swoole_buffer提供的expend操作用於為快取區擴容。

swoole_buffer->expand(int $new_size);

• $new_size 指定新的緩衝區尺寸，必須大於當前的尺寸

下面我們看下其實現過程。

static PHP_METHOD(swoole_buffer, expand)
{
    long size = -1;

    if (zend_parse_parameters(ZEND_NUM_ARGS() TSRMLS_CC, "l", &size) == FAILURE)
    {
        RETURN_FALSE;
    }

    swString *buffer = swoole_get_object(getThis());

    if (size <= buffer->size)
    {
        php_error_docref(NULL TSRMLS_CC, E_WARNING, "new size must be more than %ld", buffer->size);
        RETURN_FALSE;
    }

    if (swString_extend(buffer, size) == SW_OK)
    {
        zend_update_property_long(swoole_buffer_class_entry_ptr, getThis(), ZEND_STRL("capacity"), size TSRMLS_CC);
        RETURN_TRUE;
    }
    else
    {
        RETURN_FALSE;
    }
}