path: root/ANNOUNCE

                 PTHREADS-WIN32 SNAPSHOT 2001-06-06
                 ----------------------------------
       Web Site: http://sources.redhat.com/pthreads-win32/
      FTP Site: ftp://sources.redhat.com/pub/pthreads-win32
        Coordinator: Ross Johnson <rpj@ise.canberra.edu.au>


We are pleased to announce the availability of a new snapshot of
Pthreads-win32, an Open Source Software implementation of the
Threads component of the POSIX 1003.1c 1995 Standard for Microsoft's
Win32 environment. Some functions from POSIX 1003.1b are also
supported including semaphores. Other related functions include
the set of read-write lock functions.

Parts of the implementation also comply with the Open Group's
Single Unix specification for compatibility with major Unix
implementations and Linux.

Pthreads-win32 is free software, distributed under the GNU Library
General Public License (LGPL).

Please see the 'Acknowledgements' section at the end of this
announcement for the list of contributors.


Change Summary (since the last snapshot)
----------------------------------------

(See the ChangeLog file for details.)

New:
-	Async cancellation should now work for Windows running
	on the following processors: IX86, MIPS, ALPHA, PPC.
	- contributors name misplaced (please contact me if it's you)
 
-       New functions (no-ops) for source code compatibility:
                pthread_getconcurrency()
                  	Returns the value previously set by
			pthread_setconcurrency(), or 0 (zero)
			if no value was previously set.
			The implementation does not currently use
			this value.
                pthread_setconcurrency()
                        Accepts any value >= 0 but does not
                        have any effect; returns '0', or
                        EINVAL if the value is < 0
                pthread_attr_getscope()
                pthread_attr_setscope()
                        Currently only return ENOSYS

-       The following mutex types and related functions are now
        supported:

                pthread_mutexattr_gettype()
                pthread_mutexattr_settype()
                pthread_mutexattr_setkind_np()
                pthread_mutexattr_getkind_np()
                PTHREAD_MUTEX_DEFAULT
                PTHREAD_MUTEX_NORMAL or PTHREAD_MUTEX_FAST_NP
                PTHREAD_MUTEX_ERRORCHECK or PTHREAD_MUTEX_ERRORCHECK_NP
                PTHREAD_MUTEX_RECURSIVE or PTHREAD_MUTEX_RECURSIVE_NP

	The *_NP versions are for Linux portability.

        In this implementation PTHREAD_MUTEX_DEFAULT is
        mapped to PTHREAD_MUTEX_NORMAL for compatibility
        with major Unix vendors. This is also the default
	if no type is specified.

	Please note that the default behaviour in previous
	versions of the library was equivalent to
	PTHREAD_MUTEX_RECURSIVE. This will be a problem
	for some applications unless they are updated to
	explicitly set the type of any mutexes that are, or
	could be, locked recursively.

        PTHREAD_MUTEX_NORMAL will cause thread deadlock
        if the owner of a mutex tries to relock it without
        first unlocking it. It has slightly less overhead
	that other types.
        - Thomas Pfaff <tpfaff@gmx.net>

-       Pthreads-win32 mutexes are now based on Win32
        critical sections for all Windows versions. The
	implementation no longer depends on
	TryEnterCriticalSection.
        - Thomas Pfaff <tpfaff@gmx.net>

-	New implementation of condition variables which attempts to
	correct problems of spurious wakeups, unfairness, and
	broadcast deadlock. See README.CV for details of the
	discussion.
	  - Alexander Terekhov <TEREKHOV@de.ibm.com>
	  - Louis Thomas <lthomas@arbitrade.com>

Bugs fixed:
-       Pthread_mutex_trylock() now properly returns EBUSY
        even when the current thread owns the mutex.
        Consequently, pthread_mutex_destroy() will no longer
        destroy a locked mutex (it will return EBUSY).
        - Thomas Pfaff <tpfaff@gmx.net>

-	Errno warnings and building with /MD;
	calling conventions (stdcall v cdecl);
	thread termination problems;
	- Milan Gardian <Milan.Gardian@LEIBINGER.com>

Known bugs in this snapshot
---------------------------

1. Under MS VC++ (only tested with version 6.0), a term_func
   set via the standard C++ set_terminate() function is not called
   for some reason. The code - in private.c:ptw32_threadStart() -
   makes an explicit call to terminate() which works as expected
   under MinGW32 g++ doesn't appear to run the term_func under
   MC VC++ 6.0.

