fix: cap CPU and avoid heavy startup work

internal/repository/sqlite_busy_retry.go

@@ -0,0 +1,47 @@
+package repository
+
+import (
+	"context"
+	"strings"
+	"time"
+)
+
+const sqliteBusyRetryMaxElapsed = 6 * time.Second
+
+func withSQLiteBusyRetry(ctx context.Context, op func() error) error {
+	delay := 25 * time.Millisecond
+	deadline := time.Now().Add(sqliteBusyRetryMaxElapsed)
+	for {
+		err := op()
+		if !isSQLiteBusyError(err) {
+			return err
+		}
+		if ctxErr := ctx.Err(); ctxErr != nil {
+			return ctxErr
+		}
+		if time.Now().Add(delay).After(deadline) {
+			return err
+		}
+		timer := time.NewTimer(delay)
+		select {
+		case <-ctx.Done():
+			timer.Stop()
+			return ctx.Err()
+		case <-timer.C:
+		}
+		if delay < 500*time.Millisecond {
+			delay *= 2
+		}
+	}
+}
+
+func isSQLiteBusyError(err error) bool {
+	if err == nil {
+		return false
+	}
+	msg := strings.ToLower(err.Error())
+	return strings.Contains(msg, "sqlite_busy") ||
+		strings.Contains(msg, "sqlite_locked") ||
+		strings.Contains(msg, "database is locked") ||
+		strings.Contains(msg, "database table is locked")
+}