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113 lines
2.1 KiB
113 lines
2.1 KiB
3 years ago
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/*-
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* See the file LICENSE for redistribution information.
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*
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* Copyright (c) 1997, 1998, 1999
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* Sleepycat Software. All rights reserved.
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*/
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#include "db_config.h"
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#ifndef lint
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static const char sccsid[] = "@(#)os_spin.c 11.2 (Sleepycat) 11/3/99";
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#endif /* not lint */
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#ifndef NO_SYSTEM_INCLUDES
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#include <sys/types.h>
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#if defined(HAVE_PSTAT_GETDYNAMIC)
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#include <sys/pstat.h>
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#endif
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#include <limits.h>
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#ifndef _MSC_VER /* _WIN32 */
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#include <unistd.h>
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#endif
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#endif
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#include "db_int.h"
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#include "os_jump.h"
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#if defined(HAVE_PSTAT_GETDYNAMIC)
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/*
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* __os_pstat_getdynamic --
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* HP/UX.
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*/
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static int
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__os_pstat_getdynamic()
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{
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struct pst_dynamic psd;
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return (pstat_getdynamic(&psd,
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sizeof(psd), (size_t)1, 0) == -1 ? 1 : psd.psd_proc_cnt);
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}
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#endif
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#if defined(HAVE_SYSCONF) && defined(_SC_NPROCESSORS_ONLN)
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/*
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* CDB___os_sysconf --
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* Solaris, Linux.
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*/
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static int
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CDB___os_sysconf()
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{
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int nproc;
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return ((nproc = sysconf(_SC_NPROCESSORS_ONLN)) > 1 ? nproc : 1);
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}
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#endif
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/*
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* CDB___os_spin --
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* Return the number of default spins before blocking.
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*
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* PUBLIC: int CDB___os_spin __P((void));
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*/
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int
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CDB___os_spin()
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{
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/*
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* If the application specified a value or we've already figured it
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* out, return it.
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*
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* XXX
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* We don't want to repeatedly call the underlying function because
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* it can be expensive (e.g., requiring multiple filesystem accesses
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* under Debian Linux).
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*/
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if (DB_GLOBAL(db_tas_spins) != 0)
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return (DB_GLOBAL(db_tas_spins));
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DB_GLOBAL(db_tas_spins) = 1;
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#if defined(HAVE_PSTAT_GETDYNAMIC)
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DB_GLOBAL(db_tas_spins) = __os_pstat_getdynamic();
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#endif
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#if defined(HAVE_SYSCONF) && defined(_SC_NPROCESSORS_ONLN)
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DB_GLOBAL(db_tas_spins) = CDB___os_sysconf();
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#endif
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/*
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* Spin 50 times per processor, we have anecdotal evidence that this
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* is a reasonable value.
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*/
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if (DB_GLOBAL(db_tas_spins) != 1)
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DB_GLOBAL(db_tas_spins) *= 50;
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return (DB_GLOBAL(db_tas_spins));
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}
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/*
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* CDB___os_yield --
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* Yield the processor.
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*
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* PUBLIC: void CDB___os_yield __P((u_long));
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*/
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void
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CDB___os_yield(usecs)
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u_long usecs;
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{
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if (CDB___db_jump.j_yield != NULL && CDB___db_jump.j_yield() == 0)
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return;
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CDB___os_sleep(0, usecs);
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}
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