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Threads-Devel : |
From: Frank Mori Hess (frank.hess_at_[hidden])
Date: 2008-04-14 13:42:03
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On Monday 14 April 2008 11:02 am, vicente.botet wrote:
> > mutex_type m;
> > shared_lock<mutex_type> shared(m);
> > upgrade_lock<mutex_type> upgrade(m); (*)
> > shared.unlock();
>
> Your code deadlocks on (*). the upgrade_lock(Mutex&) constructor lock the
> mutex that is already shared.
No, an upgrade_lock shares ownership with shared_locks. It would only
deadlock against a unique_lock or another upgrade_lock.
> See the code
>
> <code>
> explicit upgrade_lock(Mutex& m_):
> m(&m_),is_locked(false)
> {
> lock(); // <<<<<<<<<<<<<<<
If you look at the implementation of upgrade_lock::lock(), it calls
lock_upgrade() on the mutex, not the unique lock().
> }
> upgrade_lock(Mutex& m_,bool do_lock):
> m(&m_),is_locked(false)
> {
> if(do_lock)
> {
> lock();
> }
> }
> <code/>
>
- --
Frank
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