refactor: wrap the zenoh session with a shared pointer (#333)

* refactor: wrap the zenoh session with a shared pointer

* fixup! refactor: wrap the zenoh session with a shared pointer

* chore: remove the automatically added headers

* fix: apply the suggested change

* fix: hold the session at the right place

Author: YuanYuYuan

rmw_zenoh_cpp/src/detail/rmw_client_data.cpp

@@ -105,7 +105,7 @@ namespace rmw_zenoh_cpp
 {
 ///=============================================================================
 std::shared_ptr<ClientData> ClientData::make(
-  const z_loaned_session_t * session,
+  std::shared_ptr<ZenohSession> session,
   const rmw_node_t * const node,
   const rmw_client_t * client,
   liveliness::NodeInfo node_info,
@@ -167,7 +167,7 @@ std::shared_ptr<ClientData> ClientData::make(
 
   std::size_t domain_id = node_info.domain_id_;
   auto entity = liveliness::Entity::make(
-    z_info_zid(session),
+    z_info_zid(session->loan()),
     std::to_string(node_id),
     std::to_string(service_id),
     liveliness::EntityType::Client,
@@ -192,6 +192,7 @@ std::shared_ptr<ClientData> ClientData::make(
       node,
       client,
       entity,
+      session,
       request_members,
       response_members,
       request_type_support,
@@ -211,13 +212,15 @@ ClientData::ClientData(
   const rmw_node_t * rmw_node,
   const rmw_client_t * rmw_client,
   std::shared_ptr<liveliness::Entity> entity,
+  std::shared_ptr<ZenohSession> sess,
   const void * request_type_support_impl,
   const void * response_type_support_impl,
   std::shared_ptr<RequestTypeSupport> request_type_support,
   std::shared_ptr<ResponseTypeSupport> response_type_support)
 : rmw_node_(rmw_node),
   rmw_client_(rmw_client),
   entity_(std::move(entity)),
+  sess_(std::move(sess)),
   request_type_support_impl_(request_type_support_impl),
   response_type_support_impl_(response_type_support_impl),
   request_type_support_(request_type_support),
@@ -232,7 +235,7 @@ ClientData::ClientData(
 }
 
 ///=============================================================================
-bool ClientData::init(const z_loaned_session_t * session)
+bool ClientData::init(std::shared_ptr<ZenohSession> session)
 {
   if (z_keyexpr_from_str(
     &this->keyexpr_,
@@ -250,7 +253,7 @@ bool ClientData::init(const z_loaned_session_t * session)
   z_view_keyexpr_t liveliness_ke;
   z_view_keyexpr_from_str(&liveliness_ke, liveliness_keyexpr.c_str());
   if (z_liveliness_declare_token(
-      session,
+      session->loan(),
       &this->token_,
       z_loan(liveliness_ke),
       NULL
@@ -266,6 +269,7 @@ bool ClientData::init(const z_loaned_session_t * session)
       z_drop(z_move(this->token_));
     });
 
+  sess_ = session;
   initialized_ = true;
 
   free_ros_keyexpr.cancel();
@@ -470,7 +474,7 @@ rmw_ret_t ClientData::send_request(
   z_owned_closure_reply_t zn_closure_reply;
   z_closure(&zn_closure_reply, client_data_handler, client_data_drop, this);
   z_get(
-    context_impl->session(),
+    sess_->loan(),
     z_loan(keyexpr_), "",
     z_move(zn_closure_reply),
     &opts);
@@ -535,6 +539,7 @@ void ClientData::_shutdown()
     z_drop(z_move(keyexpr_));
   }
 
