view src/stream/ngx_stream_upstream_round_robin.h @ 7098:7bfbf73db920

Stream: relaxed next upstream condition (ticket #1317). When switching to a next upstream, some buffers could be stuck in the middle of the filter chain. A condition existed that raised an error when this happened. As it turned out, this condition prevented switching to a next upstream if ssl preread was used with the TCP protocol (see the ticket). In fact, the condition does not make sense for TCP, since after successful connection to an upstream switching to another upstream never happens. As for UDP, the issue with stuck buffers is unlikely to happen, but is still possible. Specifically, if a filter delays sending data to upstream. The condition can be relaxed to only check the "buffered" bitmask of the upstream connection. The new condition is simpler and fixes the ticket issue as well. Additionally, the upstream_out chain is now reset for UDP prior to connecting to a new upstream to prevent repeating the client data twice.
author Roman Arutyunyan <arut@nginx.com>
date Mon, 11 Sep 2017 15:32:31 +0300
parents f41c2530dd17
children 90cc7194e993
line wrap: on
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/*
 * Copyright (C) Igor Sysoev
 * Copyright (C) Nginx, Inc.
 */


#ifndef _NGX_STREAM_UPSTREAM_ROUND_ROBIN_H_INCLUDED_
#define _NGX_STREAM_UPSTREAM_ROUND_ROBIN_H_INCLUDED_


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


typedef struct ngx_stream_upstream_rr_peer_s   ngx_stream_upstream_rr_peer_t;

struct ngx_stream_upstream_rr_peer_s {
    struct sockaddr                 *sockaddr;
    socklen_t                        socklen;
    ngx_str_t                        name;
    ngx_str_t                        server;

    ngx_int_t                        current_weight;
    ngx_int_t                        effective_weight;
    ngx_int_t                        weight;

    ngx_uint_t                       conns;
    ngx_uint_t                       max_conns;

    ngx_uint_t                       fails;
    time_t                           accessed;
    time_t                           checked;

    ngx_uint_t                       max_fails;
    time_t                           fail_timeout;
    ngx_msec_t                       slow_start;
    ngx_msec_t                       start_time;

    ngx_uint_t                       down;

    void                            *ssl_session;
    int                              ssl_session_len;

#if (NGX_STREAM_UPSTREAM_ZONE)
    ngx_atomic_t                     lock;
#endif

    ngx_stream_upstream_rr_peer_t   *next;

    NGX_COMPAT_BEGIN(25)
    NGX_COMPAT_END
};


typedef struct ngx_stream_upstream_rr_peers_s  ngx_stream_upstream_rr_peers_t;

struct ngx_stream_upstream_rr_peers_s {
    ngx_uint_t                       number;

#if (NGX_STREAM_UPSTREAM_ZONE)
    ngx_slab_pool_t                 *shpool;
    ngx_atomic_t                     rwlock;
    ngx_stream_upstream_rr_peers_t  *zone_next;
#endif

    ngx_uint_t                       total_weight;

    unsigned                         single:1;
    unsigned                         weighted:1;

    ngx_str_t                       *name;

    ngx_stream_upstream_rr_peers_t  *next;

    ngx_stream_upstream_rr_peer_t   *peer;
};


#if (NGX_STREAM_UPSTREAM_ZONE)

#define ngx_stream_upstream_rr_peers_rlock(peers)                             \
                                                                              \
    if (peers->shpool) {                                                      \
        ngx_rwlock_rlock(&peers->rwlock);                                     \
    }

#define ngx_stream_upstream_rr_peers_wlock(peers)                             \
                                                                              \
    if (peers->shpool) {                                                      \
        ngx_rwlock_wlock(&peers->rwlock);                                     \
    }

#define ngx_stream_upstream_rr_peers_unlock(peers)                            \
                                                                              \
    if (peers->shpool) {                                                      \
        ngx_rwlock_unlock(&peers->rwlock);                                    \
    }


#define ngx_stream_upstream_rr_peer_lock(peers, peer)                         \
                                                                              \
    if (peers->shpool) {                                                      \
        ngx_rwlock_wlock(&peer->lock);                                        \
    }

#define ngx_stream_upstream_rr_peer_unlock(peers, peer)                       \
                                                                              \
    if (peers->shpool) {                                                      \
        ngx_rwlock_unlock(&peer->lock);                                       \
    }

#else

#define ngx_stream_upstream_rr_peers_rlock(peers)
#define ngx_stream_upstream_rr_peers_wlock(peers)
#define ngx_stream_upstream_rr_peers_unlock(peers)
#define ngx_stream_upstream_rr_peer_lock(peers, peer)
#define ngx_stream_upstream_rr_peer_unlock(peers, peer)

#endif


typedef struct {
    ngx_uint_t                       config;
    ngx_stream_upstream_rr_peers_t  *peers;
    ngx_stream_upstream_rr_peer_t   *current;
    uintptr_t                       *tried;
    uintptr_t                        data;
} ngx_stream_upstream_rr_peer_data_t;


ngx_int_t ngx_stream_upstream_init_round_robin(ngx_conf_t *cf,
    ngx_stream_upstream_srv_conf_t *us);
ngx_int_t ngx_stream_upstream_init_round_robin_peer(ngx_stream_session_t *s,
    ngx_stream_upstream_srv_conf_t *us);
ngx_int_t ngx_stream_upstream_create_round_robin_peer(ngx_stream_session_t *s,
    ngx_stream_upstream_resolved_t *ur);
ngx_int_t ngx_stream_upstream_get_round_robin_peer(ngx_peer_connection_t *pc,
    void *data);
void ngx_stream_upstream_free_round_robin_peer(ngx_peer_connection_t *pc,
    void *data, ngx_uint_t state);


#endif /* _NGX_STREAM_UPSTREAM_ROUND_ROBIN_H_INCLUDED_ */