From a9614734228bf13cf8781060f6ddc0ccf847c4e8 Mon Sep 17 00:00:00 2001
From: Ben Johnson <benbjohnson@yahoo.com>
Date: Wed, 24 May 2017 20:10:52 -0600
Subject: [PATCH] Add statsd gauges for row count.

---
 fragment.go | 14 ++++++++++++++
 1 file changed, 14 insertions(+)

diff --git a/fragment.go b/fragment.go
index 8c0964da1..bf29cae03 100644
--- a/fragment.go
+++ b/fragment.go
@@ -86,6 +86,9 @@ type Fragment struct {
 	cache     Cache
 	CacheSize uint32
 
+	// Stats reporting.
+	maxRowID uint64
+
 	// Cache containing full rows (not just counts).
 	rowCache BitmapCache
 
@@ -166,6 +169,11 @@ func (f *Fragment) Open() error {
 		// Clear checksums.
 		f.checksums = make(map[int][]byte)
 
+		// Read last bit to determine max row.
+		pos := f.storage.Max()
+		f.maxRowID = pos / SliceWidth
+		f.stats.Gauge("rows", float64(f.maxRowID))
+
 		return nil
 	}(); err != nil {
 		f.close()
@@ -409,6 +417,12 @@ func (f *Fragment) setBit(rowID, columnID uint64) (changed bool, err error) {
 
 	f.stats.Count("setN", 1)
 
+	// Update row count if they have increased.
+	if rowID > f.maxRowID {
+		f.maxRowID = rowID
+		f.stats.Gauge("rows", float64(f.maxRowID))
+	}
+
 	return changed, nil
 }