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diff --git a/pthreads/README.NONPORTABLE b/pthreads/README.NONPORTABLE new file mode 100644 index 000000000..aa43297e1 --- /dev/null +++ b/pthreads/README.NONPORTABLE @@ -0,0 +1,285 @@ +This file documents non-portable functions and other issues. + +Non-portable functions included in pthreads-win32 +------------------------------------------------- + +BOOL +pthread_win32_test_features_np(int mask) + + This routine allows an application to check which + run-time auto-detected features are available within + the library. + + The possible features are: + + PTW32_SYSTEM_INTERLOCKED_COMPARE_EXCHANGE + Return TRUE if the native version of + InterlockedCompareExchange() is being used. + PTW32_ALERTABLE_ASYNC_CANCEL + Return TRUE is the QueueUserAPCEx package + QUSEREX.DLL is available and the AlertDrv.sys + driver is loaded into Windows, providing + alertable (pre-emptive) asyncronous threads + cancelation. If this feature returns FALSE + then the default async cancel scheme is in + use, which cannot cancel blocked threads. + + Features may be Or'ed into the mask parameter, in which case + the routine returns TRUE if any of the Or'ed features would + return TRUE. At this stage it doesn't make sense to Or features + but it may some day. + + +void * +pthread_timechange_handler_np(void *) + + 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. + + It has the same return type and argument type as a + thread routine so that it may be called directly + through pthread_create(), i.e. as a separate thread. + + Parameters + + Although a parameter must be supplied, it is ignored. + The value NULL can be used. + + Return values + + It can return an error EAGAIN to indicate that not + all condition variables were broadcast for some reason. + Otherwise, 0 is returned. + + If run as a thread, the return value is returned + through pthread_join(). + + The return value should be cast to an integer. + + +HANDLE +pthread_getw32threadhandle_np(pthread_t thread); + + Returns the win32 thread handle that the POSIX + thread "thread" is running as. + + Applications can use the win32 handle to set + win32 specific attributes of the thread. + + +int +pthread_mutexattr_setkind_np(pthread_mutexattr_t * attr, int kind) + +int +pthread_mutexattr_getkind_np(pthread_mutexattr_t * attr, int *kind) + + These two routines are included for Linux compatibility + and are direct equivalents to the standard routines + pthread_mutexattr_settype + pthread_mutexattr_gettype + + pthread_mutexattr_setkind_np accepts the following + mutex kinds: + PTHREAD_MUTEX_FAST_NP + PTHREAD_MUTEX_ERRORCHECK_NP + PTHREAD_MUTEX_RECURSIVE_NP + + These are really just equivalent to (respectively): + PTHREAD_MUTEX_NORMAL + PTHREAD_MUTEX_ERRORCHECK + PTHREAD_MUTEX_RECURSIVE + +int +pthread_delay_np (const struct timespec *interval); + + This routine causes a thread to delay execution for a specific period of time. + This period ends at the current time plus the specified interval. The routine + will not return before the end of the period is reached, but may return an + arbitrary amount of time after the period has gone by. This can be due to + system load, thread priorities, and system timer granularity. + + Specifying an interval of zero (0) seconds and zero (0) nanoseconds is + allowed and can be used to force the thread to give up the processor or to + deliver a pending cancelation request. + + This routine is a cancelation point. + + The timespec structure contains the following two fields: + + tv_sec is an integer number of seconds. + tv_nsec is an integer