77 lines
1.9 KiB
C
77 lines
1.9 KiB
C
/****************************************************************
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* *
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* Copyright 2001, 2012 Fidelity Information Services, Inc *
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* *
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* This source code contains the intellectual property *
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* of its copyright holder(s), and is made available *
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* under a license. If you do not know the terms of *
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* the license, please stop and do not read further. *
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* *
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****************************************************************/
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#include "mdef.h"
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#include "sleep_cnt.h"
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#ifdef VMS
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# include <lib$routines.h>
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#endif
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#include "gtm_stdlib.h"
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#include "gt_timer.h"
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#ifdef UNIX
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# include "random.h"
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#endif
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#include "wcs_backoff.h"
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GBLREF int4 process_id;
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void wcs_backoff(unsigned int sleepfactor)
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{
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/* wcs_backoff provides a layer over hiber_start that produces a [pseudo] random sleep varying
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* to a maximum sleep time it is intended to be used in as part of a contention backoff
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* where the argument is the attempt count. If the counter starts at 0, the invocation would
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* typically be:
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* if (count) wcs_backoff(count);
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*/
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# if defined(VMS)
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int4 day;
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double randfloat;
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# endif
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static int4 seed = 0;
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uint4 sleep_ms;
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assert(sleepfactor);
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if (0 == sleepfactor)
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return;
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if (sleepfactor > MAXSLPTIME)
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sleepfactor = MAXSLPTIME;
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# ifdef UNIX
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if (0 == seed)
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{
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init_rand_table();
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seed = 1;
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}
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sleep_ms = ((uint4)(get_rand_from_table() % sleepfactor));
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# elif defined(VMS)
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if (0 == seed) /* Seed random number generator */
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{
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lib$day(&day, 0, &seed);
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seed *= process_id;
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srandom(seed);
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}
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randfloat = ((double)random()) / RAND_MAX;
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sleep_ms = ((uint4)(sleepfactor * randfloat));
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# else
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# error "Unsupported platform"
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# endif
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if (0 == sleep_ms)
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return; /* We have no wait this time */
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if (1000 > sleep_ms) /* Use simpler sleep for shorties */
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{
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SHORT_SLEEP(sleep_ms);
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}
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else
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hiber_start(sleep_ms); /* Longer sleeps use brute force */
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return;
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}
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