bugfix

README.md

@@ -109,3 +109,21 @@ Dieses Paket ist deutlich robuster als der erste Prototyp, ersetzt aber keine fi
 - Monitoring/Logging
 - eventuell CSRF-Schutz für schreibende Formulare
 - rollenbasierte Einschränkung pro Abteilung, falls nicht jeder eingeloggte Nutzer jede Abteilung sehen darf
+
+## Fehlerbehebung: `[mysql] invalid connection`
+
+Diese Version setzt die MariaDB-Verbindungen bewusst kurzlebiger und führt Migrationen ohne `multiStatements=true` aus. Das verhindert, dass die App alte oder von MariaDB geschlossene TCP-Verbindungen aus dem Pool wiederverwendet.
+
+Nach dem Update bitte neu bauen:
+
+```bash
+docker compose down
+docker compose up --build
+```
+
+Falls du vorher mit einer leeren Testdatenbank gearbeitet hast und komplett neu starten möchtest:
+
+```bash
+docker compose down -v
+docker compose up --build
+```

cmd/server/main.go

@@ -18,7 +18,7 @@ func env(k, d string) string {
 }
 func main() {
 	ctx := context.Background()
-	database, err := db.Open(ctx, env("DATABASE_URL", "trading:trading@tcp(127.0.0.1:3306)/trading?parseTime=true&multiStatements=true"))
+	database, err := db.Open(ctx, env("DATABASE_URL", "trading:trading@tcp(127.0.0.1:3306)/trading"))
 	if err != nil {
 		log.Fatal(err)
 	}

docker-compose.yml

@@ -6,7 +6,7 @@ services:
         condition: service_healthy
     environment:
       APP_ADDR: ":8080"
-      DATABASE_URL: "trading:trading@tcp(db:3306)/trading?parseTime=true&multiStatements=true"
+      DATABASE_URL: "trading:trading@tcp(db:3306)/trading"
       PUBLIC_URL: "http://localhost:8080"
       POCKET_ID_ISSUER: "${POCKET_ID_ISSUER}"
       POCKET_ID_CLIENT_ID: "${POCKET_ID_CLIENT_ID}"

internal/db/db.go

@@ -4,29 +4,86 @@ import (
 	"context"
 	"database/sql"
 	"fmt"
+	"net/url"
 	"os"
 	"path/filepath"
 	"sort"
+	"strings"
+	"time"
 
 	_ "github.com/go-sql-driver/mysql"
 )
 
-func Open(ctx context.Context, url string) (*sql.DB, error) {
-	d, err := sql.Open("mysql", url)
+func Open(ctx context.Context, dsn string) (*sql.DB, error) {
+	dsn = normalizeDSN(dsn)
+	d, err := sql.Open("mysql", dsn)
 	if err != nil {
 		return nil, err
 	}
-	d.SetMaxOpenConns(25)
-	d.SetMaxIdleConns(10)
-	if err := d.PingContext(ctx); err != nil {
-		return nil, err
+
+	// MariaDB/MySQL can close idle TCP connections. Keep pooled connections fresh
+	// so users do not randomly hit "[mysql] invalid connection" after startup or idle time.
+	d.SetMaxOpenConns(20)
+	d.SetMaxIdleConns(5)
+	d.SetConnMaxLifetime(3 * time.Minute)
+	d.SetConnMaxIdleTime(90 * time.Second)
+
+	deadline := time.Now().Add(90 * time.Second)
+	var lastErr error
+	for {
+		pingCtx, cancel := context.WithTimeout(ctx, 5*time.Second)
+		lastErr = d.PingContext(pingCtx)
+		cancel()
+		if lastErr == nil {
+			return d, nil
+		}
+		if time.Now().After(deadline) {
+			d.Close()
+			return nil, fmt.Errorf("database not ready: %w", lastErr)
+		}
+		time.Sleep(2 * time.Second)
 	}
-	return d, nil
+}
+
+func normalizeDSN(dsn string) string {
+	parts := strings.SplitN(dsn, "?", 2)
+	base := parts[0]
+	q := url.Values{}
+	if len(parts) == 2 {
+		parsed, err := url.ParseQuery(parts[1])
+		if err == nil {
+			q = parsed
+		}
+	}
+	defaults := map[string]string{
+		"parseTime":    "true",
+		"charset":      "utf8mb4",
+		"collation":    "utf8mb4_unicode_ci",
+		"loc":          "Local",
+		"timeout":      "10s",
+		"readTimeout":  "30s",
+		"writeTimeout": "30s",
+	}
+	for k, v := range defaults {
+		if q.Get(k) == "" {
+			q.Set(k, v)
+		}
+	}
+	// Migrations are executed statement-by-statement, so multiStatements is not needed.
+	q.Del("multiStatements")
+	return base + "?" + q.Encode()
 }
 
