view src/stream/ngx_stream_upstream_least_conn_module.c @ 7726:559d19037984

Limit req: unlocking of nodes on complex value errors. Previously, if there were multiple limits configured, errors in ngx_http_complex_value() during processing of a non-first limit resulted in reference count leak in shared memory nodes of already processed limits. Fix is to explicity unlock relevant nodes, much like we do when rejecting requests.
author Maxim Dounin <mdounin@mdounin.ru>
date Thu, 08 Oct 2020 17:44:34 +0300
parents 29bf0dbc0a77
children
line wrap: on
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/*
 * Copyright (C) Maxim Dounin
 * Copyright (C) Nginx, Inc.
 */


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


static ngx_int_t ngx_stream_upstream_init_least_conn_peer(
    ngx_stream_session_t *s, ngx_stream_upstream_srv_conf_t *us);
static ngx_int_t ngx_stream_upstream_get_least_conn_peer(
    ngx_peer_connection_t *pc, void *data);
static char *ngx_stream_upstream_least_conn(ngx_conf_t *cf, ngx_command_t *cmd,
    void *conf);


static ngx_command_t  ngx_stream_upstream_least_conn_commands[] = {

    { ngx_string("least_conn"),
      NGX_STREAM_UPS_CONF|NGX_CONF_NOARGS,
      ngx_stream_upstream_least_conn,
      0,
      0,
      NULL },

      ngx_null_command
};


static ngx_stream_module_t  ngx_stream_upstream_least_conn_module_ctx = {
    NULL,                                    /* preconfiguration */
    NULL,                                    /* postconfiguration */

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

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


ngx_module_t  ngx_stream_upstream_least_conn_module = {
    NGX_MODULE_V1,
    &ngx_stream_upstream_least_conn_module_ctx, /* module context */
    ngx_stream_upstream_least_conn_commands, /* module directives */
    NGX_STREAM_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 ngx_int_t
ngx_stream_upstream_init_least_conn(ngx_conf_t *cf,
    ngx_stream_upstream_srv_conf_t *us)
{
    ngx_log_debug0(NGX_LOG_DEBUG_STREAM, cf->log, 0,
                   "init least conn");

    if (ngx_stream_upstream_init_round_robin(cf, us) != NGX_OK) {
        return NGX_ERROR;
    }

    us->peer.init = ngx_stream_upstream_init_least_conn_peer;

    return NGX_OK;
}


static ngx_int_t
ngx_stream_upstream_init_least_conn_peer(ngx_stream_session_t *s,
    ngx_stream_upstream_srv_conf_t *us)
{
    ngx_log_debug0(NGX_LOG_DEBUG_STREAM, s->connection->log, 0,
                   "init least conn peer");

    if (ngx_stream_upstream_init_round_robin_peer(s, us) != NGX_OK) {
        return NGX_ERROR;
    }

    s->upstream->peer.get = ngx_stream_upstream_get_least_conn_peer;

    return NGX_OK;
}


static ngx_int_t
ngx_stream_upstream_get_least_conn_peer(ngx_peer_connection_t *pc, void *data)
{
    ngx_stream_upstream_rr_peer_data_t *rrp = data;

    time_t                           now;
    uintptr_t                        m;
    ngx_int_t                        rc, total;
    ngx_uint_t                       i, n, p, many;
    ngx_stream_upstream_rr_peer_t   *peer, *best;
    ngx_stream_upstream_rr_peers_t  *peers;

    ngx_log_debug1(NGX_LOG_DEBUG_STREAM, pc->log, 0,
                   "get least conn peer, try: %ui", pc->tries);

    if (rrp->peers->single) {
        return ngx_stream_upstream_get_round_robin_peer(pc, rrp);
    }

    pc->connection = NULL;

    now = ngx_time();

    peers = rrp->peers;

    ngx_stream_upstream_rr_peers_wlock(peers);

    best = NULL;
    total = 0;

