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view src/http/ngx_http_upstream_round_robin.c @ 6422:768e287a6f36

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Fixed sendfile in threads (or with aio preload) and subrequests. If sendfile in threads is used, it is possible that multiple subrequests will trigger multiple ngx_linux_sendfile_thread() calls, as operations are only serialized in output chain based on r->aio, that is, on subrequest level. This resulted in "task #N already active" alerts, in particular, when running proxy_store.t with "aio threads; sendfile on;". Fix is to tolerate duplicate calls, with an additional safety check that the file is the same as previously used. The same problem also affects "aio on; sendfile on;" on FreeBSD (previously known as "aio sendfile;"), where aio->preload_handler() could be called multiple times due to similar reasons, resulting in "second aio post" alerts. Fix is the same as well. It is also believed that similar problems can arise if a filter calls the next body filter multiple times for some reason. These are mostly theoretical though.
author Maxim Dounin <mdounin@mdounin.ru>
date Thu, 03 Mar 2016 21:14:12 +0300
parents cca856715722
children 2cd019520210
line wrap: on
line source


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


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


#define ngx_http_upstream_tries(p) ((p)->number                               \
                                    + ((p)->next ? (p)->next->number : 0))


static ngx_http_upstream_rr_peer_t *ngx_http_upstream_get_peer(
    ngx_http_upstream_rr_peer_data_t *rrp);

#if (NGX_HTTP_SSL)

static ngx_int_t ngx_http_upstream_empty_set_session(ngx_peer_connection_t *pc,
    void *data);
static void ngx_http_upstream_empty_save_session(ngx_peer_connection_t *pc,
    void *data);

#endif


ngx_int_t
ngx_http_upstream_init_round_robin(ngx_conf_t *cf,
    ngx_http_upstream_srv_conf_t *us)
{
    ngx_url_t                      u;
    ngx_uint_t                     i, j, n, w;
    ngx_http_upstream_server_t    *server;
    ngx_http_upstream_rr_peer_t   *peer, **peerp;
    ngx_http_upstream_rr_peers_t  *peers, *backup;

    us->peer.init = ngx_http_upstream_init_round_robin_peer;

    if (us->servers) {
        server = us->servers->elts;

        n = 0;
        w = 0;

        for (i = 0; i < us->servers->nelts; i++) {
            if (server[i].backup) {
                continue;
            }

            n += server[i].naddrs;
            w += server[i].naddrs * server[i].weight;
        }

        if (n == 0) {
            ngx_log_error(NGX_LOG_EMERG, cf->log, 0,
                          "no servers in upstream \"%V\" in %s:%ui",
                          &us->host, us->file_name, us->line);
            return NGX_ERROR;
        }

        peers = ngx_pcalloc(cf->pool, sizeof(ngx_http_upstream_rr_peers_t));
        if (peers == NULL) {
            return NGX_ERROR;
        }

        peer = ngx_pcalloc(cf->pool, sizeof(ngx_http_upstream_rr_peer_t) * n);
        if (peer == NULL) {
            return NGX_ERROR;
        }

        peers->single = (n == 1);
        peers->number = n;
        peers->weighted = (w != n);
        peers->total_weight = w;
        peers->name = &us->host;

        n = 0;
        peerp = &peers->peer;

        for (i = 0; i < us->servers->nelts; i++) {
            if (server[i].backup) {
                continue;
            }

            for (j = 0; j < server[i].naddrs; j++) {
                peer[n].sockaddr = server[i].addrs[j].sockaddr;
                peer[n].socklen = server[i].addrs[j].socklen;
                peer[n].name = server[i].addrs[j].name;
                peer[n].weight = server[i].weight;
                peer[n].effective_weight = server[i].weight;
                peer[n].current_weight = 0;
                peer[n].max_fails = server[i].max_fails;
                peer[n].fail_timeout = server[i].fail_timeout;
                peer[n].down = server[i].down;
                peer[n].server = server[i].name;

                *peerp = &peer[n];
                peerp = &peer[n].next;
                n++;
            }
        }

        us->peer.data = peers;

