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/****************************************************************
* *
* Copyright (c) 2001-2017 Fidelity National Information *
* Services, Inc. and/or its subsidiaries. All rights reserved. *
* *
* This source code contains the intellectual property *
* of its copyright holder(s), and is made available *
* under a license. If you do not know the terms of *
* the license, please stop and do not read further. *
* *
****************************************************************/
#ifndef GTM_REL_QUANT_INCLUDED
#define GTM_REL_QUANT_INCLUDED
#include <sys/time.h>
#include <errno.h>
#include <sched.h>
#include <time.h>
#include "gtm_unistd.h"
#include "sleep.h"
GBLREF uint4 process_id;
/* yield processor macro - if argument is 0 or the (pseudo-)random value whose limit the argument defines is 0 just yield
* otherwise do a microsleep
*/
#if defined(_AIX)
/* For pSeries the "yield" system call seems a better match for
* yields to ALLprocesses instead of just those on the local processor queue.
*/
void yield(void); /* AIX doesn't have this in a header, so use prototype from the man page. */
#define RELQUANT yield()
#else
#define RELQUANT sched_yield() /* avoiding pthread_yield() avoids unnecessary linking with libpthreads */
#endif
#define USEC_IN_NSEC_MASK 0x3FF
#define GTM_REL_QUANT(MAX_TIME_MASK) \
MBSTART { \
int NANO_SLEEP_TIME; \
static uint4 TIME_ADJ = 0; \
\
/* process_id provides cheap pseudo-random across processes, but add in a timestamp/counter \
* so that the number varies a bit. \
*/ \
if (0 == TIME_ADJ) \
TIME_ADJ = (uint4) time(NULL); \
if (MAX_TIME_MASK) \
{ /* To get a value that moves a bit, xor with a timestamp/counter. */ \
NANO_SLEEP_TIME = (process_id ^ (TIME_ADJ++)) & (MAX_TIME_MASK); \
if (!NANO_SLEEP_TIME) \
NANO_SLEEP_TIME = MAX_TIME_MASK; \
assert((NANO_SLEEP_TIME < E_9) && (NANO_SLEEP_TIME > 0)); \
NANOSLEEP(NANO_SLEEP_TIME, FALSE); \
} else \
RELQUANT; \
} MBEND
/* Sleep/rel_quant <= 1 micro-second every 4 iterations and also perform caslatch check every ~4 seconds */
#define REST_FOR_LATCH(LATCH, MAX_SLEEP_MASK, RETRIES) \
MBSTART { \
if (0 == (RETRIES & LOCK_SPIN_HARD_MASK)) /* On every so many passes, sleep rather than spinning */ \
{ \
GTM_REL_QUANT((MAX_SLEEP_MASK)); /* Release processor to holder of lock (hopefully) */ \
/* Check if we're due to check for lock abandonment check or holder wakeup */ \
if (0 == (RETRIES & (LOCK_CASLATCH_CHKINTVL_USEC - 1))) \
performCASLatchCheck(LATCH, TRUE); \
} \
} MBEND
/* Sleep 1 micro-second every 4 iterations and also perform caslatch check every ~4 seconds */
#define SLEEP_FOR_LATCH(LATCH, RETRIES) \
MBSTART { \
if (0 == (RETRIES & LOCK_SPIN_HARD_MASK)) /* On every so many passes, sleep rather than spinning */ \
{ \
SLEEP_USEC(1, FALSE); /* Release processor to holder of lock (hopefully) */ \
/* Check if we're due to check for lock abandonment check or holder wakeup */ \
if (0 == (RETRIES & (LOCK_CASLATCH_CHKINTVL_USEC - 1))) \
performCASLatchCheck(LATCH, TRUE); \
} \
} MBEND
#endif /* GTM_REL_QUANT_INCLUDED */
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