SNAPSHOT 2003-09-18
-------------------

Cleanup of thread priority management. In particular, setting of thread
priority now attempts to map invalid Win32 values within the range returned
by sched_get_priority_min/max() to useful values. See README.NONPORTABLE
under "Thread priority".

Bug fixes
---------
* pthread_getschedparam() now returns the priority given by the most recent
call to pthread_setschedparam() or established by pthread_create(), as
required by the standard. Previously, pthread_getschedparam() incorrectly
returned the running thread priority at the time of the call, which may have
been adjusted or temporarily promoted/demoted.

* sched_get_priority_min() and sched_get_priority_max() now return -1 on error
and set errno. Previously, they incorrectly returned the error value directly.


SNAPSHOT 2003-09-04
-------------------

Bug fixes
---------
* ptw32_cancelableWait() now allows cancelation of waiting implicit POSIX
threads.

New test
--------
* cancel8.c tests cancelation of Win32 threads waiting at a POSIX cancelation
point.


SNAPSHOT 2003-09-03
-------------------

Bug fixes
---------
* pthread_self() would free the newly created implicit POSIX thread handle if
DuplicateHandle failed instead of recycle it (very unlikely).

* pthread_exit() was neither freeing nor recycling the POSIX thread struct
for implicit POSIX threads.

New feature - Cancelation of/by Win32 (non-POSIX) threads
---------------------------------------------------------
Since John Bossom's original implementation, the library has allowed non-POSIX
initialised threads (Win32 threads) to call pthreads-win32 routines and
therefore interact with POSIX threads. This is done by creating an on-the-fly
POSIX thread ID for the Win32 thread that, once created, allows fully
reciprical interaction. This did not extend to thread cancelation (async or
deferred). Now it does.

Any thread can be canceled by any other thread (Win32 or POSIX) if the former
thread's POSIX pthread_t value is known. It's TSD destructors and POSIX
cleanup handlers will be run before the thread exits with an exit code of
PTHREAD_CANCELED (retrieved with GetExitCodeThread()).

This allows a Win32 thread to, for example, call POSIX CV routines in the same way
that POSIX threads would/should, with pthread_cond_wait() cancelability and
cleanup handlers (pthread_cond_wait() is a POSIX cancelation point).

By adding cancelation, Win32 threads should now be able to call all POSIX
threads routines that make sense including semaphores, mutexes, condition
variables, read/write locks, barriers, spinlocks, tsd, cleanup push/pop,
cancelation, pthread_exit, scheduling, etc.

Note that these on-the-fly 'implicit' POSIX thread IDs are initialised as detached
(not joinable) with deferred cancelation type. The POSIX thread ID will be created
automatically by any POSIX routines that need a POSIX handle (unless the routine
needs a pthread_t as a parameter of course). A Win32 thread can discover it's own
POSIX thread ID by calling pthread_self(), which will create the handle if
necessary and return the pthread_t value.

New tests
---------
Test the above new feature.


SNAPSHOT 2003-08-19
-------------------

This snapshot fixes some accidental corruption to new test case sources.
There are no changes to the library source code.


SNAPSHOT 2003-08-15
-------------------

Bug fixes
---------

* pthread.dsp now uses correct compile flags (/MD).
- Viv  <vcotirlea@hotmail.com>

* pthread_win32_process_detach_np() fixed memory leak.
- Steven Reddie  <Steven.Reddie@ca.com>

* pthread_mutex_destroy() fixed incorrect return code.
- Nicolas Barry  <boozai@yahoo.com>

* pthread_spin_destroy() fixed memory leak.
- Piet van Bruggen  <pietvb@newbridges.nl>

* Various changes to tighten arg checking, and to work with later versions of
MinGW32 and MsysDTK.

* pthread_getschedparam() etc, fixed dangerous thread validity checking.
- Nicolas Barry  <boozai@yahoo.com>

* POSIX thread handles are now reused and their memory is not freed on thread exit.
This allows for stronger thread validity checking.

New standard routine
--------------------

* pthread_kill() added to provide thread validity checking to applications.
It does not accept any non zero values for the signal arg.

New test cases
--------------

* New test cases to confirm validity checking, pthread_kill(), and thread reuse.