number of nanoseconds. + + Return Values + + If an error condition occurs, this routine returns an integer value + indicating the type of error. Possible return values are as follows: + + 0 Successful completion. + [EINVAL] The value specified by interval is invalid. + +int +pthread_num_processors_np + + This routine (found on HPUX systems) returns the number of processors + in the system. This implementation actually returns the number of + processors available to the process, which can be a lower number + than the system's number, depending on the process's affinity mask. + +BOOL +pthread_win32_process_attach_np (void); + +BOOL +pthread_win32_process_detach_np (void); + +BOOL +pthread_win32_thread_attach_np (void); + +BOOL +pthread_win32_thread_detach_np (void); + + These functions contain the code normally run via dllMain + when the library is used as a dll but which need to be + called explicitly by an application when the library + is statically linked. + + You will need to call pthread_win32_process_attach_np() before + you can call any pthread routines when statically linking. + You should call pthread_win32_process_detach_np() before + exiting your application to clean up. + + pthread_win32_thread_attach_np() is currently a no-op, but + pthread_win32_thread_detach_np() is needed to clean up + the implicit pthread handle that is allocated to a Win32 thread if + it calls certain pthreads routines. Call this routine when the + Win32 thread exits. + + These functions invariably return TRUE except for + pthread_win32_process_attach_np() which will return FALSE + if pthreads-win32 initialisation fails. + +int +pthreadCancelableWait (HANDLE waitHandle); + +int +pthreadCancelableTimedWait (HANDLE waitHandle, DWORD timeout); + + These two functions provide hooks into the pthread_cancel + mechanism that will allow you to wait on a Windows handle + and make it a cancellation point. Both functions block + until either the given w32 handle is signaled, or + pthread_cancel has been called. It is implemented using + WaitForMultipleObjects on 'waitHandle' and a manually + reset w32 event used to implement pthread_cancel. + + +Non-portable issues +------------------- + +Thread priority + + POSIX defines a single contiguous range of numbers that determine a + thread's priority. Win32 defines priority classes and priority + levels relative to these classes. Classes are simply priority base + levels that the defined priority levels are relative to such that, + changing a process's priority class will change the priority of all + of it's threads, while the threads retain the same relativity to each + other. + + A Win32 system defines a single contiguous monotonic range of values + that define system priority levels, just like POSIX. However, Win32 + restricts individual threads to a subset of this range on a + per-process basis. + + The following table shows the base priority levels for combinations + of priority class and priority value in Win32. + + Process Priority Class Thread Priority Level + ----------------------------------------------------------------- + 1 IDLE_PRIORITY_CLASS THREAD_PRIORITY_IDLE + 1 BELOW_NORMAL_PRIORITY_CLASS THREAD_PRIORITY_IDLE + 1 NORMAL_PRIORITY_CLASS THREAD_PRIORITY_IDLE + 1 ABOVE_NORMAL_PRIORITY_CLASS THREAD_PRIORITY_IDLE + 1 HIGH_PRIORITY_CLASS THREAD_PRIORITY_IDLE + 2 IDLE_PRIORITY_CLASS THREAD_PRIORITY_LOWEST + 3 IDLE_PRIORITY_CLASS THREAD_PRIORITY_BELOW_NORMAL + 4 IDLE_PRIORITY_CLASS THREAD_PRIORITY_NORMAL + 4 BELOW_NORMAL_PRIORITY_CLASS THREAD_PRIORITY_LOWEST + 5 IDLE_PRIORITY_CLASS THREAD_PRIORITY_ABOVE_NORMAL + 5 