From 0f108a612dc5ff23b11d6248b543795fa0e74239 Mon Sep 17 00:00:00 2001
From: reesporte <reesedporter@gmail.com>
Date: Fri, 22 Oct 2021 11:25:03 -0500
Subject: [PATCH] refactor and add unit tests

---
 server.go    |  8 +++----
 util.go      |  9 ++++++++
 util_test.go | 59 ++++++++++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 71 insertions(+), 5 deletions(-)
 create mode 100644 util_test.go

diff --git a/server.go b/server.go
index 44e9da6f2..f6fd1ef5b 100644
--- a/server.go
+++ b/server.go
@@ -703,6 +703,7 @@ func (s *Server) Open() error {
 
 		start := time.Now()
 		prevMsg := start
+		numMsgs := uint(len(toSend))
 		s.logger.Printf("start initial cluster state sync")
 		for i := range toSend {
 			for {
@@ -721,11 +722,8 @@ func (s *Server) Open() error {
 			}
 
 			if now := time.Now(); now.Sub(prevMsg) > time.Second {
-				progressRatio := float64(i+1) / float64(len(toSend))
-				messagesLeft := len(toSend) - (i + 1)
-				avgTimePerMessage := float64(now.Sub(start)) / float64(i+1)
-				timeRemaining := time.Duration(avgTimePerMessage * float64(messagesLeft))
-				s.logger.Printf("synced %d/%d messages (%.2f%% complete; %s remaining)", i+1, len(toSend), 100*progressRatio, timeRemaining)
+				pctDone := (float64(i+1) / float64(numMsgs)) * 100
+				s.logger.Printf("synced %d/%d messages (%.2f%% complete; %s remaining)", i+1, numMsgs, pctDone, EstTimeLeft(start, now, uint(i), numMsgs))
 				prevMsg = now
 			}
 		}
diff --git a/util.go b/util.go
index 3bbeff8e3..93f5e9878 100644
--- a/util.go
+++ b/util.go
@@ -25,6 +25,7 @@ import (
 	"sort"
 	"strings"
 	"syscall"
+	"time"
 	"unsafe"
 
 	"github.com/molecula/featurebase/v2/roaring"
@@ -343,3 +344,11 @@ func roaringFragmentHasData(path string, index, field, view string, shard uint64
 
 	return
 }
+
+// EstTimeLeft returns the estimated remaining time to iterate through some items
+// given a start time, the current time, the iteration, and the number of items
+func EstTimeLeft(start time.Time, now time.Time, i uint, total uint) time.Duration {
+	msgsLeft := total - (i + 1)
+	avgMsgTime := float64(now.Sub(start)) / float64(i+1)
+	return time.Duration(avgMsgTime * float64(msgsLeft))
+}
diff --git a/util_test.go b/util_test.go
new file mode 100644
index 000000000..824035744
--- /dev/null
+++ b/util_test.go
@@ -0,0 +1,59 @@
+package pilosa
+
+// util_test.go has unit tests for utility functions from util.go
+
+import (
+	"testing"
+	"time"
+)
+
+func TestEstTimeLeft(t *testing.T) {
+	cases := []struct {
+		start time.Time
+		now   time.Time
+		i     uint
+		total uint
+	}{
+		{
+			time.Date(1969, time.June, 9, 4, 20, 0, 0, time.UTC),
+			time.Date(1969, time.June, 9, 4, 21, 0, 0, time.UTC),
+			10,
+			20,
+		},
+		{
+			time.Date(1969, time.June, 9, 4, 20, 0, 0, time.UTC),
+			time.Date(1969, time.June, 9, 4, 20, 4, 0, time.UTC),
+			10,
+			20,
+		},
+		{
+			time.Date(1969, time.June, 9, 4, 20, 0, 0, time.UTC),
+			time.Date(1969, time.June, 9, 4, 21, 1, 5, time.UTC),
+			10,
+			20,
+		},
+		{
+			time.Date(1969, time.June, 9, 4, 20, 0, 0, time.UTC),
+			time.Date(1969, time.June, 9, 4, 21, 0, 0, time.UTC),
+			1,
+			20,
+		},
+		{
+			time.Date(1969, time.June, 9, 4, 20, 0, 0, time.UTC),
+			time.Date(1969, time.June, 9, 4, 21, 0, 0, time.UTC),
+			10,
+			50,
+		},
+	}
+
+	for _, c := range cases {
+		// we expect that it will be the avg time per message times
+		// the number of remaining messages
+		expected := time.Duration((float64(c.now.Sub(c.start)) / float64(c.i+1)) * float64(c.total-(c.i+1)))
+
+		timeLeft := EstTimeLeft(c.start, c.now, c.i, c.total)
+		if timeLeft != expected {
+			t.Errorf("Time left was incorrect, expected: %d, but got: %d", expected, timeLeft)
+		}
+	}
+}