Tweak the code and add some comments

flutter · Mar 10, 2022 · a00ae5e · a00ae5e
1 parent bd8e7af
commit a00ae5e
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Showing 3 changed files with 16 additions and 2 deletions.
diff --git a/flow/raster_cache.cc b/flow/raster_cache.cc
@@ -416,8 +416,8 @@ void RasterCache::SweepOneCacheAfterFrame(RasterCacheKey::Map<Entry>& cache,
   for (auto it = cache.begin(); it != cache.end(); ++it) {
     Entry& entry = it->second;
     if (!entry.used_this_frame) {
-      entry.unused_count++;
       if (entry.unused_count < entry.unused_threshold()) {
+        entry.unused_count++;
         if (entry.image) {
           RasterCacheKeyKind kind = it->first.kind();
           switch (kind) {

diff --git a/flow/raster_cache.h b/flow/raster_cache.h
@@ -308,7 +308,9 @@ class RasterCache {
     size_t access_count = 0;
     size_t unused_count = 0;
     std::unique_ptr<RasterCacheResult> image;
-    size_t unused_threshold() const { return is_high_priority ? 3 : 1; }
+    // Return the number of frames the entry survives if it is not used. If the
+    // number is 0, then it will be evicted when not in use.
+    size_t unused_threshold() const { return is_high_priority ? 3 : 0; }
   };
 
   void Touch(const RasterCacheKey& cache_key);

diff --git a/flow/raster_cache_unittests.cc b/flow/raster_cache_unittests.cc
@@ -371,6 +371,12 @@ TEST(RasterCache, KeepUnusedSkPicturesIfIsHighPriority) {
 
   PrepareAndCleanupEmptyFrame(cache, 3);
   cache.PrepareNewFrame();
+  ASSERT_TRUE(cache.Draw(*picture, dummy_canvas));
+  cache.CleanupAfterFrame();
+
+  // The entry will be evicted when it is not used 4 times in a row.
+  PrepareAndCleanupEmptyFrame(cache, 4);
+  cache.PrepareNewFrame();
   ASSERT_FALSE(cache.Draw(*picture, dummy_canvas));
   cache.CleanupAfterFrame();
 }
@@ -408,6 +414,12 @@ TEST(RasterCache, KeepUnusedDisplayListsIfIsHighPriority) {
 
   PrepareAndCleanupEmptyFrame(cache, 3);
   cache.PrepareNewFrame();
+  ASSERT_TRUE(cache.Draw(*display_list, dummy_canvas));
+  cache.CleanupAfterFrame();
+
+  // The entry will be evicted when it is not used 4 times in a row.
+  PrepareAndCleanupEmptyFrame(cache, 4);
+  cache.PrepareNewFrame();
   ASSERT_FALSE(cache.Draw(*display_list, dummy_canvas));
   cache.CleanupAfterFrame();
 }