Revert "Try rasterizing images and layers only once , even when their rasterization fails. Further enforce the same access threshold on layers as on Pictures. Previously layers would always be cached. The latter is a semantic change. (#16545)" (#16889)

This caused regression in several benchmarks, including:
animated_placeholder_perf. Regression tracked in
flutter/flutter#51776.

This reverts commit 01a52b9.

Author: cbracken

flow/raster_cache.cc

@@ -119,15 +119,24 @@ static RasterCacheResult Rasterize(
   return {surface->makeImageSnapshot(), logical_rect};
 }
 
-bool RasterCache::Prepare(PrerollContext* context,
+RasterCacheResult RasterizePicture(SkPicture* picture,
+                                   GrContext* context,
+                                   const SkMatrix& ctm,
+                                   SkColorSpace* dst_color_space,
+                                   bool checkerboard) {
+  return Rasterize(context, ctm, dst_color_space, checkerboard,
+                   picture->cullRect(),
+                   [=](SkCanvas* canvas) { canvas->drawPicture(picture); });
+}
+
+void RasterCache::Prepare(PrerollContext* context,
                           Layer* layer,
                           const SkMatrix& ctm) {
   LayerRasterCacheKey cache_key(layer->unique_id(), ctm);
-
   Entry& entry = layer_cache_[cache_key];
-
-  if (!entry.did_rasterize && !entry.image.is_valid() &&
-      entry.access_count >= access_threshold_) {
+  entry.access_count++;
+  entry.used_this_frame = true;
+  if (!entry.image.is_valid()) {
     entry.image = Rasterize(
         context->gr_context, ctm, context->dst_color_space,
         checkerboard_images_, layer->paint_bounds(),
@@ -152,12 +161,7 @@ bool RasterCache::Prepare(PrerollContext* context,
             layer->Paint(paintContext);
           }
         });
-
-    entry.did_rasterize = true;
-
-    return true;
   }
-  return false;
 }
 
 bool RasterCache::Prepare(GrContext* context,
@@ -196,19 +200,12 @@ bool RasterCache::Prepare(GrContext* context,
     return false;
   }
 
-  // Don't try to rasterize pictures that were already attempted to be
-  // rasterized even if the image is invalid.
-  if (!entry.did_rasterize && !entry.image.is_valid()) {
-    entry.image =
-        Rasterize(context, transformation_matrix, dst_color_space,
-                  checkerboard_images_, picture->cullRect(),
-                  [=](SkCanvas* canvas) { canvas->drawPicture(picture); });
-
-    entry.did_rasterize = true;
+  if (!entry.image.is_valid()) {
+    entry.image = RasterizePicture(picture, context, transformation_matrix,
+                                   dst_color_space, checkerboard_images_);
     picture_cached_this_frame_++;
-    return true;
   }
-  return false;
+  return true;
 }
 
 RasterCacheResult RasterCache::Get(const SkPicture& picture,

flow/raster_cache.h

@@ -84,7 +84,7 @@ class RasterCache {
                bool is_complex,
                bool will_change);
 
-  bool Prepare(PrerollContext* context, Layer* layer, const SkMatrix& ctm);
+  void Prepare(PrerollContext* context, Layer* layer, const SkMatrix& ctm);
 
   RasterCacheResult Get(const SkPicture& picture, const SkMatrix& ctm) const;
 
@@ -101,7 +101,6 @@ class RasterCache {
  private:
   struct Entry {
     bool used_this_frame = false;
-    bool did_rasterize = false;
     size_t access_count = 0;
     RasterCacheResult image;
   };

flow/raster_cache_unittests.cc

@@ -4,7 +4,6 @@
 
 #include "flutter/flow/raster_cache.h"
 
-#include "flutter/flow/layers/container_layer.h"
 #include "gtest/gtest.h"
 #include "third_party/skia/include/core/SkPicture.h"
 #include "third_party/skia/include/core/SkPictureRecorder.h"
@@ -30,14 +29,16 @@ TEST(RasterCache, SimpleInitialization) {
   ASSERT_TRUE(true);
 }
 
-TEST(RasterCache, ThresholdIsRespectedForPictures) {
+TEST(RasterCache, ThresholdIsRespected) {
   size_t threshold = 2;
   flutter::RasterCache cache(threshold);
 
   SkMatrix matrix = SkMatrix::I();
 
   auto picture = GetSamplePicture();
 
