Allow spawning additional UI isolates in flutter_tester (flutter#48706)

This enables work ongoing by @derekxu16 to improve performance in flutter_tester when running multiple files from large test suites. Specifically, it: - Exposes a `Spawn` C symbol from flutter_tester that runs the current kernel in a new UI isolate with a different entrypoint and/or route name - Exposes two symbols from flutter_tester to allow a test harness to more efficiently load particular kernel files or to lookup an entrypoint from an imported source file. - Avoids re-loading the kernel file completely when spawning a new UI isolate Googlers can look at go/flutter-tester-isolates for some more context. If anyone wants I'm happy to create a public version of that doc.
3akat · Jan 5, 2024 · edbce21 · edbce21
1 parent f3496a7
commit edbce21
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Showing 17 changed files with 329 additions and 30 deletions.
diff --git a/BUILD.gn b/BUILD.gn
@@ -53,6 +53,23 @@ config("export_dynamic_symbols") {
   }
 }
 
+config("export_dynamic_test_symbols") {
+  # See comment in :export_dynamic_symbols.
+  # This config exposes an additional symbol meant for flutter_tester.
+  if (is_linux || is_fuchsia) {
+    inputs = [ "//flutter/common/exported_test_symbols.sym" ]
+    ldflags = [ "-Wl,--dynamic-list=" + rebase_path(inputs[0], root_build_dir) ]
+  } else if (is_mac) {
+    inputs = [ "//flutter/common/exported_test_symbols_mac.sym" ]
+    ldflags = [
+      "-Xlinker",
+      "-exported_symbols_list",
+      "-Xlinker",
+      rebase_path(inputs[0], root_build_dir),
+    ]
+  }
+}
+
 group("flutter") {
   testonly = true
 

diff --git a/ci/licenses_golden/licenses_flutter b/ci/licenses_golden/licenses_flutter
@@ -7414,6 +7414,8 @@ FILE: ../../../flutter/benchmarking/library.h
 FILE: ../../../flutter/common/constants.h
 FILE: ../../../flutter/common/exported_symbols.sym
 FILE: ../../../flutter/common/exported_symbols_mac.sym
+FILE: ../../../flutter/common/exported_test_symbols.sym
+FILE: ../../../flutter/common/exported_test_symbols_mac.sym
 FILE: ../../../flutter/common/graphics/gl_context_switch.cc
 FILE: ../../../flutter/common/graphics/gl_context_switch.h
 FILE: ../../../flutter/common/graphics/msaa_sample_count.h

diff --git a/common/exported_test_symbols.sym b/common/exported_test_symbols.sym
@@ -0,0 +1,13 @@
+# These symbols are looked up from within the executable at runtime and must
+# be exported in the dynamic symbol table.
+{
+  kDartVmSnapshotData;
+  kDartVmSnapshotInstructions;
+  kDartIsolateSnapshotData;
+  kDartIsolateSnapshotInstructions;
+  InternalFlutterGpu*;
+  kInternalFlutterGpu*;
+  Spawn;
+  LoadLibraryFromKernel;
+  LookupEntryPoint;
+};
diff --git a/common/exported_test_symbols_mac.sym b/common/exported_test_symbols_mac.sym
@@ -0,0 +1,11 @@
+# These symbols are looked up from within the executable at runtime and must
+# be exported in the dynamic symbol table.
+_kDartVmSnapshotData
+_kDartVmSnapshotInstructions
+_kDartIsolateSnapshotData
+_kDartIsolateSnapshotInstructions
+_InternalFlutterGpu*
+_kInternalFlutterGpu*
+_Spawn
+_LoadLibraryFromKernel
+_LookupEntryPoint
diff --git a/runtime/dart_isolate.cc b/runtime/dart_isolate.cc
@@ -522,8 +522,8 @@ bool DartIsolate::LoadKernel(const std::shared_ptr<const fml::Mapping>& mapping,
     return false;
   }
 
