optimizations for primary index lookups

arangod/Indexes/PrimaryIndex.cpp

@@ -29,6 +29,7 @@
 #include "Basics/tri-strings.h"
 #include "Indexes/SimpleAttributeEqualityMatcher.h"
 #include "Utils/Transaction.h"
+#include "Utils/TransactionContext.h"
 #include "VocBase/document-collection.h"
 #include "VocBase/transaction.h"
 
@@ -77,6 +78,13 @@ static bool IsEqualElementElement(void*, TRI_doc_mptr_t const* left,
   return l.equals(r);
 }
 
+PrimaryIndexIterator::~PrimaryIndexIterator() {
+  if (_keys != nullptr) {
+    // return the VPackBuilder to the transaction context 
+    _trx->transactionContextPtr()->returnBuilder(_keys.release());
+  }
+}
+
 TRI_doc_mptr_t* PrimaryIndexIterator::next() {
   while (_iterator.valid()) {
     auto result = _index->lookup(_trx, _iterator.value());
@@ -457,13 +465,15 @@ IndexIterator* PrimaryIndex::createInIterator(
   bool const isId = (attrNode->stringEquals(StaticStrings::IdString));
     
   TRI_ASSERT(valNode->isArray());
-    
-  // only leave the valid elements in the vector
-  auto keys = std::make_unique<VPackBuilder>();
+  
+  // lease builder, but immediately pass it to the unique_ptr so we don't leak  
+  TransactionBuilderLeaser builder(trx);
+  std::unique_ptr<VPackBuilder> keys(builder.steal());
   keys->openArray();
   
   size_t const n = valNode->numMembers();
 
+  // only leave the valid elements
   for (size_t i = 0; i < n; ++i) {
     handleValNode(context, keys.get(), valNode->getMemberUnchecked(i), isId);
   }
@@ -486,10 +496,12 @@ IndexIterator* PrimaryIndex::createEqIterator(
   // _key or _id?
   bool const isId = (attrNode->stringEquals(StaticStrings::IdString));
 
-  // only leave the valid elements in the vector
-  auto keys = std::make_unique<VPackBuilder>();
+  // lease builder, but immediately pass it to the unique_ptr so we don't leak  
+  TransactionBuilderLeaser builder(trx);
+  std::unique_ptr<VPackBuilder> keys(builder.steal());
   keys->openArray();
 
+  // handle the sole element
   handleValNode(context, keys.get(), valNode, isId);
 
   TRI_IF_FAILURE("PrimaryIndex::noIterator") {

arangod/Indexes/PrimaryIndex.h

@@ -53,7 +53,7 @@ class PrimaryIndexIterator final : public IndexIterator {
         TRI_ASSERT(_keys->slice().isArray());
       }
 
-  ~PrimaryIndexIterator() {}
+  ~PrimaryIndexIterator();
 
   TRI_doc_mptr_t* next() override;
 

arangod/Utils/Transaction.cpp

@@ -3460,6 +3460,7 @@ StringBufferLeaser::~StringBufferLeaser() {
 TransactionBuilderLeaser::TransactionBuilderLeaser(arangodb::Transaction* trx) 
       : _transactionContext(trx->transactionContextPtr()), 
         _builder(_transactionContext->leaseBuilder()) {
+  TRI_ASSERT(_builder != nullptr);
 }
 
 //////////////////////////////////////////////////////////////////////////////
@@ -3469,6 +3470,7 @@ TransactionBuilderLeaser::TransactionBuilderLeaser(arangodb::Transaction* trx)
 TransactionBuilderLeaser::TransactionBuilderLeaser(arangodb::TransactionContext* transactionContext) 
       : _transactionContext(transactionContext), 
         _builder(_transactionContext->leaseBuilder()) {
+  TRI_ASSERT(_builder != nullptr);
 }
 
 //////////////////////////////////////////////////////////////////////////////
@@ -3476,6 +3478,8 @@ TransactionBuilderLeaser::TransactionBuilderLeaser(arangodb::TransactionContext*
 //////////////////////////////////////////////////////////////////////////////
 
 TransactionBuilderLeaser::~TransactionBuilderLeaser() { 
-  _transactionContext->returnBuilder(_builder); 
+  if (_builder != nullptr) {
+    _transactionContext->returnBuilder(_builder); 
+  }
 }
 

arangod/Utils/Transaction.h

@@ -1009,9 +1009,14 @@ class TransactionBuilderLeaser {
   explicit TransactionBuilderLeaser(arangodb::Transaction*); 
   explicit TransactionBuilderLeaser(arangodb::TransactionContext*); 
   ~TransactionBuilderLeaser();
-  arangodb::velocypack::Builder* builder() const { return _builder; }
-  arangodb::velocypack::Builder* operator->() const { return _builder; }
-  arangodb::velocypack::Builder* get() const { return _builder; }
+  inline arangodb::velocypack::Builder* builder() const { return _builder; }
+  inline arangodb::velocypack::Builder* operator->() const { return _builder; }
+  inline arangodb::velocypack::Builder* get() const { return _builder; }
+  inline arangodb::velocypack::Builder* steal() { 
+    arangodb::velocypack::Builder* res = _builder;
+    _builder = nullptr;
+    return res;
+  }
  private:
   arangodb::TransactionContext* _transactionContext;
   arangodb::velocypack::Builder* _builder;