Cleanup the IO thread GrContext (flutter#14265)

Fixes flutter#19558

This is tested by the devicelab test fast_scroll_large_images__memory

Author: liyuqian

flow/skia_gpu_object.cc

@@ -5,14 +5,17 @@
 #include "flutter/flow/skia_gpu_object.h"
 
 #include "flutter/fml/message_loop.h"
+#include "flutter/fml/trace_event.h"
 
 namespace flutter {
 
 SkiaUnrefQueue::SkiaUnrefQueue(fml::RefPtr<fml::TaskRunner> task_runner,
-                               fml::TimeDelta delay)
+                               fml::TimeDelta delay,
+                               fml::WeakPtr<GrContext> context)
     : task_runner_(std::move(task_runner)),
       drain_delay_(delay),
-      drain_pending_(false) {}
+      drain_pending_(false),
+      context_(context) {}
 
 SkiaUnrefQueue::~SkiaUnrefQueue() {
   FML_DCHECK(objects_.empty());
@@ -29,6 +32,7 @@ void SkiaUnrefQueue::Unref(SkRefCnt* object) {
 }
 
 void SkiaUnrefQueue::Drain() {
+  TRACE_EVENT0("flutter", "SkiaUnrefQueue::Drain");
   std::deque<SkRefCnt*> skia_objects;
   {
     std::scoped_lock lock(mutex_);
@@ -39,6 +43,10 @@ void SkiaUnrefQueue::Drain() {
   for (SkRefCnt* skia_object : skia_objects) {
     skia_object->unref();
   }
+
+  if (context_ && skia_objects.size() > 0) {
+    context_->performDeferredCleanup(std::chrono::milliseconds(0));
+  }
 }
 
 }  // namespace flutter

flow/skia_gpu_object.h

@@ -12,6 +12,7 @@
 #include "flutter/fml/memory/weak_ptr.h"
 #include "flutter/fml/task_runner.h"
 #include "third_party/skia/include/core/SkRefCnt.h"
+#include "third_party/skia/include/gpu/GrContext.h"
 
 namespace flutter {
 
@@ -34,9 +35,14 @@ class SkiaUnrefQueue : public fml::RefCountedThreadSafe<SkiaUnrefQueue> {
   std::mutex mutex_;
   std::deque<SkRefCnt*> objects_;
   bool drain_pending_;
+  fml::WeakPtr<GrContext> context_;
 
+  // The `GrContext* context` is only used for signaling Skia to
+  // performDeferredCleanup. It can be nullptr when such signaling is not needed
+  // (e.g., in unit tests).
   SkiaUnrefQueue(fml::RefPtr<fml::TaskRunner> task_runner,
-                 fml::TimeDelta delay);
+                 fml::TimeDelta delay,
+                 fml::WeakPtr<GrContext> context = {});
 
   ~SkiaUnrefQueue();
 

flow/skia_gpu_object_unittests.cc

@@ -11,6 +11,8 @@
 #include "gtest/gtest.h"
 #include "third_party/skia/include/core/SkRefCnt.h"
 
+#include <future>
+
 namespace flutter {
 namespace testing {
 
@@ -42,6 +44,18 @@ class SkiaGpuObjectTest : public ThreadTest {
         delayed_unref_queue_(fml::MakeRefCounted<SkiaUnrefQueue>(
             unref_task_runner(),
             fml::TimeDelta::FromSeconds(3))) {
+    // The unref queues must be created in the same thread of the
+    // unref_task_runner so the queue can access the same-thread-only WeakPtr of
+    // the GrContext constructed during the creation.
+    std::promise<bool> queuesCreated;
+    unref_task_runner_->PostTask([this, &queuesCreated]() {
+      unref_queue_ = fml::MakeRefCounted<SkiaUnrefQueue>(
+          unref_task_runner(), fml::TimeDelta::FromSeconds(0));
+      delayed_unref_queue_ = fml::MakeRefCounted<SkiaUnrefQueue>(
+          unref_task_runner(), fml::TimeDelta::FromSeconds(3));
+      queuesCreated.set_value(true);
+    });
+    queuesCreated.get_future().wait();
     ::testing::FLAGS_gtest_death_test_style = "threadsafe";
   }
 

shell/common/shell_io_manager.cc

@@ -62,7 +62,8 @@ ShellIOManager::ShellIOManager(
                             : nullptr),
       unref_queue_(fml::MakeRefCounted<flutter::SkiaUnrefQueue>(
           std::move(unref_queue_task_runner),
-          fml::TimeDelta::FromMilliseconds(8))),
+          fml::TimeDelta::FromMilliseconds(8),
+          GetResourceContext())),
       weak_factory_(this),
       is_gpu_disabled_sync_switch_(is_gpu_disabled_sync_switch) {
   if (!resource_context_) {