SNAPSHOT 2003-05-10
-------------------

Bug fixes
---------

* pthread_mutex_trylock() now returns correct error values.
pthread_mutex_destroy() will no longer destroy a recursively locked mutex.
pthread_mutex_lock() is no longer inadvertantly behaving as a cancelation point.
- Thomas Pfaff  <tpfaff@gmx.net>

* pthread_mutex_timedlock() no longer occasionally sets incorrect mutex
ownership, causing deadlocks in some applications.
- Robert Strycek <strycek@posam.sk> and Alexander Terekhov  <TEREKHOV@de.ibm.com>


SNAPSHOT 2002-11-04
-------------------

Bug fixes
---------

* sem_getvalue() now returns the correct value under Win NT and WinCE.
- Rob Fanner  <rfanner@stonethree.com>

* sem_timedwait() now uses tighter checks for unreasonable
abstime values - that would result in unexpected timeout values.

* ptw32_cond_wait_cleanup() no longer mysteriously consumes
CV signals but may produce more spurious wakeups. It is believed
that the sem_timedwait() call is consuming a CV signal that it
shouldn't.
- Alexander Terekhov  <TEREKHOV@de.ibm.com>

* Fixed a memory leak in ptw32_threadDestroy() for implicit threads.

* Fixed potential for deadlock in pthread_cond_destroy().
A deadlock could occur for statically declared CVs (PTHREAD_COND_INITIALIZER),
when one thread is attempting to destroy the condition variable while another
is attempting to dynamically initialize it.
- Michael Johnson  <michaelj@maine.rr.com>


SNAPSHOT 2002-03-02
-------------------

Cleanup code default style. (IMPORTANT)
----------------------------------------------------------------------
Previously, if not defined, the cleanup style was determined automatically
from the compiler/language, and one of the following was defined accordingly:

        __CLEANUP_SEH   MSVC only
        __CLEANUP_CXX   C++, including MSVC++, GNU G++
        __CLEANUP_C             C, including GNU GCC, not MSVC

These defines determine the style of cleanup (see pthread.h) and,
most importantly, the way that cancelation and thread exit (via
pthread_exit) is performed (see the routine ptw32_throw() in private.c).

In short, the exceptions versions of the library throw an exception
when a thread is canceled or exits (via pthread_exit()), which is
caught by a handler in the thread startup routine, so that the
the correct stack unwinding occurs regardless of where the thread
is when it's canceled or exits via pthread_exit().

In this and future snapshots, unless the build explicitly defines (e.g.
via a compiler option) __CLEANUP_SEH, __CLEANUP_CXX, or __CLEANUP_C, then
the build NOW always defaults to __CLEANUP_C style cleanup. This style
uses setjmp/longjmp in the cancelation and pthread_exit implementations,
and therefore won't do stack unwinding even when linked to applications
that have it (e.g. C++ apps). This is for consistency with most
current commercial Unix POSIX threads implementations. Compaq's TRU64
may be an exception (no pun intended) and possible future trend.

Although it was not clearly documented before, it is still necessary to
build your application using the same __CLEANUP_* define as was
used for the version of the library that you link with, so that the
correct parts of pthread.h are included. That is, the possible
defines require the following library versions:

        __CLEANUP_SEH   pthreadVSE.dll
        __CLEANUP_CXX   pthreadVCE.dll or pthreadGCE.dll
        __CLEANUP_C     pthreadVC.dll or pthreadGC.dll

E.g. regardless of whether your app is C or C++, if you link with
pthreadVC.lib or libpthreadGC.a, then you must define __CLEANUP_C.


THE POINT OF ALL THIS IS: if you have not been defining one of these
explicitly, then the defaults as described at the top of this
section were being used.

THIS NOW CHANGES, as has been explained above, but to try to make this
clearer here's an example:

If you were building your application with MSVC++ i.e. using C++
exceptions and not explicitly defining one of __CLEANUP_*, then
__CLEANUP_C++ was automatically defined for you in pthread.h.
You should have been linking with pthreadVCE.dll, which does
stack unwinding.

If you now build your application as you had before, pthread.h will now
automatically set __CLEANUP_C as the default style, and you will need to
link with pthreadVC.dll. Stack unwinding will now NOT occur when a thread
is canceled, or the thread calls pthread_exit().

Your application will now most likely behave differently to previous
versions, and in non-obvious ways. Most likely is that locally
instantiated objects may not be destroyed or cleaned up after a thread
is canceled.

If you want the same behaviour as before, then you must now define
__CLEANUP_C++ explicitly using a compiler option and link with
pthreadVCE.dll as you did before.


