From f6d15759286b589204fba737a02a63eaad387b5c Mon Sep 17 00:00:00 2001
From: ASAKURA Kazuki <32762324+Arthur1@users.noreply.github.com>
Date: Wed, 23 Aug 2023 00:25:26 +0900
Subject: [PATCH] calcurate moderate values when cpu counters are reset

---
 mackerel-plugin-docker/lib/docker.go      | 23 +++++++++++++++++------
 mackerel-plugin-docker/lib/docker_test.go | 13 +++++++++++++
 2 files changed, 30 insertions(+), 6 deletions(-)

diff --git a/mackerel-plugin-docker/lib/docker.go b/mackerel-plugin-docker/lib/docker.go
index 43e8573ad..4bf9d3899 100644
--- a/mackerel-plugin-docker/lib/docker.go
+++ b/mackerel-plugin-docker/lib/docker.go
@@ -270,19 +270,30 @@ func addCPUPercentageStats(stats *map[string]interface{}, lastStat map[string]in
 		currentUserUsage, ok1 := (*stats)[internalCPUStatPrefix+name+".user"]
 		prevUserUsage, ok2 := lastStat[internalCPUStatPrefix+name+".user"]
 		if ok1 && ok2 {
-			userUsage := float64(currentUserUsage.(uint64) - uint64(prevUserUsage.(float64)))
-			if userUsage >= 0 {
-				(*stats)["docker.cpuacct_percentage."+name+".user"] = userUsage / hostUsage * 100.0 * float64(cpuNumsInt)
+			currentUserUsageUInt := currentUserUsage.(uint64)
+			prevUserUsageUInt := uint64(prevUserUsage.(float64))
+			var userUsage float64
+			if currentUserUsageUInt >= prevUserUsageUInt {
+				userUsage = float64(currentUserUsage.(uint64) - uint64(prevUserUsage.(float64)))
+			} else {
+				// counter has been reset
+				userUsage = float64(currentUserUsageUInt)
 			}
+			(*stats)["docker.cpuacct_percentage."+name+".user"] = userUsage / hostUsage * 100.0 * float64(cpuNumsInt)
 		}
 
 		currentSystemUsage, ok1 := (*stats)[internalCPUStatPrefix+name+".system"]
 		prevSystemUsage, ok2 := lastStat[internalCPUStatPrefix+name+".system"]
 		if ok1 && ok2 {
-			systemUsage := float64(currentSystemUsage.(uint64) - uint64(prevSystemUsage.(float64)))
-			if systemUsage >= 0 {
-				(*stats)["docker.cpuacct_percentage."+name+".system"] = systemUsage / hostUsage * 100.0 * float64(cpuNumsInt)
+			currentSystemUsageUInt := currentSystemUsage.(uint64)
+			prevSystemUsageUInt := uint64(prevSystemUsage.(float64))
+			var systemUsage float64
+			if currentSystemUsageUInt >= prevSystemUsageUInt {
+				systemUsage = float64(currentSystemUsageUInt - prevSystemUsageUInt)
+			} else {
+				systemUsage = float64(currentSystemUsageUInt)
 			}
+			(*stats)["docker.cpuacct_percentage."+name+".system"] = systemUsage / hostUsage * 100.0 * float64(cpuNumsInt)
 		}
 	}
 }
diff --git a/mackerel-plugin-docker/lib/docker_test.go b/mackerel-plugin-docker/lib/docker_test.go
index 89c19de92..e55fdc655 100644
--- a/mackerel-plugin-docker/lib/docker_test.go
+++ b/mackerel-plugin-docker/lib/docker_test.go
@@ -99,6 +99,10 @@ func TestAddCPUPercentageStats(t *testing.T) {
 		"docker._internal.cpuacct.containerD.host":       uint64(100000),
 		"docker._internal.cpuacct.containerD.user":       uint64(3000),
 		"docker._internal.cpuacct.containerD.system":     uint64(2000),
+		"docker._internal.cpuacct.containerF.user":       uint64(3000), // it has been reset
+		"docker._internal.cpuacct.containerF.system":     uint64(1000), // it has been reset
+		"docker._internal.cpuacct.containerF.host":       uint64(100000100000),
+		"docker._internal.cpuacct.containerF.onlineCPUs": int(2),
 	}
 	oldStats := map[string]interface{}{
 		"docker._internal.cpuacct.containerA.host":   float64(90000),
@@ -111,6 +115,9 @@ func TestAddCPUPercentageStats(t *testing.T) {
 		"docker._internal.cpuacct.containerE.host":   float64(100000),
 		"docker._internal.cpuacct.containerE.user":   float64(3000),
 		"docker._internal.cpuacct.containerE.system": float64(2000),
+		"docker._internal.cpuacct.containerF.user":   float64(40000000000),
+		"docker._internal.cpuacct.containerF.system": float64(20000000000),
+		"docker._internal.cpuacct.containerF.host":   float64(100000000000),
 	}
 	addCPUPercentageStats(&stats, oldStats)
 
@@ -135,4 +142,10 @@ func TestAddCPUPercentageStats(t *testing.T) {
 	if _, ok := stats["docker.cpuacct_percentage.containerE.user"]; ok {
 		t.Errorf("docker.cpuacct_percentage.containerE.user should not be calculated")
 	}
+
+	if stat, ok := stats["docker.cpuacct_percentage.containerF.user"]; !ok {
+		t.Errorf("docker.cpuacct_percentage.containerF.user should be calculated")
+	} else if stat != float64(6.0) {
+		t.Errorf("docker.cpuacct_percentage.containerF.user should be %f, but %f", float64(6.0), stat)
+	}
 }