Add silent events to completion queue - to allow server shutdown to complete

src/core/surface/completion_queue.c

@@ -167,6 +167,26 @@ void grpc_cq_end_op(grpc_completion_queue *cc, void *tag, grpc_call *call,
   }
 }
 
+void grpc_cq_begin_silent_op(grpc_completion_queue *cc) {
+  gpr_ref(&cc->refs);
+}
+
+void grpc_cq_end_silent_op(grpc_completion_queue *cc) {
+  int shutdown = 0;
+  gpr_mu_lock(GRPC_POLLSET_MU(&cc->pollset));
+  if (gpr_unref(&cc->refs)) {
+    GPR_ASSERT(!cc->shutdown);
+    GPR_ASSERT(cc->shutdown_called);
+    cc->shutdown = 1;
+    gpr_cv_broadcast(GRPC_POLLSET_CV(&cc->pollset));
+    shutdown = 1;
+  }
+  gpr_mu_unlock(GRPC_POLLSET_MU(&cc->pollset));
+  if (shutdown) {
+    grpc_pollset_shutdown(&cc->pollset, on_pollset_destroy_done, cc);
+  }
+}
+
 /* Create a GRPC_QUEUE_SHUTDOWN event without queuing it anywhere */
 static event *create_shutdown_event(void) {
   event *ev = gpr_malloc(sizeof(event));

src/core/surface/completion_queue.h

@@ -50,6 +50,12 @@ void grpc_cq_begin_op(grpc_completion_queue *cc, grpc_call *call);
 void grpc_cq_end_op(grpc_completion_queue *cc, void *tag, grpc_call *call,
                     int success);
 
+/* Begin a 'silent operation' - one that blocks completion queue shutdown
+   until it is ended */
+void grpc_cq_begin_silent_op(grpc_completion_queue *cc);
+/* End such an operation */
+void grpc_cq_end_silent_op(grpc_completion_queue *cc);
+
 /* disable polling for some tests */
 void grpc_completion_queue_dont_poll_test_only(grpc_completion_queue *cc);
 

src/core/surface/server.c

@@ -533,8 +533,9 @@ static void destroy_call_elem(grpc_call_element *elem) {
     call_list_remove(elem->call_data, i);
   }
   if (chand->server->shutdown && chand->server->lists[ALL_CALLS] == NULL) {
-    for (i = 0; i < chand->server->num_shutdown_tags; i++) {
     for (j = 0; j < chand->server->cq_count; j++) {
+      grpc_cq_end_silent_op(chand->server->cqs[j]);
+      for (i = 0; i < chand->server->num_shutdown_tags; i++) {
         grpc_cq_end_op(chand->server->cqs[j], chand->server->shutdown_tags[i],
                        NULL, 1);
       }
@@ -821,6 +822,10 @@ static void shutdown_internal(grpc_server *server, gpr_uint8 have_shutdown_tag,
     return;
   }
 
+  for (i = 0; i < server->cq_count; i++) {
+    grpc_cq_begin_silent_op(server->cqs[i]);
+  }
+
   nchannels = 0;
   for (c = server->root_channel_data.next; c != &server->root_channel_data;
        c = c->next) {
@@ -857,8 +862,9 @@ static void shutdown_internal(grpc_server *server, gpr_uint8 have_shutdown_tag,
 
   server->shutdown = 1;
   if (server->lists[ALL_CALLS] == NULL) {
-    for (i = 0; i < server->num_shutdown_tags; i++) {
     for (j = 0; j < server->cq_count; j++) {
+      grpc_cq_end_silent_op(server->cqs[j]);
+      for (i = 0; i < server->num_shutdown_tags; i++) {
         grpc_cq_end_op(server->cqs[j], server->shutdown_tags[i], NULL, 1);
       }
     }