thread/doc/changes.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:changes Changes since]

[heading Changes since boost 1.41]

Fixed Bugs:

* [@http://svn.boost.org/trac/boost/ticket/2309 #2309] Lack of g++ symbol visibility support in Boost.Thread. 
* [@http://svn.boost.org/trac/boost/ticket/2639 #2639] documentation should be extended(defer_lock, try_to_lock, ...).

* [@http://svn.boost.org/trac/boost/ticket/3639 #3639] Boost.Thread doesn't build with Sun-5.9 on Linux.
* [@http://svn.boost.org/trac/boost/ticket/3762 #3762] Thread can't be compiled with winscw (Codewarrior by Nokia).
* [@http://svn.boost.org/trac/boost/ticket/3885 #3885] document about mix usage of boost.thread and native thread api.
* [@http://svn.boost.org/trac/boost/ticket/3975 #3975] Incorrect precondition for promise::set_wait_callback().

* [@http://svn.boost.org/trac/boost/ticket/4048 #4048] thread::id formatting involves locale
* [@http://svn.boost.org/trac/boost/ticket/4315 #4315] gcc 4.4 Warning: inline ... declared as dllimport: attribute ignored. 
* [@http://svn.boost.org/trac/boost/ticket/4480 #4480] OpenVMS patches for compiler issues workarounds.
* [@http://svn.boost.org/trac/boost/ticket/4819 #4819] boost.thread's documentation misprints.

* [@http://svn.boost.org/trac/boost/ticket/5040 #5040] future.hpp in boost::thread does not compile with /clr.
* [@http://svn.boost.org/trac/boost/ticket/5423 #5423] thread issues with C++0x.
* [@http://svn.boost.org/trac/boost/ticket/5502 #5502] race condition between shared_mutex timed_lock and lock_shared.
* [@http://svn.boost.org/trac/boost/ticket/5594 #5594] boost::shared_mutex not fully compatible with Windows CE.
* [@http://svn.boost.org/trac/boost/ticket/5617 #5617] boost::thread::id copy ctor.
* [@http://svn.boost.org/trac/boost/ticket/5739 #5739] set-but-not-used warnings with gcc-4.6.
* [@http://svn.boost.org/trac/boost/ticket/5826 #5826] threads.cpp: resource leak on threads creation failure.
* [@http://svn.boost.org/trac/boost/ticket/5839 #5839] thread.cpp: ThreadProxy leaks on exceptions.
* [@http://svn.boost.org/trac/boost/ticket/5859 #5859] win32 shared_mutex constructor leaks on exceptions. 

* [@http://svn.boost.org/trac/boost/ticket/6100 #6100] Compute hardware_concurrency() using get_nprocs() on GLIBC systems.
* [@http://svn.boost.org/trac/boost/ticket/6141 #6141] Compilation error when boost.thread and boost.move are used together.
* [@http://svn.boost.org/trac/boost/ticket/6168 #6168] recursive_mutex is using wrong config symbol (possible typo).
* [@http://svn.boost.org/trac/boost/ticket/6175 #6175] Compile error with SunStudio.
* [@http://svn.boost.org/trac/boost/ticket/6200 #6200] patch to have condition_variable and mutex error better handle EINTR. 
* [@http://svn.boost.org/trac/boost/ticket/6207 #6207] shared_lock swap compiler error on clang 3.0 c++11. 
* [@http://svn.boost.org/trac/boost/ticket/6208 #6208] try_lock_wrapper swap compiler error on clang 3.0 c++11. 


[heading Changes since boost 1.40]

The 1.41.0 release of Boost adds futures to the thread library. There are also a few minor changes.

[heading Changes since boost 1.35]

The 1.36.0 release of Boost includes a few new features in the thread library:

* New generic __lock_multiple_ref__ and __try_lock_multiple_ref__ functions for locking multiple mutexes at once.

* Rvalue reference support for move semantics where the compilers supports it.

* A few bugs fixed and missing functions added (including the serious win32 condition variable bug).

* `scoped_try_lock` types are now backwards-compatible with Boost 1.34.0 and previous releases.

* Support for passing function arguments to the thread function by supplying additional arguments to the __thread__ constructor.

* Backwards-compatibility overloads added for `timed_lock` and `timed_wait` functions to allow use of `xtime` for timeouts.

