Iterating Over a Concurrent Queue for Debugging

The template classes concurrent_queue and concurrent_bounded_queue support STL-style iteration. This support is intended only for debugging, when you need to dump a queue. The iterators go forwards only, and are too slow to be very useful in production code. If a queue is modified, all iterators pointing to it become invalid and unsafe to use. The following snippet dumps a queue. The operator<< is defined for a Foo.

concurrent_queue<Foo> q;
...
typedef concurrent_queue<Foo>::const_iterator iter;
for(iter i(q.unsafe_begin()); i!=q.unsafe_end(); ++i ) {
    cout << *i;
}

The prefix unsafe_ on the methods is a reminder that they are not concurrency safe.