Implement safepointing of threads :

 - uses thread execution status transition to track when a thread is in a safepoint or needs to block for a safepoint
 - introduces a monitor per Thread object
 - uses a per thread safepoint handshake between the thread requesting a safepoint and the requested thread.

The ThreadRegistry class now contains only the thread list for an isolate and the functionality of scheduling a thread onto an Isolate and unscheduling it from teh isolate. We could fold this functionality into the Isolate class in a different CL.

R=rmacnak@google.com, zra@google.com

Review URL: https://codereview.chromium.org/1541073002 .

Author: a-siva

runtime/lib/isolate.cc

@@ -298,6 +298,7 @@ static const char* CanonicalizeUri(Thread* thread,
   Isolate* isolate = thread->isolate();
   Dart_LibraryTagHandler handler = isolate->library_tag_handler();
   if (handler != NULL) {
+    TransitionVMToNative transition(thread);
     Dart_EnterScope();
     Dart_Handle handle = handler(Dart_kCanonicalizeUrl,
                                  Api::NewHandle(thread, library.raw()),

runtime/lib/vmservice.cc

@@ -353,6 +353,7 @@ static void FilenameFinalizer(void* peer) {
 
 DEFINE_NATIVE_ENTRY(VMService_DecodeAssets, 1) {
   GET_NON_NULL_NATIVE_ARGUMENT(TypedData, data, arguments->NativeArgAt(0));
+  TransitionVMToNative transition(thread);
   Api::Scope scope(thread);
 
   Dart_Handle data_handle = Api::NewHandle(thread, data.raw());

runtime/vm/benchmark_test.cc

@@ -39,6 +39,7 @@ void Benchmark::RunAll(const char* executable) {
 BENCHMARK(CorelibCompileAll) {
   bin::Builtin::SetNativeResolver(bin::Builtin::kBuiltinLibrary);
   bin::Builtin::SetNativeResolver(bin::Builtin::kIOLibrary);
+  TransitionNativeToVM transition(thread);
   Timer timer(true, "Compile all of Core lib benchmark");
   timer.Start();
   const Error& error = Error::Handle(Library::CompileAll());
@@ -55,6 +56,7 @@ BENCHMARK(CorelibCompileAll) {
 BENCHMARK(CorelibCompilerStats) {
   bin::Builtin::SetNativeResolver(bin::Builtin::kBuiltinLibrary);
   bin::Builtin::SetNativeResolver(bin::Builtin::kIOLibrary);
+  TransitionNativeToVM transition(thread);
   CompilerStats* stats = thread->isolate()->compiler_stats();
   ASSERT(stats != NULL);
   stats->EnableBenchmark();
@@ -78,15 +80,15 @@ BENCHMARK(CorelibIsolateStartup) {
   const int kNumIterations = 1000;
   Timer timer(true, "CorelibIsolateStartup");
   Isolate* isolate = thread->isolate();
-  Thread::ExitIsolate();
+  Dart_ExitIsolate();
   for (int i = 0; i < kNumIterations; i++) {
     timer.Start();
     TestCase::CreateTestIsolate();
     timer.Stop();
     Dart_ShutdownIsolate();
   }
   benchmark->set_score(timer.TotalElapsedTime() / kNumIterations);
-  Thread::EnterIsolate(isolate);
+  Dart_EnterIsolate(reinterpret_cast<Dart_Isolate>(isolate));
 }
 
 
@@ -142,7 +144,7 @@ static Dart_NativeFunction bm_uda_lookup(Dart_Handle name,
                                          int argument_count,
                                          bool* auto_setup_scope) {
   ASSERT(auto_setup_scope != NULL);
-  *auto_setup_scope = false;
+  *auto_setup_scope = true;
   const char* cstr = NULL;
   Dart_Handle result = Dart_StringToCString(name, &cstr);
   EXPECT_VALID(result);
@@ -693,6 +695,7 @@ BENCHMARK(SerializeSmi) {
 
