Added a virtual base class for traverser engines.

arangod/Cluster/TraverserEngine.cpp

@@ -42,19 +42,9 @@ static const std::string EDGES = "edges";
 static const std::string VARIABLES = "variables";
 static const std::string VERTICES = "vertices";
 
-TraverserEngine::TraverserEngine(TRI_vocbase_t* vocbase,
-                                 arangodb::velocypack::Slice info)
-    : _opts(nullptr),
-      _query(nullptr),
-      _trx(nullptr),
-      _collections(vocbase) {
-  VPackSlice optsSlice = info.get(OPTIONS);
-  if (optsSlice.isNone() || !optsSlice.isObject()) {
-    THROW_ARANGO_EXCEPTION_MESSAGE(
-        TRI_ERROR_BAD_PARAMETER,
-        "The body requires a " + OPTIONS + " attribute.");
-  }
-
+BaseTraverserEngine::BaseTraverserEngine(TRI_vocbase_t* vocbase,
+                                         arangodb::velocypack::Slice info)
+    : _opts(nullptr), _query(nullptr), _trx(nullptr), _collections(vocbase) {
   VPackSlice shardsSlice = info.get(SHARDS);
   if (shardsSlice.isNone() || !shardsSlice.isObject()) {
     THROW_ARANGO_EXCEPTION_MESSAGE(
@@ -115,7 +105,6 @@ TraverserEngine::TraverserEngine(TRI_vocbase_t* vocbase,
           "The optional " + VARIABLES + " has to be an array.");
     }
     for (auto v : VPackArrayIterator(variablesSlice)) {
-      // TODO do we have to keep the variable somewhere?
       _query->ast()->variables()->createVariable(v);
     }
   }
@@ -123,10 +112,9 @@ TraverserEngine::TraverserEngine(TRI_vocbase_t* vocbase,
 
   _trx->begin(); // We begin the transaction before we lock.
                  // We also setup indexes before we lock.
-  _opts.reset(new TraverserOptions(_query, optsSlice, edgesSlice));
 }
 
-TraverserEngine::~TraverserEngine() {
+BaseTraverserEngine::~BaseTraverserEngine() {
   /*
   auto resolver = _trx->resolver();
   // TODO Do we need this or will delete trx do this already?
@@ -151,7 +139,7 @@ TraverserEngine::~TraverserEngine() {
   }
 }
 
-void TraverserEngine::getEdges(VPackSlice vertex, size_t depth, VPackBuilder& builder) {
+void BaseTraverserEngine::getEdges(VPackSlice vertex, size_t depth, VPackBuilder& builder) {
   // We just hope someone has locked the shards properly. We have no clue... Thanks locking
 
   TRI_ASSERT(vertex.isString() || vertex.isArray());
@@ -200,7 +188,7 @@ void TraverserEngine::getEdges(VPackSlice vertex, size_t depth, VPackBuilder& bu
   builder.close();
 }
 
-void TraverserEngine::getVertexData(VPackSlice vertex, VPackBuilder& builder) {
+void BaseTraverserEngine::getVertexData(VPackSlice vertex, VPackBuilder& builder) {
   // We just hope someone has locked the shards properly. We have no clue...
   // Thanks locking
   TRI_ASSERT(vertex.isString() || vertex.isArray());
@@ -248,7 +236,7 @@ void TraverserEngine::getVertexData(VPackSlice vertex, VPackBuilder& builder) {
   builder.close(); // The outer object
 }
 
-void TraverserEngine::getVertexData(VPackSlice vertex, size_t depth,
+void BaseTraverserEngine::getVertexData(VPackSlice vertex, size_t depth,
                                     VPackBuilder& builder) {
   // We just hope someone has locked the shards properly. We have no clue...
   // Thanks locking
@@ -305,12 +293,12 @@ void TraverserEngine::getVertexData(VPackSlice vertex, size_t depth,
   builder.close();
 }
 
-void TraverserEngine::smartSearch(VPackSlice,
+void BaseTraverserEngine::smartSearch(VPackSlice,
                                   VPackBuilder&) {
   THROW_ARANGO_EXCEPTION(TRI_ERROR_ONLY_ENTERPRISE);
 }
 
-bool TraverserEngine::lockCollection(std::string const& shard) {
+bool BaseTraverserEngine::lockCollection(std::string const& shard) {
   if (_locked.find(shard) != _locked.end()) {
     return false;
   }
@@ -329,6 +317,25 @@ bool TraverserEngine::lockCollection(std::string const& shard) {
   return true;
 }
 
-std::shared_ptr<arangodb::TransactionContext> TraverserEngine::context() const {
+std::shared_ptr<arangodb::TransactionContext> BaseTraverserEngine::context() const {
   return _trx->transactionContext();
 }
+
+TraverserEngine::TraverserEngine(TRI_vocbase_t* vocbase,
+                                 arangodb::velocypack::Slice info)
+    : BaseTraverserEngine(vocbase, info) {
+  VPackSlice optsSlice = info.get(OPTIONS);
+  if (optsSlice.isNone() || !optsSlice.isObject()) {
+    THROW_ARANGO_EXCEPTION_MESSAGE(
+        TRI_ERROR_BAD_PARAMETER,
+        "The body requires a " + OPTIONS + " attribute.");
+  }
+  VPackSlice shardsSlice = info.get(SHARDS);
+  VPackSlice edgesSlice = shardsSlice.get(EDGES);
+
+  _opts.reset(new TraverserOptions(_query, optsSlice, edgesSlice));
+}
+
+
+TraverserEngine::~TraverserEngine() {
+}

arangod/Cluster/TraverserEngine.h

@@ -46,8 +46,7 @@ class Slice;
 namespace traverser {
 struct TraverserOptions;
 
