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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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42
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11 /*
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12 * TODO: the P4 optimized assembler version with the "pause" operation
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13 */
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14
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112
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15 void
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16 ngx_spinlock(ngx_atomic_t *lock, ngx_uint_t spin)
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0
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17 {
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18
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19 #if (NGX_HAVE_ATOMIC_OPS)
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20
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21 ngx_uint_t tries;
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22
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23 tries = 0;
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24
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25 for ( ;; ) {
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26
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27 if (*lock) {
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28 if (ngx_ncpu > 1 && tries++ < spin) {
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29 continue;
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30 }
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31
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32 ngx_sched_yield();
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33
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34 tries = 0;
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35
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36 } else {
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37 if (ngx_atomic_cmp_set(lock, 0, 1)) {
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38 return;
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39 }
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40 }
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41 }
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42
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43 #else
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44
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45 #if (NGX_THREADS)
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46
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47 #error ngx_spinlock() or ngx_atomic_cmp_set() are not defined !
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48
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49 #endif
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50
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51 #endif
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52
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53 }
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