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

internal/collectors/mysql/mysql.go

@@ -0,0 +1,92 @@
+package mysql
+
+import (
+	"context"
+	"database/sql"
+	"strconv"
+	"time"
+
+	_ "github.com/go-sql-driver/mysql"
+
+	"bugs.watch/agent/internal/aggregate"
+)
+
+// Collector queries MySQL global status each sample interval.
+// All queries run under a 3-second timeout; any failure is silently skipped.
+type Collector struct {
+	db              *sql.DB
+	prevSlowQueries uint64
+	hasPrev         bool
+}
+
+func New(dsn string) (*Collector, error) {
+	db, err := sql.Open("mysql", dsn)
+	if err != nil {
+		return nil, err
+	}
+	db.SetMaxOpenConns(2)
+	db.SetMaxIdleConns(1)
+	db.SetConnMaxLifetime(5 * time.Minute)
+	return &Collector{db: db}, nil
+}
+
+func (c *Collector) Name() string { return "mysql" }
+
+func (c *Collector) Close() { c.db.Close() }
+
+func (c *Collector) Collect(window *aggregate.Window) {
+	ctx, cancel := context.WithTimeout(context.Background(), 3*time.Second)
+	defer cancel()
+
+	rows, err := c.db.QueryContext(ctx,
+		"SHOW GLOBAL STATUS WHERE Variable_name IN ('Threads_connected','Threads_running','Slow_queries')",
+	)
+	if err != nil {
+		return
+	}
+	defer rows.Close()
+
+	vars := make(map[string]uint64, 3)
+	for rows.Next() {
+		var name, raw string
+		if err := rows.Scan(&name, &raw); err != nil {
+			continue
+		}
+		if v, err := strconv.ParseUint(raw, 10, 64); err == nil {
+			vars[name] = v
+		}
+	}
+	if err := rows.Err(); err != nil {
+		return
+	}
+
+	var maxConn uint64
+	if err := c.db.QueryRowContext(ctx, "SELECT @@max_connections").Scan(&maxConn); err != nil || maxConn == 0 {
+		maxConn = 1
+	}
+
+	connPct := float64(vars["Threads_connected"]) / float64(maxConn) * 100
+	window.AddDBConnPct(connPct)
+	window.AddDBThreadsRunning(float64(vars["Threads_running"]))
+
+	slow := vars["Slow_queries"]
+	if c.hasPrev {
+		var delta uint64
+		if slow >= c.prevSlowQueries {
+			delta = slow - c.prevSlowQueries
+		}
+		window.AddDBSlowQueriesDelta(delta)
+	}
+	c.prevSlowQueries = slow
+	c.hasPrev = true
+
+	var sizeBytes uint64
+	err = c.db.QueryRowContext(ctx,
+		"SELECT COALESCE(SUM(data_length + index_length), 0)"+
+			" FROM information_schema.tables"+
+			" WHERE table_schema NOT IN ('information_schema','performance_schema','mysql','sys')",
+	).Scan(&sizeBytes)
+	if err == nil {
+		window.SetDBSizeBytes(sizeBytes)
+	}
+}