[event_engine] Move DNS resolution executor usage to event engine (#31230)

* [event_engine] Move DNS resolution executor usage to event engine

* Automated change: Fix sanity tests

Co-authored-by: ctiller <ctiller@users.noreply.github.com>

src/core/lib/iomgr/resolve_address_posix.cc

@@ -47,35 +47,22 @@
 namespace grpc_core {
 namespace {
 
-class NativeDNSRequest {
+void NativeDNSRequest(
- public:
+    std::string name, std::string default_port,
-  NativeDNSRequest(
+    std::function<void(absl::StatusOr<std::vector<grpc_resolved_address>>)>
-      absl::string_view name, absl::string_view default_port,
+        on_done) {
-      std::function<void(absl::StatusOr<std::vector<grpc_resolved_address>>)>
+  grpc_event_engine::experimental::GetDefaultEventEngine()->Run(
-          on_done)
+      [name = std::move(name), default_port = std::move(default_port),
-      : name_(name), default_port_(default_port), on_done_(std::move(on_done)) {
+       on_done = std::move(on_done)]() mutable {
-    GRPC_CLOSURE_INIT(&request_closure_, DoRequestThread, this, nullptr);
+        ApplicationCallbackExecCtx callback_exec_ctx;
-    Executor::Run(&request_closure_, absl::OkStatus(), ExecutorType::RESOLVER);
+        ExecCtx exec_ctx;
-  }
+        auto result =
-
+            GetDNSResolver()->LookupHostnameBlocking(name, default_port);
- private:
+        // running inline is safe since we've already been scheduled on the
-  // Callback to be passed to grpc Executor to asynch-ify
+        // executor
-  // LookupHostnameBlocking
+        on_done(std::move(result));
-  static void DoRequestThread(void* rp, grpc_error_handle /*error*/) {
+      });
-    NativeDNSRequest* r = static_cast<NativeDNSRequest*>(rp);
+}
-    auto result =
-        GetDNSResolver()->LookupHostnameBlocking(r->name_, r->default_port_);
-    // running inline is safe since we've already been scheduled on the executor
-    r->on_done_(std::move(result));
-    delete r;
-  }
-
-  const std::string name_;
-  const std::string default_port_;
-  const std::function<void(absl::StatusOr<std::vector<grpc_resolved_address>>)>
-      on_done_;
-  grpc_closure request_closure_;
-};
 
 }  // namespace
 
@@ -85,8 +72,8 @@ DNSResolver::TaskHandle NativeDNSResolver::LookupHostname(
     absl::string_view name, absl::string_view default_port,
     Duration /* timeout */, grpc_pollset_set* /* interested_parties */,
     absl::string_view /* name_server */) {
-  // self-deleting class
+  NativeDNSRequest(std::string(name), std::string(default_port),
-  new NativeDNSRequest(name, default_port, std::move(on_done));
+                   std::move(on_done));
   return kNullHandle;
 }