Age Owner Branch data TLA Line data Source code
1 : : /*-------------------------------------------------------------------------
2 : : *
3 : : * spin.h
4 : : * API for spinlocks.
5 : : *
6 : : *
7 : : * The interface to spinlocks is defined by the typedef "slock_t" and
8 : : * these functions:
9 : : *
10 : : * void SpinLockInit(volatile slock_t *lock)
11 : : * Initialize a spinlock (to the unlocked state).
12 : : *
13 : : * void SpinLockAcquire(volatile slock_t *lock)
14 : : * Acquire a spinlock, waiting if necessary.
15 : : * Time out and abort() if unable to acquire the lock in a
16 : : * "reasonable" amount of time --- typically ~ 1 minute.
17 : : *
18 : : * void SpinLockRelease(volatile slock_t *lock)
19 : : * Unlock a previously acquired lock.
20 : : *
21 : : * Load and store operations in calling code are guaranteed not to be
22 : : * reordered with respect to these operations, because they include a
23 : : * compiler barrier. (Before PostgreSQL 9.5, callers needed to use a
24 : : * volatile qualifier to access data protected by spinlocks.)
25 : : *
26 : : * Keep in mind the coding rule that spinlocks must not be held for more
27 : : * than a few instructions. In particular, we assume it is not possible
28 : : * for a CHECK_FOR_INTERRUPTS() to occur while holding a spinlock, and so
29 : : * it is not necessary to do HOLD/RESUME_INTERRUPTS() in these functions.
30 : : *
31 : : * These functions are implemented in terms of hardware-dependent macros
32 : : * supplied by s_lock.h. There is not currently any extra functionality
33 : : * added by this header, but there has been in the past and may someday
34 : : * be again.
35 : : *
36 : : *
37 : : * Portions Copyright (c) 1996-2026, PostgreSQL Global Development Group
38 : : * Portions Copyright (c) 1994, Regents of the University of California
39 : : *
40 : : * src/include/storage/spin.h
41 : : *
42 : : *-------------------------------------------------------------------------
43 : : */
44 : : #ifndef SPIN_H
45 : : #define SPIN_H
46 : :
47 : : #include "storage/s_lock.h"
48 : :
49 : : static inline void
20 nathan@postgresql.or 50 :GNC 18348021 : SpinLockInit(volatile slock_t *lock)
51 : : {
52 : 18348021 : S_INIT_LOCK(lock);
53 : 18348021 : }
54 : :
55 : : static inline void
56 : 55881599 : SpinLockAcquire(volatile slock_t *lock)
57 : : {
58 [ + + ]: 55881599 : S_LOCK(lock);
59 : 55881599 : }
60 : :
61 : : static inline void
62 : 55881599 : SpinLockRelease(volatile slock_t *lock)
63 : : {
64 : 55881599 : S_UNLOCK(lock);
65 : 55881599 : }
66 : :
67 : : #endif /* SPIN_H */
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