dataflow_cpp: check for cycles in graph

dataflow_cpp/include/embb/dataflow/internal/clock_listener.h

@@ -35,6 +35,7 @@ class ClockListener {
  public:
   virtual ~ClockListener() {}
   virtual void OnClock(int /*clock*/) = 0;
+  virtual bool OnHasCycle(ClockListener * /*node*/) { return false; }
 };
 
 } // namespace internal

dataflow_cpp/include/embb/dataflow/internal/in.h

@@ -73,6 +73,10 @@ class In {
   bool IsConnected() const { return connected_; }
   void SetConnected() { connected_ = true; }
 
+  bool HasCycle(ClockListener * node) {
+    return listener_->OnHasCycle(node);
+  }
+
   void SetSlices(int slices) {
     slices_ = slices;
     values_ = reinterpret_cast<SignalType*>(

dataflow_cpp/include/embb/dataflow/internal/inputs.h

@@ -106,6 +106,9 @@ class Inputs<T1, embb::base::internal::Nil, embb::base::internal::Nil,
       listener_->OnClock(clock);
     }
   }
+  virtual bool OnHasCycle(ClockListener * node) {
+    return listener_->OnHasCycle(node);
+  }
   bool IsFullyConnected() {
     return this->template Get<0>().IsConnected();
   }
@@ -164,6 +167,9 @@ class Inputs<T1, T2, embb::base::internal::Nil,
       listener_->OnClock(clock);
     }
   }
+  virtual bool OnHasCycle(ClockListener * node) {
+    return listener_->OnHasCycle(node);
+  }
   bool IsFullyConnected() {
     return this->template Get<0>().IsConnected() &
       this->template Get<1>().IsConnected();
@@ -228,6 +234,9 @@ class Inputs<T1, T2, T3, embb::base::internal::Nil,
       listener_->OnClock(clock);
     }
   }
+  virtual bool OnHasCycle(ClockListener * node) {
+    return listener_->OnHasCycle(node);
+  }
   bool IsFullyConnected() {
     return this->template Get<0>().IsConnected() &
       this->template Get<1>().IsConnected() &
@@ -297,6 +306,9 @@ class Inputs<T1, T2, T3, T4, embb::base::internal::Nil>
       listener_->OnClock(clock);
     }
   }
+  virtual bool OnHasCycle(ClockListener * node) {
+    return listener_->OnHasCycle(node);
+  }
   bool IsFullyConnected() {
     return this->template Get<0>().IsConnected() &
       this->template Get<1>().IsConnected() &
@@ -373,6 +385,9 @@ class Inputs
       listener_->OnClock(clock);
     }
   }
+  virtual bool OnHasCycle(ClockListener * node) {
+    return listener_->OnHasCycle(node);
+  }
   bool IsFullyConnected() {
     return this->template Get<0>().IsConnected() &&
       this->template Get<1>().IsConnected() &

dataflow_cpp/include/embb/dataflow/internal/node.h

@@ -44,6 +44,7 @@ class Node {
   virtual bool HasOutputs() const { return false; }
   virtual void Run(int clock) = 0;
   virtual bool IsFullyConnected() = 0;
+  virtual bool HasCycle() { return false; }
   virtual bool Start(int /*clock*/) {
     EMBB_THROW(embb::base::ErrorException,
       "Nodes are started implicitly.");

dataflow_cpp/include/embb/dataflow/internal/out.h

@@ -36,6 +36,7 @@ namespace dataflow {
 namespace internal {
 
 class Scheduler;
+class ClockListener;
 
 template <typename Type>
 class Out {
@@ -70,6 +71,14 @@ class Out {
     return targets_.size() > 0;
   }
 
+  bool HasCycle(ClockListener * node) {
+    bool result = false;
+    for (size_t ii = 0; ii < targets_.size() && !result; ii++) {
+      result = result || targets_[ii]->HasCycle(node);
+    }
+    return result;
+  }
+
  private:
   std::vector< InType * > targets_;
 };

dataflow_cpp/include/embb/dataflow/internal/outputs.h

@@ -42,6 +42,8 @@ template <
   typename = embb::base::internal::Nil >
 class Outputs;
 
+class ClockListener;
+
 template <>
 class Outputs<embb::base::internal::Nil, embb::base::internal::Nil,
   embb::base::internal::Nil, embb::base::internal::Nil,
@@ -53,6 +55,9 @@ class Outputs<embb::base::internal::Nil, embb::base::internal::Nil,
   bool IsFullyConnected() {
     return true;
   }
+  bool HasCycle(ClockListener * /*node*/) {
+    return false;
+  }
 };
 
 template <typename T1>
@@ -65,6 +70,9 @@ class Outputs<T1, embb::base::internal::Nil, embb::base::internal::Nil,
   bool IsFullyConnected() {
     return this->template Get<0>().IsConnected();
   }
+  bool HasCycle(ClockListener * node) {
+    return this->template Get<0>().HasCycle(node);
+  }
 };
 