-class TraverserEngine {
-
+class BaseTraverserEngine {
   friend class TraverserEngineRegistry;
   protected:
   // These are private on purpose.
@@ -56,13 +55,13 @@ class TraverserEngine {
   // We can get into undefined state if sth.
   // deletes an engine but the registry
   // does not get informed properly
-    TraverserEngine(TRI_vocbase_t*, arangodb::velocypack::Slice);
+    BaseTraverserEngine(TRI_vocbase_t*, arangodb::velocypack::Slice);
 
   public:
-    virtual ~TraverserEngine();
+    virtual ~BaseTraverserEngine();
 
    // The engine is NOT copyable.
-   TraverserEngine(TraverserEngine const&) = delete;
+   BaseTraverserEngine(BaseTraverserEngine const&) = delete;
 
    void getEdges(arangodb::velocypack::Slice, size_t,
                  arangodb::velocypack::Builder&);
@@ -80,7 +79,7 @@ class TraverserEngine {
 
    std::shared_ptr<TransactionContext> context() const;
 
-  private:
+  protected:
     std::unique_ptr<TraverserOptions> _opts;
     arangodb::aql::Query* _query;
     arangodb::Transaction* _trx;
@@ -88,6 +87,22 @@ class TraverserEngine {
     std::unordered_set<std::string> _locked;
     std::unordered_map<std::string, std::vector<std::string>> _vertexShards;
 };
+
+class TraverserEngine : public BaseTraverserEngine {
+  friend class TraverserEngineRegistry;
+  private:
+  // These are private on purpose.
+  // Only the Registry (friend) is allowed
+  // to create and destroy engines.
+  // We can get into undefined state if sth.
+  // deletes an engine but the registry
+  // does not get informed properly
+ 
+    TraverserEngine(TRI_vocbase_t*, arangodb::velocypack::Slice);
+  public:
+    ~TraverserEngine();
+};
+
 } // namespace traverser
 } // namespace arangodb
 

arangod/Cluster/TraverserEngineRegistry.cpp

@@ -70,7 +70,7 @@ void TraverserEngineRegistry::destroy(TraverserEngineID id) {
 }
 
 /// @brief Get the engine with the given id
-TraverserEngine* TraverserEngineRegistry::get(TraverserEngineID id) {
+BaseTraverserEngine* TraverserEngineRegistry::get(TraverserEngineID id) {
   WRITE_LOCKER(writeLocker, _lock);
   auto e = _engines.find(id);
   if (e == _engines.end()) {

arangod/Cluster/TraverserEngineRegistry.h

@@ -32,13 +32,13 @@ struct TRI_vocbase_t;
 namespace arangodb {
 namespace traverser {
 
-class TraverserEngine;
+class BaseTraverserEngine;
 
 /// @brief type of a Traverser Engine Id
 typedef TRI_voc_tick_t TraverserEngineID;
 
 class TraverserEngineRegistry {
-  friend class TraverserEngine;
+  friend class BaseTraverserEngine;
  public:
   TraverserEngineRegistry() {}
 
@@ -53,7 +53,7 @@ class TraverserEngineRegistry {
   /// @brief Get the engine with the given ID.
   ///        TODO Test what happens if this pointer
   ///        is requested twice in parallel?
-  TraverserEngine* get(TraverserEngineID);
+  BaseTraverserEngine* get(TraverserEngineID);
 
   /// @brief Destroys the engine with the given id.
   void destroy(TraverserEngineID);
@@ -68,11 +68,11 @@ class TraverserEngineRegistry {
   void destroy(TraverserEngineID, bool doLock);
 
   struct EngineInfo {
-    bool _isInUse;                            // Flag if this engine is in use
-    std::unique_ptr<TraverserEngine> _engine; // The real engine
+    bool _isInUse;                                 // Flag if this engine is in use
+    std::unique_ptr<BaseTraverserEngine> _engine;  // The real engine
 
-    double _timeToLive;                       // in seconds
-    double _expires;                          // UNIX UTC timestamp for expiration
+    double _timeToLive;                            // in seconds
+    double _expires;                               // UNIX UTC timestamp for expiration
 
     EngineInfo(TRI_vocbase_t*, arangodb::velocypack::Slice);
     ~EngineInfo();

arangod/Utils/Transaction.h

@@ -63,7 +63,7 @@ struct Variable;
 }
 
 namespace traverser {
-class TraverserEngine;
+class BaseTraverserEngine;
 }
 
 //////////////////////////////////////////////////////////////////////////////
@@ -76,7 +76,7 @@ struct OperationCursor;
 class TransactionContext;
 
 class Transaction {
-  friend class traverser::TraverserEngine;
+  friend class traverser::BaseTraverserEngine;
 
  public: