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// Copyright 2015 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.
#ifndef CC_TILES_IMAGE_DECODE_CONTROLLER_H_
#define CC_TILES_IMAGE_DECODE_CONTROLLER_H_
#include <stdint.h>
#include <unordered_map>
#include <unordered_set>
#include "base/hash.h"
#include "base/memory/discardable_memory_allocator.h"
#include "base/memory/ref_counted.h"
#include "base/numerics/safe_math.h"
#include "base/threading/thread_checker.h"
#include "cc/base/cc_export.h"
#include "cc/playback/decoded_draw_image.h"
#include "cc/playback/draw_image.h"
#include "cc/raster/tile_task_runner.h"
#include "skia/ext/refptr.h"
#include "ui/gfx/transform.h"
namespace cc {
// ImageDecodeControllerKey is a class that gets a cache key out of a given draw
// image. That is, this key uniquely identifies an image in the cache. Note that
// it's insufficient to use SkImage's unique id, since the same image can appear
// in the cache multiple times at different scales and filter qualities.
class CC_EXPORT ImageDecodeControllerKey {
public:
static ImageDecodeControllerKey FromDrawImage(const DrawImage& image);
bool operator==(const ImageDecodeControllerKey& other) const {
return image_id_ == other.image_id_ && src_rect_ == other.src_rect_ &&
target_size_ == other.target_size_ &&
filter_quality_ == other.filter_quality_;
}
bool operator!=(const ImageDecodeControllerKey& other) const {
return !(*this == other);
}
uint32_t image_id() const { return image_id_; }
SkFilterQuality filter_quality() const { return filter_quality_; }
gfx::Rect src_rect() const { return src_rect_; }
gfx::Size target_size() const { return target_size_; }
// Helper to figure out how much memory this decoded and scaled image would
// take.
size_t target_bytes() const {
// TODO(vmpstr): Handle formats other than RGBA.
base::CheckedNumeric<size_t> result = 4;
result *= target_size_.width();
result *= target_size_.height();
return result.ValueOrDefault(std::numeric_limits<size_t>::max());
}
std::string ToString() const;
private:
ImageDecodeControllerKey(uint32_t image_id,
const gfx::Rect& src_rect,
const gfx::Size& size,
SkFilterQuality filter_quality);
uint32_t image_id_;
gfx::Rect src_rect_;
gfx::Size target_size_;
SkFilterQuality filter_quality_;
};
// Hash function for the above ImageDecodeControllerKey.
struct ImageDecodeControllerKeyHash {
size_t operator()(const ImageDecodeControllerKey& key) const {
// TODO(vmpstr): This is a mess. Maybe it's faster to just search the vector
// always (forwards or backwards to account for LRU).
uint64_t src_rect_hash =
base::HashInts(static_cast<uint64_t>(base::HashInts(
key.src_rect().x(), key.src_rect().y())),
static_cast<uint64_t>(base::HashInts(
key.src_rect().width(), key.src_rect().height())));
uint64_t target_size_hash =
base::HashInts(key.target_size().width(), key.target_size().height());
return base::HashInts(base::HashInts(src_rect_hash, target_size_hash),
base::HashInts(key.image_id(), key.filter_quality()));
}
};
// ImageDecodeController is responsible for generating decode tasks, decoding
// images, storing images in cache, and being able to return the decoded images
// when requested.
// ImageDecodeController is responsible for the following things:
// 1. Given a DrawImage, it can return an ImageDecodeTask which when run will
// decode and cache the resulting image. If the image does not need a task to
// be decoded, then nullptr will be returned. The return value of the
// function indicates whether the image was or is going to be locked, so an
// unlock will be required.
// 2. Given a cache key and a DrawImage, it can decode the image and store it in
// the cache. Note that it is important that this function is only accessed
// via an image decode task.
// 3. Given a DrawImage, it can return a DecodedDrawImage, which represented the
// decoded version of the image. Note that if the image is not in the cache
// and it needs to be scaled/decoded, then this decode will happen as part of
// getting the image. As such, this should only be accessed from a raster
// thread.
class CC_EXPORT ImageDecodeController {
public:
using ImageKey = ImageDecodeControllerKey;
using ImageKeyHash = ImageDecodeControllerKeyHash;
ImageDecodeController();
~ImageDecodeController();
// Fill in an ImageDecodeTask which will decode the given image when run. In
// case the image is already cached, fills in nullptr. Returns true if the
// image needs to be unreffed when the caller is finished with it.
//
// This is called by the tile manager (on the compositor thread) when creating
// a raster task.
bool GetTaskForImageAndRef(const DrawImage& image,
uint64_t prepare_tiles_id,
scoped_refptr<ImageDecodeTask>* task);
// Unrefs an image. When the tile is finished, this should be called for every
// GetTaskForImageAndRef call that returned true.
void UnrefImage(const DrawImage& image);
// Returns a decoded draw image. If the image isn't found in the cache, a
// decode will happen.
