Add control_inputs in Operation #141

src/TensorFlowNET.Core/Graphs/Graph.Control.cs

@@ -0,0 +1,105 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+using Tensorflow.Eager;
+
+namespace Tensorflow
+{
+    public partial class Graph
+    {
+        public Context _control_flow_context;
+
+        private Queue<_ControlDependenciesController> _graph_control_dependencies_stack = new Queue<_ControlDependenciesController>();
+        public Queue<_ControlDependenciesController> _control_dependencies_stack
+        {
+            get
+            {
+                return _graph_control_dependencies_stack;
+            }
+            set
+            {
+                _graph_control_dependencies_stack = value;
+            }
+        }
+
+        /// <summary>
+        /// For an op that takes `input_ops` as inputs, compute control inputs.
+        /// </summary>
+        /// <param name="input_ops">The data input ops for an op to be created.</param>
+        /// <returns>A list of control inputs for the op to be created.</returns>
+        private Operation[] _control_dependencies_for_inputs(Operation[] input_ops)
+        {
+            Operation[] ret = new Operation[0];
+
+            foreach(var controller in _control_dependencies_stack)
+            {
+                bool dominated = false;
+                // If any of the input_ops already depends on the inputs from controller,
+                // we say that the new op is dominated (by that input), and we therefore
+                // do not need to add control dependencies for this controller's inputs.
+                foreach(var op in input_ops)
+                {
+                    if (controller.op_in_group(op))
+                    {
+                        dominated = true;
+                        break;
+                    }
+                }
+
+                if (!dominated)
+                    ret = controller.control_inputs.Where(x => !input_ops.Contains(x)).ToArray();
+            }
+
+            return ret;
+        }
+
+        public _ControlDependenciesController control_dependencies(Operation[] control_inputs)
+        {
+            if (control_inputs == null)
+                return new _ControlDependenciesController(this, null);
+
+            var control_ops = new List<Operation>();
+            foreach (var c in control_inputs)
+            {
+                control_ops.Add(c);
+            }
+
+            return new _ControlDependenciesController(this, control_ops);
+        }
+
+        /// <summary>
+        /// Returns the current control flow context.
+        /// </summary>
+        /// <returns>A context object.</returns>
+        public Context _get_control_flow_context()
+        {
+            return _control_flow_context;
+        }
+
+        /// <summary>
+        /// Sets the current control flow context.
+        /// </summary>
+        /// <param name="ctx">a context object.</param>
+        public void _set_control_flow_context(Context ctx)
+        {
+            _control_flow_context = ctx;
+        }
+
+        public void _push_control_dependencies_controller(_ControlDependenciesController controller)
+        {
+            _control_dependencies_stack.Enqueue(controller);
+        }
+
+        public void _pop_control_dependencies_controller(_ControlDependenciesController controller)
+        {
+            _control_dependencies_stack.Dequeue();
+        }
+
+        public void _record_op_seen_by_control_dependencies(Operation op)
+        {
+            foreach (var controller in _control_dependencies_stack)
+                controller.add_op(op);
+        }
+    }
+}

src/TensorFlowNET.Core/Graphs/Graph.cs

@@ -142,19 +142,9 @@ namespace Tensorflow
             return op;
         }
 
-        /// <summary>
-        /// For an op that takes `input_ops` as inputs, compute control inputs.
-        /// </summary>
-        /// <param name="input_ops">The data input ops for an op to be created.</param>
-        /// <returns>A list of control inputs for the op to be created.</returns>
-        private Operation[] _control_dependencies_for_inputs(Operation[] input_ops)
-        {
-            return new Operation[0];
-        }
-
         private void _create_op_helper(Operation op, bool compute_device = true)
         {
-
+            _record_op_seen_by_control_dependencies(op);
         }
 
         public void _add_op(Operation op)