#if (NGX_SUPPRESS_WARN)
    many = 0;
    p = 0;
#endif

    for (peer = peers->peer, i = 0;
         peer;
         peer = peer->next, i++)
    {
        n = i / (8 * sizeof(uintptr_t));
        m = (uintptr_t) 1 << i % (8 * sizeof(uintptr_t));

        if (rrp->tried[n] & m) {
            continue;
        }

        if (peer->down) {
            continue;
        }

        if (peer->max_fails
            && peer->fails >= peer->max_fails
            && now - peer->checked <= peer->fail_timeout)
        {
            continue;
        }

        if (peer->max_conns && peer->conns >= peer->max_conns) {
            continue;
        }

        /*
         * select peer with least number of connections; if there are
         * multiple peers with the same number of connections, select
         * based on round-robin
         */

        if (best == NULL
            || peer->conns * best->weight < best->conns * peer->weight)
        {
            best = peer;
            many = 0;
            p = i;

        } else if (peer->conns * best->weight == best->conns * peer->weight) {
            many = 1;
        }
    }

    if (best == NULL) {
        ngx_log_debug0(NGX_LOG_DEBUG_STREAM, pc->log, 0,
                       "get least conn peer, no peer found");

        goto failed;
    }

    if (many) {
        ngx_log_debug0(NGX_LOG_DEBUG_STREAM, pc->log, 0,
                       "get least conn peer, many");

        for (peer = best, i = p;
             peer;
             peer = peer->next, i++)
        {
            n = i / (8 * sizeof(uintptr_t));
            m = (uintptr_t) 1 << i % (8 * sizeof(uintptr_t));

            if (rrp->tried[n] & m) {
                continue;
            }

            if (peer->down) {
                continue;
            }

            if (peer->conns * best->weight != best->conns * peer->weight) {
                continue;
            }

            if (peer->max_fails
                && peer->fails >= peer->max_fails
                && now - peer->checked <= peer->fail_timeout)
            {
                continue;
            }

            if (peer->max_conns && peer->conns >= peer->max_conns) {
                continue;
            }

            peer->current_weight += peer->effective_weight;
            total += peer->effective_weight;

            if (peer->effective_weight < peer->weight) {
                peer->effective_weight++;
            }

            if (peer->current_weight > best->current_weight) {
                best = peer;
                p = i;
            }
        }
    }

    best->current_weight -= total;

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

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

    best->conns++;

    rrp->current = best;

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

    rrp->tried[n] |= m;

    ngx_stream_upstream_rr_peers_unlock(peers);

    return NGX_OK;

failed:

    if (peers->next) {
        ngx_log_debug0(NGX_LOG_DEBUG_STREAM, pc->log, 0,
                       "get least conn peer, backup servers");

        rrp->peers = peers->next;

        n = (rrp->peers->number + (8 * sizeof(uintptr_t) - 1))
                / (8 * sizeof(uintptr_t));

        for (i = 0; i < n; i++) {
            rrp->tried[i] = 0;
        }

        ngx_stream_upstream_rr_peers_unlock(peers);

        rc = ngx_stream_upstream_get_least_conn_peer(pc, rrp);

        if (rc != NGX_BUSY) {
            return rc;
        }

        ngx_stream_upstream_rr_peers_wlock(peers);
    }

    ngx_stream_upstream_rr_peers_unlock(peers);

    pc->name = peers->name;

    return NGX_BUSY;
}


static char *
ngx_stream_upstream_least_conn(ngx_conf_t *cf, ngx_command_t *cmd, void *conf)
{
    ngx_stream_upstream_srv_conf_t  *uscf;

    uscf = ngx_stream_conf_get_module_srv_conf(cf, ngx_stream_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_stream_upstream_init_least_conn;

    uscf->flags = NGX_STREAM_UPSTREAM_CREATE
                  |NGX_STREAM_UPSTREAM_WEIGHT
                  |NGX_STREAM_UPSTREAM_MAX_CONNS
                  |NGX_STREAM_UPSTREAM_MAX_FAILS
                  |NGX_STREAM_UPSTREAM_FAIL_TIMEOUT
                  |NGX_STREAM_UPSTREAM_DOWN
                  |NGX_STREAM_UPSTREAM_BACKUP;

    return NGX_CONF_OK;
}