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The C and C++ Include Header Files

/usr/include/python3.12/internal/pycore_condvar.h


$ cat -n /usr/include/python3.12/internal/pycore_condvar.h

     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 */