semaphore

• When the call returns , the count on the semaphore is decremented
  当调用返回时，信号量的计数将减少。
• A type of semaphore with just two states . also called a mutex
  一种只有两种状态的信号。也叫互斥信号。
• Method is called on a semaphore whose count is already at the maximum
  对计数已达到最大值的信号量调用
• Semaphores and process mutual exclusion
  信号量和进程互斥
• Threads enter the semaphore by calling the
  线程通过调用
• Gets the access control security for a named system semaphore
  获取已命名的系统信号量的访问控制安全性。
• Any thread can signal an event wait handle or semaphore
  任何线程都可以发送事件等待句柄或信号量的信号。
• Sets the access control security for a named system semaphore
  设置已命名的系统信号量的访问控制安全性。
• Class represents a named system wide or local semaphore
  类表示一个命名信号量（系统范围）或本地信号量。
• Method to assign the altered security object to the named semaphore
  对象是不可变的。信号量的安全性使用