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view src/http/modules/ngx_http_upstream_random_module.c @ 7966:5d09596909c6 stable-1.20

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Upstream: fixed timeouts with gRPC, SSL and select (ticket #2229). With SSL it is possible that an established connection is ready for reading after the handshake. Further, events might be already disabled in case of level-triggered event methods. If this happens and ngx_http_upstream_send_request() blocks waiting for some data from the upstream, such as flow control in case of gRPC, the connection will time out due to no read events on the upstream connection. Fix is to explicitly check the c->read->ready flag if sending request blocks and post a read event if it is set. Note that while it is possible to modify ngx_ssl_handshake() to keep read events active, this won't completely resolve the issue, since there can be data already received during the SSL handshake (see 573bd30e46b4).
author Maxim Dounin <mdounin@mdounin.ru>
date Fri, 20 Aug 2021 03:53:56 +0300
parents f2396ecf608b
children
line wrap: on
line source


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


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


typedef struct {
    ngx_http_upstream_rr_peer_t          *peer;
    ngx_uint_t                            range;
} ngx_http_upstream_random_range_t;


typedef struct {
    ngx_uint_t                            two;
    ngx_http_upstream_random_range_t     *ranges;
} ngx_http_upstream_random_srv_conf_t;


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

    ngx_http_upstream_random_srv_conf_t  *conf;
    u_char                                tries;
} ngx_http_upstream_random_peer_data_t;


static ngx_int_t ngx_http_upstream_init_random(ngx_conf_t *cf,
    ngx_http_upstream_srv_conf_t *us);
static ngx_int_t ngx_http_upstream_update_random(ngx_pool_t *pool,
    ngx_http_upstream_srv_conf_t *us);

static ngx_int_t ngx_http_upstream_init_random_peer(ngx_http_request_t *r,
    ngx_http_upstream_srv_conf_t *us);
static ngx_int_t ngx_http_upstream_get_random_peer(ngx_peer_connection_t *pc,
    void *data);
static ngx_int_t ngx_http_upstream_get_random2_peer(ngx_peer_connection_t *pc,
    void *data);
static ngx_uint_t ngx_http_upstream_peek_random_peer(
    ngx_http_upstream_rr_peers_t *peers,
    ngx_http_upstream_random_peer_data_t *rp);
static void *ngx_http_upstream_random_create_conf(ngx_conf_t *cf);
static char *ngx_http_upstream_random(ngx_conf_t *cf, ngx_command_t *cmd,
    void *conf);


static ngx_command_t  ngx_http_upstream_random_commands[] = {

    { ngx_string("random"),
      NGX_HTTP_UPS_CONF|NGX_CONF_NOARGS|NGX_CONF_TAKE12,
      ngx_http_upstream_random,
      NGX_HTTP_SRV_CONF_OFFSET,
      0,
      NULL },

      ngx_null_command
};


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

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

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

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


ngx_module_t  ngx_http_upstream_random_module = {
    NGX_MODULE_V1,
    &ngx_http_upstream_random_module_ctx,  /* module context */
    ngx_http_upstream_random_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 ngx_int_t
ngx_http_upstream_init_random(ngx_conf_t *cf, ngx_http_upstream_srv_conf_t *us)
{
    ngx_log_debug0(NGX_LOG_DEBUG_HTTP, cf->log, 0, "init random");

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

    us->peer.init = ngx_http_upstream_init_random_peer;