 template <typename T1, typename T2>
@@ -77,6 +85,10 @@ class Outputs<T1, T2, embb::base::internal::Nil,
     return this->template Get<0>().IsConnected() &&
       this->template Get<1>().IsConnected();
   }
+  bool HasCycle(ClockListener * node) {
+    return this->template Get<0>().HasCycle(node) ||
+      this->template Get<1>().HasCycle(node);
+  }
 };
 
 template <typename T1, typename T2, typename T3>
@@ -90,6 +102,11 @@ class Outputs<T1, T2, T3, embb::base::internal::Nil,
       this->template Get<1>().IsConnected() &&
       this->template Get<2>().IsConnected();
   }
+  bool HasCycle(ClockListener * node) {
+    return this->template Get<0>().HasCycle(node) ||
+      this->template Get<1>().HasCycle(node) ||
+      this->template Get<2>().HasCycle(node);
+  }
 };
 
 template <typename T1, typename T2, typename T3, typename T4>
@@ -103,6 +120,12 @@ class Outputs<T1, T2, T3, T4, embb::base::internal::Nil>
       this->template Get<2>().IsConnected() &&
       this->template Get<3>().IsConnected();
   }
+  bool HasCycle(ClockListener * node) {
+    return this->template Get<0>().HasCycle(node) ||
+      this->template Get<1>().HasCycle(node) ||
+      this->template Get<2>().HasCycle(node) ||
+      this->template Get<3>().HasCycle(node);
+  }
 };
 
 template <typename T1, typename T2, typename T3, typename T4,
@@ -118,6 +141,13 @@ class Outputs
       this->template Get<3>().IsConnected() &&
       this->template Get<4>().IsConnected();
   }
+  bool HasCycle(ClockListener * node) {
+    return this->template Get<0>().HasCycle(node) ||
+      this->template Get<1>().HasCycle(node) ||
+      this->template Get<2>().HasCycle(node) ||
+      this->template Get<3>().HasCycle(node) ||
+      this->template Get<4>().HasCycle(node);
+  }
 };
 
 } // namespace internal

dataflow_cpp/include/embb/dataflow/internal/process.h

@@ -98,6 +98,10 @@ class Process< Serial, Inputs<I1, I2, I3, I4, I5>,
     return inputs_.IsFullyConnected() && outputs_.IsFullyConnected();
   }
 
+  virtual bool HasCycle() {
+    return outputs_.HasCycle(this);
+  }
+
   InputsType & GetInputs() {
     return inputs_;
   }
@@ -160,6 +164,15 @@ class Process< Serial, Inputs<I1, I2, I3, I4, I5>,
     }
   }
 
+  virtual bool OnHasCycle(ClockListener * node) {
+    ClockListener * this_node = this;
+    if (this_node == node) {
+      return true;
+    } else {
+      return outputs_.HasCycle(node);
+    }
+  }
+
  private:
   InputsType inputs_;
   OutputsType outputs_;

dataflow_cpp/include/embb/dataflow/internal/select.h

@@ -85,6 +85,15 @@ class Select
     return inputs_.IsFullyConnected() && outputs_.IsFullyConnected();
   }
 
+  virtual bool OnHasCycle(ClockListener * node) {
+    ClockListener * this_node = this;
+    if (this_node == node) {
+      return true;
+    } else {
+      return outputs_.HasCycle(node);
+    }
+  }
+
   InputsType & GetInputs() {
     return inputs_;
   }

dataflow_cpp/include/embb/dataflow/internal/switch.h

@@ -82,6 +82,15 @@ class Switch
     return inputs_.IsFullyConnected() && outputs_.IsFullyConnected();
   }
 
+  virtual bool OnHasCycle(ClockListener * node) {
+    ClockListener * this_node = this;
+    if (this_node == node) {
+      return true;
+    } else {
+      return outputs_.HasCycle(node);
+    }
+  }
+
   InputsType & GetInputs() {
     return inputs_;
   }

dataflow_cpp/include/embb/dataflow/network.h

@@ -838,14 +838,19 @@ class Network : public internal::ClockListener {
 
   bool IsValid() {
     bool valid = true;
-    for (size_t ii = 0; ii < sources_.size(); ii++) {
-      valid = valid & sources_[ii]->IsFullyConnected();
+    // check connectivity
+    for (size_t ii = 0; ii < sources_.size() && valid; ii++) {
+      valid = valid && sources_[ii]->IsFullyConnected();
     }
-    for (size_t ii = 0; ii < processes_.size(); ii++) {
-      valid = valid & processes_[ii]->IsFullyConnected();
+    for (size_t ii = 0; ii < processes_.size() && valid; ii++) {
+      valid = valid && processes_[ii]->IsFullyConnected();
     }
-    for (size_t ii = 0; ii < sinks_.size(); ii++) {
-      valid = valid & sinks_[ii]->IsFullyConnected();
+    for (size_t ii = 0; ii < sinks_.size() && valid; ii++) {
+      valid = valid && sinks_[ii]->IsFullyConnected();
+    }
+    // check for cycles
+    for (size_t ii = 0; ii < processes_.size() && valid; ii++) {
+      valid = valid && !processes_[ii]->HasCycle();
     }
     return valid;
   }