Don't create client through ClientManager until first request is sent to it.

td/telegram/Client.cpp

@@ -78,6 +78,14 @@ class TdReceiver {
 class ClientManager::Impl final {
  public:
   ClientId create_client() {
+    CHECK(client_id_ != std::numeric_limits<ClientId>::max());
+    auto client_id = ++client_id_;
+    pending_clients_.insert(client_id);
+    return client_id;
+  }
+
+  void send(ClientId client_id, RequestId request_id, td_api::object_ptr<td_api::Function> &&request) {
+    if (pending_clients_.erase(client_id) != 0) {
       if (tds_.empty()) {
         CHECK(concurrent_scheduler_ == nullptr);
         CHECK(options_.net_query_stats == nullptr);
@@ -86,14 +94,9 @@ class ClientManager::Impl final {
         concurrent_scheduler_->init(0);
         concurrent_scheduler_->start();
       }
-    CHECK(client_id_ != std::numeric_limits<ClientId>::max());
-    auto client_id = ++client_id_;
       tds_[client_id] =
           concurrent_scheduler_->create_actor_unsafe<Td>(0, "Td", receiver_.create_callback(client_id), options_);
-    return client_id;
     }
-
-  void send(ClientId client_id, RequestId request_id, td_api::object_ptr<td_api::Function> &&request) {
     requests_.push_back({client_id, request_id, std::move(request)});
   }
 
@@ -196,6 +199,7 @@ class ClientManager::Impl final {
   unique_ptr<ConcurrentScheduler> concurrent_scheduler_;
   ClientId client_id_{0};
   Td::Options options_;
+  std::unordered_set<int32> pending_clients_;
   std::unordered_map<int32, ActorOwn<Td>> tds_;
 };
 
@@ -356,10 +360,15 @@ class MultiImpl {
   MultiImpl(MultiImpl &&) = delete;
   MultiImpl &operator=(MultiImpl &&) = delete;
 
-  int32 create(TdReceiver &receiver) {
-    auto id = create_id();
-    create(id, receiver.create_callback(id));
-    return id;
+  static int32 create_id() {
+    auto result = current_id_.fetch_add(1);
+    CHECK(result <= static_cast<uint32>(std::numeric_limits<int32>::max()));
+    return static_cast<int32>(result);
+  }
+
+  void create(int32 td_id, unique_ptr<TdCallback> callback) {
+    auto guard = concurrent_scheduler_->get_send_guard();
+    send_closure(multi_td_, &MultiTd::create, td_id, std::move(callback));
   }
 
   static bool is_valid_client_id(int32 client_id) {
@@ -395,17 +404,6 @@ class MultiImpl {
   ActorOwn<MultiTd> multi_td_;
 
   static std::atomic<uint32> current_id_;
-
-  static int32 create_id() {
-    auto result = current_id_.fetch_add(1);
-    CHECK(result <= static_cast<uint32>(std::numeric_limits<int32>::max()));
-    return static_cast<int32>(result);
-  }
-
-  void create(int32 td_id, unique_ptr<TdCallback> callback) {
-    auto guard = concurrent_scheduler_->get_send_guard();
-    send_closure(multi_td_, &MultiTd::create, td_id, std::move(callback));
-  }
 };
 
 std::atomic<uint32> MultiImpl::current_id_{1};
@@ -458,11 +456,10 @@ class MultiImplPool {
 class ClientManager::Impl final {
  public:
   ClientId create_client() {
-    auto impl = pool_.get();
-    auto client_id = impl->create(receiver_);
+    auto client_id = MultiImpl::create_id();
     {
       auto lock = impls_mutex_.lock_write().move_as_ok();
-      impls_[client_id].impl = std::move(impl);
+      impls_[client_id];  // create empty MultiImplInfo
     }
     return client_id;
   }
@@ -474,7 +471,22 @@ class ClientManager::Impl final {
                              td_api::make_object<td_api::error>(400, "Invalid TDLib instance specified"));
       return;
     }
+
     auto it = impls_.find(client_id);
+    if (it != impls_.end() && it->second.impl == nullptr) {
+      lock.reset();
+
+      auto write_lock = impls_mutex_.lock_write().move_as_ok();
+      it = impls_.find(client_id);
+      if (it != impls_.end() && it->second.impl == nullptr) {
+        it->second.impl = pool_.get();
+        it->second.impl->create(client_id, receiver_.create_callback(client_id));
+      }
+      write_lock.reset();
+
+      lock = impls_mutex_.lock_read().move_as_ok();
+      it = impls_.find(client_id);
+    }
     if (it == impls_.end() || it->second.is_closed) {
       receiver_.add_response(client_id, request_id, td_api::make_object<td_api::error>(500, "Request aborted"));
       return;
@@ -517,9 +529,13 @@ class ClientManager::Impl final {
     CHECK(it != impls_.end());
     if (!it->second.is_closed) {
       it->second.is_closed = true;
+      if (it->second.impl == nullptr) {
+        receiver_.add_response(client_id, 0, nullptr);
+      } else {
         it->second.impl->close(client_id);
       }
     }
+  }
 
