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// Copyright 2016 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#include <memory>
#include <unordered_map>
#include <vector>
#include "base/containers/mru_cache.h"
#include "base/memory/discardable_memory.h"
#include "base/synchronization/lock.h"
#include "base/trace_event/memory_dump_provider.h"
#include "cc/base/cc_export.h"
#include "cc/resources/resource_format.h"
#include "cc/tiles/image_decode_controller.h"
#include "third_party/skia/include/core/SkRefCnt.h"
class SkImageTextureData;
namespace cc {
class ContextProvider;
// GpuImageDecodeController handles the decode and upload of images that will
// be used by Skia's GPU raster path. It also maintains a cache of these
// decoded/uploaded images for later re-use.
// Generally, when an image is required for raster, GpuImageDecodeController
// creates two tasks, one to decode the image, and one to upload the image to
// the GPU. These tasks are completed before the raster task which depends on
// the image. We need to seperate decode and upload tasks, as decode can occur
// simultaneously on multiple threads, while upload requires the GL context
// lock must happen on our non-concurrent raster thread.
// Decoded and Uploaded image data share a single cache entry. Depending on how
// far we've progressed, this cache entry may contain CPU-side decoded data,
// GPU-side uploaded data, or both. Because CPU-side decoded data is stored in
// discardable memory, and is only locked for short periods of time (until the
// upload completes), this memory is not counted against our sized cache
// limits. Uploaded GPU memory, being non-discardable, always counts against
// our limits.
// In cases where the number of images needed exceeds our cache limits, we
// operate in an "at-raster" mode. In this mode, there are no decode/upload
// tasks, and images are decoded/uploaded as needed, immediately before being
// used in raster. Cache entries for at-raster tasks are marked as such, which
// prevents future tasks from taking a dependency on them and extending their
// lifetime longer than is necessary.
class CC_EXPORT GpuImageDecodeController
: public ImageDecodeController,
public base::trace_event::MemoryDumpProvider {
explicit GpuImageDecodeController(ContextProvider* context,
ResourceFormat decode_format,
size_t max_gpu_image_bytes);
~GpuImageDecodeController() override;
// ImageDecodeController overrides.
// Finds the existing uploaded image for the provided DrawImage. Creates an
// upload task to upload the image if an exsiting image does not exist.
bool GetTaskForImageAndRef(const DrawImage& image,
const TracingInfo& tracing_info,
scoped_refptr<TileTask>* task) override;
void UnrefImage(const DrawImage& image) override;
DecodedDrawImage GetDecodedImageForDraw(const DrawImage& draw_image) override;
void DrawWithImageFinished(const DrawImage& image,
const DecodedDrawImage& decoded_image) override;
void ReduceCacheUsage() override;
void SetShouldAggressivelyFreeResources(
bool aggressively_free_resources) override;
// MemoryDumpProvider overrides.
bool OnMemoryDump(const base::trace_event::MemoryDumpArgs& args,
base::trace_event::ProcessMemoryDump* pmd) override;
// Called by Decode / Upload tasks.
void DecodeImage(const DrawImage& image);
void UploadImage(const DrawImage& image);
// Called by Decode / Upload tasks when tasks are finished.
void OnImageDecodeTaskCompleted(const DrawImage& image);
void OnImageUploadTaskCompleted(const DrawImage& image);
// For testing only.
void SetCachedItemLimitForTesting(size_t limit) {
cached_items_limit_ = limit;
void SetCachedBytesLimitForTesting(size_t limit) {
cached_bytes_limit_ = limit;
size_t GetBytesUsedForTesting() const { return bytes_used_; }
void SetImageDecodingFailedForTesting(const DrawImage& image);
bool DiscardableIsLockedForTesting(const DrawImage& image);
enum class DecodedDataMode { GPU, CPU };
// Stores the CPU-side decoded bits of an image and supporting fields.
