1 files changed, 70 insertions, 17 deletions

diff --git a/src/armnn/Graph.hpp b/src/armnn/Graph.hpp
index 06b6fd32ae..fd81e51b7b 100644
--- a/src/armnn/Graph.hpp
+++ b/src/armnn/Graph.hpp
@@ -5,6 +5,7 @@
 #pragma once
 
 #include "LayersFwd.hpp"
+#include "IGraphObservable.hpp"
 
 #include <armnn/Types.hpp>
 #include <armnn/TensorFwd.hpp>
@@ -12,6 +13,7 @@
 #include <armnn/Exceptions.hpp>
 
 #include <list>
+#include <map>
 #include <unordered_map>
 #include <unordered_set>
 #include <vector>
@@ -21,6 +23,7 @@
 
 namespace armnn
 {
+
 class Graph
 {
 public:
@@ -31,7 +34,7 @@ public:
     }
 
     using LayersList = std::list<Layer*>;
-    using Iterator = LayersList::const_iterator; // const so pointers in the list can't be modified externally
+    using Iterator = LayersList::const_iterator; // Const so pointers in the list can't be modified externally.
     using ConstIterator = boost::transform_iterator<decltype(&PtrCast<const Layer>), Iterator>;
     using IteratorDifference = Iterator::difference_type;
 
@@ -94,7 +97,7 @@ public:
 
     Status SerializeToDot(std::ostream& stream);
 
-    /// Adds a new layer of type LaterType to the graph constructed with the arguments passed.
+    /// Adds a new layer, of type LayerType, to the graph constructed with the arguments passed.
     template <typename LayerT, typename... Args>
     LayerT* AddLayer(Args&&... args);
 
@@ -103,6 +106,10 @@ public:
     template <typename LayerT, typename... Args>
     LayerT* InsertNewLayer(InputSlot& insertBefore, Args&&... args);
 
+    /// Inserts a new layer between insertAfter and the input slot(s) currently connected to it
+    template <typename LayerT, typename... Args>
+    LayerT* InsertNewLayer(OutputSlot& insertAfter, Args&&... args);
+
     /// Deletes the layer at the specified position and returns an iterator pointing
     /// to the next element after the one being deleted.
     Iterator EraseLayer(Iterator pos);
@@ -113,22 +120,22 @@ public:
     template <typename LayerT>
     Iterator EraseLayer(LayerT*& layer);
 
-    /// Return iterator pointing to begin of list. Lowercase for range-based for loops.
+    /// Returns iterator pointing to the beginning of the list. Lowercase for range-based for loops.
     Iterator begin() { return m_Layers.begin(); }
-    /// Return iterator pointing to end of list. Lowercase for range-based for loops.
+    /// Returns iterator pointing to the end of the list. Lowercase for range-based for loops.
     Iterator end() { return m_Layers.end(); }
 
-    /// Return const iterator pointing to begin of list. Lowercase for range-based for loops.
+    /// Returns const iterator pointing to the beginning of the list. Lowercase for range-based for loops.
     ConstIterator begin() const { return {m_Layers.begin(), &PtrCast<const Layer>}; }
-    /// Return const iterator pointing to end of list. Lowercase for range-based for loops.
+    /// Returns const iterator pointing to the end of the list. Lowercase for range-based for loops.
     ConstIterator end() const { return {m_Layers.end(), &PtrCast<const Layer>}; }
 
-    /// Return const iterator pointing to begin of list. Lowercase for range-based for loops.
+    /// Returns const iterator pointing to the beginning of the list. Lowercase for range-based for loops.
     ConstIterator cbegin() const { return begin(); }
-    /// Return const iterator pointing to end of list. Lowercase for range-based for loops.
+    /// Returns const iterator pointing to the end of the list. Lowercase for range-based for loops.
     ConstIterator cend() const { return end(); }
 
-    /// Sort layers in topological order and return this.
+    /// Sorts layers in topological order and return this.
     Graph& TopologicalSort() { const_cast<const Graph*>(this)->TopologicalSort(); return *this; }
     const Graph& TopologicalSort() const;
 
@@ -136,16 +143,16 @@ public:
     size_t GetNumOutputs() const { return m_OutputIds.size(); }
 
     /// Returns a wrapper object with begin(), end() methods to iterate over the input layers
-    /// in a range-based for loop
+    /// in a range-based for loop.
     InputLayersAccessor GetInputLayers() const { return InputLayersAccessor(*this); }
 
     /// Returns a wrapper object with begin(), end() methods to iterate over the output layers
-    /// in a range-based for loop
+    /// in a range-based for loop.
     OutputLayersAccessor GetOutputLayers() const { return OutputLayersAccessor(*this); }
 
     size_t GetNumLayers() const { return m_Layers.size(); }
 
-    /// Allocate memory for all tensors under output tensor handers of each layer
+    /// Allocates memory for all tensors under output tensor handers of each layer.
     Status AllocateDynamicBuffers();
 
