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* Copyright (C) Igor Sysoev
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* Copyright (C) Nginx, Inc.
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#include <ngx_config.h>
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* find the middle queue element if the queue has odd number of elements
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* or the first element of the queue's second part otherwise
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ngx_queue_middle(ngx_queue_t *queue)
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ngx_queue_t *middle, *next;
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middle = ngx_queue_head(queue);
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if (middle == ngx_queue_last(queue)) {
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next = ngx_queue_head(queue);
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middle = ngx_queue_next(middle);
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next = ngx_queue_next(next);
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if (next == ngx_queue_last(queue)) {
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next = ngx_queue_next(next);
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if (next == ngx_queue_last(queue)) {
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/* the stable insertion sort */
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ngx_queue_sort(ngx_queue_t *queue,
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ngx_int_t (*cmp)(const ngx_queue_t *, const ngx_queue_t *))
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ngx_queue_t *q, *prev, *next;
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q = ngx_queue_head(queue);
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if (q == ngx_queue_last(queue)) {
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for (q = ngx_queue_next(q); q != ngx_queue_sentinel(queue); q = next) {
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prev = ngx_queue_prev(q);
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next = ngx_queue_next(q);
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if (cmp(prev, q) <= 0) {
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prev = ngx_queue_prev(prev);
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} while (prev != ngx_queue_sentinel(queue));
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ngx_queue_insert_after(prev, q);