-  // Mapping must be retained until isolate shutdown.
-  kernel_buffers_.push_back(mapping);
+  // Mapping must be retained until isolate group shutdown.
+  GetIsolateGroupData().AddKernelBuffer(mapping);
 
   Dart_Handle library =
       Dart_LoadLibraryFromKernel(mapping->GetMapping(), mapping->GetSize());
@@ -589,7 +589,8 @@ bool DartIsolate::LoadKernel(const std::shared_ptr<const fml::Mapping>& mapping,
   // executed leads to crashes.
   if (GetIsolateGroupData().GetChildIsolatePreparer() == nullptr) {
     GetIsolateGroupData().SetChildIsolatePreparer(
-        [buffers = kernel_buffers_](DartIsolate* isolate) {
+        [buffers =
+             GetIsolateGroupData().GetKernelBuffers()](DartIsolate* isolate) {
           for (uint64_t i = 0; i < buffers.size(); i++) {
             bool last_piece = i + 1 == buffers.size();
             const std::shared_ptr<const fml::Mapping>& buffer = buffers.at(i);
@@ -1130,6 +1131,30 @@ Dart_Handle DartIsolate::OnDartLoadLibrary(intptr_t loading_unit_id) {
   return Dart_NewApiError(error_message.c_str());
 }
 
+Dart_Handle DartIsolate::LoadLibraryFromKernel(
+    const std::shared_ptr<const fml::Mapping>& mapping) {
+  if (DartVM::IsRunningPrecompiledCode()) {
+    return Dart_Null();
+  }
+
+  auto* isolate_group_data =
+      static_cast<std::shared_ptr<DartIsolateGroupData>*>(
+          Dart_CurrentIsolateGroupData());
+  // Mapping must be retained until isolate shutdown.
+  (*isolate_group_data)->AddKernelBuffer(mapping);
+
+  auto lib =
+      Dart_LoadLibraryFromKernel(mapping->GetMapping(), mapping->GetSize());
+  if (tonic::CheckAndHandleError(lib)) {
+    return Dart_Null();
+  }
+  auto result = Dart_FinalizeLoading(false);
+  if (Dart_IsError(result)) {
+    return result;
+  }
+  return Dart_GetField(lib, Dart_NewStringFromCString("main"));
+}
+
 DartIsolate::AutoFireClosure::AutoFireClosure(const fml::closure& closure)
     : closure_(closure) {}
 

diff --git a/runtime/dart_isolate.h b/runtime/dart_isolate.h
@@ -392,6 +392,11 @@ class DartIsolate : public UIDartState {
 
   const DartIsolateGroupData& GetIsolateGroupData() const;
 
+  /// Returns the "main" entrypoint of the library contained in the kernel
+  /// data in `mapping`.
+  static Dart_Handle LoadLibraryFromKernel(
+      const std::shared_ptr<const fml::Mapping>& mapping);
+
  private:
   friend class IsolateConfiguration;
   class AutoFireClosure {
@@ -407,7 +412,6 @@ class DartIsolate : public UIDartState {
   friend class DartVM;
 
   Phase phase_ = Phase::Unknown;
-  std::vector<std::shared_ptr<const fml::Mapping>> kernel_buffers_;
   std::vector<std::unique_ptr<AutoFireClosure>> shutdown_callbacks_;
   std::unordered_set<fml::RefPtr<DartSnapshot>> loading_unit_snapshots_;
   fml::RefPtr<fml::TaskRunner> message_handling_task_runner_;

diff --git a/runtime/dart_isolate_group_data.cc b/runtime/dart_isolate_group_data.cc
@@ -83,4 +83,14 @@ DartIsolateGroupData::GetPlatformMessageHandler(
              : it->second;
 }
 
+void DartIsolateGroupData::AddKernelBuffer(
+    const std::shared_ptr<const fml::Mapping>& buffer) {
+  kernel_buffers_.push_back(buffer);
+}
+
+std::vector<std::shared_ptr<const fml::Mapping>>
+DartIsolateGroupData::GetKernelBuffers() const {
+  return kernel_buffers_;
+}
+
 }  // namespace flutter
diff --git a/runtime/dart_isolate_group_data.h b/runtime/dart_isolate_group_data.h
@@ -56,6 +56,13 @@ class DartIsolateGroupData : public PlatformMessageHandlerStorage {
 
   void SetChildIsolatePreparer(const ChildIsolatePreparer& value);
 
