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