/src/cpython-install/include/python3.15/cpython/pylock.h
Line | Count | Source |
1 | | #ifndef Py_LOCK_H |
2 | | #define Py_LOCK_H |
3 | | #ifndef Py_LIMITED_API |
4 | | #ifdef __cplusplus |
5 | | extern "C" { |
6 | | #endif |
7 | | |
8 | | |
9 | | #define _Py_UNLOCKED 0 |
10 | | #define _Py_LOCKED 1 |
11 | | |
12 | | // A mutex that occupies one byte. The lock can be zero initialized to |
13 | | // represent the unlocked state. |
14 | | // |
15 | | // Typical initialization: |
16 | | // PyMutex m = (PyMutex){0}; |
17 | | // |
18 | | // Or initialize as global variables: |
19 | | // static PyMutex m; |
20 | | // |
21 | | // Typical usage: |
22 | | // PyMutex_Lock(&m); |
23 | | // ... |
24 | | // PyMutex_Unlock(&m); |
25 | | // |
26 | | // The contents of the PyMutex are not part of the public API, but are |
27 | | // described to aid in understanding the implementation and debugging. Only |
28 | | // the two least significant bits are used. The remaining bits are always zero: |
29 | | // 0b00: unlocked |
30 | | // 0b01: locked |
31 | | // 0b10: unlocked and has parked threads |
32 | | // 0b11: locked and has parked threads |
33 | | typedef struct PyMutex { |
34 | | uint8_t _bits; // (private) |
35 | | } PyMutex; |
36 | | |
37 | | // exported function for locking the mutex |
38 | | PyAPI_FUNC(void) PyMutex_Lock(PyMutex *m); |
39 | | |
40 | | // exported function for unlocking the mutex |
41 | | PyAPI_FUNC(void) PyMutex_Unlock(PyMutex *m); |
42 | | |
43 | | // exported function for checking if the mutex is locked |
44 | | PyAPI_FUNC(int) PyMutex_IsLocked(PyMutex *m); |
45 | | |
46 | | // Locks the mutex. |
47 | | // |
48 | | // If the mutex is currently locked, the calling thread will be parked until |
49 | | // the mutex is unlocked. If the current thread holds the GIL, then the GIL |
50 | | // will be released while the thread is parked. |
51 | | static inline void |
52 | | _PyMutex_Lock(PyMutex *m) |
53 | 0 | { |
54 | 0 | uint8_t expected = _Py_UNLOCKED; |
55 | 0 | if (!_Py_atomic_compare_exchange_uint8(&m->_bits, &expected, _Py_LOCKED)) { |
56 | 0 | PyMutex_Lock(m); |
57 | 0 | } |
58 | 0 | } |
59 | | #define PyMutex_Lock _PyMutex_Lock |
60 | | |
61 | | // Unlocks the mutex. |
62 | | static inline void |
63 | | _PyMutex_Unlock(PyMutex *m) |
64 | 0 | { |
65 | 0 | uint8_t expected = _Py_LOCKED; |
66 | 0 | if (!_Py_atomic_compare_exchange_uint8(&m->_bits, &expected, _Py_UNLOCKED)) { |
67 | 0 | PyMutex_Unlock(m); |
68 | 0 | } |
69 | 0 | } |
70 | | #define PyMutex_Unlock _PyMutex_Unlock |
71 | | |
72 | | // Checks if the mutex is currently locked. |
73 | | static inline int |
74 | | _PyMutex_IsLocked(PyMutex *m) |
75 | 0 | { |
76 | 0 | return (_Py_atomic_load_uint8(&m->_bits) & _Py_LOCKED) != 0; |
77 | 0 | } |
78 | | #define PyMutex_IsLocked _PyMutex_IsLocked |
79 | | |
80 | | |
81 | | #ifdef __cplusplus |
82 | | } |
83 | | #endif |
84 | | #endif // !Py_LIMITED_API |
85 | | #endif // !Py_LOCK_H |