src/TensorFlowNET.Core/Graphs/_ControlDependenciesController.cs

@@ -0,0 +1,80 @@
+using System;
+using System.Collections.Generic;
+using System.Text;
+using Tensorflow.Eager;
+
+namespace Tensorflow
+{
+    /// <summary>
+    /// Context manager for `control_dependencies()`
+    /// </summary>
+    public class _ControlDependenciesController : IPython
+    {
+        private Graph _graph;
+        private List<Operation> _control_inputs_val;
+        private List<Operation> _seen_nodes;
+        private Queue<_ControlDependenciesController> _old_stack;
+        private bool _new_stack;
+        private Context _old_control_flow_context;
+
+        public Operation[] control_inputs => _control_inputs_val.ToArray();
+
+        public _ControlDependenciesController(Graph graph, List<Operation> control_inputs)
+        {
+            _graph = graph;
+            if (control_inputs == null)
+            {
+                _control_inputs_val = new List<Operation>();
+                _new_stack = true;
+            }
+            else
+            {
+                _control_inputs_val = control_inputs;
+                _new_stack = false;
+            }
+
+            _seen_nodes = new List<Operation>();
+        }
+
+        public void add_op(Operation op)
+        {
+            _seen_nodes.Add(op);
+        }
+
+        public bool op_in_group(Operation op)
+        {
+            return _seen_nodes.Contains(op);
+        }
+
+        public void __enter__()
+        {
+            if (_new_stack)
+            {
+                // Clear the control_dependencies graph.
+                _old_stack = _graph._control_dependencies_stack;
+                _graph._control_dependencies_stack = new Queue<_ControlDependenciesController>();
+
+                // Clear the control_flow_context too.
+                _old_control_flow_context = _graph._get_control_flow_context();
+                _graph._set_control_flow_context(null);
+            }
+
+            _graph._push_control_dependencies_controller(this);
+        }
+
+        public void __exit__()
+        {
+            _graph._pop_control_dependencies_controller(this);
+            if (_new_stack)
+            {
+                _graph._control_dependencies_stack = _old_stack;
+                _graph._set_control_flow_context(_old_control_flow_context);
+            }
+        }
+
+        public void Dispose()
+        {
+            
+        }
+    }
+}

src/TensorFlowNET.Core/Operations/Operation.Input.cs

@@ -39,6 +39,14 @@ namespace Tensorflow
 
         public int NumControlInputs => c_api.TF_OperationNumControlInputs(_handle);
 
+        public Operation[] control_inputs
+        {
+            get
+            {
+                return GetControlInputs();
+            }
+        }
+
         public unsafe Operation[] GetControlInputs()
         {
             var control_inputs = new Operation[NumControlInputs];

src/TensorFlowNET.Core/Operations/Operation.cs

@@ -49,15 +49,53 @@ namespace Tensorflow
             c_api.TF_FinishOperation(desc, status);
         }
 
-        public Operation(NodeDef node_def, Graph g, List<Tensor> inputs = null, TF_DataType[] output_types = null, object control_inputs = null, TF_DataType[] input_types = null, string original_op = "", OpDef op_def = null)
+        /// <summary>
+        /// Creates an `Operation`.
+        /// </summary>
+        /// <param name="node_def">`node_def_pb2.NodeDef`.  `NodeDef` for the `Operation`.</param>
+        /// <param name="g">`Graph`. The parent graph.</param>
+        /// <param name="inputs">list of `Tensor` objects. The inputs to this `Operation`.</param>
+        /// <param name="output_types">list of `DType` objects.</param>
+        /// <param name="control_inputs">
+        /// list of operations or tensors from which to have a
+        /// control dependency.
+        /// </param>
+        /// <param name="input_types">
+        /// List of `DType` objects representing the
+        /// types of the tensors accepted by the `Operation`. By default
+        /// uses `[x.dtype.base_dtype for x in inputs]`.  Operations that expect
+        /// reference-typed inputs must specify these explicitly.
+        /// </param>
+        /// <param name="original_op"></param>
+        /// <param name="op_def"></param>
+        public Operation(NodeDef node_def, Graph g, List<Tensor> inputs = null, TF_DataType[] output_types = null, Operation[] control_inputs = null, TF_DataType[] input_types = null, string original_op = "", OpDef op_def = null)
         {
             Graph = g;
 
