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view src/http/modules/ngx_http_upstream_keepalive_module.c @ 7281:bd6563e81cea

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Limit req: improved handling of negative times. Negative times can appear since workers only update time on an event loop iteration start. If a worker was blocked for a long time during an event loop iteration, it is possible that another worker already updated the time stored in the node. As such, time since last update of the node (ms) will be negative. Previous code used ngx_abs(ms) in the calculations. That is, negative times were effectively treated as positive ones. As a result, it was not possible to maintain high request rates, where the same node can be updated multiple times from during an event loop iteration. In particular, this affected setups with many SSL handshakes, see http://mailman.nginx.org/pipermail/nginx/2018-May/056291.html. Fix is to only update the last update time stored in the node if the new time is larger than previously stored one. If a future time is stored in the node, we preserve this time as is. To prevent breaking things on platforms without monotonic time available if system time is updated backwards, a safety limit of 60 seconds is used. If the time stored in the node is more than 60 seconds in the future, we assume that the time was changed backwards and update lr->last to the current time.
author Maxim Dounin <mdounin@mdounin.ru>
date Wed, 30 May 2018 15:40:34 +0300
parents 1cb92a2d672e
children 46174066b75f
line wrap: on
line source


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


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


typedef struct {
    ngx_uint_t                         max_cached;

    ngx_queue_t                        cache;
    ngx_queue_t                        free;

    ngx_http_upstream_init_pt          original_init_upstream;
    ngx_http_upstream_init_peer_pt     original_init_peer;

} ngx_http_upstream_keepalive_srv_conf_t;


typedef struct {
    ngx_http_upstream_keepalive_srv_conf_t  *conf;

    ngx_queue_t                        queue;
    ngx_connection_t                  *connection;

    socklen_t                          socklen;
    ngx_sockaddr_t                     sockaddr;

} ngx_http_upstream_keepalive_cache_t;


typedef struct {
    ngx_http_upstream_keepalive_srv_conf_t  *conf;

    ngx_http_upstream_t               *upstream;

    void                              *data;

    ngx_event_get_peer_pt              original_get_peer;
    ngx_event_free_peer_pt             original_free_peer;

#if (NGX_HTTP_SSL)
    ngx_event_set_peer_session_pt      original_set_session;
    ngx_event_save_peer_session_pt     original_save_session;
#endif

} ngx_http_upstream_keepalive_peer_data_t;


static ngx_int_t ngx_http_upstream_init_keepalive_peer(ngx_http_request_t *r,
    ngx_http_upstream_srv_conf_t *us);
static ngx_int_t ngx_http_upstream_get_keepalive_peer(ngx_peer_connection_t *pc,
    void *data);
static void ngx_http_upstream_free_keepalive_peer(ngx_peer_connection_t *pc,
    void *data, ngx_uint_t state);

static void ngx_http_upstream_keepalive_dummy_handler(ngx_event_t *ev);
static void ngx_http_upstream_keepalive_close_handler(ngx_event_t *ev);
static void ngx_http_upstream_keepalive_close(ngx_connection_t *c);

#if (NGX_HTTP_SSL)
static ngx_int_t ngx_http_upstream_keepalive_set_session(
    ngx_peer_connection_t *pc, void *data);
static void ngx_http_upstream_keepalive_save_session(ngx_peer_connection_t *pc,
    void *data);
#endif

static void *ngx_http_upstream_keepalive_create_conf(ngx_conf_t *cf);
static char *ngx_http_upstream_keepalive(ngx_conf_t *cf, ngx_command_t *cmd,
    void *conf);


static ngx_command_t  ngx_http_upstream_keepalive_commands[] = {

    { ngx_string("keepalive"),
      NGX_HTTP_UPS_CONF|NGX_CONF_TAKE1,
      ngx_http_upstream_keepalive,
      NGX_HTTP_SRV_CONF_OFFSET,
      0,
      NULL },

      ngx_null_command
};


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

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

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

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


ngx_module_t  ngx_http_upstream_keepalive_module = {
    NGX_MODULE_V1,
    &ngx_http_upstream_keepalive_module_ctx, /* module context */
    ngx_http_upstream_keepalive_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_keepalive(ngx_conf_t *cf,
    ngx_http_upstream_srv_conf_t *us)
{
    ngx_uint_t                               i;
    ngx_http_upstream_keepalive_srv_conf_t  *kcf;
    ngx_http_upstream_keepalive_cache_t     *cached;

    ngx_log_debug0(NGX_LOG_DEBUG_HTTP, cf->log, 0,
                   "init keepalive");

    kcf = ngx_http_conf_upstream_srv_conf(us,
                                          ngx_http_upstream_keepalive_module);

    if (kcf->original_init_upstream(cf, us) != NGX_OK) {
        return NGX_ERROR;
    }

    kcf->original_init_peer = us->peer.init;

    us->peer.init = ngx_http_upstream_init_keepalive_peer;

