tor-browser

IDecodingTask.cpp (7673B)

---

/* -*- 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 "IDecodingTask.h"

#include "nsThreadUtils.h"
#include "mozilla/AppShutdown.h"

#include "Decoder.h"
#include "DecodePool.h"
#include "RasterImage.h"
#include "SurfaceCache.h"

namespace mozilla {

using gfx::IntRect;

namespace image {

///////////////////////////////////////////////////////////////////////////////
// Helpers for sending notifications to the image associated with a decoder.
///////////////////////////////////////////////////////////////////////////////

void IDecodingTask::NotifyProgress(NotNull<RasterImage*> aImage,
                                  NotNull<Decoder*> aDecoder) {
 MOZ_ASSERT(aDecoder->HasProgress() && !aDecoder->IsMetadataDecode());

 // Capture the decoder's state. If we need to notify asynchronously, it's
 // important that we don't wait until the lambda actually runs to capture the
 // state that we're going to notify. That would both introduce data races on
 // the decoder's state and cause inconsistencies between the NotifyProgress()
 // calls we make off-main-thread and the notifications that RasterImage
 // actually receives, which would cause bugs.
 Progress progress = aDecoder->TakeProgress();
 OrientedIntRect invalidRect = aDecoder->TakeInvalidRect();
 Maybe<uint32_t> frameCount = aDecoder->TakeCompleteFrameCount();
 DecoderFlags decoderFlags = aDecoder->GetDecoderFlags();
 SurfaceFlags surfaceFlags = aDecoder->GetSurfaceFlags();

 // Synchronously notify if we can.
 if (NS_IsMainThread() && !(decoderFlags & DecoderFlags::ASYNC_NOTIFY)) {
   aImage->NotifyProgress(progress, invalidRect, frameCount, decoderFlags,
                          surfaceFlags);
   return;
 }

 // Don't try to dispatch after shutdown, we'll just leak the runnable.
 if (NS_WARN_IF(
         AppShutdown::IsInOrBeyond(ShutdownPhase::XPCOMShutdownThreads))) {
   return;
 }

 // We're forced to notify asynchronously.
 NotNull<RefPtr<RasterImage>> image = aImage;
 nsCOMPtr<nsIEventTarget> eventTarget = GetMainThreadSerialEventTarget();
 eventTarget->Dispatch(CreateRenderBlockingRunnable(NS_NewRunnableFunction(
                           "IDecodingTask::NotifyProgress",
                           [=]() -> void {
                             image->NotifyProgress(progress, invalidRect,
                                                   frameCount, decoderFlags,
                                                   surfaceFlags);
                           })),
                       NS_DISPATCH_NORMAL);
}

void IDecodingTask::NotifyDecodeComplete(NotNull<RasterImage*> aImage,
                                        NotNull<Decoder*> aDecoder) {
 MOZ_ASSERT(aDecoder->HasError() || !aDecoder->InFrame(),
            "Decode complete in the middle of a frame?");

 // Capture the decoder's state.
 DecoderFinalStatus finalStatus = aDecoder->FinalStatus();
 ImageMetadata metadata = aDecoder->GetImageMetadata();
 DecoderTelemetry telemetry = aDecoder->Telemetry();
 Progress progress = aDecoder->TakeProgress();
 OrientedIntRect invalidRect = aDecoder->TakeInvalidRect();
 Maybe<uint32_t> frameCount = aDecoder->TakeCompleteFrameCount();
 DecoderFlags decoderFlags = aDecoder->GetDecoderFlags();
 SurfaceFlags surfaceFlags = aDecoder->GetSurfaceFlags();

 // Synchronously notify if we can.
 if (NS_IsMainThread() && !(decoderFlags & DecoderFlags::ASYNC_NOTIFY)) {
   aImage->NotifyDecodeComplete(finalStatus, metadata, telemetry, progress,
                                invalidRect, frameCount, decoderFlags,
                                surfaceFlags);
   return;
 }

 // Don't try to dispatch after shutdown, we'll just leak the runnable.
 if (NS_WARN_IF(
         AppShutdown::IsInOrBeyond(ShutdownPhase::XPCOMShutdownThreads))) {
   return;
 }

 // We're forced to notify asynchronously.
 NotNull<RefPtr<RasterImage>> image = aImage;
 nsCOMPtr<nsIEventTarget> eventTarget = GetMainThreadSerialEventTarget();
 eventTarget->Dispatch(CreateRenderBlockingRunnable(NS_NewRunnableFunction(
                           "IDecodingTask::NotifyDecodeComplete",
                           [=]() -> void {
                             image->NotifyDecodeComplete(
                                 finalStatus, metadata, telemetry, progress,
                                 invalidRect, frameCount, decoderFlags,
                                 surfaceFlags);
                           })),
                       NS_DISPATCH_NORMAL);
}

///////////////////////////////////////////////////////////////////////////////
// IDecodingTask implementation.
///////////////////////////////////////////////////////////////////////////////

void IDecodingTask::Resume() { DecodePool::Singleton()->AsyncRun(this); }

///////////////////////////////////////////////////////////////////////////////
// MetadataDecodingTask implementation.
///////////////////////////////////////////////////////////////////////////////

MetadataDecodingTask::MetadataDecodingTask(NotNull<Decoder*> aDecoder)
   : mMutex("mozilla::image::MetadataDecodingTask"), mDecoder(aDecoder) {
 MOZ_ASSERT(mDecoder->IsMetadataDecode(),
            "Use DecodingTask for non-metadata decodes");
}

void MetadataDecodingTask::Run() {
 MutexAutoLock lock(mMutex);

 LexerResult result = mDecoder->Decode(WrapNotNull(this));

 if (result.is<TerminalState>()) {
   NotifyDecodeComplete(mDecoder->GetImage(), mDecoder);
   return;  // We're done.
 }

 if (result == LexerResult(Yield::NEED_MORE_DATA)) {
   // We can't make any more progress right now. We also don't want to report
   // any progress, because it's important that metadata decode results are
   // delivered atomically. The decoder itself will ensure that we get
   // reenqueued when more data is available; just return for now.
   return;
 }

 MOZ_ASSERT_UNREACHABLE("Metadata decode yielded for an unexpected reason");
}

///////////////////////////////////////////////////////////////////////////////
// AnonymousDecodingTask implementation.
///////////////////////////////////////////////////////////////////////////////

AnonymousDecodingTask::AnonymousDecodingTask(NotNull<Decoder*> aDecoder,
                                            bool aResumable)
   : mDecoder(aDecoder), mResumable(aResumable) {}

void AnonymousDecodingTask::Run() {
 while (true) {
   LexerResult result = mDecoder->Decode(WrapNotNull(this));

   if (result.is<TerminalState>()) {
     return;  // We're done.
   }

   if (result == LexerResult(Yield::NEED_MORE_DATA)) {
     // We can't make any more progress right now. Let the caller decide how to
     // handle it.
     return;
   }

   // Right now we don't do anything special for other kinds of yields, so just
   // keep working.
   MOZ_ASSERT(result.is<Yield>());
 }
}

void AnonymousDecodingTask::Resume() {
 // Anonymous decoders normally get all their data at once. We have tests
 // where they don't; typically in these situations, the test re-runs them
 // manually. However some tests want to verify Resume works, so they will
 // explicitly request this behaviour.
 if (mResumable) {
   RefPtr<AnonymousDecodingTask> self(this);
   NS_DispatchToMainThread(
       NS_NewRunnableFunction("image::AnonymousDecodingTask::Resume",
                              [self]() -> void { self->Run(); }));
 }
}

}  // namespace image
}  // namespace mozilla