RefPtr<Image> image = GetImage();

  nsAutoCString spec;
  if (image && image->GetURI()) {
    image->GetURI()->GetSpec(spec);
  }
  LOG_SCOPE_WITH_PARAM(gImgLog,
                       "ProgressTracker::SyncNotify", "uri", spec.get());

  nsIntRect rect;
  if (image) {
    int32_t width, height;
    if (NS_FAILED(image->GetWidth(&width)) ||
        NS_FAILED(image->GetHeight(&height))) {
      // Either the image has no intrinsic size, or it has an error.
      rect = GetMaxSizedIntRect();
    } else {
      rect.SizeTo(width, height);
    }
  }

  SyncNotifyInternal(aObserver, !!image, mProgress, rect);
}

void
ProgressTracker::EmulateRequestFinished(IProgressObserver* aObserver)
{
  MOZ_ASSERT(NS_IsMainThread(),
             "SyncNotifyState and mObservers are not threadsafe");
  RefPtr<IProgressObserver> kungFuDeathGrip(aObserver);

  if (!(mProgress & FLAG_LOAD_COMPLETE)) {
    aObserver->OnLoadComplete(true);
  }
}

already_AddRefed<nsIEventTarget>
ProgressTracker::GetEventTarget() const
{
  MutexAutoLock lock(mMutex);
  nsCOMPtr<nsIEventTarget> target = mEventTarget;
  return target.forget();
}

void
ProgressTracker::AddObserver(IProgressObserver* aObserver)
{
  MOZ_ASSERT(NS_IsMainThread());
  RefPtr<IProgressObserver> observer = aObserver;

  nsCOMPtr<nsIEventTarget> target = observer->GetEventTarget();
  if (target) {
    if (mObserversWithTargets == 0) {
      // On the first observer with a target (i.e. listener), always accept its
      // event target; this may be for a specific DocGroup, or it may be the
      // unlabelled main thread target.
      MutexAutoLock lock(mMutex);
      mEventTarget = WrapNotNull(target);
    } else if (mEventTarget.get() != target.get()) {
      // If a subsequent observer comes in with a different target, we need to
      // switch to use the unlabelled main thread target, if we haven't already.
      MutexAutoLock lock(mMutex);
      nsCOMPtr<nsIEventTarget> mainTarget(do_GetMainThread());
      mEventTarget = WrapNotNull(mainTarget);
    }
    ++mObserversWithTargets;
  }

  mObservers.Write([=](ObserverTable* aTable) {
    MOZ_ASSERT(!aTable->Get(observer, nullptr),
               "Adding duplicate entry for image observer");

    WeakPtr<IProgressObserver> weakPtr = observer.get();
    aTable->Put(observer, weakPtr);
  });

  MOZ_ASSERT(mObserversWithTargets <= ObserverCount());
}

bool
ProgressTracker::RemoveObserver(IProgressObserver* aObserver)
{
  MOZ_ASSERT(NS_IsMainThread());
  RefPtr<IProgressObserver> observer = aObserver;

  // Remove the observer from the list.
  bool removed = mObservers.Write([observer](ObserverTable* aTable) {
    return aTable->Remove(observer);
  });

  // Sometimes once an image is decoded, and all of its observers removed, a new
  // document may request the same image. Thus we need to clear our event target
  // state when the last observer is removed, so that we select the most
  // appropriate event target when a new observer is added. Since the event
  // target may have changed (e.g. due to the scheduler group going away before
  // we were removed), so we should be cautious comparing this target against
  // anything at this stage.
  if (removed) {
    nsCOMPtr<nsIEventTarget> target = observer->GetEventTarget();
    if (target) {
      MOZ_ASSERT(mObserversWithTargets > 0);
      --mObserversWithTargets;

      if (mObserversWithTargets == 0) {
        MutexAutoLock lock(mMutex);
        nsCOMPtr<nsIEventTarget> target(SystemGroup::EventTargetFor(TaskCategory::Other));
        mEventTarget = WrapNotNull(target);
      }
    }

    MOZ_ASSERT(mObserversWithTargets <= ObserverCount());
  }

  // Observers can get confused if they don't get all the proper teardown
  // notifications. Part ways on good terms.
  if (removed && !aObserver->NotificationsDeferred()) {
    EmulateRequestFinished(aObserver);
  }

  // Make sure we don't give callbacks to an observer that isn't interested in
  // them any more.
  AsyncNotifyRunnable* runnable =
    static_cast<AsyncNotifyRunnable*>(mRunnable.get());

  if (aObserver->NotificationsDeferred() && runnable) {
    runnable->RemoveObserver(aObserver);
    aObserver->SetNotificationsDeferred(false);
  }

  return removed;
}

uint32_t
ProgressTracker::ObserverCount() const
{
  MOZ_ASSERT(NS_IsMainThread());
  return mObservers.Read([](const ObserverTable* aTable) {
    return aTable->Count();
  });
}

void
ProgressTracker::OnUnlockedDraw()
{
  MOZ_ASSERT(NS_IsMainThread());
  mObservers.Read([](const ObserverTable* aTable) {
    ImageObserverNotifier<const ObserverTable*> notify(aTable);
    notify([](IProgressObserver* aObs) {
      aObs->Notify(imgINotificationObserver::UNLOCKED_DRAW);
    });
  });
}

void
ProgressTracker::ResetForNewRequest()
{
  MOZ_ASSERT(NS_IsMainThread());
  mProgress = NoProgress;
}

void
ProgressTracker::OnDiscard()
{
  MOZ_ASSERT(NS_IsMainThread());
  mObservers.Read([](const ObserverTable* aTable) {
    ImageObserverNotifier<const ObserverTable*> notify(aTable);
    notify([](IProgressObserver* aObs) {
      aObs->Notify(imgINotificationObserver::DISCARD);
    });
  });
}

void
ProgressTracker::OnImageAvailable()
{
  MOZ_ASSERT(NS_IsMainThread());
  // Notify any imgRequestProxys that are observing us that we have an Image.
  mObservers.Read([](const ObserverTable* aTable) {
    ImageObserverNotifier<const ObserverTable*>
      notify(aTable, /* aIgnoreDeferral = */ true);
    notify([](IProgressObserver* aObs) {
      aObs->SetHasImage();
    });
  });
}

void
ProgressTracker::FireFailureNotification()
{
  MOZ_ASSERT(NS_IsMainThread());

  // Some kind of problem has happened with image decoding.
  // Report the URI to net:failed-to-process-uri-conent observers.
  RefPtr<Image> image = GetImage();
  if (image) {
    // Should be on main thread, so ok to create a new nsIURI.
    nsCOMPtr<nsIURI> uri;
    {
      RefPtr<ImageURL> threadsafeUriData = image->GetURI();
      uri = threadsafeUriData ? threadsafeUriData->ToIURI() : nullptr;
    }
    if (uri) {
      nsCOMPtr<nsIObserverService> os = mozilla::services::GetObserverService();
      if (os) {
        os->NotifyObservers(uri, "net:failed-to-process-uri-content", nullptr);
      }
    }
  }
}

} // namespace image
} // namespace mozilla