feat(agent) multi-driver db monitoring, hot-plug config, release pipeline

internal/aggregate/window.go

@@ -15,22 +15,36 @@ type Window struct {
 	diskCount uint64
 
 	uptime uint64
+
+	// DB metrics — populated only when a DB collector is registered.
+	hasDB              bool
+	dbDriver           uint8
+	dbConnPctSum       float64
+	dbConnPctCount     uint64
+	dbThreadsSum       float64
+	dbThreadsCount     uint64
+	dbSlowQueriesDelta uint64
+	dbSizeBytes        uint64
 }
 
 type Snapshot struct {
 	Timestamp time.Time
 
-	CPUAvg float64
-	MemAvg float64
+	CPUAvg  float64
+	MemAvg  float64
 	DiskAvg float64
+	Uptime  uint64
 
-	Uptime uint64
+	// nil when DB monitoring is not enabled.
+	DBDriver         *uint8
+	DBConnPct        *float64
+	DBThreadsRunning *float64
+	DBSlowQueries    *uint64
+	DBSizeBytes      *uint64
 }
 
 func NewWindow() *Window {
-	return &Window{
-		start: time.Now(),
-	}
+	return &Window{start: time.Now()}
 }
 
 func (w *Window) AddCPU(value float64) {
@@ -43,10 +57,41 @@ func (w *Window) AddMemory(value float64) {
 	w.memCount++
 }
 
+func (w *Window) AddDisk(value float64) {
+	w.diskSum += value
+	w.diskCount++
+}
+
 func (w *Window) SetUptime(value uint64) {
 	w.uptime = value
 }
 
+func (w *Window) AddDBConnPct(v float64) {
+	w.dbConnPctSum += v
+	w.dbConnPctCount++
+	w.hasDB = true
+}
+
+func (w *Window) AddDBThreadsRunning(v float64) {
+	w.dbThreadsSum += v
+	w.dbThreadsCount++
+}
+
+func (w *Window) AddDBSlowQueriesDelta(v uint64) {
+	w.dbSlowQueriesDelta += v
+}
+
+func (w *Window) SetDBSizeBytes(v uint64) {
+	w.dbSizeBytes = v
+	w.hasDB = true
+}
+
+// SetDBDriver records the numeric driver identifier (see dbmanager.Driver* constants).
+// When multiple collectors are active this is called once per window by the manager.
+func (w *Window) SetDBDriver(v uint8) {
+	w.dbDriver = v
+}
+
 func (w *Window) Ready(windowDuration time.Duration) bool {
 	return time.Since(w.start) >= windowDuration
 }
@@ -67,16 +112,36 @@ func (w *Window) Snapshot() Snapshot {
 		diskAvg = w.diskSum / float64(w.diskCount)
 	}
 
-	return Snapshot{
+	snap := Snapshot{
 		Timestamp: time.Now(),
 		CPUAvg:    cpuAvg,
 		MemAvg:    memAvg,
 		DiskAvg:   diskAvg,
 		Uptime:    w.uptime,
 	}
-}
 
-func (w *Window) AddDisk(value float64) {
-	w.diskSum += value
-	w.diskCount++
-}
+	if w.hasDB {
+		driver := w.dbDriver
+
+		var connPct float64
+		if w.dbConnPctCount > 0 {
+			connPct = w.dbConnPctSum / float64(w.dbConnPctCount)
+		}
+
+		var threads float64
+		if w.dbThreadsCount > 0 {
+			threads = w.dbThreadsSum / float64(w.dbThreadsCount)
+		}
+
+		slow := w.dbSlowQueriesDelta
+		sizeBytes := w.dbSizeBytes
+
+		snap.DBDriver = &driver
+		snap.DBConnPct = &connPct
+		snap.DBThreadsRunning = &threads
+		snap.DBSlowQueries = &slow
+		snap.DBSizeBytes = &sizeBytes
+	}
+
+	return snap
+}