efficient thread-safe singleton in C++

Question

The usual pattern for a singleton class is something like

static Foo &getInst()
{
  static Foo *inst = NULL;
  if(inst == NULL)
    inst = new Foo(...);
         


        

Answer 1

Does TLS work here? https://en.wikipedia.org/wiki/Thread-local_storage#C_and_C++

For example,

static _thread Foo *inst = NULL;
static Foo &getInst()
{
  if(inst == NULL)
    inst = new Foo(...);
  return *inst;    
 }

But we also need a way to delete it explicitly, like

static void deleteInst() {
   if (!inst) {
     return;
   }
   delete inst;
   inst = NULL;
}