 
 BENCHMARK(SimpleMessage) {
+  TransitionNativeToVM transition(thread);
   const Array& array_object = Array::Handle(Array::New(2));
   array_object.SetAt(0, Integer::Handle(Smi::New(42)));
   array_object.SetAt(1, Object::Handle());

runtime/vm/bootstrap.cc

@@ -209,6 +209,9 @@ static Dart_Handle BootstrapLibraryTagHandler(Dart_LibraryTag tag,
                                               Dart_Handle uri) {
   Thread* thread = Thread::Current();
   Zone* zone = thread->zone();
+  // This handler calls into the VM directly and does not use the Dart
+  // API so we transition back to VM.
+  TransitionNativeToVM transition(thread);
   if (!Dart_IsLibrary(library)) {
     return Api::NewError("not a library");
   }

runtime/vm/code_descriptors_test.cc

@@ -178,7 +178,10 @@ static void NativeFunc(Dart_NativeArguments args) {
   EXPECT_EQ(10, value);
   EXPECT_VALID(Dart_IntegerToInt64(k, &value));
   EXPECT_EQ(20, value);
-  Isolate::Current()->heap()->CollectAllGarbage();
+  {
+    TransitionNativeToVM transition(Thread::Current());
+    Isolate::Current()->heap()->CollectAllGarbage();
+  }
 }
 
 
@@ -211,6 +214,8 @@ TEST_CASE(StackmapGC) {
       "}\n";
   // First setup the script and compile the script.
   TestCase::LoadTestScript(kScriptChars, native_resolver);
+  TransitionNativeToVM transition(thread);
+
   EXPECT(ClassFinalizer::ProcessPendingClasses());
   const String& name = String::Handle(String::New(TestCase::url()));
   const Library& lib = Library::Handle(Library::LookupLibrary(name));
@@ -248,7 +253,8 @@ TEST_CASE(StackmapGC) {
   const PcDescriptors& descriptors =
       PcDescriptors::Handle(code.pc_descriptors());
   int call_count = 0;
-  PcDescriptors::Iterator iter(descriptors, RawPcDescriptors::kUnoptStaticCall);
+  PcDescriptors::Iterator iter(descriptors,
+                               RawPcDescriptors::kUnoptStaticCall);
   while (iter.MoveNext()) {
     stackmap_table_builder->AddEntry(iter.PcOffset(), stack_bitmap, 0);
     ++call_count;

runtime/vm/compiler.cc

@@ -1058,14 +1058,13 @@ bool CompileParsedFunctionHelper::Compile(CompilationPipeline* pipeline) {
           // instruction object, since the creation of instruction object
           // changes code page access permissions (makes them temporary not
           // executable).
-          isolate()->thread_registry()->SafepointThreads();
           {
+            SafepointOperationScope safepoint_scope(thread());
             // Do not Garbage collect during this stage and instead allow the
             // heap to grow.
             NoHeapGrowthControlScope no_growth_control;
             FinalizeCompilation(&assembler, &graph_compiler, flow_graph);
           }
-          isolate()->thread_registry()->ResumeAllThreads();
           if (isolate()->heap()->NeedsGarbageCollection()) {
             isolate()->heap()->CollectAllGarbage();
           }
@@ -1899,9 +1898,7 @@ void BackgroundCompiler::Stop(BackgroundCompiler* task) {
   {
     MonitorLocker ml_done(done_monitor);
     while (!(*task_done)) {
-      // In case that the compiler is waiting for safepoint.
-      Isolate::Current()->thread_registry()->CheckSafepoint();
-      ml_done.Wait(1);
+      ml_done.WaitWithSafepointCheck(Thread::Current());
     }
   }
   delete task_done;

runtime/vm/compiler_test.cc

@@ -8,16 +8,16 @@
 #include "vm/compiler.h"
 #include "vm/dart_api_impl.h"
 #include "vm/object.h"
+#include "vm/safepoint.h"
 #include "vm/symbols.h"
 #include "vm/thread_pool.h"
-#include "vm/thread_registry.h"
 #include "vm/unit_test.h"
 
 namespace dart {
 
 DECLARE_FLAG(bool, background_compilation);
 
-TEST_CASE(CompileScript) {
+VM_TEST_CASE(CompileScript) {
   const char* kScriptChars =
       "class A {\n"
       "  static foo() { return 42; }\n"
@@ -32,7 +32,7 @@ TEST_CASE(CompileScript) {
 }
 
