shared_ptr的大小是两个原始指针的大小,一个指向资源,另一个指向保持引用计数的控制块。通常情况下,控制块是与资源分开分配的,但在make_shared中,控制块很可能是与资源一起分配的,我猜是这样的:
template <typename T>
struct ResourceAndControlBlock
{
struct ControlBlock{
int weakReferences, strongReferences;
}controlBlock;
char obj[sizeof(T)]; // Object can exist here or n
我有一个带有用户表和角色表的数据库模型。我想控制对多达10个不同元素的访问(权限)。可以将访问权限授予角色或单个用户。以下是用户、角色和项的表定义:
CREATE TABLE users
(
id serial NOT NULL PRIMARY KEY,
username character varying UNIQUE,
password character varying,
first_name character varying,
last_name character varying,
...
);
CREATE TABLE roles
(
id seri
从MVC控制器(带有视图的工作文件)访问资源文件字符串时出错
Could not find any resources appropriate for the specified culture or the neutral culture. Make sure "TempNameSpace.App_GlobalResources.Resource_EN_US.resources" was correctly embedded or linked into assembly "TempNameSpace" at compile time, or that al
我正在研究同步块和调度规则。我知道这两种方法都用来保证同步数据。但我不明白它们是如何工作的。同步和调度规则的优点和缺点是什么?我在这里引用了有关调度规则的说明:在本文中,它表示的规则如下:
We can fix this example by creating a simple scheduling rule that acts as a mutex (also known as a binary semaphore):
class Mutex implements ISchedulingRule {
public boolean isConflicting(ISchedu