cleanup v8 expressions in coordinator, too

arangod/Aql/Ast.cpp

@@ -1080,10 +1080,15 @@ AstNode* Ast::createArithmeticResultNode (double value) {
 
 AstNode* Ast::executeConstExpression (AstNode const* node) {
   // must enter v8 before we can execute any expression
-  v8::HandleScope scope; // do not delete this!
   _query->enterContext();
+  
+  v8::HandleScope scope; // do not delete this!
+
   TRI_json_t* result = _query->executor()->executeExpression(node); 
 
+  // context is not left here, but later
+  // this allows re-using the same context for multiple expressions
+
   if (result == nullptr) {
     THROW_ARANGO_EXCEPTION(TRI_ERROR_OUT_OF_MEMORY);
   }

arangod/Aql/ExecutionBlock.cpp

@@ -957,7 +957,7 @@ bool IndexRangeBlock::readIndex () {
         
         // must invalidate the expression now as we might be called from
         // different threads
-        if (ExecutionEngine::isDBServer()) {
+        if (ExecutionEngine::isDBServer() || ExecutionEngine::isCoordinator()) {
           for (auto e : _allVariableBoundExpressions) {
             e->invalidate();
           }
@@ -1915,7 +1915,7 @@ void CalculationBlock::doEvaluation (AqlItemBlock* result) {
       [&]() -> void { 
         // must invalidate the expression now as we might be called from
         // different threads
-        if (ExecutionEngine::isDBServer()) {
+        if (ExecutionEngine::isDBServer() || ExecutionEngine::isCoordinator()) {
           _expression->invalidate();
         }
         engine->getQuery()->exitContext(); 

arangod/Aql/Expression.cpp

@@ -82,6 +82,7 @@ Expression::Expression (Ast* ast,
 Expression::~Expression () {
   if (_type == V8) {
     delete _func;
+    _func = nullptr;
   }
   else if (_type == JSON) {
     TRI_ASSERT(_data != nullptr);