boost_1_45_0/libs/thread/doc/barrier.qbk

[/
  (C) Copyright 2007-8 Anthony Williams.
  Distributed under the Boost Software License, Version 1.0.
  (See accompanying file LICENSE_1_0.txt or copy at
  http://www.boost.org/LICENSE_1_0.txt).
]

[section:barriers Barriers]

A barrier is a simple concept. Also known as a ['rendezvous], it is a synchronization point between multiple threads. The barrier is
configured for a particular number of threads (`n`), and as threads reach the barrier they must wait until all `n` threads have
arrived. Once the `n`-th thread has reached the barrier, all the waiting threads can proceed, and the barrier is reset.

[section:barrier Class `barrier`]

    #include <boost/thread/barrier.hpp>

    class barrier
    {
    public:
        barrier(unsigned int count);
        ~barrier();

        bool wait();
    };

Instances of __barrier__ are not copyable or movable.

[heading Constructor]

    barrier(unsigned int count);

[variablelist

[[Effects:] [Construct a barrier for `count` threads.]]

[[Throws:] [__thread_resource_error__ if an error occurs.]]

]

[heading Destructor]

    ~barrier();

[variablelist

[[Precondition:] [No threads are waiting on `*this`.]]

[[Effects:] [Destroys `*this`.]]

[[Throws:] [Nothing.]]

]

[heading Member function `wait`]

    bool wait();

[variablelist

[[Effects:] [Block until `count` threads have called `wait` on `*this`. When the `count`-th thread calls `wait`, all waiting threads
are unblocked, and the barrier is reset. ]]

[[Returns:] [`true` for exactly one thread from each batch of waiting threads, `false` otherwise.]]

[[Throws:] [__thread_resource_error__ if an error occurs.]]

]

[endsect]

[endsect]