update /stats - include cpu & mem usage

socketserver/server/stats.go

@@ -4,45 +4,96 @@ import (
 	"bytes"
 	"encoding/json"
 	"net/http"
+	"runtime"
+	"time"
+
+	linuxproc "github.com/c9s/goprocinfo/linux"
 )
 
 type StatsData struct {
 	Version int
 
-	CurrentClientCount int64
+	CurrentClientCount uint64
 
-	ClientConnectsTotal    int64
-	ClientDisconnectsTotal int64
+	ClientConnectsTotal    uint64
+	ClientDisconnectsTotal uint64
 
-	DisconnectCodes   map[string]int64
+	DisconnectCodes map[string]uint64
 
-	CommandsIssuedTotal int64
-	CommandsIssuedMap   map[Command]int64
+	CommandsIssuedTotal uint64
+	CommandsIssuedMap   map[Command]uint64
 
-	MessagesSent int64
+	MessagesSent uint64
+
+	CachedStatsLastUpdate time.Time
+
+	MemoryInUse    uint64
+	MemoryRSS int64
+
+	CpuUsagePct float64
 
 	// DisconnectReasons is at the bottom because it has indeterminate size
-	DisconnectReasons map[string]int64
-}
-
-const StatsDataVersion = 1
-
-func newStatsData() *StatsData {
-	return &StatsData{
-		CommandsIssuedMap: make(map[Command]int64),
-		DisconnectCodes:   make(map[string]int64),
-		DisconnectReasons: make(map[string]int64),
-		Version:           StatsDataVersion,
-	}
+	DisconnectReasons map[string]uint64
 }
 
 // Statistics is several variables that get incremented during normal operation of the server.
 // Its structure should be versioned as it is exposed via JSON.
 var Statistics = newStatsData()
 
+const StatsDataVersion = 2
+const pageSize = 4096
+
+var cpuUsage struct {
+	UserTime uint64
+	SysTime uint64
+}
+
+func newStatsData() *StatsData {
+	return &StatsData{
+		CommandsIssuedMap: make(map[Command]uint64),
+		DisconnectCodes:   make(map[string]uint64),
+		DisconnectReasons: make(map[string]uint64),
+		Version:           StatsDataVersion,
+	}
+}
+
+func updateStatsIfNeeded() {
+	if time.Now().Add(-2 * time.Second).After(Statistics.CachedStatsLastUpdate) {
+		updatePeriodicStats()
+	}
+}
+
+func updatePeriodicStats() {
+	nowUpdate := time.Now()
+	timeDiff := nowUpdate.Sub(Statistics.CachedStatsLastUpdate)
+	Statistics.CachedStatsLastUpdate = nowUpdate
+
+	{
+		m := runtime.MemStats{}
+		runtime.ReadMemStats(&m)
+
+		Statistics.MemoryInUse = m.Alloc
+	}
+
+	{
+		pstat, err := linuxproc.ReadProcessStat("/proc/self/stat")
+		if err == nil {
+			userTicks := pstat.Utime - cpuUsage.UserTime
+			sysTicks := pstat.Stime - cpuUsage.SysTime
+			cpuUsage.UserTime = pstat.Utime
+			cpuUsage.SysTime = pstat.Stime
+
+			Statistics.CpuUsagePct = 100 * float64(userTicks + sysTicks) / (timeDiff.Seconds() * float64(ticksPerSecond))
+			Statistics.MemoryRSS = pstat.Rss * pageSize
+		}
+	}
+}
+
 func HTTPShowStatistics(w http.ResponseWriter, r *http.Request) {
 	w.Header().Set("Content-Type", "application/json")
 
+	updateStatsIfNeeded()
+
 	jsonBytes, _ := json.Marshal(Statistics)
 	outBuf := bytes.NewBuffer(nil)
 	json.Indent(outBuf, jsonBytes, "", "\t")

socketserver/server/tickspersecond.go

@@ -0,0 +1,9 @@
+package server
+
+// #include <unistd.h>
+// long get_ticks_per_second() {
+//   return sysconf(_SC_CLK_TCK);
+// }
+import "C"
+
+var ticksPerSecond = int(C.get_ticks_per_second())