Eliminate copies of encoded image data

third_party/WebKit/Source/platform/graphics/ImageFrameGenerator.cpp

 /*
  * Copyright (C) 2012 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
  *    notice, this list of conditions and the following disclaimer in the
  *    documentation and/or other materials provided with the distribution.
  *
  * THIS SOFTWARE IS PROVIDED BY APPLE COMPUTER, INC. ``AS IS'' AND ANY
  * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL APPLE COMPUTER, INC. OR
  * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
  * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
  * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
  * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
  * OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */
 
 #include "platform/graphics/ImageFrameGenerator.h"
 
 #include "SkData.h"
-#include "platform/SharedBuffer.h"
 #include "platform/TraceEvent.h"
 #include "platform/graphics/ImageDecodingStore.h"
 #include "platform/image-decoders/ImageDecoder.h"
 
 namespace blink {
 
 static bool compatibleInfo(const SkImageInfo& src, const SkImageInfo& dst)
 {
     if (src == dst)
         return true;
 
     // It is legal to write kOpaque_SkAlphaType pixels into a kPremul_SkAlphaType buffer.
     // This can happen when DeferredImageDecoder allocates an kOpaque_SkAlphaType image
     // generator based on cached frame info, while the ImageFrame-allocated dest bitmap
     // stays kPremul_SkAlphaType.
     if (src.alphaType() == kOpaque_SkAlphaType && dst.alphaType() == kPremul_SkAlphaType) {
         const SkImageInfo& tmp = src.makeAlphaType(kPremul_SkAlphaType);
         return tmp == dst;
     }
 
     return false;
 }
 
 // Creates a SkPixelRef such that the memory for pixels is given by an external body.
 // This is used to write directly to the memory given by Skia during decoding.
-class ImageFrameGenerator::ExternalMemoryAllocator final : public SkBitmap::Allocator {
+class ExternalMemoryAllocator final : public SkBitmap::Allocator {
     USING_FAST_MALLOC(ExternalMemoryAllocator);
     WTF_MAKE_NONCOPYABLE(ExternalMemoryAllocator);
 public:
     ExternalMemoryAllocator(const SkImageInfo& info, void* pixels, size_t rowBytes)
         : m_info(info)
         , m_pixels(pixels)
         , m_rowBytes(rowBytes)
     {
     }
 
@@ skipping 28 matching lines @@
     componentWidthBytes[0] = decoder->decodedYUVWidthBytes(0);
     size = decoder->decodedYUVSize(1);
     componentSizes[1].set(size.width(), size.height());
     componentWidthBytes[1] = decoder->decodedYUVWidthBytes(1);
     size = decoder->decodedYUVSize(2);
     componentSizes[2].set(size.width(), size.height());
     componentWidthBytes[2] = decoder->decodedYUVWidthBytes(2);
     return true;
 }
 
-ImageFrameGenerator::ImageFrameGenerator(const SkISize& fullSize, PassRefPtr<SharedBuffer> data, bool allDataReceived, bool isMultiFrame)
+ImageFrameGenerator::ImageFrameGenerator(const SkISize& fullSize, bool isMultiFrame)
     : m_fullSize(fullSize)
-    , m_data(adoptRef(new ThreadSafeDataTransport()))
     , m_isMultiFrame(isMultiFrame)
     , m_decodeFailed(false)
     , m_frameCount(0)
-    , m_encodedData(nullptr)
 {
-    setData(data.get(), allDataReceived);
 }
 
 ImageFrameGenerator::~ImageFrameGenerator()
 {
-    if (m_encodedData)
-        m_encodedData->unref();
     ImageDecodingStore::instance().removeCacheIndexedByGenerator(this);
 }
 
