SERVER-10159 Store the FieldRef for _id in a file static to avoid a dynamic allocation

1 files changed, 8 insertions, 1 deletions

diff --git a/src/mongo/db/field_ref.h b/src/mongo/db/field_ref.h
index 6f68f019126..d35a94d284d 100644
--- a/src/mongo/db/field_ref.h
+++ b/src/mongo/db/field_ref.h
@@ -51,7 +51,9 @@ namespace mongo {
     class FieldRef {
         MONGO_DISALLOW_COPYING(FieldRef);
     public:
-        FieldRef() : _size(0) {}
+        FieldRef();
+
+        explicit FieldRef(const StringData& path);
 
         /**
          * Field parts accessed through getPart() calls no longer would be valid, after the
@@ -126,6 +128,11 @@ namespace mongo {
         // with allocations.
         static const size_t kReserveAhead = 4;
 
+        /**
+         * Parses 'path' into parts.
+         */
+        void _parse(const StringData& path);
+
         /** Converts the field part index to the variable part equivalent */
         size_t getIndex(size_t i) const { return i-kReserveAhead; }