+  sess_.reset();
   is_shutdown_ = true;
 }
 

rmw_zenoh_cpp/src/detail/rmw_client_data.hpp

@@ -47,7 +47,7 @@ class ClientData final : public std::enable_shared_from_this<ClientData>
 public:
   // Make a shared_ptr of ClientData.
   static std::shared_ptr<ClientData> make(
-    const z_loaned_session_t * session,
+    std::shared_ptr<ZenohSession> session,
     const rmw_node_t * const node,
     const rmw_client_t * client,
     liveliness::NodeInfo node_info,
@@ -113,13 +113,14 @@ class ClientData final : public std::enable_shared_from_this<ClientData>
     const rmw_node_t * rmw_node,
     const rmw_client_t * client,
     std::shared_ptr<liveliness::Entity> entity,
+    std::shared_ptr<ZenohSession> sess,
     const void * request_type_support_impl,
     const void * response_type_support_impl,
     std::shared_ptr<RequestTypeSupport> request_type_support,
     std::shared_ptr<ResponseTypeSupport> response_type_support);
 
   // Initialize the Zenoh objects for this entity.
-  bool init(const z_loaned_session_t * session);
+  bool init(std::shared_ptr<ZenohSession> session);
 
   // Shutdown this client (the mutex is expected to be held by the caller).
   void _shutdown();
@@ -131,6 +132,8 @@ class ClientData final : public std::enable_shared_from_this<ClientData>
   const rmw_client_t * rmw_client_;
   // The Entity generated for the service.
   std::shared_ptr<liveliness::Entity> entity_;
+  // A shared session.
+  std::shared_ptr<ZenohSession> sess_;
   // An owned keyexpression.
   z_owned_keyexpr_t keyexpr_;
   // Liveliness token for the service.

rmw_zenoh_cpp/src/detail/rmw_context_impl_s.cpp

@@ -36,6 +36,7 @@
 
 #include "rcpputils/scope_exit.hpp"
 #include "rmw/error_handling.h"
+#include "zenoh_utils.hpp"
 
 // Megabytes of SHM to reserve.
 // TODO(clalancette): Make this configurable, or get it from the configuration
@@ -86,13 +87,18 @@ class rmw_context_impl_s::Data final
       });
 
     // Initialize the zenoh session.
-    if (z_open(&session_, z_move(config), NULL) != Z_OK) {
+    z_owned_session_t raw_session;
+    if (z_open(&raw_session, z_move(config), NULL) != Z_OK) {
       RMW_SET_ERROR_MSG("Error setting up zenoh session.");
       throw std::runtime_error("Error setting up zenoh session.");
     }
+    if (session_ != nullptr) {
+      session_.reset();
+    }
+    session_ = std::make_shared<rmw_zenoh_cpp::ZenohSession>(raw_session);
     auto close_session = rcpputils::make_scope_exit(
-      [this]() {
-        z_close(z_loan_mut(session_), NULL);
+      [&raw_session]() {
+        z_close(z_loan_mut(raw_session), NULL);
       });
 
     // Verify if the zenoh router is running if configured.
@@ -102,7 +108,7 @@ class rmw_context_impl_s::Data final
       uint64_t connection_attempts = 0;
       constexpr std::chrono::milliseconds sleep_time(1000);
       constexpr int64_t ticks_between_print(std::chrono::milliseconds(1000) / sleep_time);
-      while ((ret = rmw_zenoh_cpp::zenoh_router_check(z_loan(session_))) != RMW_RET_OK) {
+      while ((ret = rmw_zenoh_cpp::zenoh_router_check(session_->loan())) != RMW_RET_OK) {
         if ((connection_attempts % ticks_between_print) == 0) {
           RMW_ZENOH_LOG_WARN_NAMED(
             "rmw_zenoh_cpp",
@@ -117,7 +123,7 @@ class rmw_context_impl_s::Data final
     }
 