WHY ARE WE MAKING THE DEFAULT STYLE LESS EXCEPTION-FRIENDLY?
Because no commercial Unix POSIX threads implementation allows you to
choose to have stack unwinding. Therefore, providing it in pthread-win32
as a default is dangerous. We still provide the choice but unless
you consciously choose to do otherwise, your pthreads applications will
now run or crash in similar ways irrespective of the threads platform
you use. Or at least this is the hope.


WHY NOT REMOVE THE EXCEPTIONS VERSIONS OF THE LIBRARY ALTOGETHER?
There are a few reasons:
- because there are well respected POSIX threads people who believe
  that POSIX threads implementations should be exceptions aware and
  do the expected thing in that context. (There are equally respected
  people who believe it should not be easily accessible, if it's there
  at all, for unconditional conformity to other implementations.)
- because pthreads-win32 is one of the few implementations that has
  the choice, perhaps the only freely available one, and so offers
  a laboratory to people who may want to explore the effects;
- although the code will always be around somewhere for anyone who
  wants it, once it's removed from the current version it will not be
  nearly as visible to people who may have a use for it.


Source module splitting
-----------------------
In order to enable smaller image sizes to be generated
for applications that link statically with the library,
most routines have been separated out into individual
source code files.

This is being done in such a way as to be backward compatible.
The old source files are reused to congregate the individual
routine files into larger translation units (via a bunch of
# includes) so that the compiler can still optimise wherever
possible, e.g. through inlining, which can only be done
within the same translation unit.

It is also possible to build the entire library by compiling
the single file named "pthread.c", which just #includes all
the secondary congregation source files. The compiler
may be able to use this to do more inlining of routines.

Although the GNU compiler is able to produce libraries with
the necessary separation (the -ffunction-segments switch),
AFAIK, the MSVC and other compilers don't have this feature.

Finally, since I use makefiles and command-line compilation,
I don't know what havoc this reorganisation may wreak amongst
IDE project file users. You should be able to continue
using your existing project files without modification.


New non-portable functions
--------------------------
pthread_num_processors_np():
  Returns the number of processors in the system that are
  available to the process, as determined from the processor
  affinity mask.

pthread_timechange_handler_np():
  To improve tolerance against operator or time service initiated
  system clock changes.

  This routine can be called by an application when it
  receives a WM_TIMECHANGE message from the system. At present
  it broadcasts all condition variables so that waiting threads
  can wake up and re-evaluate their conditions and restart
  their timed waits if required.
  - Suggested by Alexander Terekhov


Platform dependence
-------------------
As Win95 doesn't provide one, the library now contains
it's own InterlockedCompareExchange() routine, which is used
whenever Windows doesn't provide it. InterlockedCompareExchange()
is used to implement spinlocks and barriers, and also in mutexes.
This routine relies on the CMPXCHG machine instruction which
is not available on i386 CPUs. This library (from snapshot
20010712 onwards) is therefore no longer supported on i386
processor platforms.


New standard routines
---------------------
For source code portability only - rwlocks cannot be process shared yet.

        pthread_rwlockattr_init()
        pthread_rwlockattr_destroy()
        pthread_rwlockattr_setpshared()
        pthread_rwlockattr_getpshared()

As defined in the new POSIX standard, and the Single Unix Spec version 3:

        sem_timedwait()
        pthread_mutex_timedlock()    - Alexander Terekhov and Thomas Pfaff
        pthread_rwlock_timedrdlock() - adapted from pthread_rwlock_rdlock()
        pthread_rwlock_timedwrlock() - adapted from pthread_rwlock_wrlock()


pthread.h no longer includes windows.h
--------------------------------------
[Not yet for G++]

This was done to prevent conflicts.

HANDLE, DWORD, and NULL are temporarily defined within pthread.h if
they are not already.


pthread.h, sched.h and semaphore.h now use dllexport/dllimport
--------------------------------------------------------------
Not only to avoid the need for the pthread.def file, but to
improve performance. Apparently, declaring functions with dllimport
generates a direct call to the function and avoids the overhead
of a stub function call.