BELOW_NORMAL_PRIORITY_CLASS THREAD_PRIORITY_BELOW_NORMAL + 5 Background NORMAL_PRIORITY_CLASS THREAD_PRIORITY_LOWEST + 6 IDLE_PRIORITY_CLASS THREAD_PRIORITY_HIGHEST + 6 BELOW_NORMAL_PRIORITY_CLASS THREAD_PRIORITY_NORMAL + 6 Background NORMAL_PRIORITY_CLASS THREAD_PRIORITY_BELOW_NORMAL + 7 BELOW_NORMAL_PRIORITY_CLASS THREAD_PRIORITY_ABOVE_NORMAL + 7 Background NORMAL_PRIORITY_CLASS THREAD_PRIORITY_NORMAL + 7 Foreground NORMAL_PRIORITY_CLASS THREAD_PRIORITY_LOWEST + 8 BELOW_NORMAL_PRIORITY_CLASS THREAD_PRIORITY_HIGHEST + 8 NORMAL_PRIORITY_CLASS THREAD_PRIORITY_ABOVE_NORMAL + 8 Foreground NORMAL_PRIORITY_CLASS THREAD_PRIORITY_BELOW_NORMAL + 8 ABOVE_NORMAL_PRIORITY_CLASS THREAD_PRIORITY_LOWEST + 9 NORMAL_PRIORITY_CLASS THREAD_PRIORITY_HIGHEST + 9 Foreground NORMAL_PRIORITY_CLASS THREAD_PRIORITY_NORMAL + 9 ABOVE_NORMAL_PRIORITY_CLASS THREAD_PRIORITY_BELOW_NORMAL + 10 Foreground NORMAL_PRIORITY_CLASS THREAD_PRIORITY_ABOVE_NORMAL + 10 ABOVE_NORMAL_PRIORITY_CLASS THREAD_PRIORITY_NORMAL + 11 Foreground NORMAL_PRIORITY_CLASS THREAD_PRIORITY_HIGHEST + 11 ABOVE_NORMAL_PRIORITY_CLASS THREAD_PRIORITY_ABOVE_NORMAL + 11 HIGH_PRIORITY_CLASS THREAD_PRIORITY_LOWEST + 12 ABOVE_NORMAL_PRIORITY_CLASS THREAD_PRIORITY_HIGHEST + 12 HIGH_PRIORITY_CLASS THREAD_PRIORITY_BELOW_NORMAL + 13 HIGH_PRIORITY_CLASS THREAD_PRIORITY_NORMAL + 14 HIGH_PRIORITY_CLASS THREAD_PRIORITY_ABOVE_NORMAL + 15 HIGH_PRIORITY_CLASS THREAD_PRIORITY_HIGHEST + 15 HIGH_PRIORITY_CLASS THREAD_PRIORITY_TIME_CRITICAL + 15 IDLE_PRIORITY_CLASS THREAD_PRIORITY_TIME_CRITICAL + 15 BELOW_NORMAL_PRIORITY_CLASS THREAD_PRIORITY_TIME_CRITICAL + 15 NORMAL_PRIORITY_CLASS THREAD_PRIORITY_TIME_CRITICAL + 15 ABOVE_NORMAL_PRIORITY_CLASS THREAD_PRIORITY_TIME_CRITICAL + 16 REALTIME_PRIORITY_CLASS THREAD_PRIORITY_IDLE + 17 REALTIME_PRIORITY_CLASS -7 + 18 REALTIME_PRIORITY_CLASS -6 + 19 REALTIME_PRIORITY_CLASS -5 + 20 REALTIME_PRIORITY_CLASS -4 + 21 REALTIME_PRIORITY_CLASS -3 + 22 REALTIME_PRIORITY_CLASS THREAD_PRIORITY_LOWEST + 23 REALTIME_PRIORITY_CLASS THREAD_PRIORITY_BELOW_NORMAL + 24 REALTIME_PRIORITY_CLASS THREAD_PRIORITY_NORMAL + 25 REALTIME_PRIORITY_CLASS THREAD_PRIORITY_ABOVE_NORMAL + 26 REALTIME_PRIORITY_CLASS THREAD_PRIORITY_HIGHEST + 27 REALTIME_PRIORITY_CLASS 3 + 28 REALTIME_PRIORITY_CLASS 4 + 29 REALTIME_PRIORITY_CLASS 5 + 30 REALTIME_PRIORITY_CLASS 6 + 31 REALTIME_PRIORITY_CLASS THREAD_PRIORITY_TIME_CRITICAL + + Windows NT: Values -7, -6, -5, -4, -3, 3, 4, 5, and 6 are not supported. + + + As you can see, the real priority levels available to any individual + Win32 thread are non-contiguous. + + An application using pthreads-win32 should not make assumptions about + the numbers used to represent thread priority levels, except that they + are monotonic between the values returned by sched_get_priority_min() + and sched_get_priority_max(). E.g. Windows 95, 98, NT, 2000, XP make + available a non-contiguous range of numbers between -15 and 15, while + at least one version of WinCE (3.0) defines the minimum priority + (THREAD_PRIORITY_LOWEST) as 5, and the maximum priority + (THREAD_PRIORITY_HIGHEST) as 1. + + Internally, pthreads-win32 maps any priority levels between + THREAD_PRIORITY_IDLE and THREAD_PRIORITY_LOWEST to THREAD_PRIORITY_LOWEST, + or between THREAD_PRIORITY_TIME_CRITICAL and THREAD_PRIORITY_HIGHEST to + THREAD_PRIORITY_HIGHEST. Currently, this also applies to + REALTIME_PRIORITY_CLASSi even if levels -7, -6, -5, -4, -3, 3, 4, 5, and 6 + are supported. + + If it wishes, a Win32 application using pthreads-win32 can use the Win32 + defined priority macros THREAD_PRIORITY_IDLE through + THREAD_PRIORITY_TIME_CRITICAL. |