FlutterEngineGroup for Android

.gitignore

@@ -4,6 +4,7 @@
 .*.sw?
 .DS_Store
 .ccls-cache
+.cache
 .classpath
 .clangd/
 .cproject

ci/licenses_golden/licenses_flutter

@@ -748,6 +748,7 @@ FILE: ../../../flutter/shell/platform/android/io/flutter/embedding/android/Trans
 FILE: ../../../flutter/shell/platform/android/io/flutter/embedding/engine/FlutterEngine.java
 FILE: ../../../flutter/shell/platform/android/io/flutter/embedding/engine/FlutterEngineCache.java
 FILE: ../../../flutter/shell/platform/android/io/flutter/embedding/engine/FlutterEngineConnectionRegistry.java
+FILE: ../../../flutter/shell/platform/android/io/flutter/embedding/engine/FlutterEngineGroup.java
 FILE: ../../../flutter/shell/platform/android/io/flutter/embedding/engine/FlutterJNI.java
 FILE: ../../../flutter/shell/platform/android/io/flutter/embedding/engine/FlutterOverlaySurface.java
 FILE: ../../../flutter/shell/platform/android/io/flutter/embedding/engine/FlutterShellArgs.java

runtime/isolate_configuration.h

@@ -54,7 +54,7 @@ class IsolateConfiguration {
   ///                            using the legacy settings fields that specify
   ///                            the asset by name instead of a mappings
   ///                            callback.
-  /// @param[in]  io_worker      An optional IO worker. Specify `nullptr` is a
+  /// @param[in]  io_worker      An optional IO worker. Specify `nullptr` if a
   ///                            worker should not be used or one is not
   ///                            available.
   ///

shell/common/shell.cc

@@ -475,12 +475,12 @@ Shell::~Shell() {
 }
 
 std::unique_ptr<Shell> Shell::Spawn(
-    Settings settings,
+    RunConfiguration run_configuration,
     const CreateCallback<PlatformView>& on_create_platform_view,
     const CreateCallback<Rasterizer>& on_create_rasterizer) const {
   FML_DCHECK(task_runners_.IsValid());
   std::unique_ptr<Shell> result(Shell::Create(
-      task_runners_, PlatformData{}, settings,
+      task_runners_, PlatformData{}, GetSettings(),
       vm_->GetVMData()->GetIsolateSnapshot(), on_create_platform_view,
       on_create_rasterizer, vm_,
       [engine = this->engine_.get()](
@@ -498,10 +498,8 @@ std::unique_ptr<Shell> Shell::Spawn(
                              /*settings=*/settings,
                              /*animator=*/std::move(animator));
       }));
-  RunConfiguration configuration =
-      RunConfiguration::InferFromSettings(settings);
   result->shared_resource_context_ = io_manager_->GetSharedResourceContext();
-  result->RunEngine(std::move(configuration));
+  result->RunEngine(std::move(run_configuration));
   return result;
 }
 

shell/common/shell.h

@@ -219,9 +219,19 @@ class Shell final : public PlatformView::Delegate,
   ///             and a smaller memory footprint than an Shell created with a
   ///             Create function.
   ///
+  ///             The new Shell is returned in a running state so RunEngine
+  ///             shouldn't be called again on the Shell. Once running, the
+  ///             second Shell is mostly independent from the original Shell
+  ///             and the original Shell doesn't need to keep running for the
+  ///             spawned Shell to keep functioning.
+  /// @param[in]  run_configuration  A RunConfiguration used to run the Isolate
+  ///             associated with this new Shell. It doesn't have to be the same
+  ///             configuration as the current Shell but it needs to be in the
+  ///             same snapshot or AOT.
+  ///
   /// @see        http://flutter.dev/go/multiple-engines
   std::unique_ptr<Shell> Spawn(
-      Settings settings,
+      RunConfiguration run_configuration,
       const CreateCallback<PlatformView>& on_create_platform_view,
       const CreateCallback<Rasterizer>& on_create_rasterizer) const;
 

shell/common/shell_unittests.cc

@@ -2438,39 +2438,61 @@ TEST_F(ShellTest, Spawn) {
   ASSERT_TRUE(configuration.IsValid());
   configuration.SetEntrypoint("fixturesAreFunctionalMain");
 
+  auto second_configuration = RunConfiguration::InferFromSettings(settings);
+  ASSERT_TRUE(second_configuration.IsValid());
+  second_configuration.SetEntrypoint("testCanLaunchSecondaryIsolate");
+
   fml::AutoResetWaitableEvent main_latch;
+  std::string last_entry_point;
+  // Fulfill native function for the first Shell's entrypoint.
   AddNativeCallback(
-      "SayHiFromFixturesAreFunctionalMain",
-      CREATE_NATIVE_ENTRY([&main_latch](auto args) { main_latch.Signal(); }));
+      "SayHiFromFixturesAreFunctionalMain", CREATE_NATIVE_ENTRY([&](auto args) {
+        last_entry_point = shell->GetEngine()->GetLastEntrypoint();
+        main_latch.Signal();
+      }));
+  // Fulfill native function for the second Shell's entrypoint.
+  AddNativeCallback(
+      // The Dart native function names aren't very consistent but this is just
+      // the native function name of the second vm entrypoint in the fixture.
+      "NotifyNative", CREATE_NATIVE_ENTRY([&](auto args) {}));
 