+            // Build the list of control inputs.
+            var control_input_ops = new List<Operation>();
+            if(control_inputs != null)
+            {
+                foreach(var c in control_inputs)
+                {
+                    switch (c)
+                    {
+                        case Operation c1:
+                            control_input_ops.Add(c1);
+                            break;
+                        default:
+                            throw new NotImplementedException($"Control input must be an Operation, a Tensor, or IndexedSlices: {c}");
+                    }
+                }
+            }
+
+            // This will be set by self.inputs.
+
             _id_value = Graph._next_id();
             if(op_def == null)
                 op_def = g.GetOpDef(node_def.Op);
 
-            _handle = ops._create_c_op(g, node_def, inputs);
+            _handle = ops._create_c_op(g, node_def, inputs, control_input_ops.ToArray());
 
             output_types = new TF_DataType[NumOutputs];
 

src/TensorFlowNET.Core/Operations/c_api.ops.cs

@@ -34,6 +34,14 @@ namespace Tensorflow
         [DllImport(TensorFlowLibName)]
         public static extern void TF_AddInput(IntPtr desc, TF_Output input);
 
+        /// <summary>
+        /// Call once per control input to `desc`.
+        /// </summary>
+        /// <param name="desc">TF_OperationDescription*</param>
+        /// <param name="input">TF_Operation*</param>
+        [DllImport(TensorFlowLibName)]
+        public static extern void TF_AddControlInput(IntPtr desc, IntPtr input);
+
         /// <summary>
         /// For inputs that take a list of tensors.
         /// inputs must point to TF_Output[num_inputs].

src/TensorFlowNET.Core/Operations/control_flow_ops.py.cs

@@ -13,9 +13,8 @@ namespace Tensorflow
             {
                 name = namescope;
 
-                var ops_on_device = new Dictionary<string, Operation[]>();
-
                 // Sorts *inputs according to their devices.
+                var ops_on_device = new Dictionary<string, Operation[]>();
                 foreach (var inp in inputs)
                 {
                     ops_on_device[inp.Device] = new Operation[] { inp };
@@ -24,7 +23,9 @@ namespace Tensorflow
                 // 1-level tree. The root node is the returned NoOp node.
                 if (ops_on_device.Count == 1)
                 {
-                    return _GroupControlDeps(ops_on_device.Keys.First(), ops_on_device.Values.First(), name);
+                    var dev = ops_on_device.Keys.First();
+                    var deps = ops_on_device.Values.First();
+                    return _GroupControlDeps(dev, deps, name);
                 }
 
                 // 2-level tree. The root node is the returned NoOp node.
@@ -35,12 +36,21 @@ namespace Tensorflow
 
         private static Operation _GroupControlDeps(string dev, Operation[] deps, string name = "")
         {
-            if (string.IsNullOrEmpty(dev))
+            Operation result = null;
+
+            Python.with(ops.control_dependencies(deps), delegate
             {
-                return gen_control_flow_ops.no_op(name);
-            }
+                if (string.IsNullOrEmpty(dev))
+                {
+                    result = gen_control_flow_ops.no_op(name);
+                }
+                else
+                {
+                    result = gen_control_flow_ops.no_op(name);
+                }
+            });
 
