Break infinite connection retry loop

Previously, we'd keep retrying a connection until the channel closed.
With this change, we only retry connecting *if there's a watcher on the
subchannel connection state*. This ultimately means that if the
lb_policy doesn't care if the subchannel connects, it'll stop trying.

2 files changed, 13 insertions, 5 deletions

diff --git a/src/core/lib/transport/connectivity_state.c b/src/core/lib/transport/connectivity_state.c
index 89072879d9..4f49d7cf7d 100644
--- a/src/core/lib/transport/connectivity_state.c
+++ b/src/core/lib/transport/connectivity_state.c
@@ -100,7 +100,12 @@ grpc_connectivity_state grpc_connectivity_state_check(
   return tracker->current_state;
 }
 
-int grpc_connectivity_state_notify_on_state_change(
+bool grpc_connectivity_state_has_watchers(
+    grpc_connectivity_state_tracker *connectivity_state) {
+  return connectivity_state->watchers != NULL;
+}
+
+bool grpc_connectivity_state_notify_on_state_change(
     grpc_exec_ctx *exec_ctx, grpc_connectivity_state_tracker *tracker,
     grpc_connectivity_state *current, grpc_closure *notify) {
   if (grpc_connectivity_state_trace) {
@@ -119,7 +124,7 @@ int grpc_connectivity_state_notify_on_state_change(
       grpc_exec_ctx_sched(exec_ctx, notify, GRPC_ERROR_CANCELLED, NULL);
       tracker->watchers = w->next;
       gpr_free(w);
-      return 0;
+      return false;
     }
     while (w != NULL) {
       grpc_connectivity_state_watcher *rm_candidate = w->next;
@@ -127,11 +132,11 @@ int grpc_connectivity_state_notify_on_state_change(
         grpc_exec_ctx_sched(exec_ctx, notify, GRPC_ERROR_CANCELLED, NULL);
         w->next = w->next->next;
         gpr_free(rm_candidate);
-        return 0;
+        return false;
       }
       w = w->next;
     }
-    return 0;
+    return false;
   } else {
     if (tracker->current_state != *current) {
       *current = tracker->current_state;
diff --git a/src/core/lib/transport/connectivity_state.h b/src/core/lib/transport/connectivity_state.h
index 7a2fa52c10..769c675b79 100644
--- a/src/core/lib/transport/connectivity_state.h
+++ b/src/core/lib/transport/connectivity_state.h
@@ -75,13 +75,16 @@ void grpc_connectivity_state_set(grpc_exec_ctx *exec_ctx,
                                  grpc_error *associated_error,
                                  const char *reason);
 
+bool grpc_connectivity_state_has_watchers(
+    grpc_connectivity_state_tracker *tracker);
+
 grpc_connectivity_state grpc_connectivity_state_check(
     grpc_connectivity_state_tracker *tracker, grpc_error **current_error);
 
 /** Return 1 if the channel should start connecting, 0 otherwise.
     If current==NULL cancel notify if it is already queued (success==0 in that
     case) */
-int grpc_connectivity_state_notify_on_state_change(
+bool grpc_connectivity_state_notify_on_state_change(
     grpc_exec_ctx *exec_ctx, grpc_connectivity_state_tracker *tracker,
     grpc_connectivity_state *current, grpc_closure *notify);