     // Initialize the graph cache.
-    const z_id_t zid = z_info_zid(z_loan(session_));
+    const z_id_t zid = z_info_zid(session_->loan());
     graph_cache_ = std::make_shared<rmw_zenoh_cpp::GraphCache>(zid);
     // Setup liveliness subscriptions for discovery.
     std::string liveliness_str = rmw_zenoh_cpp::liveliness::subscription_token(domain_id);
@@ -144,7 +150,7 @@ class rmw_context_impl_s::Data final
     z_view_keyexpr_t keyexpr;
     z_view_keyexpr_from_str(&keyexpr, liveliness_str.c_str());
     z_liveliness_get(
-      z_loan(session_), z_loan(keyexpr),
+      session_->loan(), z_loan(keyexpr),
       z_move(closure), NULL);
     z_owned_reply_t reply;
     while (z_recv(z_loan(handler), &reply) == Z_OK) {
@@ -203,7 +209,7 @@ class rmw_context_impl_s::Data final
     z_view_keyexpr_t liveliness_ke;
     z_view_keyexpr_from_str(&liveliness_ke, liveliness_str.c_str());
     if (z_liveliness_declare_subscriber(
-        z_loan(session_),
+        session_->loan(),
         &graph_subscriber_, z_loan(liveliness_ke),
         z_move(callback), &sub_options) != Z_OK)
     {
@@ -240,11 +246,8 @@ class rmw_context_impl_s::Data final
       // to avoid an AB/BA deadlock if shutdown is racing with graph_sub_data_handler().
     }
 
-    // Close the zenoh session
-    if (z_close(z_loan_mut(session_), NULL) != Z_OK) {
-      RMW_SET_ERROR_MSG("Error while closing zenoh session");
-      return RMW_RET_ERROR;
-    }
+    // Drop the shared session.
+    session_.reset();
 
     return RMW_RET_OK;
   }
@@ -255,10 +258,10 @@ class rmw_context_impl_s::Data final
     return enclave_;
   }
 
-  const z_loaned_session_t * session() const
+  std::shared_ptr<rmw_zenoh_cpp::ZenohSession> session() const
   {
     std::lock_guard<std::recursive_mutex> lock(mutex_);
-    return z_loan(session_);
+    return session_;
   }
 
   std::optional<z_owned_shm_provider_t> & shm_provider()
@@ -288,7 +291,7 @@ class rmw_context_impl_s::Data final
   bool session_is_valid() const
   {
     std::lock_guard<std::recursive_mutex> lock(mutex_);
-    return !z_session_is_closed(z_loan(session_));
+    return !z_session_is_closed(session_->loan());
   }
 
   std::shared_ptr<rmw_zenoh_cpp::GraphCache> graph_cache()
@@ -309,7 +312,7 @@ class rmw_context_impl_s::Data final
     }
 
     // Check that the Zenoh session is still valid.
-    if (z_session_is_closed(z_loan(session_))) {
+    if (z_session_is_closed(session_->loan())) {
       RMW_ZENOH_LOG_ERROR_NAMED(
         "rmw_zenoh_cpp",
         "Unable to create NodeData as Zenoh session is invalid.");
@@ -319,7 +322,7 @@ class rmw_context_impl_s::Data final
     auto node_data = rmw_zenoh_cpp::NodeData::make(
       node,
       this->get_next_entity_id(),
-      z_loan(session_),
+      session_->loan(),
       domain_id_,
       ns,
       node_name,
@@ -395,8 +398,8 @@ class rmw_context_impl_s::Data final
   std::size_t domain_id_;
   // Enclave, name used to find security artifacts in a sros2 keystore.
   std::string enclave_;
-  // An owned session.
-  z_owned_session_t session_;
+  // A shared session.
+  std::shared_ptr<rmw_zenoh_cpp::ZenohSession> session_{nullptr};
   // An optional SHM manager that is initialized of SHM is enabled in the
   // zenoh session config.
   std::optional<z_owned_shm_provider_t> shm_provider_;
@@ -472,7 +475,7 @@ std::string rmw_context_impl_s::enclave() const
 }
 
