Fix ASAN failure

include/grpc++/impl/codegen/completion_queue.h

@@ -247,6 +247,12 @@ class CompletionQueue : private GrpcLibraryCodegen {
 
   /// Performs a single polling pluck on \a tag.
   /// \warning Must not be mixed with calls to \a Next.
+  ///
+  /// TODO: sreek - This calls tag->FinalizeResult() even if the cq_ is already
+  /// shutdown. This is most likely a bug and if it is a bug, then change this
+  /// implementation to simple call the other TryPluck function with a zero
+  /// timeout. i.e:
+  ///      TryPluck(tag, gpr_time_0(GPR_CLOCK_REALTIME))
   void TryPluck(CompletionQueueTag* tag) {
     auto deadline = g_core_codegen_interface->gpr_time_0(GPR_CLOCK_REALTIME);
     auto ev = g_core_codegen_interface->grpc_completion_queue_pluck(
@@ -258,6 +264,23 @@ class CompletionQueue : private GrpcLibraryCodegen {
     GPR_CODEGEN_ASSERT(!tag->FinalizeResult(&ignored, &ok));
   }
 
+  /// Performs a single polling pluck on \a tag. Calls tag->FinalizeResult if
+  /// the pluck() was successful and returned the tag.
+  ///
+  /// This exects tag->FinalizeResult (if called) to return 'false' i.e expects
+  /// that the tag is internal not something that is returned to the user.
+  void TryPluck(CompletionQueueTag* tag, gpr_timespec deadline) {
+    auto ev = g_core_codegen_interface->grpc_completion_queue_pluck(
+        cq_, tag, deadline, nullptr);
+    if (ev.type == GRPC_QUEUE_TIMEOUT || ev.type == GRPC_QUEUE_SHUTDOWN) {
+      return;
+    }
+
+    bool ok = ev.success != 0;
+    void* ignored = tag;
+    GPR_CODEGEN_ASSERT(!tag->FinalizeResult(&ignored, &ok));
+  }
+
   grpc_completion_queue* cq_;  // owned
 
   gpr_atm avalanches_in_flight_;

include/grpc++/impl/codegen/server_context.h

@@ -41,6 +41,7 @@
 #include <grpc/impl/codegen/compression_types.h>
 #include <grpc/load_reporting.h>
 
+#include <grpc++/impl/codegen/completion_queue_tag.h>
 #include <grpc++/impl/codegen/config.h>
 #include <grpc++/impl/codegen/create_auth_context.h>
 #include <grpc++/impl/codegen/metadata_map.h>
@@ -212,6 +213,8 @@ class ServerContext {
   class CompletionOp;
 
   void BeginCompletionOp(Call* call);
+  // Return the tag queued by BeginCompletionOp()
+  CompletionQueueTag* GetCompletionOpTag();
 
   ServerContext(gpr_timespec deadline, grpc_metadata_array* arr);
 

src/cpp/server/server_cc.cc

@@ -221,9 +221,14 @@ class Server::SyncRequest final : public CompletionQueueTag {
           MethodHandler::HandlerParameter(&call_, &ctx_, request_payload_));
       global_callbacks->PostSynchronousRequest(&ctx_);
       request_payload_ = nullptr;
-      DummyTag ignored_tag;
+
       cq_.Shutdown();
-      /* Ensure the cq_ is shutdown (else this will hang indefinitely) */
+
+      CompletionQueueTag* op_tag = ctx_.GetCompletionOpTag();
+      cq_.TryPluck(op_tag, gpr_inf_future(GPR_CLOCK_REALTIME));
+
+     /* Ensure the cq_ is shutdown */
+      DummyTag ignored_tag;
       GPR_ASSERT(cq_.Pluck(&ignored_tag) == false);
     }
 

src/cpp/server/server_context.cc

@@ -166,6 +166,10 @@ void ServerContext::BeginCompletionOp(Call* call) {
   call->PerformOps(completion_op_);
 }
 
+CompletionQueueTag* ServerContext::GetCompletionOpTag() {
+  return static_cast<CompletionQueueTag*>(completion_op_);
+}
+
 void ServerContext::AddInitialMetadata(const grpc::string& key,
                                        const grpc::string& value) {
   initial_metadata_.insert(std::make_pair(key, value));