1  #ifndef Py_INTERNAL_CONDVAR_H
       2  #define Py_INTERNAL_CONDVAR_H
       3  
       4  #ifndef Py_BUILD_CORE
       5  #  error "this header requires Py_BUILD_CORE define"
       6  #endif
       7  
       8  #ifndef _POSIX_THREADS
       9  /* This means pthreads are not implemented in libc headers, hence the macro
      10     not present in unistd.h. But they still can be implemented as an external
      11     library (e.g. gnu pth in pthread emulation) */
      12  # ifdef HAVE_PTHREAD_H
      13  #  include <pthread.h> /* _POSIX_THREADS */
      14  # endif
      15  #endif
      16  
      17  #ifdef _POSIX_THREADS
      18  /*
      19   * POSIX support
      20   */
      21  #define Py_HAVE_CONDVAR
      22  
      23  #ifdef HAVE_PTHREAD_H
      24  #  include <pthread.h>
      25  #endif
      26  
      27  #define PyMUTEX_T pthread_mutex_t
      28  #define PyCOND_T pthread_cond_t
      29  
      30  #elif defined(NT_THREADS)
      31  /*
      32   * Windows (XP, 2003 server and later, as well as (hopefully) CE) support
      33   *
      34   * Emulated condition variables ones that work with XP and later, plus
      35   * example native support on VISTA and onwards.
      36   */
      37  #define Py_HAVE_CONDVAR
      38  
      39  /* include windows if it hasn't been done before */
      40  #define WIN32_LEAN_AND_MEAN
      41  #include <windows.h>
      42  
      43  /* options */
      44  /* non-emulated condition variables are provided for those that want
      45   * to target Windows Vista.  Modify this macro to enable them.
      46   */
      47  #ifndef _PY_EMULATED_WIN_CV
      48  #define _PY_EMULATED_WIN_CV 1  /* use emulated condition variables */
      49  #endif
      50  
      51  /* fall back to emulation if not targeting Vista */
      52  #if !defined NTDDI_VISTA || NTDDI_VERSION < NTDDI_VISTA
      53  #undef _PY_EMULATED_WIN_CV
      54  #define _PY_EMULATED_WIN_CV 1
      55  #endif
      56  
      57  #if _PY_EMULATED_WIN_CV
      58  
      59  typedef CRITICAL_SECTION PyMUTEX_T;
      60  
      61  /* The ConditionVariable object.  From XP onwards it is easily emulated
      62     with a Semaphore.
      63     Semaphores are available on Windows XP (2003 server) and later.
      64     We use a Semaphore rather than an auto-reset event, because although
      65     an auto-reset event might appear to solve the lost-wakeup bug (race
      66     condition between releasing the outer lock and waiting) because it
      67     maintains state even though a wait hasn't happened, there is still
      68     a lost wakeup problem if more than one thread are interrupted in the
      69     critical place.  A semaphore solves that, because its state is
      70     counted, not Boolean.
      71     Because it is ok to signal a condition variable with no one
      72     waiting, we need to keep track of the number of
      73     waiting threads.  Otherwise, the semaphore's state could rise
      74     without bound.  This also helps reduce the number of "spurious wakeups"
      75     that would otherwise happen.
      76   */
      77  
      78  typedef struct _PyCOND_T
      79  {
      80      HANDLE sem;
      81      int waiting; /* to allow PyCOND_SIGNAL to be a no-op */
      82  } PyCOND_T;
      83  
      84  #else /* !_PY_EMULATED_WIN_CV */
      85  
      86  /* Use native Win7 primitives if build target is Win7 or higher */
      87  
      88  /* SRWLOCK is faster and better than CriticalSection */
      89  typedef SRWLOCK PyMUTEX_T;
      90  
      91  typedef CONDITION_VARIABLE  PyCOND_T;
      92  
      93  #endif /* _PY_EMULATED_WIN_CV */
      94  
      95  #endif /* _POSIX_THREADS, NT_THREADS */
      96  
      97  #endif /* Py_INTERNAL_CONDVAR_H */