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view src/http/modules/ngx_http_upstream_ip_hash_module.c @ 7985:ec2e6893caaa

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Simplified sendfile(SF_NODISKIO) usage. Starting with FreeBSD 11, there is no need to use AIO operations to preload data into cache for sendfile(SF_NODISKIO) to work. Instead, sendfile() handles non-blocking loading data from disk by itself. It still can, however, return EBUSY if a page is already being loaded (for example, by a different process). If this happens, we now post an event for the next event loop iteration, so sendfile() is retried "after a short period", as manpage recommends. The limit of the number of EBUSY tolerated without any progress is preserved, but now it does not result in an alert, since on an idle system event loop iteration might be very short and EBUSY can happen many times in a row. Instead, SF_NODISKIO is simply disabled for one call once the limit is reached. With this change, sendfile(SF_NODISKIO) is now used automatically as long as sendfile() is enabled, and no longer requires "aio on;".
author Maxim Dounin <mdounin@mdounin.ru>
date Mon, 27 Dec 2021 19:48:33 +0300
parents ed599ea6c1f1
children
line wrap: on
line source


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


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


typedef struct {
    /* the round robin data must be first */
    ngx_http_upstream_rr_peer_data_t   rrp;

    ngx_uint_t                         hash;

    u_char                             addrlen;
    u_char                            *addr;

    u_char                             tries;

    ngx_event_get_peer_pt              get_rr_peer;
} ngx_http_upstream_ip_hash_peer_data_t;


static ngx_int_t ngx_http_upstream_init_ip_hash_peer(ngx_http_request_t *r,
    ngx_http_upstream_srv_conf_t *us);
static ngx_int_t ngx_http_upstream_get_ip_hash_peer(ngx_peer_connection_t *pc,
    void *data);
static char *ngx_http_upstream_ip_hash(ngx_conf_t *cf, ngx_command_t *cmd,
    void *conf);


static ngx_command_t  ngx_http_upstream_ip_hash_commands[] = {

    { ngx_string("ip_hash"),
      NGX_HTTP_UPS_CONF|NGX_CONF_NOARGS,
      ngx_http_upstream_ip_hash,
      0,
      0,
      NULL },

      ngx_null_command
};


static ngx_http_module_t  ngx_http_upstream_ip_hash_module_ctx = {
    NULL,                                  /* preconfiguration */
    NULL,                                  /* postconfiguration */

    NULL,                                  /* create main configuration */
    NULL,                                  /* init main configuration */

    NULL,                                  /* create server configuration */
    NULL,                                  /* merge server configuration */

    NULL,                                  /* create location configuration */
    NULL                                   /* merge location configuration */
};


ngx_module_t  ngx_http_upstream_ip_hash_module = {
    NGX_MODULE_V1,
    &ngx_http_upstream_ip_hash_module_ctx, /* module context */
    ngx_http_upstream_ip_hash_commands,    /* module directives */
    NGX_HTTP_MODULE,                       /* module type */
    NULL,                                  /* init master */
    NULL,                                  /* init module */
    NULL,                                  /* init process */
    NULL,                                  /* init thread */
    NULL,                                  /* exit thread */
    NULL,                                  /* exit process */
    NULL,                                  /* exit master */
    NGX_MODULE_V1_PADDING
};


static u_char ngx_http_upstream_ip_hash_pseudo_addr[3];


static ngx_int_t
ngx_http_upstream_init_ip_hash(ngx_conf_t *cf, ngx_http_upstream_srv_conf_t *us)
{
    if (ngx_http_upstream_init_round_robin(cf, us) != NGX_OK) {
        return NGX_ERROR;
    }

    us->peer.init = ngx_http_upstream_init_ip_hash_peer;

    return NGX_OK;
}


static ngx_int_t
ngx_http_upstream_init_ip_hash_peer(ngx_http_request_t *r,
    ngx_http_upstream_srv_conf_t *us)
{
    struct sockaddr_in                     *sin;
#if (NGX_HAVE_INET6)
    struct sockaddr_in6                    *sin6;
#endif
    ngx_http_upstream_ip_hash_peer_data_t  *iphp;

    iphp = ngx_palloc(r->pool, sizeof(ngx_http_upstream_ip_hash_peer_data_t));
    if (iphp == NULL) {
        return NGX_ERROR;
    }

    r->upstream->peer.data = &iphp->rrp;

    if (ngx_http_upstream_init_round_robin_peer(r, us) != NGX_OK) {
        return NGX_ERROR;
    }

    r->upstream->peer.get = ngx_http_upstream_get_ip_hash_peer;

    switch (r->connection->sockaddr->sa_family) {

    case AF_INET:
        sin = (struct sockaddr_in *) r->connection->sockaddr;
        iphp->addr = (u_char *) &sin->sin_addr.s_addr;
        iphp->addrlen = 3;
        break;

