view src/http/modules/ngx_http_upstream_least_conn_module.c @ 7534:ac5a741d39cf

Gzip: use zlib to write header and trailer. When nginx is used with zlib patched with [1], which provides integration with the future IBM Z hardware deflate acceleration, it ends up computing CRC32 twice: one time in hardware, which always does this, and one time in software by explicitly calling crc32(). crc32() calls were added in changesets 133:b27548f540ad ("nginx-0.0.1- 2003-09-24-23:51:12 import") and 134:d57c6835225c ("nginx-0.0.1- 2003-09-26-09:45:21 import") as part of gzip wrapping feature - back then zlib did not support it. However, since then gzip wrapping was implemented in zlib v1.2.0.4, and it's already being used by nginx for log compression. This patch replaces hand-written gzip wrapping with the one provided by zlib. It simplifies the code, and makes it avoid computing CRC32 twice when using hardware acceleration. [1] https://github.com/madler/zlib/pull/410
author Ilya Leoshkevich <iii@linux.ibm.com>
date Fri, 12 Jul 2019 12:43:08 +0200
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_http.h>


static ngx_int_t ngx_http_upstream_init_least_conn_peer(ngx_http_request_t *r,
    ngx_http_upstream_srv_conf_t *us);
static ngx_int_t ngx_http_upstream_get_least_conn_peer(
    ngx_peer_connection_t *pc, void *data);
static char *ngx_http_upstream_least_conn(ngx_conf_t *cf, ngx_command_t *cmd,
    void *conf);


static ngx_command_t  ngx_http_upstream_least_conn_commands[] = {

    { ngx_string("least_conn"),
      NGX_HTTP_UPS_CONF|NGX_CONF_NOARGS,
      ngx_http_upstream_least_conn,
      0,
      0,
      NULL },

      ngx_null_command
};


static ngx_http_module_t  ngx_http_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 */

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


ngx_module_t  ngx_http_upstream_least_conn_module = {
    NGX_MODULE_V1,
    &ngx_http_upstream_least_conn_module_ctx, /* module context */
    ngx_http_upstream_least_conn_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_least_conn(ngx_conf_t *cf,
    ngx_http_upstream_srv_conf_t *us)
{
    ngx_log_debug0(NGX_LOG_DEBUG_HTTP, cf->log, 0,
                   "init least conn");

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

    us->peer.init = ngx_http_upstream_init_least_conn_peer;

    return NGX_OK;
}


static ngx_int_t
ngx_http_upstream_init_least_conn_peer(ngx_http_request_t *r,
    ngx_http_upstream_srv_conf_t *us)
{
    ngx_log_debug0(NGX_LOG_DEBUG_HTTP, r->connection->log, 0,
                   "init least conn peer");

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

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

    return NGX_OK;
}


static ngx_int_t
ngx_http_upstream_get_least_conn_peer(ngx_peer_connection_t *pc, void *data)
{
    ngx_http_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_http_upstream_rr_peer_t   *peer, *best;
    ngx_http_upstream_rr_peers_t  *peers;

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

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

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

    now = ngx_time();

    peers = rrp->peers;

    ngx_http_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_HTTP, pc->log, 0,
                       "get least conn peer, no peer found");

        goto failed;
    }

    if (many) {
        ngx_log_debug0(NGX_LOG_DEBUG_HTTP, 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_http_upstream_rr_peers_unlock(peers);

    return NGX_OK;

failed:

    if (peers->next) {
        ngx_log_debug0(NGX_LOG_DEBUG_HTTP, 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_http_upstream_rr_peers_unlock(peers);

        rc = ngx_http_upstream_get_least_conn_peer(pc, rrp);

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

        ngx_http_upstream_rr_peers_wlock(peers);
    }

    ngx_http_upstream_rr_peers_unlock(peers);

    pc->name = peers->name;

    return NGX_BUSY;
}


static char *
ngx_http_upstream_least_conn(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_least_conn;

    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
                  |NGX_HTTP_UPSTREAM_BACKUP;

    return NGX_CONF_OK;
}