view src/stream/ngx_stream_upstream_least_conn_module.c @ 7908:0dcec8e5d50a

HTTP/2: reworked body reading to better match HTTP/1.x code. In particular, now the code always uses a buffer limited by client_body_buffer_size. At the cost of an additional copy it ensures that small DATA frames are not directly mapped to small write() syscalls, but rather buffered in memory before writing. Further, requests without Content-Length are no longer forced to use temporary files.
author Maxim Dounin <mdounin@mdounin.ru>
date Sun, 29 Aug 2021 22:20:36 +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;
}