#if (NGX_HAVE_INET6)
    case AF_INET6:
        sin6 = (struct sockaddr_in6 *) r->connection->sockaddr;
        iphp->addr = (u_char *) &sin6->sin6_addr.s6_addr;
        iphp->addrlen = 16;
        break;
#endif

    default:
        iphp->addr = ngx_http_upstream_ip_hash_pseudo_addr;
        iphp->addrlen = 3;
    }

    iphp->hash = 89;
    iphp->tries = 0;
    iphp->get_rr_peer = ngx_http_upstream_get_round_robin_peer;

    return NGX_OK;
}


static ngx_int_t
ngx_http_upstream_get_ip_hash_peer(ngx_peer_connection_t *pc, void *data)
{
    ngx_http_upstream_ip_hash_peer_data_t  *iphp = data;

    time_t                        now;
    ngx_int_t                     w;
    uintptr_t                     m;
    ngx_uint_t                    i, n, p, hash;
    ngx_http_upstream_rr_peer_t  *peer;

    ngx_log_debug1(NGX_LOG_DEBUG_HTTP, pc->log, 0,
                   "get ip hash peer, try: %ui", pc->tries);

    /* TODO: cached */

    ngx_http_upstream_rr_peers_rlock(iphp->rrp.peers);

    if (iphp->tries > 20 || iphp->rrp.peers->single) {
        ngx_http_upstream_rr_peers_unlock(iphp->rrp.peers);
        return iphp->get_rr_peer(pc, &iphp->rrp);
    }

    now = ngx_time();

    pc->cached = 0;
    pc->connection = NULL;

    hash = iphp->hash;

    for ( ;; ) {

        for (i = 0; i < (ngx_uint_t) iphp->addrlen; i++) {
            hash = (hash * 113 + iphp->addr[i]) % 6271;
        }

        w = hash % iphp->rrp.peers->total_weight;
        peer = iphp->rrp.peers->peer;
        p = 0;

        while (w >= peer->weight) {
            w -= peer->weight;
            peer = peer->next;
            p++;
        }

        n = p / (8 * sizeof(uintptr_t));
        m = (uintptr_t) 1 << p % (8 * sizeof(uintptr_t));

        if (iphp->rrp.tried[n] & m) {
            goto next;
        }

        ngx_log_debug2(NGX_LOG_DEBUG_HTTP, pc->log, 0,
                       "get ip hash peer, hash: %ui %04XL", p, (uint64_t) m);

        ngx_http_upstream_rr_peer_lock(iphp->rrp.peers, peer);

        if (peer->down) {
            ngx_http_upstream_rr_peer_unlock(iphp->rrp.peers, peer);
            goto next;
        }

        if (peer->max_fails
            && peer->fails >= peer->max_fails
            && now - peer->checked <= peer->fail_timeout)
        {
            ngx_http_upstream_rr_peer_unlock(iphp->rrp.peers, peer);
            goto next;
        }

        if (peer->max_conns && peer->conns >= peer->max_conns) {
            ngx_http_upstream_rr_peer_unlock(iphp->rrp.peers, peer);
            goto next;
        }

        break;

    next:

        if (++iphp->tries > 20) {
            ngx_http_upstream_rr_peers_unlock(iphp->rrp.peers);
            return iphp->get_rr_peer(pc, &iphp->rrp);
        }
    }

    iphp->rrp.current = peer;

    pc->sockaddr = peer->sockaddr;
    pc->socklen = peer->socklen;
    pc->name = &peer->name;

    peer->conns++;

    if (now - peer->checked > peer->fail_timeout) {
        peer->checked = now;
    }

    ngx_http_upstream_rr_peer_unlock(iphp->rrp.peers, peer);
    ngx_http_upstream_rr_peers_unlock(iphp->rrp.peers);

    iphp->rrp.tried[n] |= m;
    iphp->hash = hash;

    return NGX_OK;
}


static char *
ngx_http_upstream_ip_hash(ngx_conf_t *cf, ngx_command_t *cmd, void *conf)
{
    ngx_http_upstream_srv_conf_t  *uscf;

    uscf = ngx_http_conf_get_module_srv_conf(cf, ngx_http_upstream_module);

    if (uscf->peer.init_upstream) {
        ngx_conf_log_error(NGX_LOG_WARN, cf, 0,
                           "load balancing method redefined");
    }

    uscf->peer.init_upstream = ngx_http_upstream_init_ip_hash;

    uscf->flags = NGX_HTTP_UPSTREAM_CREATE
                  |NGX_HTTP_UPSTREAM_WEIGHT
                  |NGX_HTTP_UPSTREAM_MAX_CONNS
                  |NGX_HTTP_UPSTREAM_MAX_FAILS
                  |NGX_HTTP_UPSTREAM_FAIL_TIMEOUT
                  |NGX_HTTP_UPSTREAM_DOWN;

    return NGX_CONF_OK;
}