intermediate changes

ref:cde9a383711a11544ce7e107a78147fb96cc4029

1 files changed, 64 insertions, 0 deletions

diff --git a/library/cpp/actors/dnsresolver/dnsresolver_ondemand.cpp b/library/cpp/actors/dnsresolver/dnsresolver_ondemand.cpp
new file mode 100644
index 0000000000..2025162e95
--- /dev/null
+++ b/library/cpp/actors/dnsresolver/dnsresolver_ondemand.cpp
@@ -0,0 +1,64 @@
+#include "dnsresolver.h"
+
+#include <library/cpp/actors/core/hfunc.h>
+
+namespace NActors {
+namespace NDnsResolver {
+
+    class TOnDemandDnsResolver : public TActor<TOnDemandDnsResolver> {
+    public:
+        TOnDemandDnsResolver(TOnDemandDnsResolverOptions options)
+            : TActor(&TThis::StateWork)
+            , Options(std::move(options))
+        { }
+
+        static constexpr EActivityType ActorActivityType() {
+            return DNS_RESOLVER;
+        }
+
+    private:
+        STRICT_STFUNC(StateWork, {
+            cFunc(TEvents::TEvPoison::EventType, PassAway);
+            fFunc(TEvDns::TEvGetHostByName::EventType, Forward);
+            fFunc(TEvDns::TEvGetAddr::EventType, Forward);
+        });
+
+        void Forward(STATEFN_SIG) {
+            ev->Rewrite(ev->GetTypeRewrite(), GetUpstream());
+            TActivationContext::Send(std::move(ev));
+        }
+
+    private:
+        TActorId GetUpstream() {
+            if (Y_UNLIKELY(!CachingResolverId)) {
+                if (Y_LIKELY(!SimpleResolverId)) {
+                    SimpleResolverId = RegisterWithSameMailbox(CreateSimpleDnsResolver(Options));
+                }
+                CachingResolverId = RegisterWithSameMailbox(CreateCachingDnsResolver(SimpleResolverId, Options));
+            }
+            return CachingResolverId;
+        }
+
+        void PassAway() override {
+            if (CachingResolverId) {
+                Send(CachingResolverId, new TEvents::TEvPoison);
+                CachingResolverId = { };
+            }
+            if (SimpleResolverId) {
+                Send(SimpleResolverId, new TEvents::TEvPoison);
+                SimpleResolverId = { };
+            }
+        }
+
+    private:
+        TOnDemandDnsResolverOptions Options;
+        TActorId SimpleResolverId;
+        TActorId CachingResolverId;
+    };
+
+    IActor* CreateOnDemandDnsResolver(TOnDemandDnsResolverOptions options) {
+        return new TOnDemandDnsResolver(std::move(options));
+    }
+
+} // namespace NDnsResolver
+} // namespace NActors