fix race condition in ProtocolClient::Socket()

Signed-off-by: kostas <[email protected]>

Author: kostasrim

src/server/protocol_client.cc

@@ -109,11 +109,17 @@ ProtocolClient::ProtocolClient(string host, uint16_t port) {
 #ifdef DFLY_USE_SSL
   MaybeInitSslCtx();
 #endif
+
+  // We initialize the proactor thread here such that it never races with Sock().
+  // ProtocolClient is never migrated to a different thread, so this is safe.
+  socket_thread_ = ProactorBase::me();
 }
+
 ProtocolClient::ProtocolClient(ServerContext context) : server_context_(std::move(context)) {
 #ifdef DFLY_USE_SSL
   MaybeInitSslCtx();
 #endif
+  socket_thread_ = ProactorBase::me();
 }
 
 ProtocolClient::~ProtocolClient() {
@@ -162,6 +168,7 @@ error_code ProtocolClient::ResolveHostDns() {
 error_code ProtocolClient::ConnectAndAuth(std::chrono::milliseconds connect_timeout_ms,
                                           ExecutionState* cntx) {
   ProactorBase* mythread = ProactorBase::me();
+  DCHECK(mythread == socket_thread_);
   CHECK(mythread);
   {
     unique_lock lk(sock_mu_);

src/server/protocol_client.h

@@ -107,7 +107,7 @@ class ProtocolClient {
   }
 
   auto* Proactor() const {
-    return sock_->proactor();
+    return socket_thread_;
   }
 
   util::FiberSocketBase* Sock() const {
@@ -142,6 +142,7 @@ class ProtocolClient {
 #else
   void* ssl_ctx_{nullptr};
 #endif
+  util::fb2::ProactorBase* socket_thread_;
 };
 
 }  // namespace dfly

src/server/replica.cc

@@ -1207,19 +1207,7 @@ auto Replica::GetSummary() const -> Summary {
     return res;
   };
 
-  if (Sock())
-    return Proactor()->AwaitBrief(f);
-
-  /**
-   * when this branch happens: there is a very short grace period
-   * where Sock() is not initialized, yet the server can
-   * receive ROLE/INFO commands. That period happens when launching
-   * an instance with '--replicaof' and then immediately
-   * sending a command.
-   *
-   * In that instance, we have to run f() on the current fiber.
-   */
-  return f();
+  return Proactor()->AwaitBrief(f);
 }
 
 std::vector<uint64_t> Replica::GetReplicaOffset() const {