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1
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2 /*
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3 * Copyright (C) Igor Sysoev
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4 */
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5
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6
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7 #include <ngx_config.h>
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8 #include <ngx_core.h>
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9
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10
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11 void ngx_spinlock(ngx_atomic_t *lock, ngx_uint_t spin)
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12 {
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13
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14 #if (NGX_HAVE_ATOMIC_OPS)
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15
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16 ngx_uint_t tries;
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17
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18 tries = 0;
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19
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20 for ( ;; ) {
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21
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22 if (*lock) {
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23 if (ngx_ncpu > 1 && tries++ < spin) {
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24 continue;
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25 }
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26
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27 ngx_sched_yield();
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28
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29 tries = 0;
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30
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31 } else {
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32 if (ngx_atomic_cmp_set(lock, 0, 1)) {
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33 return;
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34 }
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35 }
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36 }
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37
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38 #else
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39
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40 #if (NGX_THREADS)
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41
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42 #error ngx_spinlock() or ngx_atomic_cmp_set() are not defined !
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43
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44 #endif
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45
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46 #endif
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47
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48 }
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