   Impl() = default;
   Impl(const Impl &) = delete;
@@ -554,7 +570,8 @@ class Client::Impl final {
   Impl() {
     static MultiImplPool pool;
     multi_impl_ = pool.get();
-    td_id_ = multi_impl_->create(receiver_);
+    td_id_ = MultiImpl::create_id();
+    multi_impl_->create(td_id_, receiver_.create_callback(td_id_));
   }
 
   void send(Request request) {

td/telegram/Client.h

@@ -184,6 +184,7 @@ class ClientManager final {
 
   /**
    * Creates a new TDLib client and returns its opaque identifier.
+   * The client will not send updates until the first request is sent to it.
    */
   ClientId create_client();
 

td/telegram/ClientJson.cpp

@@ -125,11 +125,11 @@ static std::mutex extra_mutex;
 static std::unordered_map<int64, string> extra;
 static std::atomic<uint64> extra_id{1};
 
-int td_json_create_client() {
+int json_create_client() {
   return static_cast<int>(get_manager()->create_client());
 }
 
-void td_json_send(int client_id, Slice request) {
+void json_send(int client_id, Slice request) {
   auto parsed_request = to_request(request);
   auto request_id = extra_id.fetch_add(1, std::memory_order_relaxed);
   if (!parsed_request.second.empty()) {
@@ -139,7 +139,7 @@ void td_json_send(int client_id, Slice request) {
   get_manager()->send(client_id, request_id, std::move(parsed_request.first));
 }
 
-const char *td_json_receive(double timeout) {
+const char *json_receive(double timeout) {
   auto response = get_manager()->receive(timeout);
   if (!response.object) {
     return nullptr;
@@ -157,7 +157,7 @@ const char *td_json_receive(double timeout) {
   return store_string(from_response(*response.object, extra_str, response.client_id));
 }
 
-const char *td_json_execute(Slice request) {
+const char *json_execute(Slice request) {
   auto parsed_request = to_request(request);
   return store_string(
       from_response(*ClientManager::execute(std::move(parsed_request.first)), parsed_request.second, 0));

td/telegram/ClientJson.h

@@ -33,12 +33,12 @@ class ClientJson final {
   std::atomic<std::uint64_t> extra_id_{1};
 };
 
-int td_json_create_client();
+int json_create_client();
 
-void td_json_send(int client_id, Slice request);
+void json_send(int client_id, Slice request);
 
-const char *td_json_receive(double timeout);
+const char *json_receive(double timeout);
 
-const char *td_json_execute(Slice request);
+const char *json_execute(Slice request);
 
 }  // namespace td

td/telegram/td_json_client.cpp

@@ -31,17 +31,17 @@ const char *td_json_client_execute(void *client, const char *request) {
 }
 
 int td_create_client() {
-  return td::td_json_create_client();
+  return td::json_create_client();
 }
 
 void td_send(int client_id, const char *request) {
-  td::td_json_send(client_id, td::Slice(request == nullptr ? "" : request));
+  td::json_send(client_id, td::Slice(request == nullptr ? "" : request));
 }
 
 const char *td_receive(double timeout) {
-  return td::td_json_receive(timeout);
+  return td::json_receive(timeout);
 }
 
 const char *td_execute(const char *request) {
-  return td::td_json_execute(td::Slice(request == nullptr ? "" : request));
+  return td::json_execute(td::Slice(request == nullptr ? "" : request));
 }

td/telegram/td_json_client.h

@@ -126,8 +126,8 @@ TDJSON_EXPORT void td_json_client_destroy(void *client);
  */
 
 /**
- * Creates a new instance of TDLib.
- * \return Opaque indentifier of the created TDLib client.
+ * Creates a new instance of TDLib. The TDLib instance will not send updates until the first request is sent to it.
+ * \return Opaque indentifier of the created TDLib instance.
  */
 TDJSON_EXPORT int td_create_client();
 

test/tdclient.cpp

@@ -941,10 +941,12 @@ TEST(Client, Manager) {
   client.send(-1, 3, td::make_tl_object<td::td_api::testSquareInt>(3));
   for (int i = 0; i < threads_n; i++) {
     threads.emplace_back([&] {
-      for (int i = 0; i < clients_n; i++) {
+      for (int i = 0; i <= clients_n; i++) {
         auto id = client.create_client();
+        if (i != 0) {
           client.send(id, 3, td::make_tl_object<td::td_api::testSquareInt>(3));
         }
+      }
     });
   }
   for (auto &thread : threads) {