2. Cancellation problems in optimised code
   - Milan Gardian

   The cancellation (actually, cleanup-after-cancel) tests fail when using VC
   (professional) optimisation switches (/O1 or /O2) in pthreads library. I
   have not investigated which concrete optimisation technique causes this
   problem (/Og, /Oi, /Ot, /Oy, /Ob1, /Gs, /Gf, /Gy, etc.), but here is a
   summary of builds and corresponding failures:

     * pthreads VSE (optimised tests): OK
     * pthreads VCE (optimised tests): Failed "cleanup1" test (runtime)
   
     * pthreads VSE (DLL in CRT, optimised tests): OK
     * pthreads VCE (DLL in CRT, optimised tests): Failed "cleanup1" test
   (runtime)

   Please note that while in VSE version of the pthreads library the
   optimisation does not really have any impact on the tests (they pass OK), in
   VCE version addition of optimisation (/O2 in this case) causes the tests to
   fail uniformly - either in "cleanup0" or "cleanup1" test cases.
   
   Please note that all the tests above use default pthreads DLL (no
   optimisations, linked with either static or DLL CRT, based on test type).
   Therefore the problem lies not within the pthreads DLL but within the
   compiled client code (the application using pthreads -> involvement of
   "pthread.h").

   I think the message of this section is that usage of VCE version of pthreads
   in applications relying on cancellation/cleanup AND using optimisations for
   creation of production code is highly unreliable for the current version of
   the pthreads library.


Caveats
-------

1. Due to what is believed to be a C++ compliance error in VC++,
if your application contains catch(...) blocks in your POSIX threads
then you will need to replace the "catch(...)" with the macro
"PtW32Catch", eg.

	#ifdef PtW32Catch
		PtW32Catch {
			...
		}
	#else
		catch(...) {
			...
		}
	#endif

Otherwise neither pthreads cancelation nor pthread_exit() will work
reliably.


Level of standards conformance
------------------------------

The following POSIX 1003.1c 1995 options are defined:

      _POSIX_THREADS
      _POSIX_THREAD_SAFE_FUNCTIONS
      _POSIX_THREAD_ATTR_STACKSIZE


The following POSIX 1003.1c 1995 options are not defined:

      _POSIX_THREAD_ATTR_STACKADDR
      _POSIX_THREAD_PRIORITY_SCHEDULING
      _POSIX_THREAD_PRIO_INHERIT
      _POSIX_THREAD_PRIO_PROTECT
      _POSIX_THREAD_PROCESS_SHARED

The following POSIX 1003.1b option is defined:

      _POSIX_SEMAPHORES

The following functions are implemented:

      ---------------------------
      PThreads
      ---------------------------
      pthread_attr_init
      pthread_attr_destroy
      pthread_attr_getdetachstate
      pthread_attr_getstackaddr
      pthread_attr_getstacksize
      pthread_attr_setdetachstate
      pthread_attr_setstackaddr
      pthread_attr_setstacksize

      pthread_create
      pthread_detach
      pthread_equal
      pthread_exit
      pthread_join
      pthread_once
      pthread_self

      pthread_cancel
      pthread_cleanup_pop
      pthread_cleanup_push
      pthread_setcancelstate
      pthread_setcanceltype
      pthread_testcancel
          
      ---------------------------
      Thread Specific Data   
      ---------------------------
      pthread_key_create
      pthread_key_delete
      pthread_setspecific
      pthread_getspecific
                
      ---------------------------
      Mutexes
      ---------------------------
      pthread_mutexattr_init
      pthread_mutexattr_destroy
      pthread_mutexattr_getpshared
      pthread_mutexattr_setpshared
      pthread_mutexattr_gettype
      pthread_mutexattr_settype (types: PTHREAD_MUTEX_DEFAULT
                                        PTHREAD_MUTEX_NORMAL
                                        PTHREAD_MUTEX_ERRORCHECK
                                        PTHREAD_MUTEX_RECURSIVE  )
      pthread_mutex_init
      pthread_mutex_destroy
      pthread_mutex_lock
      pthread_mutex_trylock      
      pthread_mutex_unlock

