From 03c8b2b7ec66795dc9d83365a435d0463202c9e4 Mon Sep 17 00:00:00 2001
From: Steve Yen <steve.yen@gmail.com>
Date: Wed, 7 Feb 2018 14:16:58 -0800
Subject: [PATCH] scorch mem segment optimizes DictEntry's across Next() calls

This change optimizes the scorch/mem DictionaryIterator by reusing a
DictEntry struct across multiple Next() calls.  This follows the same
optimization trick and Next() semantics as upsidedown's FieldDict
implementation.
---
 index/scorch/segment/mem/dict.go | 9 +++++----
 1 file changed, 5 insertions(+), 4 deletions(-)

diff --git a/index/scorch/segment/mem/dict.go b/index/scorch/segment/mem/dict.go
index 939c287e..cf92ef71 100644
--- a/index/scorch/segment/mem/dict.go
+++ b/index/scorch/segment/mem/dict.go
@@ -76,6 +76,8 @@ type DictionaryIterator struct {
 	prefix string
 	end    string
 	offset int
+
+	dictEntry index.DictEntry // reused across Next()'s
 }
 
 // Next returns the next entry in the dictionary
@@ -95,8 +97,7 @@ func (d *DictionaryIterator) Next() (*index.DictEntry, error) {
 
 	d.offset++
 	postingID := d.d.segment.Dicts[d.d.fieldID][next]
-	return &index.DictEntry{
-		Term:  next,
-		Count: d.d.segment.Postings[postingID-1].GetCardinality(),
-	}, nil
+	d.dictEntry.Term = next
+	d.dictEntry.Count = d.d.segment.Postings[postingID-1].GetCardinality()
+	return &d.dictEntry, nil
 }