自动加锁类和自动解锁类

 自动回锁类

// A helper class that acquires the given Lock while the AutoLock is in scope.
class AutoLock {
 public:
  explicit AutoLock(Lock& lock) : lock_(lock) {
    lock_.Acquire();
  }

  ~AutoLock() {
    lock_.AssertAcquired();
    lock_.Release();
  }

 private:
  Lock& lock_;
  DISALLOW_COPY_AND_ASSIGN(AutoLock);
};

 

自动解锁类

class AutoUnlock {
 public:
  explicit AutoUnlock(Lock& lock) : lock_(lock) {
    // We require our caller to have the lock.
    lock_.AssertAcquired();
    lock_.Release();
  }

  ~AutoUnlock() {
    lock_.Acquire();
  }

 private:
  Lock& lock_;
  DISALLOW_COPY_AND_ASSIGN(AutoUnlock);
};