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c7b8998ebb
Change pg_bsd_indent to follow upstream rules for placement of comments
to the right of code, and remove pgindent hack that caused comments
following #endif to not obey the general rule.
Commit e3860ffa4d wasn't actually using
the published version of pg_bsd_indent, but a hacked-up version that
tried to minimize the amount of movement of comments to the right of
code. The situation of interest is where such a comment has to be
moved to the right of its default placement at column 33 because there's
code there. BSD indent has always moved right in units of tab stops
in such cases --- but in the previous incarnation, indent was working
in 8-space tab stops, while now it knows we use 4-space tabs. So the
net result is that in about half the cases, such comments are placed
one tab stop left of before. This is better all around: it leaves
more room on the line for comment text, and it means that in such
cases the comment uniformly starts at the next 4-space tab stop after
the code, rather than sometimes one and sometimes two tabs after.
Also, ensure that comments following #endif are indented the same
as comments following other preprocessor commands such as #else.
That inconsistency turns out to have been self-inflicted damage
from a poorly-thought-through post-indent "fixup" in pgindent.
This patch is much less interesting than the first round of indent
changes, but also bulkier, so I thought it best to separate the effects.
Discussion: https://postgr.es/m/E1dAmxK-0006EE-1r@gemulon.postgresql.org
Discussion: https://postgr.es/m/30527.1495162840@sss.pgh.pa.us
77 lines
2.4 KiB
C
77 lines
2.4 KiB
C
/*-------------------------------------------------------------------------
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*
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* spin.h
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* Hardware-independent implementation of spinlocks.
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*
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*
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* The hardware-independent interface to spinlocks is defined by the
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* typedef "slock_t" and these macros:
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*
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* void SpinLockInit(volatile slock_t *lock)
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* Initialize a spinlock (to the unlocked state).
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*
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* void SpinLockAcquire(volatile slock_t *lock)
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* Acquire a spinlock, waiting if necessary.
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* Time out and abort() if unable to acquire the lock in a
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* "reasonable" amount of time --- typically ~ 1 minute.
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*
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* void SpinLockRelease(volatile slock_t *lock)
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* Unlock a previously acquired lock.
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*
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* bool SpinLockFree(slock_t *lock)
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* Tests if the lock is free. Returns TRUE if free, FALSE if locked.
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* This does *not* change the state of the lock.
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*
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* Callers must beware that the macro argument may be evaluated multiple
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* times!
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*
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* Load and store operations in calling code are guaranteed not to be
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* reordered with respect to these operations, because they include a
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* compiler barrier. (Before PostgreSQL 9.5, callers needed to use a
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* volatile qualifier to access data protected by spinlocks.)
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*
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* Keep in mind the coding rule that spinlocks must not be held for more
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* than a few instructions. In particular, we assume it is not possible
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* for a CHECK_FOR_INTERRUPTS() to occur while holding a spinlock, and so
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* it is not necessary to do HOLD/RESUME_INTERRUPTS() in these macros.
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*
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* These macros are implemented in terms of hardware-dependent macros
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* supplied by s_lock.h. There is not currently any extra functionality
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* added by this header, but there has been in the past and may someday
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* be again.
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*
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*
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* Portions Copyright (c) 1996-2017, PostgreSQL Global Development Group
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* Portions Copyright (c) 1994, Regents of the University of California
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*
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* src/include/storage/spin.h
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*
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*-------------------------------------------------------------------------
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*/
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#ifndef SPIN_H
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#define SPIN_H
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#include "storage/s_lock.h"
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#ifndef HAVE_SPINLOCKS
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#include "storage/pg_sema.h"
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#endif
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#define SpinLockInit(lock) S_INIT_LOCK(lock)
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#define SpinLockAcquire(lock) S_LOCK(lock)
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#define SpinLockRelease(lock) S_UNLOCK(lock)
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#define SpinLockFree(lock) S_LOCK_FREE(lock)
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extern int SpinlockSemas(void);
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extern Size SpinlockSemaSize(void);
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#ifndef HAVE_SPINLOCKS
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extern void SpinlockSemaInit(void);
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extern PGSemaphore *SpinlockSemaArray;
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#endif
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#endif /* SPIN_H */
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