Fix for issue 25236

runtime/vm/os_thread.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_OS_THREAD_H_
 #define VM_OS_THREAD_H_
 
 #include "platform/globals.h"
 #include "vm/allocation.h"
 #include "vm/globals.h"
@@ skipping 32 matching lines @@
   friend class Thread;
   friend class OSThread;
 
   DISALLOW_IMPLICIT_CONSTRUCTORS(BaseThread);
 };
 
 
 // Low-level operations on OS platform threads.
 class OSThread : public BaseThread {
  public:
-  OSThread();
+  // The constructor of OSThread is never called directly, instead we call
+  // this factory style method 'CreateOSThread' to create OSThread structures.
+  // The method can return a NULL if the Dart VM is in shutdown mode.
+  static OSThread* CreateOSThread();
   ~OSThread();
 
   ThreadId id() const {
     ASSERT(id_ != OSThread::kInvalidThreadId);
     return id_;
   }
 
   ThreadJoinId join_id() const {
     ASSERT(join_id_ != OSThread::kInvalidThreadJoinId);
     return join_id_;
@@ skipping 104 matching lines @@
   static intptr_t ThreadIdToIntPtr(ThreadId id);
   static ThreadId ThreadIdFromIntPtr(intptr_t id);
   static bool Compare(ThreadId a, ThreadId b);
   static void GetThreadCpuUsage(ThreadId thread_id, int64_t* cpu_usage);
 
   // Called at VM startup and shutdown.
   static void InitOnce();
 
   static bool IsThreadInList(ThreadJoinId join_id);
 
+  static void DisableOSThreadCreation();
+  static void EnableOSThreadCreation();
+
   static const intptr_t kStackSizeBuffer = (4 * KB * kWordSize);
 
   static const ThreadId kInvalidThreadId;
   static const ThreadJoinId kInvalidThreadJoinId;
 
  private:
+  // The constructor is private as CreateOSThread should be used
+  // to create a new OSThread structure.
+  OSThread();
+
   // These methods should not be used in a generic way and hence
   // are private, they have been added to solve the problem of
   // accessing the VM thread structure from an OSThread object
   // in the windows thread interrupter which is used for profiling.
   // We could eliminate this requirement if the windows thread interrupter
   // is implemented differently.
   Thread* thread() const { return thread_; }
   void set_thread(Thread* value) {
     thread_ = value;
   }
 
   static void Cleanup();
   static ThreadId GetCurrentThreadTraceId();
   static ThreadJoinId GetCurrentThreadJoinId();
   static OSThread* GetOSThreadFromThread(Thread* thread);
-  static void AddThreadToList(OSThread* thread);
+  static void AddThreadToListLocked(OSThread* thread);
   static void RemoveThreadFromList(OSThread* thread);
   static OSThread* CreateAndSetUnknownThread();
 
   static ThreadLocalKey thread_key_;
 
   const ThreadId id_;
   const ThreadJoinId join_id_;
   const ThreadId trace_id_;  // Used to interface with tracing tools.
   char* name_;  // A name for this thread.
 
   Mutex* timeline_block_lock_;
   TimelineEventBlock* timeline_block_;
 
   // All |Thread|s are registered in the thread list.
   OSThread* thread_list_next_;
 
   uintptr_t thread_interrupt_disabled_;
   Log* log_;
   uword stack_base_;
   Thread* thread_;
 
   static OSThread* thread_list_head_;
   static Mutex* thread_list_lock_;
+  static bool creation_enabled_;
 
   friend class OSThreadIterator;
   friend class ThreadInterrupterWin;
   friend class ThreadRegistry;
 };
 
 
 // Note that this takes the thread list lock, prohibiting threads from coming
 // on- or off-line.
 class OSThreadIterator : public ValueObject {
@@ skipping 83 matching lines @@
 #endif  // defined(DEBUG)
 
   DISALLOW_COPY_AND_ASSIGN(Monitor);
 };
 
 
 }  // namespace dart
 
 
 #endif  // VM_OS_THREAD_H_