        /* backup servers */

        n = 0;
        w = 0;

        for (i = 0; i < us->servers->nelts; i++) {
            if (!server[i].backup) {
                continue;
            }

            n += server[i].naddrs;
            w += server[i].naddrs * server[i].weight;
        }

        if (n == 0) {
            return NGX_OK;
        }

        backup = ngx_pcalloc(cf->pool, sizeof(ngx_http_upstream_rr_peers_t));
        if (backup == NULL) {
            return NGX_ERROR;
        }

        peer = ngx_pcalloc(cf->pool, sizeof(ngx_http_upstream_rr_peer_t) * n);
        if (peer == NULL) {
            return NGX_ERROR;
        }

        peers->single = 0;
        backup->single = 0;
        backup->number = n;
        backup->weighted = (w != n);
        backup->total_weight = w;
        backup->name = &us->host;

        n = 0;
        peerp = &backup->peer;

        for (i = 0; i < us->servers->nelts; i++) {
            if (!server[i].backup) {
                continue;
            }

            for (j = 0; j < server[i].naddrs; j++) {
                peer[n].sockaddr = server[i].addrs[j].sockaddr;
                peer[n].socklen = server[i].addrs[j].socklen;
                peer[n].name = server[i].addrs[j].name;
                peer[n].weight = server[i].weight;
                peer[n].effective_weight = server[i].weight;
                peer[n].current_weight = 0;
                peer[n].max_fails = server[i].max_fails;
                peer[n].fail_timeout = server[i].fail_timeout;
                peer[n].down = server[i].down;
                peer[n].server = server[i].name;

                *peerp = &peer[n];
                peerp = &peer[n].next;
                n++;
            }
        }

        peers->next = backup;

        return NGX_OK;
    }


    /* an upstream implicitly defined by proxy_pass, etc. */

    if (us->port == 0) {
        ngx_log_error(NGX_LOG_EMERG, cf->log, 0,
                      "no port in upstream \"%V\" in %s:%ui",
                      &us->host, us->file_name, us->line);
        return NGX_ERROR;
    }

    ngx_memzero(&u, sizeof(ngx_url_t));

    u.host = us->host;
    u.port = us->port;

    if (ngx_inet_resolve_host(cf->pool, &u) != NGX_OK) {
        if (u.err) {
            ngx_log_error(NGX_LOG_EMERG, cf->log, 0,
                          "%s in upstream \"%V\" in %s:%ui",
                          u.err, &us->host, us->file_name, us->line);
        }

        return NGX_ERROR;
    }

    n = u.naddrs;

    peers = ngx_pcalloc(cf->pool, sizeof(ngx_http_upstream_rr_peers_t));
    if (peers == NULL) {
        return NGX_ERROR;
    }

    peer = ngx_pcalloc(cf->pool, sizeof(ngx_http_upstream_rr_peer_t) * n);
    if (peer == NULL) {
        return NGX_ERROR;
    }

    peers->single = (n == 1);
    peers->number = n;
    peers->weighted = 0;
    peers->total_weight = n;
    peers->name = &us->host;

    peerp = &peers->peer;

    for (i = 0; i < u.naddrs; i++) {
        peer[i].sockaddr = u.addrs[i].sockaddr;
        peer[i].socklen = u.addrs[i].socklen;
        peer[i].name = u.addrs[i].name;
        peer[i].weight = 1;
        peer[i].effective_weight = 1;
        peer[i].current_weight = 0;
        peer[i].max_fails = 1;
        peer[i].fail_timeout = 10;
        *peerp = &peer[i];
        peerp = &peer[i].next;
    }

    us->peer.data = peers;

    /* implicitly defined upstream has no backup servers */

    return NGX_OK;
}


ngx_int_t
ngx_http_upstream_init_round_robin_peer(ngx_http_request_t *r,
    ngx_http_upstream_srv_conf_t *us)
{
    ngx_uint_t                         n;
    ngx_http_upstream_rr_peer_data_t  *rrp;

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

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

        r->upstream->peer.data = rrp;
    }

    rrp->peers = us->peer.data;
    rrp->current = NULL;

    n = rrp->peers->number;

    if (rrp->peers->next && rrp->peers->next->number > n) {
        n = rrp->peers->next->number;
    }

    if (n <= 8 * sizeof(uintptr_t)) {
        rrp->tried = &rrp->data;
        rrp->data = 0;

