prevent spurious wake up and unstarted/already shutdown server

include/grpc++/server.h

@@ -179,6 +179,7 @@ class Server GRPC_FINAL : public ServerInterface, private GrpcLibraryCodegen {
   grpc::mutex mu_;
   bool started_;
   bool shutdown_;
+  bool shutdown_notified_;
   // The number of threads which are running callbacks.
   int num_running_cb_;
   grpc::condition_variable callback_cv_;

src/cpp/server/server.cc

@@ -281,6 +281,7 @@ Server::Server(ThreadPoolInterface* thread_pool, bool thread_pool_owned,
     : max_message_size_(max_message_size),
       started_(false),
       shutdown_(false),
+      shutdown_notified_(false),
       num_running_cb_(0),
       sync_methods_(new std::list<SyncRequest>),
       has_generic_service_(false),
@@ -462,14 +463,18 @@ void Server::ShutdownInternal(gpr_timespec deadline) {
     while (num_running_cb_ != 0) {
       callback_cv_.wait(lock);
     }
+
+    shutdown_notified_ = true;
     shutdown_cv_.notify_all();
   }
 }
 
 void Server::Wait() {
   grpc::unique_lock<grpc::mutex> lock(mu_);
+  while (started_ && !shutdown_notified_) {
     shutdown_cv_.wait(lock);
   }
+}
 
 void Server::PerformOpsOnCall(CallOpSetInterface* ops, Call* call) {
   static const size_t MAX_OPS = 8;

test/cpp/end2end/async_end2end_test.cc

@@ -363,6 +363,13 @@ TEST_P(AsyncEnd2endTest, WaitAndShutdownTest) {
   delete wait_thread;
 }
 
+TEST_P(AsyncEnd2endTest, ShutdownThenWait) {
+  ResetStub();
+  SendRpc(1);
+  server_->Shutdown();
+  server_->Wait();
+}
+
 // Test a simple RPC using the async version of Next
 TEST_P(AsyncEnd2endTest, AsyncNextRpc) {
   ResetStub();