embed comment into sql

findCaller.go

func findCaller() (*runtime.Frame, string) {
    // skip starts 6. 0: Callers, 1: findCaller, 2: sqlComment, 3: hooks, 4: proxy-funcs, 5: database/sql, and equals or greater than 6: user-funcs
    skip := 6
    for {
        var rpc [8]uintptr
        var i int
        n := runtime.Callers(skip, rpc[:])
        frames := runtime.CallersFrames(rpc[:])
        for i = 0; ; i++ {
            frame, more := frames.Next()
            if !more {
                break
            }
            name := frame.Function
            if name == "" || strings.HasPrefix(name, "runtime.") {
                continue
            }
            // http://stackoverflow.com/questions/25262754/how-to-get-name-of-current-package-in-go
            dotIdx := 0
            for j := len(name) - 1; j >= 0; j-- {
                if name[j] == '.' {
                    dotIdx = j
                } else if name[j] == '/' {
                    break
                }
            }
            packageName := name[:dotIdx]
            if !skipForSQLComment(frame, packageName) {
                return &frame, packageName
            }
        }
        if n < len(rpc) {
            break
        }
        skip += i
    }
    return nil, ""
}

proxyRegister.go

sql.Register("sql-proxy", proxy.NewProxy(&mysql.MySQLDriver{}, &proxy.HooksContext{
    PrePrepare: func(ctx context.Context, stmt *proxy.Stmt) (interface{}, error) {
        sqlComment(stmt)
        return nil, nil
    },
    PreExec: func(ctx context.Context, stmt *proxy.Stmt, _ []driver.NamedValue) (interface{}, error) {
        if stmt.Stmt == nil {
            sqlComment(stmt)
        }
        return nil, nil
    },
    PreQuery: func(ctx context.Context, stmt *proxy.Stmt, _ []driver.NamedValue) (interface{}, error) {
        if stmt.Stmt == nil {
            sqlComment(stmt)
        }
        return nil, nil
    },
}

sqlComment.go

func sqlComment(stmt *proxy.Stmt) {
    f, pkgName := findCaller()
    if f != nil {
        fname := filepath.Base(f.File)
        relPath := strings.TrimPrefix(pkgName, "github.com/owner/myprojrepo/")
        comment := fmt.Sprintf("%s/%s:%d", relPath, fname, f.Line)
        comment = strings.ReplaceAll(comment, "*", "")
        stmt.QueryString = fmt.Sprintf("/* %s */\n%s", comment, stmt.QueryString)
    }
}