add ROS2UnityCore script

Author: adamdbrw

src/Ros2ForUnity/Scripts/ROS2UnityCore.cs

@@ -0,0 +1,142 @@
+// Copyright 2019-2022 Robotec.ai.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+using UnityEngine;
+using System;
+using System.Collections.Generic;
+using System.Threading;
+using ROS2;
+
+namespace ROS2
+{
+
+    /// <summary>
+    /// The principal class for handling ros2 nodes and executables.
+    /// Use this to create ros2 node, check ros2 status.
+    /// Spins and executes actions (e. g. clock, sensor publish triggers) in a dedicated thread
+    /// TODO: this is meant to be used as a one-of (a singleton). Enforce. However, things should work
+    /// anyway with more than one since the underlying library can handle multiple init and shutdown calls,
+    /// and does node name uniqueness check independently.
+    /// </summary>
+    public class ROS2UnityCore
+    {
+        private ROS2ForUnity ros2forUnity;
+        private List<ROS2Node> nodes;
+        private List<INode> ros2csNodes; // For performance in spinning
+        private List<Action> executableActions;
+        private bool quitting = false;
+        private int interval = 2;  // Spinning / executor interval in ms
+        private object mutex = new object();
+        private double spinTimeout = 0.0001;
+
+        public bool Ok()
+        {
+            lock (mutex)
+            {
+                return (nodes != null && ros2forUnity.Ok());
+            }
+        }
+
+        public ROS2UnityCore()
+        {
+            lock (mutex)
+            {
+                ros2forUnity = new ROS2ForUnity();
+                nodes = new List<ROS2Node>();
+                ros2csNodes = new List<INode>();
+                executableActions = new List<Action>();
+
+                Thread publishThread = new Thread(() => Tick());
+                publishThread.Start();
+            }
+        }
+
+        public ROS2Node CreateNode(string name)
+        {
+            lock (mutex)
+            {
+                foreach (ROS2Node n in nodes)
+                {  // Assumed to be a rare operation on rather small (<1k) list
+                    if (n.name == name)
+                    {
+                        throw new InvalidOperationException("Cannot create node " + name + ". A node with this name already exists!");
+                    }
+                }
+                ROS2Node node = new ROS2Node(name);
+                nodes.Add(node);
+                ros2csNodes.Add(node.node);
+                return node;
+            }
+        }
+
+        public void RemoveNode(ROS2Node node)
+        {
+            lock (mutex)
+            {
+                ros2csNodes.Remove(node.node);
+                nodes.Remove(node); //Node will be later deleted if unused, by GC
+            }
+        }
+
+        /// <summary>
+        /// Works as a simple executor registration analogue. These functions will be called with each Tick()
+        /// Actions need to take care of correct call resolution by checking in their body (TODO)
+        /// Make sure actions are lightweight (TODO - separate out threads for spinning and executables?)
+        /// </summary>
+        public void RegisterExecutable(Action executable)
+        {
+            lock (mutex)
+            {
+                executableActions.Add(executable);
+            }
+        }
+
+        public void UnregisterExecutable(Action executable)
+        {
+            lock (mutex)
+            {
+                executableActions.Remove(executable);
+            }
+        }
+
+        /// <summary>
+        /// "Executor" thread will tick all clocks and spin the node
+        /// </summary>
+        private void Tick()
+        {
+            while (!quitting)
+            {
+                if (Ok())
+                {
+                    lock (mutex)
+                    {
+                        foreach (Action action in executableActions)
+                        {
+                            action();
+                        }
+                        Ros2cs.SpinOnce(ros2csNodes, spinTimeout);
+                    }
+                }
+                Thread.Sleep(interval);
+            }
+        }
+
+        public void DestroyNow()
+        {
+            quitting = true;
+            ros2forUnity.DestroyROS2ForUnity();
+        }
+    }
+
+}  // namespace ROS2