//
// This is called by a raster task (on a worker thread) when an image is
// required.
DecodedDrawImage GetDecodedImageForDraw(const DrawImage& image);
// Unrefs an image. This should be called for every GetDecodedImageForDraw
// when the draw with the image is finished.
void DrawWithImageFinished(const DrawImage& image,
const DecodedDrawImage& decoded_image);
// Decode the given image and store it in the cache. This is only called by an
// image decode task from a worker thread.
void DecodeImage(const ImageKey& key, const DrawImage& image);
void ReduceCacheUsage();
void RemovePendingTask(const ImageKey& key);
// Info the controller whether we're using gpu rasterization or not. Since the
// decode and caching behavior is different for SW and GPU decodes, when the
// state changes, we clear all of the caches. This means that this is only
// safe to call when there are no pending tasks (and no refs on any images).
void SetIsUsingGpuRasterization(bool is_using_gpu_rasterization);
private:
// DecodedImage is a convenience storage for discardable memory. It can also
// construct an image out of SkImageInfo and stored discardable memory.
// TODO(vmpstr): Make this scoped_ptr.
class DecodedImage : public base::RefCounted<DecodedImage> {
public:
DecodedImage(const SkImageInfo& info,
scoped_ptr<base::DiscardableMemory> memory,
const SkSize& src_rect_offset);
SkImage* image() const {
DCHECK(locked_);
return image_.get();
}
const SkSize& src_rect_offset() const { return src_rect_offset_; }
bool is_locked() const { return locked_; }
bool Lock();
void Unlock();
private:
friend class base::RefCounted<DecodedImage>;
~DecodedImage();
bool locked_;
SkImageInfo image_info_;
scoped_ptr<base::DiscardableMemory> memory_;
skia::RefPtr<SkImage> image_;
SkSize src_rect_offset_;
};
// MemoryBudget is a convenience class for memory bookkeeping and ensuring
// that we don't go over the limit when pre-decoding.
// TODO(vmpstr): Add memory infra to keep track of memory usage of this class.
class MemoryBudget {
public:
explicit MemoryBudget(size_t limit_bytes);
size_t AvailableMemoryBytes() const;
void AddUsage(size_t usage);
void SubtractUsage(size_t usage);
void ResetUsage();
private:
size_t GetCurrentUsageSafe() const;
size_t limit_bytes_;
base::CheckedNumeric<size_t> current_usage_bytes_;
};
using AnnotatedDecodedImage =
std::pair<ImageKey, scoped_refptr<DecodedImage>>;
// Looks for the key in the cache and returns true if it was found and was
// successfully locked (or if it was already locked). Note that if this
// function returns true, then a ref count is increased for the image.
bool LockDecodedImageIfPossibleAndRef(const ImageKey& key);
// Actually decode the image. Note that this function can (and should) be
// called with no lock acquired, since it can do a lot of work. Note that it
// can also return nullptr to indicate the decode failed.
scoped_refptr<DecodedImage> DecodeImageInternal(const ImageKey& key,
const SkImage* image);
void SanityCheckState(int line, bool lock_acquired);
void RefImage(const ImageKey& key);
void RefAtRasterImage(const ImageKey& key);
void UnrefAtRasterImage(const ImageKey& key);
// These functions indicate whether the images can be handled and cached by
// ImageDecodeController or whether they will fall through to Skia (with
// exception of possibly prerolling them). Over time these should return
// "false" in less cases, as the ImageDecodeController should start handling
// more of them.
bool CanHandleImage(const ImageKey& key, const DrawImage& image);
bool CanHandleFilterQuality(SkFilterQuality filter_quality);
bool is_using_gpu_rasterization_;
std::unordered_map<ImageKey, scoped_refptr<ImageDecodeTask>, ImageKeyHash>
pending_image_tasks_;
// The members below this comment can only be accessed if the lock is held to
// ensure that they are safe to access on multiple threads.
base::Lock lock_;
std::deque<AnnotatedDecodedImage> decoded_images_;
std::unordered_map<ImageKey, int, ImageKeyHash> decoded_images_ref_counts_;
std::deque<AnnotatedDecodedImage> at_raster_decoded_images_;
std::unordered_map<ImageKey, int, ImageKeyHash>
at_raster_decoded_images_ref_counts_;
MemoryBudget locked_images_budget_;
// Note that this is used for cases where the only thing we do is preroll the
// image the first time we see it. This mimics the previous behavior and
// should over time change as the compositor starts to handle more cases.
std::unordered_set<uint32_t> prerolled_images_;
};
} // namespace cc
#endif // CC_TILES_IMAGE_DECODE_CONTROLLER_H_