Refactor Thread lifecycle interface, add Thread::Enter/ExitIsolate.

runtime/vm/isolate.h

 // Copyright (c) 2013, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 #ifndef VM_ISOLATE_H_
 #define VM_ISOLATE_H_
 
 #include "include/dart_api.h"
 #include "platform/assert.h"
 #include "vm/base_isolate.h"
@@ skipping 104 matching lines @@
   V(TypeParameter)                                                             \
 
 class Isolate : public BaseIsolate {
  public:
   ~Isolate();
 
   static inline Isolate* Current() {
     Thread* thread = Thread::Current();
     return thread == NULL ? NULL : thread->isolate();
   }
-  static void SetCurrent(Isolate* isolate);
 
   static void InitOnce();
   static Isolate* Init(const char* name_prefix, bool is_vm_isolate = false);
   void Shutdown();
 
   Isolate* ShallowCopy();
 
   // Register a newly introduced class.
   void RegisterClass(const Class& cls);
   void RegisterClassAt(intptr_t index, const Class& cls);
@@ skipping 27 matching lines @@
     return message_notify_callback_;
   }
   void set_message_notify_callback(Dart_MessageNotifyCallback value) {
     message_notify_callback_ = value;
   }
 
   // A thread that operates on this isolate and may execute Dart code.
   // No other threads operating on this isolate may execute Dart code.
   // TODO(koda): Remove after caching current thread in generated code.
   Thread* mutator_thread() {
-    DEBUG_ASSERT(IsIsolateOf(mutator_thread_));
+    DEBUG_ASSERT(mutator_thread_ == NULL || IsIsolateOf(mutator_thread_));
     return mutator_thread_;
   }
 #if defined(DEBUG)
   bool IsIsolateOf(Thread* thread);
 #endif  // DEBUG
 
   const char* name() const { return name_; }
   const char* debugger_name() const { return debugger_name_; }
   void set_debugger_name(const char* name);
 
@@ skipping 492 matching lines @@
 
   void BuildName(const char* name_prefix);
   void PrintInvokedFunctions();
 
   void ProfileIdle();
 
   void set_user_tag(uword tag) {
     user_tag_ = tag;
   }
 
+  void set_mutator_thread(Thread* thread) {
+    mutator_thread_ = thread;
+  }
+
   template<class T> T* AllocateReusableHandle();
 
   Thread* mutator_thread_;
   uword vm_tag_;
   StoreBuffer store_buffer_;
   ClassTable class_table_;
   MegamorphicCacheTable megamorphic_cache_table_;
   Dart_MessageNotifyCallback message_notify_callback_;
   char* name_;
   char* debugger_name_;
@@ skipping 122 matching lines @@
   DISALLOW_COPY_AND_ASSIGN(Isolate);
 };
 
 
 // When we need to execute code in an isolate, we use the
 // StartIsolateScope.
 class StartIsolateScope {
  public:
   explicit StartIsolateScope(Isolate* new_isolate)
       : new_isolate_(new_isolate), saved_isolate_(Isolate::Current()) {
+    // TODO(koda): Audit users; passing NULL goes against naming of this class.
     if (new_isolate_ == NULL) {
       // Do nothing.
       return;
     }
     if (saved_isolate_ != new_isolate_) {
       ASSERT(Isolate::Current() == NULL);
-      Isolate::SetCurrent(new_isolate_);
+      Thread::EnterIsolate(new_isolate_);
       new_isolate_->SetStackLimitFromStackBase(
           Isolate::GetCurrentStackPointer());
     }
   }
 
   ~StartIsolateScope() {
     if (new_isolate_ == NULL) {
       // Do nothing.
       return;
     }
     if (saved_isolate_ != new_isolate_) {
       new_isolate_->ClearStackLimit();
-      Isolate::SetCurrent(saved_isolate_);
+      Thread::ExitIsolate();
+      if (saved_isolate_ != NULL) {
+        Thread::EnterIsolate(saved_isolate_);
+      }
     }
   }
 
  private:
   Isolate* new_isolate_;
   Isolate* saved_isolate_;
 
   DISALLOW_COPY_AND_ASSIGN(StartIsolateScope);
 };
 
 // When we need to temporarily become another isolate, we use the
 // SwitchIsolateScope.  It is not permitted to run dart code while in
 // a SwitchIsolateScope.
 class SwitchIsolateScope {
  public:
   explicit SwitchIsolateScope(Isolate* new_isolate)
       : new_isolate_(new_isolate),
         saved_isolate_(Isolate::Current()),
         saved_stack_limit_(saved_isolate_
                            ? saved_isolate_->saved_stack_limit() : 0) {
+    // TODO(koda): Audit users; why would these two ever be equal?
     if (saved_isolate_ != new_isolate_) {
-      Isolate::SetCurrent(new_isolate_);
-      if (new_isolate_ != NULL) {
+      if (new_isolate_ == NULL) {
+        Thread::ExitIsolate();
+      } else {
+        Thread::EnterIsolate(new_isolate_);
         // Don't allow dart code to execute.
         new_isolate_->SetStackLimit(~static_cast<uword>(0));
       }
     }
   }
 
   ~SwitchIsolateScope() {
     if (saved_isolate_ != new_isolate_) {
-      Isolate::SetCurrent(saved_isolate_);
+      if (new_isolate_ != NULL) {
+        Thread::ExitIsolate();
+      }
       if (saved_isolate_ != NULL) {
+        Thread::EnterIsolate(saved_isolate_);
         saved_isolate_->SetStackLimit(saved_stack_limit_);
       }
     }
   }
 
  private:
   Isolate* new_isolate_;
   Isolate* saved_isolate_;
   uword saved_stack_limit_;
 
@@ skipping 43 matching lines @@
   uint8_t* serialized_args_;
   intptr_t serialized_args_len_;
   uint8_t* serialized_message_;
   intptr_t serialized_message_len_;
   bool paused_;
 };
 
 }  // namespace dart
 
 #endif  // VM_ISOLATE_H_