     /// Modifies the graph in-place, removing edges connecting layers using different compute devices,
@@ -154,6 +161,14 @@ public:
 
     void InferTensorInfos();
 
+    void AttachObservable(IGraphObservable* const observable, GraphEvent notifyOnEvent) {
+        m_Views[notifyOnEvent].emplace_back(observable);
+    }
+
+    void DetachObservable(IGraphObservable* const observable, GraphEvent notifyOnEvent) {
+        m_Views[notifyOnEvent].remove(observable);
+    }
+
 private:
     template <typename LayerT>
     class LayerInGraphBase;
@@ -179,9 +194,18 @@ private:
         return it;
     }
 
-    /// Get the position of a layer in the graph.
+    /// Gets the position of a layer in the graph.
     Iterator GetPosInGraph(Layer& layer);
 
+    void NotifyObservables(GraphEvent event, Layer* graphState)
+    {
+        // Iterate over all observables observing this event
+        for (auto& observable : m_Views[event])
+        {
+            observable->Update(graphState);
+        }
+    }
+
     std::unordered_set<LayerBindingId> m_InputIds;
     std::unordered_set<LayerBindingId> m_OutputIds;
     std::unordered_map<const Layer*, Iterator> m_PosInGraphMap;
@@ -189,9 +213,11 @@ private:
     /// Mutable to allow sorting on const object.
     mutable LayersList m_Layers;
     mutable bool m_LayersInOrder;
+
+    std::map<const GraphEvent, std::list<IGraphObservable*>> m_Views;
 };
 
-/// Common base class for layers in the graph
+/// Common base class for layers in the graph.
 template <typename LayerT>
 class Graph::LayerInGraphBase : public LayerT
 {
@@ -212,7 +238,7 @@ protected:
     Graph& m_Graph;
 };
 
-/// Input/Output layers specialize this template
+/// Input/Output layers specialize this template.
 template <typename LayerT>
 class Graph::LayerInGraph final : public LayerInGraphBase<LayerT>
 {
@@ -305,24 +331,51 @@ inline LayerT* Graph::AddLayer(Args&&... args)
 {
     m_LayersInOrder = m_LayersInOrder &&
         ((LayerEnumOf<LayerT>() == LayerType::Input) || (LayerEnumOf<LayerT>() == LayerType::Output));
-    return new LayerInGraph<LayerT>(*this, std::forward<Args>(args)...);
+    LayerT* const layer = new LayerInGraph<LayerT>(*this, std::forward<Args>(args)...);
+
+    NotifyObservables(GraphEvent::LayerAdded, layer);
+
+    return layer;
 }
 
 template <typename LayerT, typename... Args>
 inline LayerT* Graph::InsertNewLayer(InputSlot& insertBefore, Args&&... args)
 {
-    // Insert after the parent if any, or before the child otherwise, so topological order is kept.
+    // Insert after the parent if any, or before the child otherwise, so the topological order is kept.
     OutputSlot* parentOut = insertBefore.GetConnectedOutputSlot();
     const Iterator pos = (parentOut != nullptr)
                          ? std::next(GetPosInGraph(parentOut->GetOwningLayer()))
                          : GetPosInGraph(insertBefore.GetOwningLayer());
     LayerT* const layer = new LayerInGraph<LayerT>(*this, pos, std::forward<Args>(args)...);
     insertBefore.Insert(*layer);
+
+    NotifyObservables(GraphEvent::LayerAdded, layer);
+
+    return layer;
+}
+
+template <typename LayerT, typename... Args>
+inline LayerT* Graph::InsertNewLayer(OutputSlot& insertAfter, Args&&... args)
+{
+    Layer& owningLayer = insertAfter.GetOwningLayer();
+
+    const Iterator pos = std::next(GetPosInGraph(owningLayer));
+    LayerT* const layer = new LayerInGraph<LayerT>(*this, pos, std::forward<Args>(args)...);
+
+    BOOST_ASSERT(layer->GetNumInputSlots() == 1);
+
+    insertAfter.MoveAllConnections(layer->GetOutputSlot());
+    insertAfter.Connect(layer->GetInputSlot(0));
+
+    NotifyObservables(GraphEvent::LayerAdded, layer);
+
     return layer;
 }
 
 inline Graph::Iterator Graph::EraseLayer(Iterator pos)
 {
+    NotifyObservables(GraphEvent::LayerErased, *pos);
+
     delete *pos;
     return m_Layers.erase(pos);
 }