nginx 1.3.0 *) Feature: the "debug_connection" directive now supports IPv6 addresses and the "unix:" parameter. *) Feature: the "set_real_ip_from" directive and the "proxy" parameter of the "geo" directive now support IPv6 addresses. *) Feature: the "real_ip_recursive", "geoip_proxy", and "geoip_proxy_recursive" directives. *) Feature: the "proxy_recursive" parameter of the "geo" directive. *) Bugfix: a segmentation fault might occur in a worker process if the "resolver" directive was used. *) Bugfix: a segmentation fault might occur in a worker process if the "fastcgi_pass", "scgi_pass", or "uwsgi_pass" directives were used and backend returned incorrect response. *) Bugfix: a segmentation fault might occur in a worker process if the "rewrite" directive was used and new request arguments in a replacement used variables. *) Bugfix: nginx might hog CPU if the open file resource limit was reached. *) Bugfix: nginx might loop infinitely over backends if the "proxy_next_upstream" directive with the "http_404" parameter was used and there were backup servers specified in an upstream block. *) Bugfix: adding the "down" parameter of the "server" directive might cause unneeded client redistribution among backend servers if the "ip_hash" directive was used. *) Bugfix: socket leak. Thanks to Yichun Zhang. *) Bugfix: in the ngx_http_fastcgi_module.

/*
 * Copyright (C) Igor Sysoev
 * Copyright (C) Nginx, Inc.
 */


#include <ngx_config.h>
#include <ngx_core.h>


/*
 * find the middle queue element if the queue has odd number of elements
 * or the first element of the queue's second part otherwise
 */

ngx_queue_t *
ngx_queue_middle(ngx_queue_t *queue)
{
    ngx_queue_t  *middle, *next;

    middle = ngx_queue_head(queue);

    if (middle == ngx_queue_last(queue)) {
        return middle;
    }

    next = ngx_queue_head(queue);

    for ( ;; ) {
        middle = ngx_queue_next(middle);

        next = ngx_queue_next(next);

        if (next == ngx_queue_last(queue)) {
            return middle;
        }

        next = ngx_queue_next(next);

        if (next == ngx_queue_last(queue)) {
            return middle;
        }
    }
}


/* the stable insertion sort */

void
ngx_queue_sort(ngx_queue_t *queue,
    ngx_int_t (*cmp)(const ngx_queue_t *, const ngx_queue_t *))
{
    ngx_queue_t  *q, *prev, *next;

    q = ngx_queue_head(queue);

    if (q == ngx_queue_last(queue)) {
        return;
    }

    for (q = ngx_queue_next(q); q != ngx_queue_sentinel(queue); q = next) {

        prev = ngx_queue_prev(q);
        next = ngx_queue_next(q);

        ngx_queue_remove(q);

        do {
            if (cmp(prev, q) <= 0) {
                break;
            }

            prev = ngx_queue_prev(prev);

        } while (prev != ngx_queue_sentinel(queue));

        ngx_queue_insert_after(prev, q);
    }
}