Source: errors.go in package github.com/jackc/pgconn

Timeout checks if err was was caused by a timeout. To be specific, it is true if err is or was caused by a context.Canceled, context.DeadlineExceeded or an implementer of net.Error where Timeout() is true.

func Timeout(err error) bool {
	if errors.Is(err, context.Canceled) || errors.Is(err, context.DeadlineExceeded) {
		return true
	}

	var netErr net.Error
	return errors.As(err, &netErr) && netErr.Timeout()
}

PgError represents an error reported by the PostgreSQL server. See http://www.postgresql.org/docs/11/static/protocol-error-fields.html for detailed field description.

type PgError struct {
	Severity         string
	Code             string
	Message          string
	Detail           string
	Hint             string
	Position         int32
	InternalPosition int32
	InternalQuery    string
	Where            string
	SchemaName       string
	TableName        string
	ColumnName       string
	DataTypeName     string
	ConstraintName   string
	File             string
	Line             int32
	Routine          string
}

func (pe *PgError) Error() string {
	return pe.Severity + ": " + pe.Message + " (SQLSTATE " + pe.Code + ")"
}

SQLState returns the SQLState of the error.

func (pe *PgError) SQLState() string {
	return pe.Code
}

type connectError struct {
	config *Config
	msg    string
	err    error
}

func (e *connectError) Error() string {
	sb := &strings.Builder{}
	fmt.Fprintf(sb, "failed to connect to `host=%s user=%s database=%s`: %s", e.config.Host, e.config.User, e.config.Database, e.msg)
	if e.err != nil {
		fmt.Fprintf(sb, " (%s)", e.err.Error())
	}
	return sb.String()
}

func (e *connectError) Unwrap() error {
	return e.err
}

type connLockError struct {
	status string
}

func (e *connLockError) SafeToRetry() bool {
	return true // a lock failure by definition happens before the connection is used.
}

func (e *connLockError) Error() string {
	return e.status
}

type parseConfigError struct {
	connString string
	msg        string
	err        error
}

func (e *parseConfigError) Error() string {
	connString := redactPW(e.connString)
	if e.err == nil {
		return fmt.Sprintf("cannot parse `%s`: %s", connString, e.msg)
	}
	return fmt.Sprintf("cannot parse `%s`: %s (%s)", connString, e.msg, e.err.Error())
}

func (e *parseConfigError) Unwrap() error {
	return e.err
}

type pgconnError struct {
	msg         string
	err         error
	safeToRetry bool
}

func (e *pgconnError) Error() string {
	if e.msg == "" {
		return e.err.Error()
	}
	if e.err == nil {
		return e.msg
	}
	return fmt.Sprintf("%s: %s", e.msg, e.err.Error())
}

func (e *pgconnError) SafeToRetry() bool {
	return e.safeToRetry
}

func (e *pgconnError) Unwrap() error {
	return e.err
}

type contextAlreadyDoneError struct {
	err error
}

func (e *contextAlreadyDoneError) Error() string {
	return fmt.Sprintf("context already done: %s", e.err.Error())
}

func (e *contextAlreadyDoneError) SafeToRetry() bool {
	return true
}

func (e *contextAlreadyDoneError) Unwrap() error {
	return e.err
}

type writeError struct {
	err         error
	safeToRetry bool
}

func (e *writeError) Error() string {
	return fmt.Sprintf("write failed: %s", e.err.Error())
}

func (e *writeError) SafeToRetry() bool {
	return e.safeToRetry
}

func (e *writeError) Unwrap() error {
	return e.err
}

func redactPW(connString string) string {
	if strings.HasPrefix(connString, "postgres://") || strings.HasPrefix(connString, "postgresql://") {
		if u, err := url.Parse(connString); err == nil {
			return redactURL(u)
		}
	}
	quotedDSN := regexp.MustCompile(`password='[^']*'`)
	connString = quotedDSN.ReplaceAllLiteralString(connString, "password=xxxxx")
	plainDSN := regexp.MustCompile(`password=[^ ]*`)
	connString = plainDSN.ReplaceAllLiteralString(connString, "password=xxxxx")
	brokenURL := regexp.MustCompile(`:[^:@]+?@`)
	connString = brokenURL.ReplaceAllLiteralString(connString, ":xxxxxx@")
	return connString
}

func redactURL(u *url.URL) string {
	if u == nil {
		return ""
	}
	if _, pwSet := u.User.Password(); pwSet {
		u.User = url.UserPassword(u.User.Username(), "xxxxx")
	}
	return u.String()