query result cache: add fake stringify for some nodes

arangod/Aql/ExecutionNode.cpp

@@ -76,27 +76,24 @@ std::unordered_map<int, std::string const> const ExecutionNode::TypeNames{
     {static_cast<int>(SHORTEST_PATH), "ShortestPathNode"}};
 
 
-std::string ExecutionNode::fakeQueryString() const {
+bool ExecutionNode::fakeQueryString(std::string& outString) const {
 // returns fake querystring that is used to create a hash key
 // for queries on DBServers in cluster-mode
-  std::string rv="";
-  std::string thisNode = fakeQueryStringThisNode();
-  if (thisNode.empty()) { return thisNode; }
+  bool rv = fakeQueryStringThisNode(outString);
+  if (!rv) { return false; }
 
   else {
     for(auto* node : this->getDependencies()){
-      std::string childString = node->fakeQueryString();
-      if(childString.empty()){ return childString; }
-      rv += childString;
+      rv = node->fakeQueryString(outString);
+      if(!rv){ return false; }
     }
-    rv += thisNode;
   }
   return rv;
 }
 
 // protected - virtual 
-std::string ExecutionNode::fakeQueryStringThisNode() const {
-  return ""; // override in cache-able Nodes
+bool ExecutionNode::fakeQueryStringThisNode(std::string&) const {
+  return false;
 }
 
 /// @brief returns the type name of the node
@@ -1155,6 +1152,11 @@ double SingletonNode::estimateCost(size_t& nrItems) const {
   return 1.0;
 }
 
+bool SingletonNode::fakeQueryStringThisNode(std::string& outString) const {
+  outString.append("S");
+  return true;
+}
+
 EnumerateCollectionNode::EnumerateCollectionNode(
     ExecutionPlan* plan, arangodb::velocypack::Slice const& base)
     : ExecutionNode(plan, base),
@@ -1167,6 +1169,15 @@ EnumerateCollectionNode::EnumerateCollectionNode(
   TRI_ASSERT(_collection != nullptr);
 }
 
+bool EnumerateCollectionNode::fakeQueryStringThisNode(std::string& outString) const {
+  if(_random) { return false; }
+  outString.append("EC");
+  outString.append(_collection->name);
+  outString.append(_outVariable->name); // is this ok?
+  //vocbase? do we alrady have the db context outside?!
+  return true;
+}
+
 /// @brief toVelocyPack, for EnumerateCollectionNode
 void EnumerateCollectionNode::toVelocyPackHelper(VPackBuilder& nodes,
                                                  bool verbose) const {
@@ -1227,6 +1238,14 @@ EnumerateListNode::EnumerateListNode(ExecutionPlan* plan,
       _inVariable(Variable::varFromVPack(plan->getAst(), base, "inVariable")),
       _outVariable(Variable::varFromVPack(plan->getAst(), base, "outVariable")) {}
 
+bool EnumerateListNode::fakeQueryStringThisNode(std::string& outString) const {
+  outString.append("EL");
+  outString.append(_outVariable->name);
+  outString.append(_inVariable->name);
+  //outString.append(_inVariable->);
+  return true;
+}
+
 /// @brief toVelocyPack, for EnumerateListNode
 void EnumerateListNode::toVelocyPackHelper(VPackBuilder& nodes,
                                            bool verbose) const {
@@ -1672,6 +1691,12 @@ ReturnNode::ReturnNode(ExecutionPlan* plan, arangodb::velocypack::Slice const& b
     : ExecutionNode(plan, base),
       _inVariable(Variable::varFromVPack(plan->getAst(), base, "inVariable")) {}
 
+bool ReturnNode::fakeQueryStringThisNode(std::string& outString) const {
+  outString.append("R");
+  outString.append(_inVariable->name);
+  return true;
+}
+
 /// @brief toVelocyPack, for ReturnNode
 void ReturnNode::toVelocyPackHelper(VPackBuilder& nodes, bool verbose) const {
   ExecutionNode::toVelocyPackHelperGeneric(nodes,

arangod/Aql/ExecutionNode.h

@@ -156,7 +156,7 @@ class ExecutionNode {
   static ExecutionNode* fromVPackFactory(ExecutionPlan* plan,
                                          arangodb::velocypack::Slice const& slice);
 
-  std::string fakeQueryString() const;
+  bool fakeQueryString(std::string&) const;
 
   /// @brief return the node's id
   inline size_t id() const { return _id; }
@@ -580,7 +580,7 @@ class ExecutionNode {
 
  protected:
   /// create sting representation of this node and its children
-  virtual std::string fakeQueryStringThisNode() const;
+  virtual bool fakeQueryStringThisNode(std::string&) const;
 
   /// @brief factory for sort elements
   static void getSortElements(SortElementVector& elements, ExecutionPlan* plan,
@@ -663,6 +663,7 @@ class SingletonNode : public ExecutionNode {
   SingletonNode(ExecutionPlan* plan, arangodb::velocypack::Slice const& base)
       : ExecutionNode(plan, base) {}
 
+  bool fakeQueryStringThisNode(std::string& outString) const override;
   /// @brief return the type of the node
   NodeType getType() const override final { return SINGLETON; }
 
@@ -706,7 +707,8 @@ class EnumerateCollectionNode : public ExecutionNode, public DocumentProducingNo
 
   EnumerateCollectionNode(ExecutionPlan* plan,
                           arangodb::velocypack::Slice const& base);
-
+
+  virtual bool fakeQueryStringThisNode(std::string&) const override;
   /// @brief return the type of the node
   NodeType getType() const override final { return ENUMERATE_COLLECTION; }
 
@@ -770,6 +772,8 @@ class EnumerateListNode : public ExecutionNode {
 
   EnumerateListNode(ExecutionPlan*, arangodb::velocypack::Slice const& base);
 
+  virtual bool fakeQueryStringThisNode(std::string&) const override;
+
   /// @brief return the type of the node
   NodeType getType() const override final { return ENUMERATE_LIST; }
 
@@ -1185,6 +1189,8 @@ class ReturnNode : public ExecutionNode {
 
   ReturnNode(ExecutionPlan*, arangodb::velocypack::Slice const& base);
 
+  bool fakeQueryStringThisNode(std::string& outString) const override;
+
   /// @brief return the type of the node
   NodeType getType() const override final { return RETURN; }