Critical Path Optimization v1

schedulers/tetrisched/include/tetrisched/Expression.hpp

@@ -231,6 +231,13 @@ enum ExpressionType {
 };
 using ExpressionType = enum ExpressionType;
 
+/// A representation of the ranges on start and finish time.
+struct ExpressionTimeBounds {
+  TimeRange startTimeRange;
+  TimeRange endTimeRange;
+  std::string toString() const;
+};
+
 /// A Base Class for all expressions in the STRL language.
 class Expression : public std::enable_shared_from_this<Expression> {
  protected:
@@ -253,9 +260,6 @@ class Expression : public std::enable_shared_from_this<Expression> {
   /// Adds a parent to this expression.
   void addParent(ExpressionPtr parent);
 
-  /// Returns the parents of this Expression.
-  std::vector<ExpressionPtr> getParents() const;
-
  public:
   /// Construct the Expression class of the given type.
   Expression(std::string name, ExpressionType type);
@@ -283,12 +287,15 @@ class Expression : public std::enable_shared_from_this<Expression> {
   /// Returns the ID of this Expression.
   std::string getId() const;
 
-  /// Returns the number of children of this Expression.
-  size_t getNumChildren() const;
-
   /// Returns the number of parents of this Expression.
   size_t getNumParents() const;
 
+  /// Returns the parents of this Expression.
+  std::vector<ExpressionPtr> getParents() const;
+
+  /// Returns the number of children of this Expression.
+  size_t getNumChildren() const;
+
   /// Returns the children of this Expression.
   std::vector<ExpressionPtr> getChildren() const;
 

schedulers/tetrisched/include/tetrisched/OptimizationPasses.hpp

@@ -24,6 +24,15 @@ class CriticalPathOptimizationPass : public OptimizationPass {
   /// A map from an Expression's ID to the valid time bounds for it.
   std::unordered_map<std::string, ExpressionTimeBounds> expressionTimeBoundMap;
 
+  /// A helper method to recursively compute the time bounds for an Expression.
+  void computeTimeBounds(ExpressionPtr expression);
+
+  /// A helper method to push down the time bounds into the Expression tree.
+  void pushDownTimeBounds(ExpressionPtr expression);
+
+  /// A helper method to purge the nodes that do not fit their time bounds.
+  void purgeNodes(ExpressionPtr expression);
+
  public:
   /// Instantiate the Critical Path optimization pass.
   CriticalPathOptimizationPass();

schedulers/tetrisched/include/tetrisched/Types.hpp

@@ -79,12 +79,6 @@ using Time = uint32_t;
 /// start or the finish times from each Expression.
 using TimeRange = std::pair<Time, Time>;
 
-/// A representation of the ranges on start and finish time.
-struct ExpressionTimeBounds {
-  TimeRange startTimeRange;
-  TimeRange endTimeRange;
-};
-
 /// General forward declarations.
 class Expression;
 using ExpressionPtr = std::shared_ptr<Expression>;

schedulers/tetrisched/src/Expression.cpp

@@ -164,6 +164,13 @@ size_t CapacityConstraintMap::size() const {
 
 /* Method definitions for Expression */
 
+std::string ExpressionTimeBounds::toString() const {
+  return "Start: [" + std::to_string(startTimeRange.first) + ", " +
+         std::to_string(startTimeRange.second) + "], End: [" +
+         std::to_string(endTimeRange.first) + ", " +
+         std::to_string(endTimeRange.second) + "]";
+}
+
 Expression::Expression(std::string name, ExpressionType type)
     : name(name), id(tetrisched::uuid::generate_uuid()), type(type) {}
 
@@ -420,7 +427,7 @@ void Expression::exportToDot(std::string fileName) const {
 }
 
 std::string Expression::getDescriptiveName() const {
-  return this->getTypeString();
+  return this->getTypeString() + "(" + name + ")";
 }
 
 /* Method definitions for ChooseExpression */