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From: Howard Hinnant (hinnant_at_[hidden])
Date: 2007-03-19 18:48:11

On Mar 19, 2007, at 5:29 PM, Sohail Somani wrote:

> I was pretty much hoping for boost threads + cancellation.

Fwiw, this is the approach of N2184:

The very biggest change between boost::thread and N2184 is the
addition of cancellation. And, imho, this is a huge change.

There are several more minor changes:

* The N2184::thread is non-copyable like boost::thread, but movable
(taking advantage of new C++ language and std::lib features). Movable
N2184::thread maintains the one-to-one mapping between the std::thread
and the OS thread which boost has (sole ownership semantics). It just
adds the ability to move the thread between scopes (such as return
from factory functions). I recently drew the analogy this way:

boost::thread is like a scoped_ptr to the OS thread.
N2184::thread is like an auto_ptr to the OS thread (the proposed
unique_ptr would be a more accurate analogy).

* N2184::thread separates out the concept of thread identity and
thread handle. In boost these are both just boost::thread. The
thread::id is copyable. The only thing you can do with it is equality
compare it.

* N2184::thread moves some of the static boost thread members (yield,
sleep) to a namespace called this_thread. So the syntax for calling
them is std::this_thread::yield() as opposed to boost::thread::yield().

* N2184::threads adds a "back door escape hatch" to the OS thread
called native_handle(). You can get that from the std::thread and do
non-portable things with it at the OS level (setting thread priority
is the poster child).

N2184 does not mention the rest of boost::threads (mutex, locks,
condition, thread_once, TLS, etc.). All of that stuff is pretty much
assumed modulo details - TLS will be in the language, not the lib.
N2184 just concentrates on the thread class (which has been much more


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