 
-TEST_CASE(CompileFunction) {
+VM_TEST_CASE(CompileFunction) {
   const char* kScriptChars =
             "class A {\n"
             "  static foo() { return 42; }\n"
@@ -73,7 +73,7 @@ TEST_CASE(CompileFunction) {
 }
 
 
-TEST_CASE(CompileFunctionOnHelperThread) {
+VM_TEST_CASE(CompileFunctionOnHelperThread) {
   // Create a simple function and compile it without optimization.
   const char* kScriptChars =
             "class A {\n"
@@ -106,8 +106,7 @@ TEST_CASE(CompileFunctionOnHelperThread) {
   Monitor* m = new Monitor();
   MonitorLocker ml(m);
   while (!func.HasOptimizedCode()) {
-    Isolate::Current()->thread_registry()->CheckSafepoint();
-    ml.Wait(1);
+    ml.WaitWithSafepointCheck(thread, 1);
   }
   BackgroundCompiler::Stop(isolate->background_compiler());
 }
@@ -167,6 +166,7 @@ TEST_CASE(EvalExpression) {
       Dart_Invoke(lib, Dart_NewStringFromCString("makeObj"), 0,  NULL);
   EXPECT(!Dart_IsNull(obj_handle));
   EXPECT(!Dart_IsError(obj_handle));
+  TransitionNativeToVM transition(thread);
   const Object& obj = Object::Handle(Api::UnwrapHandle(obj_handle));
   EXPECT(!obj.IsNull());
   EXPECT(obj.IsInstance());
@@ -184,7 +184,7 @@ TEST_CASE(EvalExpression) {
 }
 
 
-TEST_CASE(EvalExpressionWithLazyCompile) {
+VM_TEST_CASE(EvalExpressionWithLazyCompile) {
   Library& lib = Library::Handle(Library::CoreLibrary());
 
   const String& expression = String::Handle(String::New(
@@ -199,7 +199,7 @@ TEST_CASE(EvalExpressionWithLazyCompile) {
 }
 
 
-TEST_CASE(EvalExpressionExhaustCIDs) {
+VM_TEST_CASE(EvalExpressionExhaustCIDs) {
   Library& lib = Library::Handle(Library::CoreLibrary());
 
   const String& expression = String::Handle(String::New("3 + 4"));

runtime/vm/coverage_test.cc

@@ -9,6 +9,7 @@
 namespace dart {
 
 static RawObject* ExecuteScript(const char* script) {
+  TransitionVMToNative transition(Thread::Current());
   Dart_Handle h_lib = TestCase::LoadTestScript(script, NULL);
   EXPECT_VALID(h_lib);
   Library& lib = Library::Handle();
@@ -34,7 +35,7 @@ class FunctionCoverageFilter : public CoverageFilter {
 };
 
 
-TEST_CASE(Coverage_Empty) {
+VM_TEST_CASE(Coverage_Empty) {
   const char* kScript =
       "main() {\n"
       "}";
@@ -56,7 +57,7 @@ TEST_CASE(Coverage_Empty) {
 }
 
 
-TEST_CASE(Coverage_MainWithClass) {
+VM_TEST_CASE(Coverage_MainWithClass) {
   const char* kScript =
       "class Foo {\n"
       "  var x;\n"
@@ -100,7 +101,7 @@ TEST_CASE(Coverage_MainWithClass) {
 }
 
 
-TEST_CASE(Coverage_FilterFunction) {
+VM_TEST_CASE(Coverage_FilterFunction) {
   const char* kScript =
       "class Foo {\n"
       "  var x;\n"

runtime/vm/custom_isolate_test.cc

@@ -230,7 +230,7 @@ static Dart_NativeFunction NativeLookup(Dart_Handle name,
                                         int argc,
                                         bool* auto_setup_scope) {
   ASSERT(auto_setup_scope != NULL);
-  *auto_setup_scope = false;
+  *auto_setup_scope = true;
   const char* name_str = NULL;
   EXPECT(Dart_IsString(name));
   EXPECT_VALID(Dart_StringToCString(name, &name_str));