    /* allocate cache items and add to free queue */

    cached = ngx_pcalloc(cf->pool,
                sizeof(ngx_http_upstream_keepalive_cache_t) * kcf->max_cached);
    if (cached == NULL) {
        return NGX_ERROR;
    }

    ngx_queue_init(&kcf->cache);
    ngx_queue_init(&kcf->free);

    for (i = 0; i < kcf->max_cached; i++) {
        ngx_queue_insert_head(&kcf->free, &cached[i].queue);
        cached[i].conf = kcf;
    }

    return NGX_OK;
}


static ngx_int_t
ngx_http_upstream_init_keepalive_peer(ngx_http_request_t *r,
    ngx_http_upstream_srv_conf_t *us)
{
    ngx_http_upstream_keepalive_peer_data_t  *kp;
    ngx_http_upstream_keepalive_srv_conf_t   *kcf;

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

    kcf = ngx_http_conf_upstream_srv_conf(us,
                                          ngx_http_upstream_keepalive_module);

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

    if (kcf->original_init_peer(r, us) != NGX_OK) {
        return NGX_ERROR;
    }

    kp->conf = kcf;
    kp->upstream = r->upstream;
    kp->data = r->upstream->peer.data;
    kp->original_get_peer = r->upstream->peer.get;
    kp->original_free_peer = r->upstream->peer.free;

    r->upstream->peer.data = kp;
    r->upstream->peer.get = ngx_http_upstream_get_keepalive_peer;
    r->upstream->peer.free = ngx_http_upstream_free_keepalive_peer;

#if (NGX_HTTP_SSL)
    kp->original_set_session = r->upstream->peer.set_session;
    kp->original_save_session = r->upstream->peer.save_session;
    r->upstream->peer.set_session = ngx_http_upstream_keepalive_set_session;
    r->upstream->peer.save_session = ngx_http_upstream_keepalive_save_session;
#endif

    return NGX_OK;
}


static ngx_int_t
ngx_http_upstream_get_keepalive_peer(ngx_peer_connection_t *pc, void *data)
{
    ngx_http_upstream_keepalive_peer_data_t  *kp = data;
    ngx_http_upstream_keepalive_cache_t      *item;

    ngx_int_t          rc;
    ngx_queue_t       *q, *cache;
    ngx_connection_t  *c;

    ngx_log_debug0(NGX_LOG_DEBUG_HTTP, pc->log, 0,
                   "get keepalive peer");

    /* ask balancer */

    rc = kp->original_get_peer(pc, kp->data);

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

    /* search cache for suitable connection */

    cache = &kp->conf->cache;

    for (q = ngx_queue_head(cache);
         q != ngx_queue_sentinel(cache);
         q = ngx_queue_next(q))
    {
        item = ngx_queue_data(q, ngx_http_upstream_keepalive_cache_t, queue);
        c = item->connection;

        if (ngx_memn2cmp((u_char *) &item->sockaddr, (u_char *) pc->sockaddr,
                         item->socklen, pc->socklen)
            == 0)
        {
            ngx_queue_remove(q);
            ngx_queue_insert_head(&kp->conf->free, q);

            goto found;
        }
    }

    return NGX_OK;

found:

    ngx_log_debug1(NGX_LOG_DEBUG_HTTP, pc->log, 0,
                   "get keepalive peer: using connection %p", c);

    c->idle = 0;
    c->sent = 0;
    c->log = pc->log;
    c->read->log = pc->log;
    c->write->log = pc->log;
    c->pool->log = pc->log;

    pc->connection = c;
    pc->cached = 1;

    return NGX_DONE;
}


static void
ngx_http_upstream_free_keepalive_peer(ngx_peer_connection_t *pc, void *data,
    ngx_uint_t state)
{
    ngx_http_upstream_keepalive_peer_data_t  *kp = data;
    ngx_http_upstream_keepalive_cache_t      *item;

    ngx_queue_t          *q;
    ngx_connection_t     *c;
    ngx_http_upstream_t  *u;

    ngx_log_debug0(NGX_LOG_DEBUG_HTTP, pc->log, 0,
                   "free keepalive peer");

    /* cache valid connections */

    u = kp->upstream;
    c = pc->connection;

    if (state & NGX_PEER_FAILED
        || c == NULL
        || c->read->eof
        || c->read->error
        || c->read->timedout
        || c->write->error
        || c->write->timedout)
    {
        goto invalid;
    }

    if (!u->keepalive) {
        goto invalid;
    }

    if (!u->request_body_sent) {
        goto invalid;
    }

    if (ngx_terminate || ngx_exiting) {
        goto invalid;
    }

    if (ngx_handle_read_event(c->read, 0) != NGX_OK) {
        goto invalid;
    }

    ngx_log_debug1(NGX_LOG_DEBUG_HTTP, pc->log, 0,
                   "free keepalive peer: saving connection %p", c);

    if (ngx_queue_empty(&kp->conf->free)) {

        q = ngx_queue_last(&kp->conf->cache);
        ngx_queue_remove(q);

        item = ngx_queue_data(q, ngx_http_upstream_keepalive_cache_t, queue);

        ngx_http_upstream_keepalive_close(item->connection);