    } else {
        n = (n + (8 * sizeof(uintptr_t) - 1)) / (8 * sizeof(uintptr_t));

        rrp->tried = ngx_pcalloc(r->pool, n * sizeof(uintptr_t));
        if (rrp->tried == NULL) {
            return NGX_ERROR;
        }
    }

    r->upstream->peer.get = ngx_http_upstream_get_round_robin_peer;
    r->upstream->peer.free = ngx_http_upstream_free_round_robin_peer;
    r->upstream->peer.tries = ngx_http_upstream_tries(rrp->peers);
#if (NGX_HTTP_SSL)
    r->upstream->peer.set_session =
                               ngx_http_upstream_set_round_robin_peer_session;
    r->upstream->peer.save_session =
                               ngx_http_upstream_save_round_robin_peer_session;
#endif

    return NGX_OK;
}


ngx_int_t
ngx_http_upstream_create_round_robin_peer(ngx_http_request_t *r,
    ngx_http_upstream_resolved_t *ur)
{
    u_char                            *p;
    size_t                             len;
    socklen_t                          socklen;
    ngx_uint_t                         i, n;
    struct sockaddr                   *sockaddr;
    ngx_http_upstream_rr_peer_t       *peer, **peerp;
    ngx_http_upstream_rr_peers_t      *peers;
    ngx_http_upstream_rr_peer_data_t  *rrp;

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

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

        r->upstream->peer.data = rrp;
    }

    peers = ngx_pcalloc(r->pool, sizeof(ngx_http_upstream_rr_peers_t));
    if (peers == NULL) {
        return NGX_ERROR;
    }

    peer = ngx_pcalloc(r->pool, sizeof(ngx_http_upstream_rr_peer_t)
                                * ur->naddrs);
    if (peer == NULL) {
        return NGX_ERROR;
    }

    peers->single = (ur->naddrs == 1);
    peers->number = ur->naddrs;
    peers->name = &ur->host;

    if (ur->sockaddr) {
        peer[0].sockaddr = ur->sockaddr;
        peer[0].socklen = ur->socklen;
        peer[0].name = ur->host;
        peer[0].weight = 1;
        peer[0].effective_weight = 1;
        peer[0].current_weight = 0;
        peer[0].max_fails = 1;
        peer[0].fail_timeout = 10;
        peers->peer = peer;

    } else {
        peerp = &peers->peer;

        for (i = 0; i < ur->naddrs; i++) {

            socklen = ur->addrs[i].socklen;

            sockaddr = ngx_palloc(r->pool, socklen);
            if (sockaddr == NULL) {
                return NGX_ERROR;
            }

            ngx_memcpy(sockaddr, ur->addrs[i].sockaddr, socklen);

            switch (sockaddr->sa_family) {
#if (NGX_HAVE_INET6)
            case AF_INET6:
                ((struct sockaddr_in6 *) sockaddr)->sin6_port = htons(ur->port);
                break;
#endif
            default: /* AF_INET */
                ((struct sockaddr_in *) sockaddr)->sin_port = htons(ur->port);
            }

            p = ngx_pnalloc(r->pool, NGX_SOCKADDR_STRLEN);
            if (p == NULL) {
                return NGX_ERROR;
            }

            len = ngx_sock_ntop(sockaddr, socklen, p, NGX_SOCKADDR_STRLEN, 1);

            peer[i].sockaddr = sockaddr;
            peer[i].socklen = socklen;
            peer[i].name.len = len;
            peer[i].name.data = p;
            peer[i].weight = 1;
            peer[i].effective_weight = 1;
            peer[i].current_weight = 0;
            peer[i].max_fails = 1;
            peer[i].fail_timeout = 10;
            *peerp = &peer[i];
            peerp = &peer[i].next;
        }
    }

    rrp->peers = peers;
    rrp->current = NULL;

    if (rrp->peers->number <= 8 * sizeof(uintptr_t)) {
        rrp->tried = &rrp->data;
        rrp->data = 0;

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

        rrp->tried = ngx_pcalloc(r->pool, n * sizeof(uintptr_t));
        if (rrp->tried == NULL) {
            return NGX_ERROR;
        }
    }

    r->upstream->peer.get = ngx_http_upstream_get_round_robin_peer;
    r->upstream->peer.free = ngx_http_upstream_free_round_robin_peer;
    r->upstream->peer.tries = ngx_http_upstream_tries(rrp->peers);
#if (NGX_HTTP_SSL)
    r->upstream->peer.set_session = ngx_http_upstream_empty_set_session;
    r->upstream->peer.save_session = ngx_http_upstream_empty_save_session;
#endif

    return NGX_OK;
}


ngx_int_t
ngx_http_upstream_get_round_robin_peer(ngx_peer_connection_t *pc, void *data)
{
    ngx_http_upstream_rr_peer_data_t  *rrp = data;

    ngx_int_t                      rc;
    ngx_uint_t                     i, n;
    ngx_http_upstream_rr_peer_t   *peer;
    ngx_http_upstream_rr_peers_t  *peers;