#if (NGX_HTTP_UPSTREAM_ZONE)
    if (us->shm_zone) {
        return NGX_OK;
    }
#endif

    return ngx_http_upstream_update_random(cf->pool, us);
}


static ngx_int_t
ngx_http_upstream_update_random(ngx_pool_t *pool,
    ngx_http_upstream_srv_conf_t *us)
{
    size_t                                size;
    ngx_uint_t                            i, total_weight;
    ngx_http_upstream_rr_peer_t          *peer;
    ngx_http_upstream_rr_peers_t         *peers;
    ngx_http_upstream_random_range_t     *ranges;
    ngx_http_upstream_random_srv_conf_t  *rcf;

    rcf = ngx_http_conf_upstream_srv_conf(us, ngx_http_upstream_random_module);

    peers = us->peer.data;

    size = peers->number * sizeof(ngx_http_upstream_random_range_t);

    ranges = pool ? ngx_palloc(pool, size) : ngx_alloc(size, ngx_cycle->log);
    if (ranges == NULL) {
        return NGX_ERROR;
    }

    total_weight = 0;

    for (peer = peers->peer, i = 0; peer; peer = peer->next, i++) {
        ranges[i].peer = peer;
        ranges[i].range = total_weight;
        total_weight += peer->weight;
    }

    rcf->ranges = ranges;

    return NGX_OK;
}


static ngx_int_t
ngx_http_upstream_init_random_peer(ngx_http_request_t *r,
    ngx_http_upstream_srv_conf_t *us)
{
    ngx_http_upstream_random_srv_conf_t   *rcf;
    ngx_http_upstream_random_peer_data_t  *rp;

    ngx_log_debug0(NGX_LOG_DEBUG_HTTP, r->connection->log, 0,
                   "init random peer");

    rcf = ngx_http_conf_upstream_srv_conf(us, ngx_http_upstream_random_module);

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

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

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

    if (rcf->two) {
        r->upstream->peer.get = ngx_http_upstream_get_random2_peer;

    } else {
        r->upstream->peer.get = ngx_http_upstream_get_random_peer;
    }

    rp->conf = rcf;
    rp->tries = 0;

    ngx_http_upstream_rr_peers_rlock(rp->rrp.peers);

#if (NGX_HTTP_UPSTREAM_ZONE)
    if (rp->rrp.peers->shpool && rcf->ranges == NULL) {
        if (ngx_http_upstream_update_random(NULL, us) != NGX_OK) {
            ngx_http_upstream_rr_peers_unlock(rp->rrp.peers);
            return NGX_ERROR;
        }
    }
#endif

    ngx_http_upstream_rr_peers_unlock(rp->rrp.peers);

    return NGX_OK;
}


static ngx_int_t
ngx_http_upstream_get_random_peer(ngx_peer_connection_t *pc, void *data)
{
    ngx_http_upstream_random_peer_data_t  *rp = data;

    time_t                             now;
    uintptr_t                          m;
    ngx_uint_t                         i, n;
    ngx_http_upstream_rr_peer_t       *peer;
    ngx_http_upstream_rr_peers_t      *peers;
    ngx_http_upstream_rr_peer_data_t  *rrp;

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

    rrp = &rp->rrp;
    peers = rrp->peers;

    ngx_http_upstream_rr_peers_rlock(peers);

    if (rp->tries > 20 || peers->single) {
        ngx_http_upstream_rr_peers_unlock(peers);
        return ngx_http_upstream_get_round_robin_peer(pc, rrp);
    }

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

    now = ngx_time();

    for ( ;; ) {

        i = ngx_http_upstream_peek_random_peer(peers, rp);

        peer = rp->conf->ranges[i].peer;

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

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

        ngx_http_upstream_rr_peer_lock(peers, peer);

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

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

        break;

    next:

        if (++rp->tries > 20) {
            ngx_http_upstream_rr_peers_unlock(peers);
            return ngx_http_upstream_get_round_robin_peer(pc, rrp);
        }
    }

    rrp->current = peer;