struct DecodedImageData {
bool is_locked() const { return is_locked_; }
bool Lock();
void Unlock();
void SetLockedData(std::unique_ptr<base::DiscardableMemory> data);
void ResetData();
base::DiscardableMemory* data() const { return data_.get(); }
void mark_used() { usage_stats_.used = true; }
// May be null if image not yet decoded.
uint32_t ref_count = 0;
// Set to true if the image was corrupt and could not be decoded.
bool decode_failure = false;
struct UsageStats {
int lock_count = 1;
bool used = false;
bool first_lock_wasted = false;
void ReportUsageStats() const;
std::unique_ptr<base::DiscardableMemory> data_;
bool is_locked_ = false;
UsageStats usage_stats_;
// Stores the GPU-side image and supporting fields.
struct UploadedImageData {
void SetImage(sk_sp<SkImage> image);
const sk_sp<SkImage>& image() const { return image_; }
void mark_used() { usage_stats_.used = true; }
void notify_ref_reached_zero() {
if (++usage_stats_.ref_reached_zero_count == 1)
usage_stats_.first_ref_wasted = !usage_stats_.used;
// True if the image is counting against our memory limits.
bool budgeted = false;
uint32_t ref_count = 0;
struct UsageStats {
bool used = false;
bool first_ref_wasted = false;
int ref_reached_zero_count = 0;
void ReportUsageStats() const;
// May be null if image not yet uploaded / prepared.
sk_sp<SkImage> image_;
UsageStats usage_stats_;
struct ImageData {
ImageData(DecodedDataMode mode, size_t size);
const DecodedDataMode mode;
const size_t size;
bool is_at_raster = false;
DecodedImageData decode;
UploadedImageData upload;
using ImageDataMRUCache =
base::MRUCache<uint32_t, std::unique_ptr<ImageData>>;
// All private functions should only be called while holding |lock_|. Some
// functions also require the |context_| lock. These are indicated by
// additional comments.
// Similar to GetTaskForImageAndRef, but gets the dependent decode task
// rather than the upload task, if necessary.
scoped_refptr<TileTask> GetImageDecodeTaskAndRef(
const DrawImage& image,
const TracingInfo& tracing_info);
void RefImageDecode(const DrawImage& draw_image);
void UnrefImageDecode(const DrawImage& draw_image);
void RefImage(const DrawImage& draw_image);
void UnrefImageInternal(const DrawImage& draw_image);
void RefCountChanged(ImageData* image_data);
// Ensures that the cache can hold an element of |required_size|, freeing
// unreferenced cache entries if necessary to make room.
bool EnsureCapacity(size_t required_size);
bool CanFitSize(size_t size) const;
bool ExceedsPreferredCount() const;
void DecodeImageIfNecessary(const DrawImage& draw_image,
ImageData* image_data);
std::unique_ptr<GpuImageDecodeController::ImageData> CreateImageData(
const DrawImage& image);
SkImageInfo CreateImageInfoForDrawImage(const DrawImage& draw_image) const;
// The following two functions also require the |context_| lock to be held.
void UploadImageIfNecessary(const DrawImage& draw_image,
ImageData* image_data);
void DeletePendingImages();
const ResourceFormat format_;
ContextProvider* context_;
sk_sp<GrContextThreadSafeProxy> context_threadsafe_proxy_;
// All members below this point must only be accessed while holding |lock_|.
base::Lock lock_;
std::unordered_map<uint32_t, scoped_refptr<TileTask>>
std::unordered_map<uint32_t, scoped_refptr<TileTask>>
ImageDataMRUCache image_data_;
size_t cached_items_limit_;
size_t cached_bytes_limit_;
size_t bytes_used_;
const size_t max_gpu_image_bytes_;
// We can't release GPU backed SkImages without holding the context lock,
// so we add them to this list and defer deletion until the next time the lock
// is held.
std::vector<sk_sp<SkImage>> images_pending_deletion_;
} // namespace cc