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

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

    peers = rrp->peers;
    ngx_http_upstream_rr_peers_wlock(peers);

    if (peers->single) {
        peer = peers->peer;

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

        rrp->current = peer;

    } else {

        /* there are several peers */

        peer = ngx_http_upstream_get_peer(rrp);

        if (peer == NULL) {
            goto failed;
        }

        ngx_log_debug2(NGX_LOG_DEBUG_HTTP, pc->log, 0,
                       "get rr peer, current: %p %i",
                       peer, peer->current_weight);
    }

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

    peer->conns++;

    ngx_http_upstream_rr_peers_unlock(peers);

    return NGX_OK;

failed:

    if (peers->next) {

        ngx_log_debug0(NGX_LOG_DEBUG_HTTP, pc->log, 0, "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_round_robin_peer(pc, rrp);

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

        ngx_http_upstream_rr_peers_wlock(peers);
    }

    /* all peers failed, mark them as live for quick recovery */

    for (peer = peers->peer; peer; peer = peer->next) {
        peer->fails = 0;
    }

    ngx_http_upstream_rr_peers_unlock(peers);

    pc->name = peers->name;

    return NGX_BUSY;
}


static ngx_http_upstream_rr_peer_t *
ngx_http_upstream_get_peer(ngx_http_upstream_rr_peer_data_t *rrp)
{
    time_t                        now;
    uintptr_t                     m;
    ngx_int_t                     total;
    ngx_uint_t                    i, n, p;
    ngx_http_upstream_rr_peer_t  *peer, *best;

    now = ngx_time();

    best = NULL;
    total = 0;

#if (NGX_SUPPRESS_WARN)
    p = 0;
#endif

    for (peer = rrp->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;
        }

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

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

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

    if (best == NULL) {
        return NULL;
    }

    rrp->current = best;

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

    rrp->tried[n] |= m;

    best->current_weight -= total;

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

    return best;
}


void
ngx_http_upstream_free_round_robin_peer(ngx_peer_connection_t *pc, void *data,
    ngx_uint_t state)
{
    ngx_http_upstream_rr_peer_data_t  *rrp = data;

    time_t                       now;
    ngx_http_upstream_rr_peer_t  *peer;

    ngx_log_debug2(NGX_LOG_DEBUG_HTTP, pc->log, 0,
                   "free rr peer %ui %ui", pc->tries, state);

    /* TODO: NGX_PEER_KEEPALIVE */

    peer = rrp->current;

    ngx_http_upstream_rr_peers_rlock(rrp->peers);
    ngx_http_upstream_rr_peer_lock(rrp->peers, peer);

    if (rrp->peers->single) {

        peer->conns--;

        ngx_http_upstream_rr_peer_unlock(rrp->peers, peer);
        ngx_http_upstream_rr_peers_unlock(rrp->peers);

        pc->tries = 0;
        return;
    }

    if (state & NGX_PEER_FAILED) {
        now = ngx_time();

        peer->fails++;
        peer->accessed = now;
        peer->checked = now;

        if (peer->max_fails) {
            peer->effective_weight -= peer->weight / peer->max_fails;

            if (peer->fails >= peer->max_fails) {
                ngx_log_error(NGX_LOG_WARN, pc->log, 0,
                              "upstream server temporarily disabled");
            }
        }

        ngx_log_debug2(NGX_LOG_DEBUG_HTTP, pc->log, 0,
                       "free rr peer failed: %p %i",
                       peer, peer->effective_weight);

        if (peer->effective_weight < 0) {
            peer->effective_weight = 0;
        }

    } else {

        /* mark peer live if check passed */

        if (peer->accessed < peer->checked) {
            peer->fails = 0;
        }
    }

    peer->conns--;

    ngx_http_upstream_rr_peer_unlock(rrp->peers, peer);
    ngx_http_upstream_rr_peers_unlock(rrp->peers);

    if (pc->tries) {
        pc->tries--;
    }
}


#if (NGX_HTTP_SSL)

ngx_int_t
ngx_http_upstream_set_round_robin_peer_session(ngx_peer_connection_t *pc,
    void *data)
{
    ngx_http_upstream_rr_peer_data_t  *rrp = data;

    ngx_int_t                      rc;
    ngx_ssl_session_t             *ssl_session;
    ngx_http_upstream_rr_peer_t   *peer;
#if (NGX_HTTP_UPSTREAM_ZONE)
    int                            len;
#if OPENSSL_VERSION_NUMBER >= 0x0090707fL
    const
#endif
    u_char                        *p;
    ngx_http_upstream_rr_peers_t  *peers;
    u_char                         buf[NGX_SSL_MAX_SESSION_SIZE];
#endif

    peer = rrp->current;