-void ImageFrameGenerator::setData(PassRefPtr<SharedBuffer> data, bool allDataReceived)
+bool ImageFrameGenerator::decodeAndScale(SegmentReader* data, bool allDataReceived, size_t index, const SkImageInfo& info, void* pixels, size_t rowBytes)
 {
-    m_data->setData(data.get(), allDataReceived);
-}
-
-static void sharedSkDataReleaseCallback(const void* address, void* context)
-{
-    // This gets called when m_encodedData reference count becomes 0 - and it could happen in
-    // ImageFrameGenerator destructor or later when m_encodedData gets dereferenced.
-    // In this method, we deref ThreadSafeDataTransport, as ThreadSafeDataTransport is the owner
-    // of data returned via refEncodedData.
-
-    ThreadSafeDataTransport* dataTransport = static_cast<ThreadSafeDataTransport*>(context);
-#if ENABLE(ASSERT)
-    ASSERT(dataTransport);
-    SharedBuffer* buffer = 0;
-    bool allDataReceived = false;
-    dataTransport->data(&buffer, &allDataReceived);
-    ASSERT(allDataReceived && buffer && buffer->data() == address);
-#endif
-    // Dereference m_data now.
-    dataTransport->deref();
-}
-
-SkData* ImageFrameGenerator::refEncodedData()
-{
-    // SkData is returned only when full image (encoded) data is received. This is important
-    // since DeferredImageDecoder::setData is called only once with allDataReceived set to true,
-    // and after that m_data->m_readBuffer.data() is not changed. See also RELEASE_ASSERT used in
-    // ThreadSafeDataTransport::data().
-    SharedBuffer* buffer = 0;
-    bool allDataReceived = false;
-    m_data->data(&buffer, &allDataReceived);
-    if (!allDataReceived)
-        return nullptr;
-
-    {
-        // Prevents concurrent access to m_encodedData creation.
-        MutexLocker lock(m_decodeMutex);
-        if (m_encodedData) {
-            m_encodedData->ref();
-            return m_encodedData;
-        }
-        // m_encodedData is created with initial reference count == 1. ImageFrameGenerator always holds one
-        // reference to m_encodedData, as it prevents write access in SkData::writable_data.
-        m_encodedData = SkData::NewWithProc(buffer->data(), buffer->size(), sharedSkDataReleaseCallback, m_data.get());
-        // While m_encodedData is referenced, prevent disposing m_data and its content.
-        // it is dereferenced in sharedSkDataReleaseCallback, called when m_encodedData gets dereferenced.
-        m_data->ref();
-    }
-    // Increase the reference, caller must decrease it. One reference is always kept by ImageFrameGenerator and released
-    // in destructor.
-    m_encodedData->ref();
-    return m_encodedData;
-}
-
-bool ImageFrameGenerator::decodeAndScale(size_t index, const SkImageInfo& info, void* pixels, size_t rowBytes)
-{
-    // Prevent concurrent decode or scale operations on the same image data.
-    MutexLocker lock(m_decodeMutex);
-
     if (m_decodeFailed)
         return false;
 
     TRACE_EVENT1("blink", "ImageFrameGenerator::decodeAndScale", "frame index", static_cast<int>(index));
 
-    m_externalAllocator = adoptPtr(new ExternalMemoryAllocator(info, pixels, rowBytes));
+    RefPtr<ExternalMemoryAllocator> externalAllocator = adoptRef(new ExternalMemoryAllocator(info, pixels, rowBytes));
 
     // This implementation does not support scaling so check the requested size.
     SkISize scaledSize = SkISize::Make(info.width(), info.height());
     ASSERT(m_fullSize == scaledSize);
 
-    SkBitmap bitmap = tryToResumeDecode(index, scaledSize);
+    // TODO (scroggo): Convert tryToResumeDecode() and decode() to take a
+    // PassRefPtr<SkBitmap::Allocator> instead of a bare pointer.
+    SkBitmap bitmap = tryToResumeDecode(data, allDataReceived, index, scaledSize, externalAllocator.get());
     if (bitmap.isNull())
         return false;
 
-    // Don't keep the allocator because it contains a pointer to memory
-    // that we do not own.
-    m_externalAllocator.clear();
+    externalAllocator.clear();

[f(malita), 2016/03/25 18:47:53]

Nit: since externalAllocator is now local, I think it's fine to let it go out of
scope - no need to clear explicitly.

[scroggo_chromium, 2016/03/25 18:56:21]

Done.

 
     // Check to see if the decoder has written directly to the pixel memory
     // provided. If not, make a copy.
     ASSERT(bitmap.width() == scaledSize.width());
     ASSERT(bitmap.height() == scaledSize.height());
     SkAutoLockPixels bitmapLock(bitmap);
     if (bitmap.getPixels() != pixels)
         return bitmap.copyPixelsTo(pixels, rowBytes * info.height(), rowBytes);
     return true;
 }
 
-bool ImageFrameGenerator::decodeToYUV(size_t index, const SkISize componentSizes[3], void* planes[3], const size_t rowBytes[3])
+bool ImageFrameGenerator::decodeToYUV(SegmentReader* data, size_t index, const SkISize componentSizes[3], void* planes[3], const size_t rowBytes[3])
 {
-    // Prevent concurrent decode or scale operations on the same image data.
-    MutexLocker lock(m_decodeMutex);
-
+    // TODO (scroggo): The only interesting thing this uses from the ImageFrameGenerator is m_decodeFailed.
+    // Move this into DecodingImageGenerator, which is the only class that calls it.
     if (m_decodeFailed)
         return false;
 
