Revert of Eliminate copies of encoded image data

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

Index: third_party/WebKit/Source/platform/graphics/ImageFrameGenerator.cpp
diff --git a/third_party/WebKit/Source/platform/graphics/ImageFrameGenerator.cpp b/third_party/WebKit/Source/platform/graphics/ImageFrameGenerator.cpp
index 1decd0f70f6f26e911b59732117b69f7bffea6ac..312dba24c3dd11a02830bf9cf60c3f94ab0f24c4 100644
--- a/third_party/WebKit/Source/platform/graphics/ImageFrameGenerator.cpp
+++ b/third_party/WebKit/Source/platform/graphics/ImageFrameGenerator.cpp
@@ -26,6 +26,7 @@
 #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"
@@ -51,7 +52,7 @@
 
 // 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 ExternalMemoryAllocator final : public SkBitmap::Allocator {
+class ImageFrameGenerator::ExternalMemoryAllocator final : public SkBitmap::Allocator {
     USING_FAST_MALLOC(ExternalMemoryAllocator);
     WTF_MAKE_NONCOPYABLE(ExternalMemoryAllocator);
 public:
@@ -100,38 +101,104 @@
     return true;
 }
 
-ImageFrameGenerator::ImageFrameGenerator(const SkISize& fullSize, bool isMultiFrame)
+ImageFrameGenerator::ImageFrameGenerator(const SkISize& fullSize, PassRefPtr<SharedBuffer> data, bool allDataReceived, bool isMultiFrame)
     : m_fullSize(fullSize)
+    , m_data(adoptRef(new ThreadSafeDataTransport()))
     , m_isMultiFrame(isMultiFrame)
     , m_decodeFailed(false)
     , m_yuvDecodingFailed(false)
     , m_frameCount(0)
-{
+    , m_encodedData(nullptr)
+{
+    setData(data.get(), allDataReceived);
 }
 
 ImageFrameGenerator::~ImageFrameGenerator()
 {
+    if (m_encodedData)
+        m_encodedData->unref();
     ImageDecodingStore::instance().removeCacheIndexedByGenerator(this);
 }
 
-bool ImageFrameGenerator::decodeAndScale(SegmentReader* data, bool allDataReceived, size_t index, const SkImageInfo& info, void* pixels, size_t rowBytes)
-{
+void ImageFrameGenerator::setData(PassRefPtr<SharedBuffer> data, bool allDataReceived)
+{
+    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));
 
-    RefPtr<ExternalMemoryAllocator> externalAllocator = adoptRef(new ExternalMemoryAllocator(info, pixels, rowBytes));
+    m_externalAllocator = adoptPtr(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);
 
-    // 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());
+    SkBitmap bitmap = tryToResumeDecode(index, scaledSize);
     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();
 
     // Check to see if the decoder has written directly to the pixel memory
     // provided. If not, make a copy.
@@ -143,10 +210,11 @@
     return true;
 }
 
-bool ImageFrameGenerator::decodeToYUV(SegmentReader* data, size_t index, const SkISize componentSizes[3], void* planes[3], const size_t rowBytes[3])
-{
-    // 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.
+bool ImageFrameGenerator::decodeToYUV(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);
+
     if (m_decodeFailed)
         return false;
 
@@ -157,11 +225,18 @@
         return false;
     }
 
+    SharedBuffer* data = 0;
+    bool allDataReceived = false;
+    m_data->data(&data, &allDataReceived);
+
+    // FIXME: YUV decoding does not currently support progressive decoding.
+    ASSERT(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);
-
-    decoder->setData(data, true);
+    if (!decoder)
+        return false;
+
+    decoder->setData(data, allDataReceived);
 
     OwnPtr<ImagePlanes> imagePlanes = adoptPtr(new ImagePlanes(planes, rowBytes));
     decoder->setImagePlanes(imagePlanes.release());
@@ -178,19 +253,16 @@
     return false;
 }
 
-SkBitmap ImageFrameGenerator::tryToResumeDecode(SegmentReader* data, bool allDataReceived, size_t index, const SkISize& scaledSize, SkBitmap::Allocator* allocator)
+SkBitmap ImageFrameGenerator::tryToResumeDecode(size_t index, const SkISize& scaledSize)
 {
     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(data, allDataReceived, index, &decoder, &fullSizeImage, allocator);
+    bool complete = decode(index, &decoder, &fullSizeImage);
 
     if (!decoder)
         return SkBitmap();
@@ -250,10 +322,13 @@
     m_hasAlpha[index] = hasAlpha;
 }
 
-bool ImageFrameGenerator::decode(SegmentReader* data, bool allDataReceived, size_t index, ImageDecoder** decoder, SkBitmap* bitmap, SkBitmap::Allocator* allocator)
-{
-    ASSERT(m_decodeMutex.locked());
+bool ImageFrameGenerator::decode(size_t index, ImageDecoder** decoder, SkBitmap* bitmap)
+{
     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);
@@ -273,8 +348,8 @@
     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(allocator);
-        (*decoder)->setMemoryAllocator(allocator);
+        ASSERT(m_externalAllocator.get());
+        (*decoder)->setMemoryAllocator(m_externalAllocator.get());
     }
 
     (*decoder)->setData(data, allDataReceived);
@@ -287,7 +362,7 @@
     if (allDataReceived)
         m_frameCount = (*decoder)->frameCount();
 
-    (*decoder)->setData(PassRefPtr<SegmentReader>(nullptr), false); // Unref SegmentReader from ImageDecoder.
+    (*decoder)->setData(0, false); // Unref SharedBuffer from ImageDecoder.
     (*decoder)->clearCacheExceptFrame(index);
     (*decoder)->setMemoryAllocator(0);
 
@@ -317,11 +392,19 @@
     return true;
 }
 
-bool ImageFrameGenerator::getYUVComponentSizes(SegmentReader* data, SkYUVSizeInfo* sizeInfo)
+bool ImageFrameGenerator::getYUVComponentSizes(SkYUVSizeInfo* sizeInfo)
 {
     TRACE_EVENT2("blink", "ImageFrameGenerator::getYUVComponentSizes", "width", m_fullSize.width(), "height", m_fullSize.height());
 
     if (m_yuvDecodingFailed)
+        return false;
+
+    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);
@@ -329,7 +412,7 @@
         return false;
 
     // Setting a dummy ImagePlanes object signals to the decoder that we want to do YUV decoding.
-    decoder->setData(data, true);
+    decoder->setData(data, allDataReceived);
     OwnPtr<ImagePlanes> dummyImagePlanes = adoptPtr(new ImagePlanes);
     decoder->setImagePlanes(dummyImagePlanes.release());