From 6ed8ca396200b2cd421122777551ab1c229f3f12 Mon Sep 17 00:00:00 2001
From: Emil Koutanov <ekoutanov@gmail.com>
Date: Sun, 19 Apr 2020 20:31:05 +1000
Subject: [PATCH] Added Deadline methods

---
 concurrent/deadline.go      | 13 ++++++++++---
 concurrent/deadline_test.go | 10 ++++++----
 2 files changed, 16 insertions(+), 7 deletions(-)

diff --git a/concurrent/deadline.go b/concurrent/deadline.go
index cdcfb37..ebba09a 100644
--- a/concurrent/deadline.go
+++ b/concurrent/deadline.go
@@ -35,9 +35,10 @@ func (t *timeCas) set(time time.Time) {
 type Deadline interface {
 	TryRun(f func()) bool
 	Elapsed() time.Duration
-	Lapsed() bool
+	Expired() bool
 	Move(new time.Time)
 	Last() time.Time
+	Remaining() time.Duration
 }
 
 type deadline struct {
@@ -75,8 +76,8 @@ func (d *deadline) Elapsed() time.Duration {
 	return time.Now().Sub(d.Last())
 }
 
-// Lapsed returns true if the deadline has lapsed.
-func (d *deadline) Lapsed() bool {
+// Expired returns true if the deadline has lapsed.
+func (d *deadline) Expired() bool {
 	return time.Now().Sub(d.Last()) > d.interval
 }
 
@@ -84,3 +85,9 @@ func (d *deadline) Lapsed() bool {
 func (d *deadline) Move(new time.Time) {
 	d.lastRun.set(new)
 }
+
+// Remaining returns the duration to the upcoming expiry point. If the deadlines has already lapsed, the returned
+// value is negative.
+func (d *deadline) Remaining() time.Duration {
+	return d.interval - d.Elapsed()
+}
diff --git a/concurrent/deadline_test.go b/concurrent/deadline_test.go
index 0dc1bbb..3f9fdc0 100644
--- a/concurrent/deadline_test.go
+++ b/concurrent/deadline_test.go
@@ -43,12 +43,14 @@ func TestDeadline(t *testing.T) {
 		called = true
 	}
 	assert.Equal(t, zeroTime, d.Last())
-	assert.True(t, d.Lapsed())
+	assert.True(t, d.Expired())
+	assert.LessOrEqual(t, int(d.Remaining()), 0)
 
 	assert.True(t, d.TryRun(setter))
 	assert.True(t, called)
 	assert.NotEqual(t, zeroTime, d.Last())
-	assert.False(t, d.Lapsed())
+	assert.False(t, d.Expired())
+	assert.GreaterOrEqual(t, int(d.Remaining()), 0)
 
 	called = false
 	assert.False(t, d.TryRun(setter))
@@ -60,9 +62,9 @@ func TestDeadline(t *testing.T) {
 
 func TestDeadlineMove(t *testing.T) {
 	d := NewDeadline(1 * time.Hour)
-	assert.True(t, d.Lapsed())
+	assert.True(t, d.Expired())
 	d.Move(time.Now())
-	assert.False(t, d.Lapsed())
+	assert.False(t, d.Expired())
 
 	called := false
 	setter := func() {