     TRACE_EVENT1("blink", "ImageFrameGenerator::decodeToYUV", "frame index", static_cast<int>(index));
 
     if (!planes || !planes[0] || !planes[1] || !planes[2]
         || !rowBytes || !rowBytes[0] || !rowBytes[1] || !rowBytes[2]) {
         return false;
     }
 
-    SharedBuffer* data = 0;
-    bool allDataReceived = false;
-    m_data->data(&data, &allDataReceived);
+    OwnPtr<ImageDecoder> decoder = ImageDecoder::create(*data, ImageDecoder::AlphaPremultiplied, ImageDecoder::GammaAndColorProfileApplied);
+    // getYUVComponentSizes was already called and was successful, so ImageDecoder::create must succeed.
+    ASSERT(decoder);
 
-    // FIXME: YUV decoding does not currently support progressive decoding.
-    ASSERT(allDataReceived);
-
-    OwnPtr<ImageDecoder> decoder = ImageDecoder::create(*data, ImageDecoder::AlphaPremultiplied, ImageDecoder::GammaAndColorProfileApplied);
-    if (!decoder)
-        return false;
-
-    decoder->setData(data, allDataReceived);
+    decoder->setData(data, true);
 
     OwnPtr<ImagePlanes> imagePlanes = adoptPtr(new ImagePlanes(planes, rowBytes));
     decoder->setImagePlanes(imagePlanes.release());
 
     ASSERT(decoder->canDecodeToYUV());
 
     if (decoder->decodeToYUV()) {
         setHasAlpha(0, false); // YUV is always opaque
         return true;
     }
 
     ASSERT(decoder->failed());
     m_decodeFailed = true;
     return false;
 }
 
-SkBitmap ImageFrameGenerator::tryToResumeDecode(size_t index, const SkISize& scaledSize)
+SkBitmap ImageFrameGenerator::tryToResumeDecode(SegmentReader* data, bool allDataReceived, size_t index, const SkISize& scaledSize, SkBitmap::Allocator* allocator)
 {
     TRACE_EVENT1("blink", "ImageFrameGenerator::tryToResumeDecode", "frame index", static_cast<int>(index));
 
     ImageDecoder* decoder = 0;
+
+    // Lock the mutex, so only one thread can use the decoder at once.
+    MutexLocker lock(m_decodeMutex);
     const bool resumeDecoding = ImageDecodingStore::instance().lockDecoder(this, m_fullSize, &decoder);
     ASSERT(!resumeDecoding || decoder);
 
     SkBitmap fullSizeImage;
-    bool complete = decode(index, &decoder, &fullSizeImage);
+    bool complete = decode(data, allDataReceived, index, &decoder, &fullSizeImage, allocator);
 
     if (!decoder)
         return SkBitmap();
 
     // If we are not resuming decoding that means the decoder is freshly
     // created and we have ownership. If we are resuming decoding then
     // the decoder is owned by ImageDecodingStore.
     OwnPtr<ImageDecoder> decoderContainer;
     if (!resumeDecoding)
         decoderContainer = adoptPtr(decoder);
@@ skipping 39 matching lines @@
     MutexLocker lock(m_alphaMutex);
     if (index >= m_hasAlpha.size()) {
         const size_t oldSize = m_hasAlpha.size();
         m_hasAlpha.resize(index + 1);
         for (size_t i = oldSize; i < m_hasAlpha.size(); ++i)
             m_hasAlpha[i] = true;
     }
     m_hasAlpha[index] = hasAlpha;
 }
 
-bool ImageFrameGenerator::decode(size_t index, ImageDecoder** decoder, SkBitmap* bitmap)
+bool ImageFrameGenerator::decode(SegmentReader* data, bool allDataReceived, size_t index, ImageDecoder** decoder, SkBitmap* bitmap, SkBitmap::Allocator* allocator)
 {
+    ASSERT(m_decodeMutex.locked());
     TRACE_EVENT2("blink", "ImageFrameGenerator::decode", "width", m_fullSize.width(), "height", m_fullSize.height());
 