#if (NGX_HTTP_UPSTREAM_ZONE)
    peers = rrp->peers;

    if (peers->shpool) {
        ngx_http_upstream_rr_peers_rlock(peers);
        ngx_http_upstream_rr_peer_lock(peers, peer);

        if (peer->ssl_session == NULL) {
            ngx_http_upstream_rr_peer_unlock(peers, peer);
            ngx_http_upstream_rr_peers_unlock(peers);
            return NGX_OK;
        }

        len = peer->ssl_session_len;

        ngx_memcpy(buf, peer->ssl_session, len);

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

        p = buf;
        ssl_session = d2i_SSL_SESSION(NULL, &p, len);

        rc = ngx_ssl_set_session(pc->connection, ssl_session);

        ngx_log_debug1(NGX_LOG_DEBUG_HTTP, pc->log, 0,
                       "set session: %p", ssl_session);

        ngx_ssl_free_session(ssl_session);

        return rc;
    }
#endif

    ssl_session = peer->ssl_session;

    rc = ngx_ssl_set_session(pc->connection, ssl_session);

    ngx_log_debug1(NGX_LOG_DEBUG_HTTP, pc->log, 0,
                   "set session: %p", ssl_session);

    return rc;
}


void
ngx_http_upstream_save_round_robin_peer_session(ngx_peer_connection_t *pc,
    void *data)
{
    ngx_http_upstream_rr_peer_data_t  *rrp = data;

    ngx_ssl_session_t             *old_ssl_session, *ssl_session;
    ngx_http_upstream_rr_peer_t   *peer;
#if (NGX_HTTP_UPSTREAM_ZONE)
    int                            len;
    u_char                        *p;
    ngx_http_upstream_rr_peers_t  *peers;
    u_char                         buf[NGX_SSL_MAX_SESSION_SIZE];
#endif

#if (NGX_HTTP_UPSTREAM_ZONE)
    peers = rrp->peers;

    if (peers->shpool) {

        ssl_session = SSL_get0_session(pc->connection->ssl->connection);

        if (ssl_session == NULL) {
            return;
        }

        ngx_log_debug1(NGX_LOG_DEBUG_HTTP, pc->log, 0,
                       "save session: %p", ssl_session);

        len = i2d_SSL_SESSION(ssl_session, NULL);

        /* do not cache too big session */

        if (len > NGX_SSL_MAX_SESSION_SIZE) {
            return;
        }

        p = buf;
        (void) i2d_SSL_SESSION(ssl_session, &p);

        peer = rrp->current;

        ngx_http_upstream_rr_peers_rlock(peers);
        ngx_http_upstream_rr_peer_lock(peers, peer);

        if (len > peer->ssl_session_len) {
            ngx_shmtx_lock(&peers->shpool->mutex);

            if (peer->ssl_session) {
                ngx_slab_free_locked(peers->shpool, peer->ssl_session);
            }

            peer->ssl_session = ngx_slab_alloc_locked(peers->shpool, len);

            ngx_shmtx_unlock(&peers->shpool->mutex);

            if (peer->ssl_session == NULL) {
                peer->ssl_session_len = 0;

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

            peer->ssl_session_len = len;
        }

        ngx_memcpy(peer->ssl_session, buf, len);

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

        return;
    }
#endif

    ssl_session = ngx_ssl_get_session(pc->connection);

    if (ssl_session == NULL) {
        return;
    }

    ngx_log_debug1(NGX_LOG_DEBUG_HTTP, pc->log, 0,
                   "save session: %p", ssl_session);

    peer = rrp->current;

    old_ssl_session = peer->ssl_session;
    peer->ssl_session = ssl_session;

    if (old_ssl_session) {

        ngx_log_debug1(NGX_LOG_DEBUG_HTTP, pc->log, 0,
                       "old session: %p", old_ssl_session);

        /* TODO: may block */

        ngx_ssl_free_session(old_ssl_session);
    }
}


static ngx_int_t
ngx_http_upstream_empty_set_session(ngx_peer_connection_t *pc, void *data)
{
    return NGX_OK;
}


static void
ngx_http_upstream_empty_save_session(ngx_peer_connection_t *pc, void *data)
{
    return;
}

#endif