-            return null;
+            return result;
         }
     }
 }

src/TensorFlowNET.Core/Python.cs

@@ -13,5 +13,30 @@ namespace Tensorflow
         {
             Console.WriteLine(obj.ToString());
         }
+
+        public static void with(IPython py, Action action)
+        {
+            try
+            {
+                py.__enter__();
+                action();
+            }
+            catch (Exception ex)
+            {
+                throw ex;
+            }
+            finally
+            {
+                py.__exit__();
+                py.Dispose();
+            }
+        }
+    }
+
+    public interface IPython : IDisposable
+    {
+        void __enter__();
+
+        void __exit__();
     }
 }

src/TensorFlowNET.Core/Variables/RefVariable.Implicit.cs

@@ -20,5 +20,10 @@ namespace Tensorflow
         {
             return var._AsTensor();
         }
+
+        public static implicit operator RefVariable(Tensor var)
+        {
+            return null;
+        }
     }
 }

src/TensorFlowNET.Core/Variables/RefVariable.cs

@@ -166,5 +166,10 @@ namespace Tensorflow
             // Recursively build initializer expressions for inputs.
             return op;
         }
+
+        public override string ToString()
+        {
+            return $"tf.Variable '{name}' shape={shape} dtype={dtype}";
+        }
     }
 }

src/TensorFlowNET.Core/ops.py.cs

@@ -78,7 +78,29 @@ namespace Tensorflow
             }
         }
 
-        public static unsafe IntPtr _create_c_op(Graph graph, NodeDef node_def, List<Tensor> inputs)
+        /// <summary>
+        /// Wrapper for `Graph.control_dependencies()` using the default graph.
+        /// </summary>
+        /// <param name="control_inputs"></param>
+        public static _ControlDependenciesController control_dependencies(Operation[] control_inputs)
+        {
+            return get_default_graph().control_dependencies(control_inputs);
+        }
+
+        /// <summary>
+        /// Creates a TF_Operation.
+        /// </summary>
+        /// <param name="graph">a `Graph`.</param>
+        /// <param name="node_def">`node_def_pb2.NodeDef` for the operation to create.</param>
+        /// <param name="inputs">
+        /// A list of `Tensor`s (corresponding to scalar inputs) and lists of
+        /// `Tensor`s (corresponding to sequence inputs, e.g. "int64 * N",
+        /// "list(int64)"). The length of the list should be equal to the number of
+        /// inputs specified by this operation's op def.
+        /// </param>
+        /// <param name="control_inputs">A list of `Operation`s to set as control dependencies.</param>
+        /// <returns>A wrapped TF_Operation*.</returns>
+        public static IntPtr _create_c_op(Graph graph, NodeDef node_def, List<Tensor> inputs, Operation[] control_inputs)
         {
             var op_desc = graph.NewOperation(node_def.Op, node_def.Name);
 
@@ -102,6 +124,8 @@ namespace Tensorflow
             var status = new Status();
 
             // Add control inputs
+            foreach (var control_input in control_inputs)
+                c_api.TF_AddControlInput(op_desc, control_input);
 
             // Add attrs
             foreach (var attr in node_def.Attr)
@@ -170,8 +194,11 @@ namespace Tensorflow
             // inner_device_stack = default_graph._device_function_stack
             // var outer_context = default_graph.as_default;
 
-            var outer_graph = get_default_graph();
-            // outer_device_stack = None
+            Python.with(ops.control_dependencies(null), delegate
+            {
+                var outer_graph = get_default_graph();
+                // outer_device_stack = None
+            });
         }
 
         private static int uid_number = 0;

test/TensorFlowNET.UnitTest/VariableTest.cs

@@ -46,14 +46,13 @@ namespace TensorFlowNET.UnitTest
             var x = tf.Variable(10, name: "x");
 
             var model = tf.global_variables_initializer();
-
             using (var session = tf.Session())
             {
-                session.run(x.initializer);
+                session.run(model);
                 for(int i = 0; i < 5; i++)
                 {
-                    var x1 = x + 1;
-                    var result = session.run(x1);
+                    x = x + 1;
+                    var result = session.run(x);
                     print(result);
                 }
             }