Mutex

继承： RefCounted < Object

A binary Semaphore for synchronization of multiple Thread s.

描述

A synchronization mutex (mutual exclusion). This is used to synchronize multiple Thread s, and is equivalent to a binary Semaphore. It guarantees that only one thread can access a critical section at a time.

This is a reentrant mutex, meaning that it can be locked multiple times by one thread, provided it also unlocks it as many times.

Warning: Mutexes must be used carefully to avoid deadlocks.

Warning: To ensure proper cleanup without crashes or deadlocks, the following conditions must be met:

  • When a Mutex's reference count reaches zero and it is therefore destroyed, no threads (including the one on which the destruction will happen) must have it locked.

  • When a Thread's reference count reaches zero and it is therefore destroyed, it must not have any mutex locked.

方法
voidlock ( )
booltry_lock ( )
voidunlock ( )

方法说明

void lock ( )

Locks this Mutex, blocks until it is unlocked by the current owner.

Note: This function returns without blocking if the thread already has ownership of the mutex.

bool try_lock ( )

Tries locking this Mutex, but does not block. Returns true on success, false otherwise.

Note: This function returns true if the thread already has ownership of the mutex.

void unlock ( )

Unlocks this Mutex, leaving it to other threads.

Note: If a thread called lock or try_lock multiple times while already having ownership of the mutex, it must also call unlock the same number of times in order to unlock it correctly.

Warning: Calling unlock more times that lock on a given thread, thus ending up trying to unlock a non-locked mutex, is wrong and may causes crashes or deadlocks.

1

本方法通常需要用户覆盖才能生效。

2

本方法无副作用，不会修改该实例的任何成员变量。

3

本方法除了能接受在此处描述的参数外，还能够继续接受任意数量的参数。

4

本方法用于构造某个类型。

5

调用本方法无需实例，可直接使用类名进行调用。

6

本方法描述的是使用本类型作为左操作数的有效运算符。

7

这个值是由下列位标志构成位掩码的整数。

8

无返回值。