Andrew Dunstan <[EMAIL PROTECTED]> writes:patch + new file attached. Haven't tested on Windows, but should be fine.
I wrote:
There are a couple of other places where [select()] is used for small sleeps (storage/lmgr/s_lock.c and access/transam/xact.c) -
What is the preferred way to handle these 2 cases? We could handle them with #ifdef'd code inline, or create a new function pg_usleep(), or possibly handle it with conditional macros inline. If a new function or macro, where should they go?
I'd go with a new function. There is no reason to try to "optimize" this code by putting it inline; if you're trying to delay, another few nanoseconds to enter a subroutine doesn't matter.
As for where, maybe make a new file in src/port/. That would make it relatively easy to use the same function in client-side code if we needed to.
cheers
andrew
/*------------------------------------------------------------------------- * * pg_usleep.c * platform independent version of usleep * * Portions Copyright (c) 1996-2003, PostgreSQL Global Development Group * * Uses select() everywhere except for Windows, where it doesn't work * * IDENTIFICATION * $PostgreSQL$ * *------------------------------------------------------------------------- */
#include "postgres.h"
#ifdef WIN32
#include <windows.h>
#else
#include <unistd.h>
#include <sys/time.h>
#endif
void
pg_usleep (unsigned int usecs)
{
#ifdef WIN32
Sleep(usecs < 500 : 1 : (usecs+500)/ 1000);
#else
struct timeval tv;
tv.tv_sec = usecs / 1000000;
tv.tv_usec = usecs % 1000000;
select(0,NULL,NULL,NULL,&tv);
#endif
}
Index: src/Makefile.global.in
===================================================================
RCS file: /projects/cvsroot/pgsql-server/src/Makefile.global.in,v
retrieving revision 1.172
diff -c -w -r1.172 Makefile.global.in
*** src/Makefile.global.in 19 Dec 2003 23:29:15 -0000 1.172
--- src/Makefile.global.in 30 Dec 2003 18:50:56 -0000
***************
*** 342,348 ****
#
# substitute implementations of the C library
! LIBOBJS = @LIBOBJS@ path.o sprompt.o thread.o
ifneq (,$(LIBOBJS))
LIBS += -lpgport
--- 342,348 ----
#
# substitute implementations of the C library
! LIBOBJS = @LIBOBJS@ path.o sprompt.o thread.o pg_usleep.o
ifneq (,$(LIBOBJS))
LIBS += -lpgport
Index: src/backend/access/transam/xact.c
===================================================================
RCS file: /projects/cvsroot/pgsql-server/src/backend/access/transam/xact.c,v
retrieving revision 1.158
diff -c -w -r1.158 xact.c
*** src/backend/access/transam/xact.c 2 Dec 2003 19:26:47 -0000 1.158
--- src/backend/access/transam/xact.c 30 Dec 2003 18:50:56 -0000
***************
*** 562,572 ****
if (CommitDelay > 0 && enableFsync &&
CountActiveBackends() >= CommitSiblings)
{
! struct timeval delay;
!
! delay.tv_sec = 0;
! delay.tv_usec = CommitDelay;
! (void) select(0, NULL, NULL, NULL, &delay);
}
XLogFlush(recptr);
--- 562,569 ----
if (CommitDelay > 0 && enableFsync &&
CountActiveBackends() >= CommitSiblings)
{
! /* call platform independent usleep */
! pg_usleep(CommitDelay);
}
XLogFlush(recptr);
Index: src/backend/storage/lmgr/s_lock.c
===================================================================
RCS file: /projects/cvsroot/pgsql-server/src/backend/storage/lmgr/s_lock.c,v
retrieving revision 1.23
diff -c -w -r1.23 s_lock.c
*** src/backend/storage/lmgr/s_lock.c 27 Dec 2003 20:58:58 -0000 1.23
--- src/backend/storage/lmgr/s_lock.c 30 Dec 2003 18:50:56 -0000
***************
*** 46,52 ****
s_lock(volatile slock_t *lock, const char *file, int line)
{
/*
! * We loop tightly for awhile, then delay using select() and try
* again. Preferably, "awhile" should be a small multiple of the
* maximum time we expect a spinlock to be held. 100 iterations seems
* about right. In most multi-CPU scenarios, the spinlock is probably
--- 46,52 ----
s_lock(volatile slock_t *lock, const char *file, int line)
{
/*
! * We loop tightly for awhile, then delay using pg_usleep() and try
* again. Preferably, "awhile" should be a small multiple of the
* maximum time we expect a spinlock to be held. 100 iterations seems
* about right. In most multi-CPU scenarios, the spinlock is probably
***************
*** 84,90 ****
int spins = 0;
int delays = 0;
int cur_delay = MIN_DELAY_CSEC;
- struct timeval delay;
while (TAS(lock))
{
--- 84,89 ----
***************
*** 97,105 ****
if (++delays > NUM_DELAYS)
s_lock_stuck(lock, file, line);
! delay.tv_sec = cur_delay / 100;
! delay.tv_usec = (cur_delay % 100) * 10000;
! (void) select(0, NULL, NULL, NULL, &delay);
#if defined(S_LOCK_TEST)
fprintf(stdout, "*");
--- 96,102 ----
if (++delays > NUM_DELAYS)
s_lock_stuck(lock, file, line);
! pg_usleep(cur_delay * 10000);
#if defined(S_LOCK_TEST)
fprintf(stdout, "*");
Index: src/include/port.h
===================================================================
RCS file: /projects/cvsroot/pgsql-server/src/include/port.h,v
retrieving revision 1.15
diff -c -w -r1.15 port.h
*** src/include/port.h 29 Nov 2003 22:40:53 -0000 1.15
--- src/include/port.h 30 Dec 2003 18:50:56 -0000
***************
*** 122,124 ****
--- 122,127 ----
char *buffer, size_t buflen,
struct hostent **result,
int *herrno);
+
+ extern void pg_usleep(unsigned int usecs);
+
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