      ---------------------------
      Condition Variables
      ---------------------------
      pthread_condattr_init
      pthread_condattr_destroy
      pthread_condattr_getpshared
      pthread_condattr_setpshared

      pthread_cond_init
      pthread_cond_destroy
      pthread_cond_wait
      pthread_cond_timedwait
      pthread_cond_signal
      pthread_cond_broadcast  

      ---------------------------
      Read/Write Locks:
      ---------------------------
      pthread_rwlock_init
      pthread_rwlock_destroy
      pthread_rwlock_tryrdlock
      pthread_rwlock_trywrlock
      pthread_rwlock_rdlock
      pthread_rwlock_rwlock
      pthread_rwlock_unlock

      ---------------------------
      Semaphores
      ---------------------------
      sem_init               (POSIX 1b)
      sem_destroy            (POSIX 1b)
      sem_post               (POSIX 1b)
      sem_wait               (POSIX 1b)
      sem_trywait            (POSIX 1b)
      sem_open               (POSIX 1b - returns an error ENOSYS)
      sem_close              (POSIX 1b - returns an error ENOSYS)
      sem_unlink             (POSIX 1b - returns an error ENOSYS)
      sem_getvalue           (POSIX 1b - returns an error ENOSYS)

      ---------------------------
      RealTime Scheduling
      ---------------------------
      pthread_attr_getschedparam  
      pthread_attr_setschedparam  
      pthread_getschedparam
      pthread_setschedparam
      pthread_getconcurrency
      pthread_setconcurrency
      pthread_attr_getscope  (returns an error ENOSYS)
      pthread_attr_setscope  (returns an error ENOSYS)
      sched_get_priority_max (POSIX 1b)
      sched_get_priority_min (POSIX 1b)
      sched_yield            (POSIX 1b)

      ---------------------------
      Signals
      ---------------------------
      pthread_sigmask

      ---------------------------
      Non-portable routines (see the README.NONPORTABLE file for usage)
      ---------------------------
      pthread_getw32threadhandle_np
      pthread_delay_np
      pthread_mutexattr_getkind_np
      pthread_mutexattr_setkind_np      (types: PTHREAD_MUTEX_FAST_NP,
                                                PTHREAD_MUTEX_ERRORCHECK_NP,
                                                PTHREAD_MUTEX_RECURSIVE_NP)
      pthread_win32_process_attach_np
      pthread_win32_process_detach_np
      pthread_win32_thread_attach_np
      pthread_win32_thread_detach_np

      ---------------------------
      Static Initializers (macros)
      ---------------------------
      PTHREAD_ONCE_INIT
      PTHREAD_MUTEX_INITIALIZER
      PTHREAD_COND_INITIALIZER
      PTHREAD_RWLOCK_INITIALIZER
      
      ---------------------------
      Thread-Safe C Runtime Library (macros)
      ---------------------------
      strtok_r
      asctime_r
      ctime_r
      gmtime_r
      localtime_r
      rand_r


The following functions are not implemented:
      
      ---------------------------
      RealTime Scheduling
      ---------------------------
      pthread_attr_getinheritsched
      pthread_attr_getschedpolicy
      pthread_attr_setinheritsched
      pthread_attr_setschedpolicy
      pthread_mutex_getprioceiling
      pthread_mutex_setprioceiling
      pthread_mutex_attr_getprioceiling
      pthread_mutex_attr_getprotocol
      pthread_mutex_attr_setprioceiling
      pthread_mutex_attr_setprotocol
      
      ---------------------------
      Fork Handlers
      ---------------------------
      pthread_atfork

      ---------------------------
      Stdio
      --------------------------- 
      flockfile
      ftrylockfile
      funlockfile
      getc_unlocked
      getchar_unlocked  
      putc_unlocked
      putchar_unlocked

      ---------------------------
      Thread-Safe C Runtime Library
      ---------------------------
      readdir_r
      getgrgid_r
      getgrnam_r
      getpwuid_r
      getpwnam_r
      
      ---------------------------
      Signals
      ---------------------------
      pthread_kill
      sigtimedwait
      sigwait
      sigwaitinfo
      
      
The library includes two non-API functions for creating cancellation
points in applications and libraries:
      
      pthreadCancelableWait
      pthreadCancelableTimedWait

      
Availability
------------ 

The prebuilt DLL, export libs (for both MSVC and Mingw32), and the header
files (pthread.h, semaphore.h, sched.h) are available along with the
complete source code.