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

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

    peer->conns++;

    ngx_http_upstream_rr_peer_unlock(peers, peer);
    ngx_http_upstream_rr_peers_unlock(peers);

    rrp->tried[n] |= m;

    return NGX_OK;
}


static ngx_int_t
ngx_http_upstream_get_random2_peer(ngx_peer_connection_t *pc, void *data)
{
    ngx_http_upstream_random_peer_data_t  *rp = data;

    time_t                             now;
    uintptr_t                          m;
    ngx_uint_t                         i, n, p;
    ngx_http_upstream_rr_peer_t       *peer, *prev;
    ngx_http_upstream_rr_peers_t      *peers;
    ngx_http_upstream_rr_peer_data_t  *rrp;

    ngx_log_debug1(NGX_LOG_DEBUG_HTTP, pc->log, 0,
                   "get random2 peer, try: %ui", pc->tries);

    rrp = &rp->rrp;
    peers = rrp->peers;

    ngx_http_upstream_rr_peers_wlock(peers);

    if (rp->tries > 20 || peers->single) {
        ngx_http_upstream_rr_peers_unlock(peers);
        return ngx_http_upstream_get_round_robin_peer(pc, rrp);
    }

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

    now = ngx_time();

    prev = NULL;

#if (NGX_SUPPRESS_WARN)
    p = 0;
#endif

    for ( ;; ) {

        i = ngx_http_upstream_peek_random_peer(peers, rp);

        peer = rp->conf->ranges[i].peer;

        if (peer == prev) {
            goto next;
        }

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

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

        if (peer->down) {
            goto next;
        }

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

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

        if (prev) {
            if (peer->conns * prev->weight > prev->conns * peer->weight) {
                peer = prev;
                n = p / (8 * sizeof(uintptr_t));
                m = (uintptr_t) 1 << p % (8 * sizeof(uintptr_t));
            }

            break;
        }

        prev = peer;
        p = i;

    next:

        if (++rp->tries > 20) {
            ngx_http_upstream_rr_peers_unlock(peers);
            return ngx_http_upstream_get_round_robin_peer(pc, rrp);
        }
    }

    rrp->current = peer;

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

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

    peer->conns++;

    ngx_http_upstream_rr_peers_unlock(peers);

    rrp->tried[n] |= m;

    return NGX_OK;
}


static ngx_uint_t
ngx_http_upstream_peek_random_peer(ngx_http_upstream_rr_peers_t *peers,
    ngx_http_upstream_random_peer_data_t *rp)
{
    ngx_uint_t  i, j, k, x;

    x = ngx_random() % peers->total_weight;

    i = 0;
    j = peers->number;

    while (j - i > 1) {
        k = (i + j) / 2;

        if (x < rp->conf->ranges[k].range) {
            j = k;

        } else {
            i = k;
        }
    }

    return i;
}


static void *
ngx_http_upstream_random_create_conf(ngx_conf_t *cf)
{
    ngx_http_upstream_random_srv_conf_t  *conf;

    conf = ngx_pcalloc(cf->pool, sizeof(ngx_http_upstream_random_srv_conf_t));
    if (conf == NULL) {
        return NULL;
    }

    /*
     * set by ngx_pcalloc():
     *
     *     conf->two = 0;
     */

    return conf;
}


static char *
ngx_http_upstream_random(ngx_conf_t *cf, ngx_command_t *cmd, void *conf)
{
    ngx_http_upstream_random_srv_conf_t  *rcf = conf;

    ngx_str_t                     *value;
    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_random;

    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;

    if (cf->args->nelts == 1) {
        return NGX_CONF_OK;
    }

    value = cf->args->elts;

    if (ngx_strcmp(value[1].data, "two") == 0) {
        rcf->two = 1;

    } else {
        ngx_conf_log_error(NGX_LOG_EMERG, cf, 0,
                           "invalid parameter \"%V\"", &value[1]);
        return NGX_CONF_ERROR;
    }

    if (cf->args->nelts == 2) {
        return NGX_CONF_OK;
    }

    if (ngx_strcmp(value[2].data, "least_conn") != 0) {
        ngx_conf_log_error(NGX_LOG_EMERG, cf, 0,
                           "invalid parameter \"%V\"", &value[2]);
        return NGX_CONF_ERROR;
    }

    return NGX_CONF_OK;
}