   RunEngine(shell.get(), std::move(configuration));
   main_latch.Wait();
   ASSERT_TRUE(DartVMRef::IsInstanceRunning());
+  // Check first Shell ran the first entrypoint.
+  ASSERT_EQ("fixturesAreFunctionalMain", last_entry_point);
 
-  PostSync(shell->GetTaskRunners().GetPlatformTaskRunner(), [this,
-                                                             &spawner = shell,
-                                                             settings]() {
-    MockPlatformViewDelegate platform_view_delegate;
-    auto spawn = spawner->Spawn(
-        settings,
-        [&platform_view_delegate](Shell& shell) {
-          auto result = std::make_unique<MockPlatformView>(
-              platform_view_delegate, shell.GetTaskRunners());
-          ON_CALL(*result, CreateRenderingSurface())
-              .WillByDefault(::testing::Invoke(
-                  [] { return std::make_unique<MockSurface>(); }));
-          return result;
-        },
-        [](Shell& shell) { return std::make_unique<Rasterizer>(shell); });
-    ASSERT_NE(nullptr, spawn.get());
-    ASSERT_TRUE(ValidateShell(spawn.get()));
-
-    PostSync(spawner->GetTaskRunners().GetIOTaskRunner(), [&spawner, &spawn] {
-      ASSERT_EQ(spawner->GetIOManager()->GetResourceContext().get(),
-                spawn->GetIOManager()->GetResourceContext().get());
-    });
-    DestroyShell(std::move(spawn));
-  });
+  PostSync(
+      shell->GetTaskRunners().GetPlatformTaskRunner(),
+      [this, &spawner = shell, &second_configuration]() {
+        MockPlatformViewDelegate platform_view_delegate;
+        auto spawn = spawner->Spawn(
+            std::move(second_configuration),
+            [&platform_view_delegate](Shell& shell) {
+              auto result = std::make_unique<MockPlatformView>(
+                  platform_view_delegate, shell.GetTaskRunners());
+              ON_CALL(*result, CreateRenderingSurface())
+                  .WillByDefault(::testing::Invoke(
+                      [] { return std::make_unique<MockSurface>(); }));
+              return result;
+            },
+            [](Shell& shell) { return std::make_unique<Rasterizer>(shell); });
+        ASSERT_NE(nullptr, spawn.get());
+        ASSERT_TRUE(ValidateShell(spawn.get()));
+
+        PostSync(spawner->GetTaskRunners().GetUITaskRunner(), [&spawn] {
+          // Check second shell ran the second entrypoint.
+          ASSERT_EQ("testCanLaunchSecondaryIsolate",
+                    spawn->GetEngine()->GetLastEntrypoint());
+        });
+
+        PostSync(
+            spawner->GetTaskRunners().GetIOTaskRunner(), [&spawner, &spawn] {
+              ASSERT_EQ(spawner->GetIOManager()->GetResourceContext().get(),
+                        spawn->GetIOManager()->GetResourceContext().get());
+            });
+        DestroyShell(std::move(spawn));
+      });
 
   DestroyShell(std::move(shell));
   ASSERT_FALSE(DartVMRef::IsInstanceRunning());

shell/platform/android/BUILD.gn

@@ -151,6 +151,7 @@ android_java_sources = [
   "io/flutter/embedding/engine/FlutterEngine.java",
   "io/flutter/embedding/engine/FlutterEngineCache.java",
   "io/flutter/embedding/engine/FlutterEngineConnectionRegistry.java",
+  "io/flutter/embedding/engine/FlutterEngineGroup.java",
   "io/flutter/embedding/engine/FlutterJNI.java",
   "io/flutter/embedding/engine/FlutterOverlaySurface.java",
   "io/flutter/embedding/engine/FlutterShellArgs.java",
@@ -465,6 +466,7 @@ action("robolectric_tests") {
     "test/io/flutter/embedding/android/RobolectricFlutterActivity.java",
     "test/io/flutter/embedding/engine/FlutterEngineCacheTest.java",
     "test/io/flutter/embedding/engine/FlutterEngineConnectionRegistryTest.java",
+    "test/io/flutter/embedding/engine/FlutterEngineGroupComponentTest.java",
     "test/io/flutter/embedding/engine/FlutterEngineTest.java",
     "test/io/flutter/embedding/engine/FlutterJNITest.java",
     "test/io/flutter/embedding/engine/FlutterShellArgsTest.java",