 ///=============================================================================
-const z_loaned_session_t * rmw_context_impl_s::session() const
+std::shared_ptr<rmw_zenoh_cpp::ZenohSession> rmw_context_impl_s::session() const
 {
   return data_->session();
 }

rmw_zenoh_cpp/src/detail/rmw_context_impl_s.hpp

@@ -47,8 +47,8 @@ class rmw_context_impl_s final
   // Get a copy of the enclave.
   std::string enclave() const;
 
-  // Loan the Zenoh session.
-  const z_loaned_session_t * session() const;
+  // Share the Zenoh session.
+  std::shared_ptr<rmw_zenoh_cpp::ZenohSession> session() const;
 
   // Get a reference to the shm_provider.
   // Note: This is not thread-safe.

rmw_zenoh_cpp/src/detail/rmw_node_data.cpp

@@ -121,7 +121,7 @@ std::size_t NodeData::id() const
 ///=============================================================================
 bool NodeData::create_pub_data(
   const rmw_publisher_t * const publisher,
-  const z_loaned_session_t * session,
+  std::shared_ptr<ZenohSession> session,
   std::size_t id,
   const std::string & topic_name,
   const rosidl_message_type_support_t * type_support,
@@ -187,7 +187,7 @@ void NodeData::delete_pub_data(const rmw_publisher_t * const publisher)
 ///=============================================================================
 bool NodeData::create_sub_data(
   const rmw_subscription_t * const subscription,
-  const z_loaned_session_t * session,
+  std::shared_ptr<ZenohSession> session,
   std::shared_ptr<GraphCache> graph_cache,
   std::size_t id,
   const std::string & topic_name,
@@ -255,7 +255,7 @@ void NodeData::delete_sub_data(const rmw_subscription_t * const subscription)
 ///=============================================================================
 bool NodeData::create_service_data(
   const rmw_service_t * const service,
-  const z_loaned_session_t * session,
+  std::shared_ptr<ZenohSession> session,
   std::size_t id,
   const std::string & service_name,
   const rosidl_service_type_support_t * type_supports,
@@ -322,7 +322,7 @@ void NodeData::delete_service_data(const rmw_service_t * const service)
 ///=============================================================================
 bool NodeData::create_client_data(
   const rmw_client_t * const client,
-  const z_loaned_session_t * session,
+  std::shared_ptr<ZenohSession> session,
   std::size_t id,
   const std::string & service_name,
   const rosidl_service_type_support_t * type_supports,

rmw_zenoh_cpp/src/detail/rmw_node_data.hpp

@@ -55,7 +55,7 @@ class NodeData final
   // Create a new PublisherData for a given rmw_publisher_t.
   bool create_pub_data(
     const rmw_publisher_t * const publisher,
-    const z_loaned_session_t * session,
+    std::shared_ptr<ZenohSession> sess,
     std::size_t id,
     const std::string & topic_name,
     const rosidl_message_type_support_t * type_support,
@@ -70,7 +70,7 @@ class NodeData final
   // Create a new SubscriptionData for a given rmw_subscription_t.
   bool create_sub_data(
     const rmw_subscription_t * const subscription,
-    const z_loaned_session_t * session,
+    std::shared_ptr<ZenohSession> sess,
     std::shared_ptr<GraphCache> graph_cache,
     std::size_t id,
     const std::string & topic_name,
@@ -86,7 +86,7 @@ class NodeData final
   // Create a new ServiceData for a given rmw_service_t.
   bool create_service_data(
     const rmw_service_t * const service,
-    const z_loaned_session_t * session,
+    std::shared_ptr<ZenohSession> session,
     std::size_t id,
     const std::string & service_name,
     const rosidl_service_type_support_t * type_support,
@@ -101,7 +101,7 @@ class NodeData final
   // Create a new ClientData for a given rmw_client_t.
   bool create_client_data(
     const rmw_client_t * const client,
-    const z_loaned_session_t * session,
+    std::shared_ptr<ZenohSession> session,
     std::size_t id,
     const std::string & service_name,
     const rosidl_service_type_support_t * type_support,