    } else {
        q = ngx_queue_head(&kp->conf->free);
        ngx_queue_remove(q);

        item = ngx_queue_data(q, ngx_http_upstream_keepalive_cache_t, queue);
    }

    ngx_queue_insert_head(&kp->conf->cache, q);

    item->connection = c;

    pc->connection = NULL;

    if (c->read->timer_set) {
        c->read->delayed = 0;
        ngx_del_timer(c->read);
    }
    if (c->write->timer_set) {
        ngx_del_timer(c->write);
    }

    c->write->handler = ngx_http_upstream_keepalive_dummy_handler;
    c->read->handler = ngx_http_upstream_keepalive_close_handler;

    c->data = item;
    c->idle = 1;
    c->log = ngx_cycle->log;
    c->read->log = ngx_cycle->log;
    c->write->log = ngx_cycle->log;
    c->pool->log = ngx_cycle->log;

    item->socklen = pc->socklen;
    ngx_memcpy(&item->sockaddr, pc->sockaddr, pc->socklen);

    if (c->read->ready) {
        ngx_http_upstream_keepalive_close_handler(c->read);
    }

invalid:

    kp->original_free_peer(pc, kp->data, state);
}


static void
ngx_http_upstream_keepalive_dummy_handler(ngx_event_t *ev)
{
    ngx_log_debug0(NGX_LOG_DEBUG_HTTP, ev->log, 0,
                   "keepalive dummy handler");
}


static void
ngx_http_upstream_keepalive_close_handler(ngx_event_t *ev)
{
    ngx_http_upstream_keepalive_srv_conf_t  *conf;
    ngx_http_upstream_keepalive_cache_t     *item;

    int                n;
    char               buf[1];
    ngx_connection_t  *c;

    ngx_log_debug0(NGX_LOG_DEBUG_HTTP, ev->log, 0,
                   "keepalive close handler");

    c = ev->data;

    if (c->close) {
        goto close;
    }

    n = recv(c->fd, buf, 1, MSG_PEEK);

    if (n == -1 && ngx_socket_errno == NGX_EAGAIN) {
        ev->ready = 0;

        if (ngx_handle_read_event(c->read, 0) != NGX_OK) {
            goto close;
        }

        return;
    }

close:

    item = c->data;
    conf = item->conf;

    ngx_http_upstream_keepalive_close(c);

    ngx_queue_remove(&item->queue);
    ngx_queue_insert_head(&conf->free, &item->queue);
}


static void
ngx_http_upstream_keepalive_close(ngx_connection_t *c)
{

#if (NGX_HTTP_SSL)

    if (c->ssl) {
        c->ssl->no_wait_shutdown = 1;
        c->ssl->no_send_shutdown = 1;

        if (ngx_ssl_shutdown(c) == NGX_AGAIN) {
            c->ssl->handler = ngx_http_upstream_keepalive_close;
            return;
        }
    }

#endif

    ngx_destroy_pool(c->pool);
    ngx_close_connection(c);
}


#if (NGX_HTTP_SSL)

static ngx_int_t
ngx_http_upstream_keepalive_set_session(ngx_peer_connection_t *pc, void *data)
{
    ngx_http_upstream_keepalive_peer_data_t  *kp = data;

    return kp->original_set_session(pc, kp->data);
}


static void
ngx_http_upstream_keepalive_save_session(ngx_peer_connection_t *pc, void *data)
{
    ngx_http_upstream_keepalive_peer_data_t  *kp = data;

    kp->original_save_session(pc, kp->data);
    return;
}

#endif


static void *
ngx_http_upstream_keepalive_create_conf(ngx_conf_t *cf)
{
    ngx_http_upstream_keepalive_srv_conf_t  *conf;

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

    /*
     * set by ngx_pcalloc():
     *
     *     conf->original_init_upstream = NULL;
     *     conf->original_init_peer = NULL;
     *     conf->max_cached = 0;
     */

    return conf;
}


static char *
ngx_http_upstream_keepalive(ngx_conf_t *cf, ngx_command_t *cmd, void *conf)
{
    ngx_http_upstream_srv_conf_t            *uscf;
    ngx_http_upstream_keepalive_srv_conf_t  *kcf = conf;

    ngx_int_t    n;
    ngx_str_t   *value;

    if (kcf->max_cached) {
        return "is duplicate";
    }

    /* read options */

    value = cf->args->elts;

    n = ngx_atoi(value[1].data, value[1].len);

    if (n == NGX_ERROR || n == 0) {
        ngx_conf_log_error(NGX_LOG_EMERG, cf, 0,
                           "invalid value \"%V\" in \"%V\" directive",
                           &value[1], &cmd->name);
        return NGX_CONF_ERROR;
    }

    kcf->max_cached = n;

    uscf = ngx_http_conf_get_module_srv_conf(cf, ngx_http_upstream_module);

    kcf->original_init_upstream = uscf->peer.init_upstream
                                  ? uscf->peer.init_upstream
                                  : ngx_http_upstream_init_round_robin;

    uscf->peer.init_upstream = ngx_http_upstream_init_keepalive;

    return NGX_CONF_OK;
}