[boost::condition_variable_any] Telling cond to unlock_share()
Hello users. Documentation says that cond.wait(mtx) blocks the current thread and invokes mtx.unlock(). What if I want cond.wait(mtx) to call mtx.unlock_shared() instead? Is there any way to do so? Regards, Panagiotis Foteinos
AMDG On 03/28/2011 03:03 PM, Panagiotis Foteinos wrote:
Hello users.
Documentation says that cond.wait(mtx) blocks the current thread and invokes mtx.unlock().
What if I want cond.wait(mtx) to call mtx.unlock_shared() instead? Is there any way to do so?
You should pass the unique_lock or shared_lock to cond.wait, instead of passing the mutex itself. In Christ, Steven Watanabe
Thank you for the reply. To clarify things in my mind: Should I pass the lock itself to cond.wait for safety/correctness, or because this way I will get the desired behavior? Best Regards, Panagiotis Foteinos On Mon, Mar 28, 2011 at 6:20 PM, Steven Watanabe <watanabesj@gmail.com>wrote:
AMDG
On 03/28/2011 03:03 PM, Panagiotis Foteinos wrote:
Hello users.
Documentation says that cond.wait(mtx) blocks the current thread and invokes mtx.unlock().
What if I want cond.wait(mtx) to call mtx.unlock_shared() instead? Is there any way to do so?
You should pass the unique_lock or shared_lock to cond.wait, instead of passing the mutex itself.
In Christ, Steven Watanabe _______________________________________________ Boost-users mailing list Boost-users@lists.boost.org http://lists.boost.org/mailman/listinfo.cgi/boost-users
On Mar 28, 2011, at 6:34 PM, Panagiotis Foteinos wrote:
Thank you for the reply.
To clarify things in my mind: Should I pass the lock itself to cond.wait for safety/correctness, or because this way I will get the desired behavior?
To have cond.wait call unlock_shared() / lock_shared(), cond should be of type condition_variable_any, and you should pass in shared_lock<shared_mutex> with owns_lock() == true. If you pass a shared_mutex directly to condition_variable_any::wait(), it will call unlock() on the mutex, which will be a run time error if the mutex has been lock_shared(). If you pass a shared_mutex or shared_lock to a condition_variable::wait() (as opposed to condition_variable_any), you will get a compile time error. -Howard
participants (3)
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Howard Hinnant -
Panagiotis Foteinos -
Steven Watanabe