 func Migrate(ctx context.Context, d *sql.DB) error {
-	d.ExecContext(ctx, `SELECT GET_LOCK('trading_tool_migrate', 30)`)
-	defer d.ExecContext(ctx, `SELECT RELEASE_LOCK('trading_tool_migrate')`)
+	var locked int
+	if err := d.QueryRowContext(ctx, `SELECT GET_LOCK('trading_tool_migrate', 30)`).Scan(&locked); err != nil {
+		return err
+	}
+	if locked != 1 {
+		return fmt.Errorf("could not acquire migration lock")
+	}
+	defer d.ExecContext(context.Background(), `SELECT RELEASE_LOCK('trading_tool_migrate')`)
+
 	if _, err := d.ExecContext(ctx, `CREATE TABLE IF NOT EXISTS schema_migrations(version VARCHAR(255) PRIMARY KEY, applied_at TIMESTAMP NOT NULL DEFAULT CURRENT_TIMESTAMP)`); err != nil {
 		return err
 	}
@@ -47,7 +104,7 @@ func Migrate(ctx context.Context, d *sql.DB) error {
 		if err != nil {
 			return err
 		}
-		if _, err := d.ExecContext(ctx, string(b)); err != nil {
+		if err := execSQLFile(ctx, d, string(b)); err != nil {
 			return fmt.Errorf("%s: %w", f, err)
 		}
 		if _, err := d.ExecContext(ctx, `INSERT INTO schema_migrations(version) VALUES(?)`, f); err != nil {
@@ -56,3 +113,61 @@ func Migrate(ctx context.Context, d *sql.DB) error {
 	}
 	return nil
 }
+
+func execSQLFile(ctx context.Context, d *sql.DB, content string) error {
+	for _, stmt := range splitSQLStatements(content) {
+		stmt = strings.TrimSpace(stmt)
+		if stmt == "" {
+			continue
+		}
+		if _, err := d.ExecContext(ctx, stmt); err != nil {
+			return err
+		}
+	}
+	return nil
+}
+
+func splitSQLStatements(s string) []string {
+	var out []string
+	var b strings.Builder
+	inSingle, inDouble, inBacktick := false, false, false
+	escaped := false
+	for i := 0; i < len(s); i++ {
+		c := s[i]
+		if escaped {
+			b.WriteByte(c)
+			escaped = false
+			continue
+		}
+		if c == '\\' && (inSingle || inDouble) {
+			b.WriteByte(c)
+			escaped = true
+			continue
+		}
+		switch c {
+		case '\'':
+			if !inDouble && !inBacktick {
+				inSingle = !inSingle
+			}
+		case '"':
+			if !inSingle && !inBacktick {
+				inDouble = !inDouble
+			}
+		case '`':
+			if !inSingle && !inDouble {
+				inBacktick = !inBacktick
+			}
+		case ';':
+			if !inSingle && !inDouble && !inBacktick {
+				out = append(out, b.String())
+				b.Reset()
+				continue
+			}
+		}
+		b.WriteByte(c)
+	}
+	if strings.TrimSpace(b.String()) != "" {
+		out = append(out, b.String())
+	}
+	return out
+}