Support multi entity spawn

CMakeLists.txt

@@ -3,7 +3,7 @@ cmake_minimum_required(VERSION 3.5.1 FATAL_ERROR)
 #============================================================================
 # Initialize the project
 #============================================================================
-project(ignition-gazebo2 VERSION 2.17.0)
+project(ignition-gazebo2 VERSION 2.18.0)
 
 #============================================================================
 # Find ignition-cmake

Changelog.md

@@ -1,6 +1,9 @@
 ## Ignition Gazebo 2.x
 
-### Ignition Gazebo 2.xx.xx (2020-xx-xx)
+### Ignition Gazebo 2.18.0 (2020-05-20)
+
+1. Added a `/world/<world_name>/create_multiple` service that parallels the current `/world/<world_name>/create` service. The `create_multiple` service can handle an `ignition::msgs::EntityFactory_V` message that may contain one or more entities to spawn.
+    * [Pull Request 146](https://github.com/ignitionrobotics/ign-gazebo/pull/146)
 
 ### Ignition Gazebo 2.17.0 (2020-05-13)
 

src/systems/user_commands/UserCommands.cc

@@ -157,6 +157,14 @@ class ignition::gazebo::systems::UserCommandsPrivate
   public: bool CreateService(const msgs::EntityFactory &_req,
       msgs::Boolean &_res);
 
+  /// \brief Callback for multiple create service
+  /// \param[in] _req Request containing one or more entity descriptions.
+  /// \param[in] _res True if message successfully received and queued.
+  /// It does not mean that the entities will be successfully spawned.
+  /// \return True if successful.
+  public: bool CreateServiceMultiple(
+              const msgs::EntityFactory_V &_req, msgs::Boolean &_res);
+
   /// \brief Callback for remove service
   /// \param[in] _req Request containing identification of entity to be removed.
   /// \param[in] _res True if message successfully received and queued.
@@ -215,6 +223,11 @@ void UserCommands::Configure(const Entity &_entity,
   this->dataPtr->node.Advertise(createService,
       &UserCommandsPrivate::CreateService, this->dataPtr.get());
 
+  // Create service for EntityFactory_V
+  std::string createServiceMultiple{"/world/" + worldName + "/create_multiple"};
+  this->dataPtr->node.Advertise(createServiceMultiple,
+      &UserCommandsPrivate::CreateServiceMultiple, this->dataPtr.get());
+
   ignmsg << "Create service on [" << createService << "]" << std::endl;
 
   // Remove service
@@ -265,6 +278,25 @@ void UserCommands::PreUpdate(const UpdateInfo &/*_info*/,
   // TODO(louise) Clear redo list
 }
 
+//////////////////////////////////////////////////
+bool UserCommandsPrivate::CreateServiceMultiple(
+    const msgs::EntityFactory_V &_req, msgs::Boolean &_res)
+{
+  std::lock_guard<std::mutex> lock(this->pendingMutex);
+  for (int i = 0; i < _req.data_size(); ++i)
+  {
+    const msgs::EntityFactory &msg = _req.data(i);
+    // Create command and push it to queue
+    auto msgCopy = msg.New();
+    msgCopy->CopyFrom(msg);
+    auto cmd = std::make_unique<CreateCommand>(msgCopy, this->iface);
+    this->pendingCmds.push_back(std::move(cmd));
+  }
+
+  _res.set_data(true);
+  return true;
+}
+
 //////////////////////////////////////////////////
 bool UserCommandsPrivate::CreateService(const msgs::EntityFactory &_req,
     msgs::Boolean &_res)

src/systems/user_commands/UserCommands.hh

@@ -45,6 +45,15 @@ namespace systems
   /// * **Request type*: ignition.msgs.EntityFactory
   /// * **Response type*: ignition.msgs.Boolean
   ///
+  /// # Spawn multiple entities
+  ///
+  /// This service can spawn multiple entities in the same iteration,
+  /// thereby eliminating simulation steps between entity spawn times.
+  ///
+  /// * **Service**: `/world/<world name>/create_multiple`
+  /// * **Request type*: ignition.msgs.EntityFactory_V
+  /// * **Response type*: ignition.msgs.Boolean
+  ///
   /// Try some examples described on examples/worlds/empty.sdf
   class IGNITION_GAZEBO_VISIBLE UserCommands:
     public System,