зеркало из https://github.com/mozilla/gecko-dev.git
62 строки
1.3 KiB
C
62 строки
1.3 KiB
C
/*-
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* See the file LICENSE for redistribution information.
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*
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* Copyright (c) 1997, 1998
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* Sleepycat Software. All rights reserved.
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*/
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#include "config.h"
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#ifndef lint
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static const char sccsid[] = "@(#)os_spin.c 10.7 (Sleepycat) 5/20/98";
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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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#include <limits.h>
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#include <unistd.h>
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#endif
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#include "db_int.h"
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/*
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* __os_spin --
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* Return the number of default spins before blocking.
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*
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* PUBLIC: int __os_spin __P((void));
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*/
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int
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__os_spin()
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{
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static long sys_val;
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/* If the application specified the spins, use its value. */
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if (DB_GLOBAL(db_tsl_spins) != 0)
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return (DB_GLOBAL(db_tsl_spins));
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/* If we've already figured this out, return the value. */
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if (sys_val != 0)
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return (sys_val);
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/*
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* XXX
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* Solaris and Linux use _SC_NPROCESSORS_ONLN to return the number of
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* online processors. We don't want to repeatedly call sysconf because
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* it's quite expensive (requiring multiple filesystem accesses) under
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* Debian Linux.
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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 defined(HAVE_SYSCONF) && defined(_SC_NPROCESSORS_ONLN)
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if ((sys_val = sysconf(_SC_NPROCESSORS_ONLN)) > 1)
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sys_val *= 50;
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else
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sys_val = 1;
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#else
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sys_val = 1;
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#endif
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return (sys_val);
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}
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