Add dns_resolver changes

src/core/ext/filters/client_channel/resolver/dns/native/dns_resolver.cc

@@ -66,7 +66,9 @@ class NativeDnsResolver : public Resolver {
   void MaybeStartResolvingLocked();
   void StartResolvingLocked();
 
+  static void OnNextResolution(void* arg, grpc_error* error);
   static void OnNextResolutionLocked(void* arg, grpc_error* error);
+  static void OnResolved(void* arg, grpc_error* error);
   static void OnResolvedLocked(void* arg, grpc_error* error);
 
   /// name to resolve
@@ -115,11 +117,6 @@ NativeDnsResolver::NativeDnsResolver(ResolverArgs args)
   if (args.pollset_set != nullptr) {
     grpc_pollset_set_add_pollset_set(interested_parties_, args.pollset_set);
   }
-  GRPC_CLOSURE_INIT(&on_next_resolution_,
-                    NativeDnsResolver::OnNextResolutionLocked, this,
-                    grpc_combiner_scheduler(args.combiner));
-  GRPC_CLOSURE_INIT(&on_resolved_, NativeDnsResolver::OnResolvedLocked, this,
-                    grpc_combiner_scheduler(args.combiner));
 }
 
 NativeDnsResolver::~NativeDnsResolver() {
@@ -150,6 +147,15 @@ void NativeDnsResolver::ShutdownLocked() {
   }
 }
 
+void NativeDnsResolver::OnNextResolution(void* arg, grpc_error* error) {
+  NativeDnsResolver* r = static_cast<NativeDnsResolver*>(arg);
+  r->combiner()->Run(
+      GRPC_CLOSURE_INIT(&r->on_next_resolution_,
+                        NativeDnsResolver::OnNextResolutionLocked, this,
+                        nullptr),
+      GRPC_ERROR_NONE);
+}
+
 void NativeDnsResolver::OnNextResolutionLocked(void* arg, grpc_error* error) {
   NativeDnsResolver* r = static_cast<NativeDnsResolver*>(arg);
   r->have_next_resolution_timer_ = false;
@@ -159,6 +165,14 @@ void NativeDnsResolver::OnNextResolutionLocked(void* arg, grpc_error* error) {
   r->Unref(DEBUG_LOCATION, "retry-timer");
 }
 
+void NativeDnsResolver::OnResolved(void* arg, grpc_error* error) {
+  NativeDnsResolver* r = static_cast<NativeDnsResolver*>(arg);
+  r->combiner()->Run(
+      GRPC_CLOSURE_INIT(&on_resolved_, NativeDnsResolver::OnResolvedLocked,
+                        this, nullptr),
+      GRPC_ERROR_NONE)
+}
+
 void NativeDnsResolver::OnResolvedLocked(void* arg, grpc_error* error) {
   NativeDnsResolver* r = static_cast<NativeDnsResolver*>(arg);
   GPR_ASSERT(r->resolving_);
@@ -202,6 +216,9 @@ void NativeDnsResolver::OnResolvedLocked(void* arg, grpc_error* error) {
     } else {
       gpr_log(GPR_DEBUG, "retrying immediately");
     }
+    GRPC_CLOSURE_INIT(&r->on_next_resolution_,
+                      NativeDnsResolver::OnNextResolution, this,
+                      grpc_schedule_on_exec_ctx);
     grpc_timer_init(&r->next_resolution_timer_, next_try,
                     &r->on_next_resolution_);
   }
@@ -229,6 +246,9 @@ void NativeDnsResolver::MaybeStartResolvingLocked() {
       // new closure API is done, find a way to track this ref with the timer
       // callback as part of the type system.
       Ref(DEBUG_LOCATION, "next_resolution_timer_cooldown").release();
+      GRPC_CLOSURE_INIT(&on_next_resolution_,
+                        NativeDnsResolver::OnNextResolution, this,
+                        grpc_schedule_on_exec_ctx);
       grpc_timer_init(&next_resolution_timer_,
                       ExecCtx::Get()->Now() + ms_until_next_resolution,
                       &on_next_resolution_);
@@ -247,6 +267,8 @@ void NativeDnsResolver::StartResolvingLocked() {
   GPR_ASSERT(!resolving_);
   resolving_ = true;
   addresses_ = nullptr;
+  GRPC_CLOSURE_INIT(&on_resolved_, NativeDnsResolver::OnResolved, this,
+                    grpc_schedule_on_exec_ctx);
   grpc_resolve_address(name_to_resolve_, kDefaultPort, interested_parties_,
                        &on_resolved_, &addresses_);
   last_resolution_timestamp_ = grpc_core::ExecCtx::Get()->Now();

src/core/ext/filters/client_channel/resolver/fake/fake_resolver.cc

@@ -128,7 +128,7 @@ void FakeResolver::RequestReresolutionLocked() {
       reresolution_closure_pending_ = true;
       Ref().release();  // ref held by closure
       GRPC_CLOSURE_INIT(&reresolution_closure_, ReturnReresolutionResult, this,
-                        grpc_combiner_scheduler(combiner()));
+                        nullptr);
       combiner()->Run(&reresolution_closure_, GRPC_ERROR_NONE);
     }
   }