Use the ThreadPool for all isolates and native ports. Previously,

runtime/vm/isolate.h

 // Copyright (c) 2012, 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 "platform/thread.h"
@@ skipping 15 matching lines @@
 class MessageHandler;
 class Mutex;
 class ObjectPointerVisitor;
 class ObjectStore;
 class RawContext;
 class RawError;
 class StackResource;
 class StubCode;
 class Zone;
 
-
 class Isolate : public BaseIsolate {
  public:
   ~Isolate();
 
   static inline Isolate* Current() {
     return reinterpret_cast<Isolate*>(Thread::GetThreadLocal(isolate_key));
   }
 
   static void SetCurrent(Isolate* isolate);
 
@@ skipping 85 matching lines @@
   void SetStackLimitFromCurrentTOS(uword isolate_stack_top);
 
   uword stack_limit_address() const {
     return reinterpret_cast<uword>(&stack_limit_);
   }
 
   // The current stack limit.  This may be overwritten with a special
   // value to trigger interrupts.
   uword stack_limit() const { return stack_limit_; }
 
-  // The true stack limit for this isolate.  This does not change
-  // after isolate initialization.
+  // The true stack limit for this isolate.
   uword saved_stack_limit() const { return saved_stack_limit_; }
 
   enum {
     kApiInterrupt = 0x1,      // An interrupt from Dart_InterruptIsolate.
     kMessageInterrupt = 0x2,  // An interrupt to process an out of band message.
 
     kInterruptsMask = kApiInterrupt | kMessageInterrupt,
   };
 
   void ScheduleInterrupts(uword interrupt_bits);
   uword GetAndClearInterrupts();
 
   MessageHandler* message_handler() const { return message_handler_; }
   void set_message_handler(MessageHandler* value) { message_handler_ = value; }
 
-  // Returns null on success, a RawError on failure.
-  RawError* StandardRunLoop();
+  uword spawn_data() const { return spawn_data_; }
+  void set_spawn_data(uword value) { spawn_data_ = value; }
 
   intptr_t ast_node_id() const { return ast_node_id_; }
   void set_ast_node_id(int value) { ast_node_id_ = value; }
 
   Debugger* debugger() const { return debugger_; }
 
   static void SetCreateCallback(Dart_IsolateCreateCallback cback);
   static Dart_IsolateCreateCallback CreateCallback();
 
   static void SetInterruptCallback(Dart_IsolateInterruptCallback cback);
@@ skipping 33 matching lines @@
   ApiState* api_state_;
   StubCode* stub_code_;
   Debugger* debugger_;
   LongJump* long_jump_base_;
   TimerList timer_list_;
   intptr_t ast_node_id_;
   Mutex* mutex_;  // protects stack_limit_ and saved_stack_limit_.
   uword stack_limit_;
   uword saved_stack_limit_;
   MessageHandler* message_handler_;
+  uword spawn_data_;
   GcPrologueCallbacks gc_prologue_callbacks_;
   GcEpilogueCallbacks gc_epilogue_callbacks_;
 
   static Dart_IsolateCreateCallback create_callback_;
   static Dart_IsolateInterruptCallback interrupt_callback_;
 
   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()) {
+    ASSERT(new_isolate_ != NULL);
+    if (saved_isolate_ != new_isolate_) {
+      ASSERT(Isolate::Current() == NULL);
+      Isolate::SetCurrent(new_isolate_);
+      new_isolate_->SetStackLimitFromCurrentTOS(reinterpret_cast<uword>(this));
+    }
+  }
+
+  ~StartIsolateScope() {
+    if (saved_isolate_ != new_isolate_) {
+      new_isolate_->SetStackLimit(~static_cast<uword>(0));
+      Isolate::SetCurrent(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) {
+    if (saved_isolate_ != new_isolate_) {
+      Isolate::SetCurrent(new_isolate_);
+      if (new_isolate_ != NULL) {
+        // 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 (saved_isolate_ != NULL) {
+        saved_isolate_->SetStackLimit(saved_stack_limit_);
+      }
+    }
+  }
+
+ private:
+  Isolate* new_isolate_;
+  Isolate* saved_isolate_;
+  uword saved_stack_limit_;
+
+  DISALLOW_COPY_AND_ASSIGN(SwitchIsolateScope);
+};
+
 }  // namespace dart
 
 #endif  // VM_ISOLATE_H_