Avoid race in isolate shutdown; add assertions, error messages

runtime/vm/thread.cc

 // Copyright (c) 2015, 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.
 
 #include "vm/thread.h"
 
 #include "vm/growable_array.h"
 #include "vm/isolate.h"
 #include "vm/lockers.h"
 #include "vm/object.h"
 #include "vm/os_thread.h"
 #include "vm/profiler.h"
 #include "vm/stub_code.h"
 #include "vm/thread_interrupter.h"
 #include "vm/thread_registry.h"
 
 namespace dart {
 
 // The single thread local key which stores all the thread local data
 // for a thread.
 // TODO(koda): Can we merge this with ThreadInterrupter::thread_state_key_?
 ThreadLocalKey Thread::thread_key_ = OSThread::kUnsetThreadLocalKey;
 
 
 static void DeleteThread(void* thread) {
   delete reinterpret_cast<Thread*>(thread);
 }
 
 
+Thread::~Thread() {
+  // We should cleanly exit any isolate before destruction.
+  ASSERT(isolate_ == NULL);
+}
+
+
 void Thread::InitOnceBeforeIsolate() {
   ASSERT(thread_key_ == OSThread::kUnsetThreadLocalKey);
   thread_key_ = OSThread::CreateThreadLocal(DeleteThread);
   ASSERT(thread_key_ != OSThread::kUnsetThreadLocalKey);
   ASSERT(Thread::Current() == NULL);
   // Postpone initialization of VM constants for this first thread.
   SetCurrent(new Thread(false));
 }
 
 
@@ skipping 206 matching lines @@
 #define COMPUTE_OFFSET(type_name, member_name, expr, default_init_value)       \
   ASSERT((expr)->IsVMHeapObject());                                            \
   if (object.raw() == expr) return Thread::member_name##offset();
 CACHED_VM_OBJECTS_LIST(COMPUTE_OFFSET)
 #undef COMPUTE_OFFSET
   UNREACHABLE();
   return -1;
 }
 
 }  // namespace dart