LXC is a userspace interface for the Linux kernel containment features. Through a powerful API and simple tools, it lets Linux users easily create and manage system or application containers.

The linux containers, lxc, aims to use these new functionalities to provide a userspace container object which provides full resource isolation and resource control for an application or a system.

Linux container技术的目标是为应用程序或系统提供完整的资源隔离和控制。LXC项目通过提供一组API接口和工具,可以让其他程序方便地使用Linux container技术。

The container technology is actively being pushed into the mainstream linux kernel. It provides the resource management through the control groups aka process containers and resource isolation through the namespaces.

Linux container技术cgroups(control groups)namespaces实现。两者的功能如下:

cgroups = limits how much you can use;
namespaces = limits what you can see (and therefore use)


Anatomy of a Container: Namespaces, cgroups & Some Filesystem Magic




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下面选自“More effective C++, item 27”:

Simply put, dynamic_casting a pointer to void* (or const void* or volatile void* or, for those who can’t get enough modifiers in their usual diet, const volatile void*) yields a pointer to the beginning of the memory for the object pointed to by the pointer. But dynamic_cast is applicable only to pointers to objects that have at least one virtual function.




Polymorphism means “many forms”. It is where one type of thing comes in many forms. So you can treat it according to its type, but it will behave differently according to which form of that type it happens to be.


Polymorphism stems from inheritance. The whole idea is that you have a general base class and more specific derived classes. You can then write code that works with the base class… and polymorphims makes your code not only work with the base class, but all derived classes.


One of the features of derived classes is that a pointer to a derived class is type-compatible with a pointer to its base class. Polymorphism takes advantage of this feature.


A class that declares or inherits a virtual function is called a polymorphic class.

Polymorphism class是定义或继承了virtual functionclass

Pure virtual function定义:

virtual void f() = 0;

包含pure virtual function定义的类是abstract class

I don’t understand Polymorphism at all?
C++ polymorphism and abstract base class