[heading Changes since boost 1.34]

Almost every line of code in __boost_thread__ has been changed since the 1.34 release of boost. However, most of the interface
changes have been extensions, so the new code is largely backwards-compatible with the old code. The new features and breaking
changes are described below.

[heading New Features]

* Instances of __thread__ and of the various lock types are now movable.

* Threads can be interrupted at __interruption_points__.

* Condition variables can now be used with any type that implements the __lockable_concept__, through the use of
`boost::condition_variable_any` (`boost::condition` is a `typedef` to `boost::condition_variable_any`, provided for backwards
compatibility). `boost::condition_variable` is provided as an optimization, and will only work with
`boost::unique_lock<boost::mutex>` (`boost::mutex::scoped_lock`).

* Thread IDs are separated from __thread__, so a thread can obtain it's own ID (using `boost::this_thread::get_id()`), and IDs can
be used as keys in associative containers, as they have the full set of comparison operators.

* Timeouts are now implemented using the Boost DateTime library, through a typedef `boost::system_time` for absolute timeouts, and
with support for relative timeouts in many cases. `boost::xtime` is supported for backwards compatibility only.

* Locks are implemented as publicly accessible templates `boost::lock_guard`, `boost::unique_lock`, `boost::shared_lock`, and
`boost::upgrade_lock`, which are templated on the type of the mutex. The __lockable_concept__ has been extended to include publicly
available __lock_ref__ and __unlock_ref__ member functions, which are used by the lock types.

[heading Breaking Changes]

The list below should cover all changes to the public interface which break backwards compatibility.

* __try_mutex__ has been removed, and the functionality subsumed into __mutex__. __try_mutex__ is left as a `typedef`,
but is no longer a separate class.

* __recursive_try_mutex__ has been removed, and the functionality subsumed into
__recursive_mutex__. __recursive_try_mutex__ is left as a `typedef`, but is no longer a separate class.

* `boost::detail::thread::lock_ops` has been removed. Code that relies on the `lock_ops` implementation detail will no longer work,
as this has been removed, as it is no longer necessary now that mutex types now have public __lock_ref__ and __unlock_ref__ member
functions.

* `scoped_lock` constructors with a second parameter of type `bool` are no longer provided. With previous boost releases,
``boost::mutex::scoped_lock some_lock(some_mutex,false);`` could be used to create a lock object that was associated with a mutex,
but did not lock it on construction. This facility has now been replaced with the constructor that takes a
`boost::defer_lock_type` as the second parameter: ``boost::mutex::scoped_lock some_lock(some_mutex,boost::defer_lock);``

* The `locked()` member function of the `scoped_lock` types has been renamed to __owns_lock_ref__.

* You can no longer obtain a __thread__ instance representing the current thread: a default-constructed __thread__ object is not
associated with any thread. The only use for such a thread object was to support the comparison operators: this functionality has
been moved to __thread_id__.

* The broken `boost::read_write_mutex` has been replaced with __shared_mutex__.

* __mutex__ is now never recursive. For Boost releases prior to 1.35 __mutex__ was recursive on Windows and not on POSIX platforms.

* When using a __recursive_mutex__ with a call to [cond_any_wait_link `boost::condition_variable_any::wait()`], the mutex is only
  unlocked one level, and not completely. This prior behaviour was not guaranteed and did not feature in the tests.

[endsect]

[section:future Future]

The following features will be included in next releases. By order of priority:

* [@http://svn.boost.org/trac/boost/ticket/6194 #6194] Adapt to Boost.Move. 
* [@http://svn.boost.org/trac/boost/ticket/4710 #4710] Missing async(). 
* [@http://svn.boost.org/trac/boost/ticket/6195 #6195] Provide the standard time related interface using Boost.Chrono. 
  * [@http://svn.boost.org/trac/boost/ticket/2637 #2637] shared mutex lock
* Lock guards
  * [@http://svn.boost.org/trac/boost/ticket/1850 #1850]	request for unlock_guard (and/or unique_unlock) to compliment lock_guard/unique_lock
  * [@http://svn.boost.org/trac/boost/ticket/3567 #3567] 	Request for shared_lock_guard
* [@http://svn.boost.org/trac/boost/ticket/2741 #2741] Proposal to manage portable and non portable thread attributes. 
  * #2880 	Request for Thread scheduler support for boost ..
  * #3696 	Boost Thread library lacks any way to set priority of threads
  * #5956 	Add optional stack_size argument to thread::start_thread()

[endsect]