The source code can be found at:

	ftp://sources.redhat.com/pub/pthreads-win32

and as individual source code files at

	ftp://sources.redhat.com/pub/pthreads-win32/source

The pre-built DLL, export libraries and include files can be found at:

	ftp://sources.redhat.com/pub/pthreads-win32/dll-latest


      
Mailing List 
------------  
      
There is a mailing list for discussing pthreads on Win32. To join,
send email to:

        pthreads-win32-subscribe@sourceware.cygnus.com
      

Application Development Environments
------------------------------------

See the README file for more information.
      
MSVC:
MSVC using SEH works. Distribute pthreadVSE.dll with your application.
MSVC using C++ EH works. Distribute pthreadVCE.dll with your application.
MSVC using C setjmp/longjmp works. Distribute pthreadVC.dll with your application.


Mingw32:
You need gcc-2.95.2-1 modified as per pthreads-win32 FAQ answer (6), with
binutils-19990818-1 and msvcrt runtime-2000-03-27. Mingw32 must use
the thread-safe MSVCRT library (see the FAQ). You need to distribute
the gcc.dll DLL from Mingw32 with your application.

Mingw using C++ EH works. Distribute pthreadGCE.dll with your application.
Mingw using C setjmp/longjmp works. Distribute pthreadGC.dll with your application.


Cygwin: (http://sourceware.cygnus.com/cygwin/)
Cygwin aims to provide a complete POSIX environment on top of Win32, including
threads. When this is complete, developers using Cygwin will not need
pthreads-win32. At this time, Cygwin has preliminary support for multithreaded
development, however, this is not turned on by default. We have not tested
pthreads-win32 against Cygwin.


UWIN:
UWIN is a complete Unix-like environment for Windows from AT&T. Pthreads-win32
doesn't currently support UWIN (and vice versa), but that may change in the
future.

Generally:
For convenience, the following pre-built files are available on the FTP site
(see Availability above):

	pthread.h	- for POSIX 1c threads
	semaphore.h	- for POSIX 1b semaphores
	sched.h		- for POSIX 1b scheduling
	pthreadVCE.dll	- built with MSVC++ compiler using C++ EH
	pthreadVCE.lib
	pthreadVC.dll	- built with MSVC compiler using C setjmp/longjmp
	pthreadVC.lib
	pthreadVSE.dll	- built with MSVC compiler using SEH
	pthreadVSE.lib
	pthreadGCE.dll	- built with Mingw32 G++ 2.95.2-1
	pthreadGC.dll	- built with Mingw32 GCC 2.95.2-1 using setjmp/longjmp
	libpthreadGCE.a	- derived from pthreadGCE.dll
	libpthreadGC.a	- derived from pthreadGC.dll
        gcc.dll         - needed if distributing applications that use pthreadGCE.dll

These are the only files you need in order to build POSIX threads
applications for Win32 using either MSVC or Mingw32.
      
See the FAQ file in the source tree for additional information.


Documentation
-------------

Currently, there is no documentation included in the package apart
from the copious comments in the source code.

For POSIX Thread API programming, several reference books are
available:  

        Programming with POSIX Threads
        David R. Butenhof
        Addison-Wesley (pub)

        Pthreads Programming
        By Bradford Nichols, Dick Buttlar & Jacqueline Proulx Farrell
        O'Reilly (pub)

On the web: see the links at the bottom of the pthreads-win32 site:

        http://sources.redhat.com/pthreads-win32/


Acknowledgements
----------------
      
This library is based substantially on a Win32 pthreads
implementation contributed by John Bossom <John.Bossom@cognos.com>.
      
The implementation of Condition Variables uses algorithms developed
by Alexander Terekhov and Louis Thomas.

The implementation of POSIX mutexes has been improved by Thomas Pfaff.

The implementation of read/write locks was contributed by
Aurelio Medina and improved by Alexander Terekhov.

Many others have contributed significant time and effort to solve critical
problems in order to make the library workable, robust and reliable.

There is also a separate CONTRIBUTORS file. This file and others are
on the web site:

        http://sources.redhat.com/pthreads-win32

As much as possible, the ChangeLog file acknowledges contributions to the
code base in more detail.

Enjoy!

Ross Johnson