+  /// Adds a kernel buffer mapping to the kernels loaded for this isolate group.
+  void AddKernelBuffer(const std::shared_ptr<const fml::Mapping>& buffer);
+
+  /// A copy of the mappings for all kernel buffer objects loaded into this
+  /// isolate group.
+  std::vector<std::shared_ptr<const fml::Mapping>> GetKernelBuffers() const;
+
   // |PlatformMessageHandlerStorage|
   void SetPlatformMessageHandler(
       int64_t root_isolate_token,
@@ -66,6 +73,7 @@ class DartIsolateGroupData : public PlatformMessageHandlerStorage {
       int64_t root_isolate_token) const override;
 
  private:
+  std::vector<std::shared_ptr<const fml::Mapping>> kernel_buffers_;
   const Settings settings_;
   const fml::RefPtr<const DartSnapshot> isolate_snapshot_;
   const std::string advisory_script_uri_;

diff --git a/shell/common/run_configuration.cc b/shell/common/run_configuration.cc
@@ -12,12 +12,14 @@
 #include "flutter/fml/file.h"
 #include "flutter/fml/unique_fd.h"
 #include "flutter/runtime/dart_vm.h"
+#include "runtime/isolate_configuration.h"
 
 namespace flutter {
 
 RunConfiguration RunConfiguration::InferFromSettings(
     const Settings& settings,
-    const fml::RefPtr<fml::TaskRunner>& io_worker) {
+    const fml::RefPtr<fml::TaskRunner>& io_worker,
+    IsolateLaunchType launch_type) {
   auto asset_manager = std::make_shared<AssetManager>();
 
   if (fml::UniqueFD::traits_type::IsValid(settings.assets_dir)) {
@@ -31,7 +33,7 @@ RunConfiguration RunConfiguration::InferFromSettings(
       true));
 
   return {IsolateConfiguration::InferFromSettings(settings, asset_manager,
-                                                  io_worker),
+                                                  io_worker, launch_type),
           asset_manager};
 }
 

diff --git a/shell/common/run_configuration.h b/shell/common/run_configuration.h
@@ -51,13 +51,16 @@ class RunConfiguration {
   ///                        serial worker is kept alive for the lifetime of the
   ///                        shell associated with the engine that this run
   ///                        configuration is given to.
+  /// @param[in]  launch_type Whether to launch the new isolate into an existing
+  ///                         group or a new one.
   ///
   /// @return     A run configuration. Depending on the completeness of the
   ///             settings, This object may potentially be invalid.
   ///
   static RunConfiguration InferFromSettings(
       const Settings& settings,
-      const fml::RefPtr<fml::TaskRunner>& io_worker = nullptr);
+      const fml::RefPtr<fml::TaskRunner>& io_worker = nullptr,
+      IsolateLaunchType launch_type = IsolateLaunchType::kNewGroup);
 
   //----------------------------------------------------------------------------
   /// @brief      Creates a run configuration with only an isolate

diff --git a/shell/testing/BUILD.gn b/shell/testing/BUILD.gn
@@ -18,7 +18,7 @@ executable("testing") {
 
   public_configs = [
     "//flutter:config",
-    "//flutter:export_dynamic_symbols",
+    "//flutter:export_dynamic_test_symbols",
   ]
 
   sources = [ "tester_main.cc" ]
@@ -42,6 +42,7 @@ executable("testing") {
     "//flutter/shell/gpu:gpu_surface_software",
     "//flutter/skia",
     "//flutter/third_party/tonic",
+    "//third_party/abseil-cpp/absl/base:no_destructor",
     "//third_party/dart/runtime:libdart_jit",
     "//third_party/dart/runtime/bin:dart_io_api",
   ]