cpp/thread/lock guard/lock guard

Acquires ownership of the given mutex.

@1@ Effectively calls. @2@ Acquires ownership of the mutex without attempting to lock it. The behavior is undefined if the current thread does not hold a non-shared lock (i.e., a lock acquired by, , , or ) on. @3@ Copy constructor is deleted.

The behavior is undefined if is destroyed before the  object is.

Exceptions
@1@ Throws any exceptions thrown by.

@2@ Throws nothing.