defer close(cacheStmt.prepared)

	// Reason why cannot lock conn.PrepareContext
	// suppose the maxopen is 1, g1 is creating record and g2 is querying record.
	// 1. g1 begin tx, g1 is requeue because of waiting for the system call, now `db.ConnPool` db.numOpen == 1.
	// 2. g2 select lock `conn.PrepareContext(ctx, query)`, now db.numOpen == db.maxOpen , wait for release.

	db.mu.Lock()
	if n > 0 {
		db.maxIdleCount = n
	} else {
		// No idle connections.
		db.maxIdleCount = -1
	}
	// Make sure maxIdle doesn't exceed maxOpen
	if db.maxOpen > 0 && db.maxIdleConnsLocked() > db.maxOpen {
		db.maxIdleCount = db.maxOpen
	}
	var closing []*driverConn
	idleCount := len(db.freeConn)
	maxIdle := db.maxIdleConnsLocked()
	if idleCount > maxIdle {
		closing = db.freeConn[maxIdle:]

    *serialized_model = std::string{std::istreambuf_iterator<char>(std::cin),
                                    std::istreambuf_iterator<char>()};
  } else {
    std::ifstream t(file_path);
    if (!t.is_open()) {
      std::cerr << "Failed to open input file.\n";
      return true;
    }
    *serialized_model = std::string{std::istreambuf_iterator<char>(t),
                                    std::istreambuf_iterator<char>()};

	IN_ACCESS                = 0x00000001
	IN_MODIFY                = 0x00000002
	IN_ATTRIB                = 0x00000004
	IN_CLOSE_WRITE           = 0x00000008
	IN_CLOSE_NOWRITE         = 0x00000010
	IN_OPEN                  = 0x00000020
	IN_MOVED_FROM            = 0x00000040
	IN_MOVED_TO              = 0x00000080
	IN_CREATE                = 0x00000100
	IN_DELETE                = 0x00000200
	IN_DELETE_SELF           = 0x00000400

		t.Errorf("free conns = %d; want %d", g, w)
	}
}

// Issue 10886: tests that all connection attempts return when more than
// DB.maxOpen connections are in flight and the first DB.maxOpen fail.
func TestPendingConnsAfterErr(t *testing.T) {
	const (
		maxOpen = 2
		tryOpen = maxOpen*2 + 2
	)

	// No queries will be run.
	db, err := Open("test", fakeDBName)
	if err != nil {
		t.Fatalf("Open: %v", err)

	IN_MOVED_TO                                 = 0x80
	IN_MOVE_SELF                                = 0x800
	IN_ONESHOT                                  = 0x80000000
	IN_ONLYDIR                                  = 0x1000000
	IN_OPEN                                     = 0x20
	IN_Q_OVERFLOW                               = 0x4000
	IN_UNMOUNT                                  = 0x2000
	IPPROTO_AH                                  = 0x33

		{"IN_MOVED_FROM", Const, 0},
		{"IN_MOVED_TO", Const, 0},
		{"IN_MOVE_SELF", Const, 0},
		{"IN_NONBLOCK", Const, 0},
		{"IN_ONESHOT", Const, 0},
		{"IN_ONLYDIR", Const, 0},
		{"IN_OPEN", Const, 0},
		{"IN_Q_OVERFLOW", Const, 0},
		{"IN_RFC3021_HOST", Const, 1},
		{"IN_RFC3021_MASK", Const, 1},
		{"IN_RFC3021_NET", Const, 1},
		{"IN_RFC3021_NSHIFT", Const, 1},