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Get rid of the SpinLockAcquire/SpinLockAcquire_NoHoldoff distinction

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in favor of having just one set of macros that don't do HOLD/RESUME_INTERRUPTS
(hence, these correspond to the old SpinLockAcquire_NoHoldoff case).
Given our coding rules for spinlock use, there is no reason to allow
CHECK_FOR_INTERRUPTS to be done while holding a spinlock, and also there
is no situation where ImmediateInterruptOK will be true while holding a
spinlock.  Therefore doing HOLD/RESUME_INTERRUPTS while taking/releasing a
spinlock is just a waste of cycles.  Qingqing Zhou and Tom Lane.
This commit is contained in:
Tom Lane
2005-12-29 18:08:05 +00:00
parent e135d9631b
commit 195f164228
6 changed files with 80 additions and 112 deletions
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20
src/include/storage/buf_internals.h
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@@ -8,7 +8,7 @@
* Portions Copyright (c) 1996-2005, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
* $PostgreSQL: pgsql/src/include/storage/buf_internals.h,v 1.83 2005/11/22 18:17:31 momjian Exp $
* $PostgreSQL: pgsql/src/include/storage/buf_internals.h,v 1.84 2005/12/29 18:08:05 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@@ -138,24 +138,16 @@ typedef struct sbufdesc
#define FREENEXT_NOT_IN_LIST (-2)
/*
* Macros for acquiring/releasing a buffer header's spinlock. The
* NoHoldoff cases may be used when we know that we hold some LWLock
* and therefore interrupts are already held off. Do not apply these
* to local buffers!
* Macros for acquiring/releasing a shared buffer header's spinlock.
* Do not apply these to local buffers!
*
* Note: as a general coding rule, if you are using these then you probably
* want to be using a volatile-qualified pointer to the buffer header, to
* need to be using a volatile-qualified pointer to the buffer header, to
* ensure that the compiler doesn't rearrange accesses to the header to
* occur before or after the spinlock is acquired/released.
*/
#define LockBufHdr(bufHdr) \
SpinLockAcquire(&(bufHdr)->buf_hdr_lock)
#define UnlockBufHdr(bufHdr) \
SpinLockRelease(&(bufHdr)->buf_hdr_lock)
#define LockBufHdr_NoHoldoff(bufHdr) \
SpinLockAcquire_NoHoldoff(&(bufHdr)->buf_hdr_lock)
#define UnlockBufHdr_NoHoldoff(bufHdr) \
SpinLockRelease_NoHoldoff(&(bufHdr)->buf_hdr_lock)
#define LockBufHdr(bufHdr) SpinLockAcquire(&(bufHdr)->buf_hdr_lock)
#define UnlockBufHdr(bufHdr) SpinLockRelease(&(bufHdr)->buf_hdr_lock)
/* in buf_init.c */