From bbf29e946a23e90591d3e59d2228d678778066bc Mon Sep 17 00:00:00 2001
From: Oleksandr Ieremeev <yeremeyev.alexander@gmail.com>
Date: Sun, 19 Aug 2018 19:06:59 +0300
Subject: [PATCH] Calculate and sleep checkpoint intervals for services

---
 core/checker.go  | 8 +++++++-
 types/service.go | 1 +
 2 files changed, 8 insertions(+), 1 deletion(-)

diff --git a/core/checker.go b/core/checker.go
index 45a62da2..ca349b3e 100644
--- a/core/checker.go
+++ b/core/checker.go
@@ -40,6 +40,8 @@ func CheckServices() {
 }
 
 func CheckQueue(s *Service, record bool) {
+	s.Checkpoint = time.Now()
+
 CheckLoop:
 	for {
 		select {
@@ -49,7 +51,11 @@ CheckLoop:
 		default:
 			utils.Log(1, fmt.Sprintf("Checking service: %v", s.Name))
 			ServiceCheck(s, record)
-			time.Sleep(time.Duration(s.Interval) * time.Second)
+			// Set next time checkpoint and maybe sleep.
+			s.Checkpoint = s.Checkpoint.Add(time.Duration(s.Interval) * time.Second)
+			if sleepDuration := s.Checkpoint.Sub(time.Now()); sleepDuration > 0 {
+				time.Sleep(sleepDuration)
+			}
 			continue
 		}
 	}
diff --git a/types/service.go b/types/service.go
index e49eca19..45afcdbc 100644
--- a/types/service.go
+++ b/types/service.go
@@ -41,6 +41,7 @@ type Service struct {
 	Failures       []*Failure `json:"failures"`
 	Checkins       []*Checkin `json:"checkins"`
 	Running        chan bool  `json:"-"`
+	Checkpoint     time.Time  `json:"-"`
 	LastResponse   string
 	LastStatusCode int
 	LastOnline     time.Time