Bug fixes
---------
* Fixed potential NULL pointer dereferences in pthread_mutexattr_init,
pthread_mutexattr_getpshared, pthread_barrierattr_init,
pthread_barrierattr_getpshared, and pthread_condattr_getpshared.
- Scott McCaskill <scott@magruder.org>

* Removed potential race condition in pthread_mutex_trylock and
pthread_mutex_lock;
- Alexander Terekhov <TEREKHOV@de.ibm.com>

* The behaviour of pthread_mutex_trylock in relation to
recursive mutexes was inconsistent with commercial implementations.
Trylock would return EBUSY if the lock was owned already by the
calling thread regardless of mutex type. Trylock now increments the
recursion count and returns 0 for RECURSIVE mutexes, and will
return EDEADLK rather than EBUSY for ERRORCHECK mutexes. This is
consistent with Solaris.
- Thomas Pfaff <tpfaff@gmx.net>

* Found a fix for the library and workaround for applications for
the known bug #2, i.e. where __CLEANUP_CXX or __CLEANUP_SEH is defined.
See the "Known Bugs in this snapshot" section below.

This could be made transparent to applications by replacing the macros that
define the current C++ and SEH versions of pthread_cleanup_push/pop
with the C version, but AFAIK cleanup handlers would not then run in the
correct sequence with destructors and exception cleanup handlers when
an exception occurs.

* Cancelation once started in a thread cannot now be inadvertantly
double canceled. That is, once a thread begins it's cancelation run,
cancelation is disabled and a subsequent cancel request will
return an error (ESRCH).

* errno: An incorrect compiler directive caused a local version
of errno to be used instead of the Win32 errno. Both instances are
thread-safe but applications checking errno after a pthreads-win32
call would be wrong. Fixing this also fixed a bad compiler
option in the testsuite (/MT should have been /MD) which is
needed to link with the correct library MSVCRT.LIB.


SNAPSHOT 2001-07-12
-------------------

To be added


SNAPSHOT 2001-07-03
-------------------

To be added


SNAPSHOT 2000-08-13
-------------------

New:
-       Renamed DLL and LIB files:
                pthreadVSE.dll  (MS VC++/Structured EH)
                pthreadVSE.lib
                pthreadVCE.dll  (MS VC++/C++ EH)
                pthreadVCE.lib
                pthreadGCE.dll  (GNU G++/C++ EH)
                libpthreadw32.a

        Both your application and the pthread dll should use the
        same exception handling scheme.

Bugs fixed:
-       MSVC++ C++ exception handling.

Some new tests have been added.


SNAPSHOT 2000-08-10
-------------------

New:
-       asynchronous cancelation on X86 (Jason Nye)
-       Makefile compatible with MS nmake to replace
        buildlib.bat
-       GNUmakefile for Mingw32
-       tests/Makefile for MS nmake replaces runall.bat
-       tests/GNUmakefile for Mingw32

Bugs fixed:
-       kernel32 load/free problem
-       attempt to hide internel exceptions from application
        exception handlers (__try/__except and try/catch blocks)
-       Win32 thread handle leakage bug
        (David Baggett/Paul Redondo/Eyal Lebedinsky)

Some new tests have been added.


SNAPSHOT 1999-11-02
-------------------

Bugs fixed:
-       ctime_r macro had an incorrect argument (Erik Hensema),
-       threads were not being created 
        PTHREAD_CANCEL_DEFERRED. This should have
        had little effect as deferred is the only
        supported type. (Ross Johnson).

Some compatibility improvements added, eg.
-       pthread_setcancelstate accepts NULL pointer
        for the previous value argument. Ditto for
        pthread_setcanceltype. This is compatible
        with Solaris but should not affect
        standard applications (Erik Hensema)

Some new tests have been added.


SNAPSHOT 1999-10-17
-------------------

Bug fix - Cancelation of threads waiting on condition variables
now works properly (Lorin Hochstein and Peter Slacik)


SNAPSHOT 1999-08-12
-------------------

Fixed exception stack cleanup if calling pthread_exit()
- (Lorin Hochstein and John Bossom).

Fixed bugs in condition variables - (Peter Slacik):
        - additional contention checks
        - properly adjust number of waiting threads after timed
          condvar timeout.


SNAPSHOT 1999-05-30
-------------------

Some minor bugs have been fixed. See the ChangeLog file for details.

Some more POSIX 1b functions are now included but ony return an
error (ENOSYS) if called. They are:

        sem_open
        sem_close
        sem_unlink
        sem_getvalue


SNAPSHOT 1999-04-07
-------------------

Some POSIX 1b functions which were internally supported are now
available as exported functions:

        sem_init
        sem_destroy
        sem_wait
        sem_trywait
        sem_post
        sched_yield
        sched_get_priority_min
        sched_get_priority_max

Some minor bugs have been fixed. See the ChangeLog file for details.


SNAPSHOT 1999-03-16
-------------------

Initial release.

