view src/os/unix/ngx_user.c @ 4667:d05ab8793a69 stable-1.2

Merge of r4622, r4623: balancing changes. *) Upstream: smooth weighted round-robin balancing. For edge case weights like { 5, 1, 1 } we now produce { a, a, b, a, c, a, a } sequence instead of { c, b, a, a, a, a, a } produced previously. Algorithm is as follows: on each peer selection we increase current_weight of each eligible peer by its weight, select peer with greatest current_weight and reduce its current_weight by total number of weight points distributed among peers. In case of { 5, 1, 1 } weights this gives the following sequence of current_weight's: a b c 0 0 0 (initial state) 5 1 1 (a selected) -2 1 1 3 2 2 (a selected) -4 2 2 1 3 3 (b selected) 1 -4 3 6 -3 4 (a selected) -1 -3 4 4 -2 5 (c selected) 4 -2 -2 9 -1 -1 (a selected) 2 -1 -1 7 0 0 (a selected) 0 0 0 To preserve weight reduction in case of failures the effective_weight variable was introduced, which usually matches peer's weight, but is reduced temporarily on peer failures. This change also fixes loop with backup servers and proxy_next_upstream http_404 (ticket #47), and skipping alive upstreams in some cases if there are multiple dead ones (ticket #64). *) Upstream: fixed ip_hash rebalancing with the "down" flag. Due to weight being set to 0 for down peers, order of peers after sorting wasn't the same as without the "down" flag (with down peers at the end), resulting in client rebalancing for clients on other servers. The only rebalancing which should happen after adding "down" to a server is one for clients on the server. The problem was introduced in r1377 (which fixed endless loop by setting weight to 0 for down servers). The loop is no longer possible with new smooth algorithm, so preserving original weight is safe.
author Maxim Dounin <mdounin@mdounin.ru>
date Mon, 04 Jun 2012 11:21:58 +0000
parents 778ef9c3fd2d
children 6ccd3a50b40f
line wrap: on
line source


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


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


/*
 * Solaris has thread-safe crypt()
 * Linux has crypt_r(); "struct crypt_data" is more than 128K
 * FreeBSD needs the mutex to protect crypt()
 *
 * TODO:
 *     ngx_crypt_init() to init mutex
 */


#if (NGX_CRYPT)

#if (NGX_HAVE_GNU_CRYPT_R)

ngx_int_t
ngx_libc_crypt(ngx_pool_t *pool, u_char *key, u_char *salt, u_char **encrypted)
{
    char               *value;
    size_t              len;
    ngx_err_t           err;
    struct crypt_data   cd;

    ngx_set_errno(0);

    cd.initialized = 0;
    /* work around the glibc bug */
    cd.current_salt[0] = ~salt[0];

    value = crypt_r((char *) key, (char *) salt, &cd);

    err = ngx_errno;

    if (err == 0) {
        len = ngx_strlen(value) + 1;

        *encrypted = ngx_pnalloc(pool, len);
        if (*encrypted) {
            ngx_memcpy(*encrypted, value, len);
            return NGX_OK;
        }
    }

    ngx_log_error(NGX_LOG_CRIT, pool->log, err, "crypt_r() failed");

    return NGX_ERROR;
}

#else

ngx_int_t
ngx_libc_crypt(ngx_pool_t *pool, u_char *key, u_char *salt, u_char **encrypted)
{
    char       *value;
    size_t      len;
    ngx_err_t   err;

#if (NGX_THREADS && NGX_NONREENTRANT_CRYPT)

    /* crypt() is a time consuming function, so we only try to lock */

    if (ngx_mutex_trylock(ngx_crypt_mutex) != NGX_OK) {
        return NGX_AGAIN;
    }

#endif

    ngx_set_errno(0);

    value = crypt((char *) key, (char *) salt);

    if (value) {
        len = ngx_strlen(value) + 1;

        *encrypted = ngx_pnalloc(pool, len);
        if (*encrypted) {
            ngx_memcpy(*encrypted, value, len);
        }

#if (NGX_THREADS && NGX_NONREENTRANT_CRYPT)
        ngx_mutex_unlock(ngx_crypt_mutex);
#endif
        return NGX_OK;
    }

    err = ngx_errno;

#if (NGX_THREADS && NGX_NONREENTRANT_CRYPT)
    ngx_mutex_unlock(ngx_crypt_mutex);
#endif

    ngx_log_error(NGX_LOG_CRIT, pool->log, err, "crypt() failed");

    return NGX_ERROR;
}

#endif

#endif /* NGX_CRYPT */