+  sk_sp<SkImage> image;
+
   sk_sp<SkColorSpace> srgb = SkColorSpace::MakeSRGB();
   ASSERT_FALSE(
       cache.Prepare(NULL, picture.get(), matrix, srgb.get(), true, false));
@@ -60,28 +61,21 @@ TEST(RasterCache, ThresholdIsRespectedForPictures) {
   ASSERT_TRUE(cache.Get(*picture, matrix).is_valid());
 }
 
-TEST(RasterCache, ThresholdIsRespectedForLayers) {
-  size_t threshold = 2;
+TEST(RasterCache, AccessThresholdOfZeroDisablesCaching) {
+  size_t threshold = 0;
   flutter::RasterCache cache(threshold);
 
   SkMatrix matrix = SkMatrix::I();
 
-  ContainerLayer layer;
-
-  sk_sp<SkColorSpace> srgb = SkColorSpace::MakeSRGB();
-  ASSERT_FALSE(cache.Prepare(nullptr, &layer, matrix));
-  ASSERT_FALSE(cache.Prepare(nullptr, &layer, matrix));
-  ASSERT_FALSE(cache.Prepare(nullptr, &layer, matrix));
-
-  // 1st access.
-  ASSERT_FALSE(cache.Get(&layer, matrix).is_valid());
+  auto picture = GetSamplePicture();
 
-  ASSERT_FALSE(cache.Prepare(nullptr, &layer, matrix));
+  sk_sp<SkImage> image;
 
-  // 2st access.
-  ASSERT_FALSE(cache.Get(&layer, matrix).is_valid());
+  sk_sp<SkColorSpace> srgb = SkColorSpace::MakeSRGB();
+  ASSERT_FALSE(
+      cache.Prepare(NULL, picture.get(), matrix, srgb.get(), true, false));
 
-  // Calling Prepare now would crash due to the nullptr.
+  ASSERT_FALSE(cache.Get(*picture, matrix).is_valid());
 }
 
 TEST(RasterCache, PictureCacheLimitPerFrameIsRespectedWhenZero) {
@@ -92,6 +86,8 @@ TEST(RasterCache, PictureCacheLimitPerFrameIsRespectedWhenZero) {
 
   auto picture = GetSamplePicture();
 
+  sk_sp<SkImage> image;
+
   sk_sp<SkColorSpace> srgb = SkColorSpace::MakeSRGB();
   ASSERT_FALSE(
       cache.Prepare(NULL, picture.get(), matrix, srgb.get(), true, false));
@@ -107,6 +103,8 @@ TEST(RasterCache, SweepsRemoveUnusedFrames) {
 
   auto picture = GetSamplePicture();
 
+  sk_sp<SkImage> image;
+
   sk_sp<SkColorSpace> srgb = SkColorSpace::MakeSRGB();
   ASSERT_FALSE(cache.Prepare(NULL, picture.get(), matrix, srgb.get(), true,
                              false));  // 1
@@ -124,29 +122,5 @@ TEST(RasterCache, SweepsRemoveUnusedFrames) {
   ASSERT_FALSE(cache.Get(*picture, matrix).is_valid());
 }
 
-TEST(RasterCache, TryRasterizngOnlyOnce) {
-  size_t threshold = 1;
-  flutter::RasterCache cache(threshold);
-
-  SkMatrix matrix = SkMatrix::I();
-  // Test picture too large to successfully rasterize.
-  auto picture = SkPicture::MakePlaceholder(SkRect::MakeWH(2e12, 2e12));
-
-  sk_sp<SkColorSpace> srgb = SkColorSpace::MakeSRGB();
-  ASSERT_FALSE(cache.Prepare(nullptr, picture.get(), matrix, srgb.get(), true,
-                             false));  // 1
-  ASSERT_FALSE(cache.Get(*picture, matrix).is_valid());
-
-  // Rasterization ran, though Get() below returns an invalid image.
-  ASSERT_TRUE(cache.Prepare(nullptr, picture.get(), matrix, srgb.get(), true,
-                            false));  // 2
-  ASSERT_FALSE(cache.Get(*picture, matrix).is_valid());
-
-  // This time we should not try again to rasterize.
-  ASSERT_FALSE(cache.Prepare(nullptr, picture.get(), matrix, srgb.get(), true,
-                             false));  // 2
-  ASSERT_FALSE(cache.Get(*picture, matrix).is_valid());
-}
-
 }  // namespace testing
 }  // namespace flutter