Refactor isolate startup code in preparation for making isolate spawning more truly non-blocking.

runtime/vm/port.h

 // Copyright (c) 2011, 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_PORT_H_
 #define VM_PORT_H_
 
 #include "include/dart_api.h"
 #include "vm/allocation.h"
 #include "vm/globals.h"
 #include "vm/random.h"
 
 namespace dart {
 
 class Isolate;
 class Message;
 class MessageHandler;
 class Mutex;
 class PortMapTestPeer;
 
 class PortMap: public AllStatic {
  public:
+  enum PortState {
+    kNewPort = 0,      // a newly allocated port
+    kLivePort = 1,     // a regular port (has a ReceivePort)
+    kControlPort = 2,  // a special control port (has a ReceivePort)
+  };
+
   // Allocate a port for the provided handler and return its VM-global id.
   static Dart_Port CreatePort(MessageHandler* handler);
 
   // Indicates that a port has had a ReceivePort created for it at the
   // dart language level.  The port remains live until it is closed.
-  static void SetLive(Dart_Port id);
+  static void SetPortState(Dart_Port id, PortState kind);
 
   // Close the port with id. All pending messages will be dropped.
   //
   // Returns true if the port is successfully closed.
   static bool ClosePort(Dart_Port id);
 
   // Close all the ports for the provided handler.
   static void ClosePorts(MessageHandler* handler);
 
   // Enqueues the message in the port with id. Returns false if the port is not
@@ skipping 13 matching lines @@
  private:
   friend class dart::PortMapTestPeer;
 
   // Mapping between port numbers and handlers.
   //
   // Free entries have id == 0 and handler == NULL. Deleted entries
   // have id == 0 and handler == deleted_entry_.
   typedef struct {
     Dart_Port port;
     MessageHandler* handler;
-    bool live;
+    PortState state;
   } Entry;
 
+  static const char* PortStateString(PortState state);
+
   // Allocate a new unique port.
   static Dart_Port AllocatePort();
 
   static bool IsActivePort(Dart_Port id);
   static bool IsLivePort(Dart_Port id);
 
   static intptr_t FindPort(Dart_Port port);
   static void Rehash(intptr_t new_capacity);
 
   static void MaintainInvariants();
 
   // Lock protecting access to the port map.
   static Mutex* mutex_;
 
   // Hashmap of ports.
   static Entry* map_;
   static MessageHandler* deleted_entry_;
   static intptr_t capacity_;
   static intptr_t used_;
   static intptr_t deleted_;
 
   static Random* prng_;
 };
 
 }  // namespace dart
 
 #endif  // VM_PORT_H_