-    SharedBuffer* data = 0;
-    bool allDataReceived = false;
-    m_data->data(&data, &allDataReceived);
-
     // Try to create an ImageDecoder if we are not given one.
     ASSERT(decoder);
     bool newDecoder = false;
     if (!*decoder) {
         newDecoder = true;
         if (m_imageDecoderFactory)
             *decoder = m_imageDecoderFactory->create().leakPtr();
 
         if (!*decoder)
             *decoder = ImageDecoder::create(*data, ImageDecoder::AlphaPremultiplied, ImageDecoder::GammaAndColorProfileApplied).leakPtr();
 
         if (!*decoder)
             return false;
     }
 
     if (!m_isMultiFrame && newDecoder && allDataReceived) {
         // If we're using an external memory allocator that means we're decoding
         // directly into the output memory and we can save one memcpy.
-        ASSERT(m_externalAllocator.get());
-        (*decoder)->setMemoryAllocator(m_externalAllocator.get());
+        ASSERT(allocator);
+        (*decoder)->setMemoryAllocator(allocator);
     }
 
     (*decoder)->setData(data, allDataReceived);
     ImageFrame* frame = (*decoder)->frameBufferAtIndex(index);
 
     // For multi-frame image decoders, we need to know how many frames are
     // in that image in order to release the decoder when all frames are
     // decoded. frameCount() is reliable only if all data is received and set in
     // decoder, particularly with GIF.
     if (allDataReceived)
         m_frameCount = (*decoder)->frameCount();
 
-    (*decoder)->setData(0, false); // Unref SharedBuffer from ImageDecoder.
+    (*decoder)->setData(PassRefPtr<SegmentReader>(nullptr), false); // Unref SegmentReader from ImageDecoder.

[f(malita), 2016/03/25 18:47:53]

nit: would straight nullptr not work here? (we have implicit nullptr ->
PassRefPtr conversion)

[scroggo_chromium, 2016/03/25 18:56:21]

It would, except that this method is overloaded - that nullptr could either be a
PassRefPtr<SegmentReader> or a PassRefPtr<SharedBuffer>

     (*decoder)->clearCacheExceptFrame(index);
     (*decoder)->setMemoryAllocator(0);
 
     if (!frame || frame->getStatus() == ImageFrame::FrameEmpty)
         return false;
 
     // A cache object is considered complete if we can decode a complete frame.
     // Or we have received all data. The image might not be fully decoded in
     // the latter case.
     const bool isDecodeComplete = frame->getStatus() == ImageFrame::FrameComplete || allDataReceived;
 
     SkBitmap fullSizeBitmap = frame->getSkBitmap();
     if (!fullSizeBitmap.isNull()) {
         ASSERT(fullSizeBitmap.width() == m_fullSize.width() && fullSizeBitmap.height() == m_fullSize.height());
         setHasAlpha(index, !fullSizeBitmap.isOpaque());
     }
 
     *bitmap = fullSizeBitmap;
     return isDecodeComplete;
 }
 
 bool ImageFrameGenerator::hasAlpha(size_t index)
 {
     MutexLocker lock(m_alphaMutex);
     if (index < m_hasAlpha.size())
         return m_hasAlpha[index];
     return true;
 }
 
-bool ImageFrameGenerator::getYUVComponentSizes(SkYUVSizeInfo* sizeInfo)
+bool ImageFrameGenerator::getYUVComponentSizes(SegmentReader* data, SkYUVSizeInfo* sizeInfo)
 {
     TRACE_EVENT2("blink", "ImageFrameGenerator::getYUVComponentSizes", "width", m_fullSize.width(), "height", m_fullSize.height());
 
-    SharedBuffer* data = 0;
-    bool allDataReceived = false;
-    m_data->data(&data, &allDataReceived);
-
-    // FIXME: YUV decoding does not currently support progressive decoding.
-    if (!allDataReceived)
-        return false;
-
     OwnPtr<ImageDecoder> decoder = ImageDecoder::create(*data, ImageDecoder::AlphaPremultiplied, ImageDecoder::GammaAndColorProfileApplied);
     if (!decoder)
         return false;
 
     // Setting a dummy ImagePlanes object signals to the decoder that we want to do YUV decoding.
-    decoder->setData(data, allDataReceived);
+    decoder->setData(data, true);
     OwnPtr<ImagePlanes> dummyImagePlanes = adoptPtr(new ImagePlanes);
     decoder->setImagePlanes(dummyImagePlanes.release());
 
     return updateYUVComponentSizes(decoder.get(), sizeInfo->fSizes, sizeInfo->fWidthBytes);
 }
 
 } // namespace blink