nginx/src/http/modules/ngx_http_upstream_ip_hash_module.c

   1
   2 /*
   3  * Copyright (C) Igor Sysoev
   4  */
   5
   6
   7 #include <ngx_config.h>
   8 #include <ngx_core.h>
   9 #include <ngx_http.h>
  10
  11
  12 typedef struct {
  13     /* the round robin data must be first */
  14     ngx_http_upstream_rr_peer_data_t   rrp;
  15
  16     ngx_uint_t                         hash;
  17
  18     /* AF_INET only */
  19     u_char                             addr[3];
  20
  21     u_char                             tries;
  22
  23     ngx_event_get_peer_pt              get_rr_peer;
  24 } ngx_http_upstream_ip_hash_peer_data_t;
  25
  26
  27 static ngx_int_t ngx_http_upstream_init_ip_hash_peer(ngx_http_request_t *r,
  28     ngx_http_upstream_srv_conf_t *us);
  29 static ngx_int_t ngx_http_upstream_get_ip_hash_peer(ngx_peer_connection_t *pc,
  30     void *data);
  31 static char *ngx_http_upstream_ip_hash(ngx_conf_t *cf, ngx_command_t *cmd,
  32     void *conf);
  33
  34
  35 static ngx_command_t  ngx_http_upstream_ip_hash_commands[] = {
  36
  37     { ngx_string("ip_hash"),
  38       NGX_HTTP_UPS_CONF|NGX_CONF_NOARGS,
  39       ngx_http_upstream_ip_hash,
  40       0,
  41       0,
  42       NULL },
  43
  44       ngx_null_command
  45 };
  46
  47
  48 static ngx_http_module_t  ngx_http_upstream_ip_hash_module_ctx = {
  49     NULL,                                  /* preconfiguration */
  50     NULL,                                  /* postconfiguration */
  51
  52     NULL,                                  /* create main configuration */
  53     NULL,                                  /* init main configuration */
  54
  55     NULL,                                  /* create server configuration */
  56     NULL,                                  /* merge server configuration */
  57
  58     NULL,                                  /* create location configuration */
  59     NULL                                   /* merge location configuration */
  60 };
  61
  62
  63 ngx_module_t  ngx_http_upstream_ip_hash_module = {
  64     NGX_MODULE_V1,
  65     &ngx_http_upstream_ip_hash_module_ctx, /* module context */
  66     ngx_http_upstream_ip_hash_commands,    /* module directives */
  67     NGX_HTTP_MODULE,                       /* module type */
  68     NULL,                                  /* init master */
  69     NULL,                                  /* init module */
  70     NULL,                                  /* init process */
  71     NULL,                                  /* init thread */
  72     NULL,                                  /* exit thread */
  73     NULL,                                  /* exit process */
  74     NULL,                                  /* exit master */
  75     NGX_MODULE_V1_PADDING
  76 };
  77
  78
  79 ngx_int_t
  80 ngx_http_upstream_init_ip_hash(ngx_conf_t *cf, ngx_http_upstream_srv_conf_t *us)
  81 {
  82     if (ngx_http_upstream_init_round_robin(cf, us) != NGX_OK) {
  83         return NGX_ERROR;
  84     }
  85
  86     us->peer.init = ngx_http_upstream_init_ip_hash_peer;
  87
  88     return NGX_OK;
  89 }
  90
  91
  92 static ngx_int_t
  93 ngx_http_upstream_init_ip_hash_peer(ngx_http_request_t *r,
  94     ngx_http_upstream_srv_conf_t *us)
  95 {
  96     u_char                                 *p;
  97     struct sockaddr_in                     *sin;
  98     ngx_http_upstream_ip_hash_peer_data_t  *iphp;
  99
 100     iphp = ngx_palloc(r->pool, sizeof(ngx_http_upstream_ip_hash_peer_data_t));
 101     if (iphp == NULL) {
 102         return NGX_ERROR;
 103     }
 104
 105     r->upstream->peer.data = &iphp->rrp;
 106
 107     if (ngx_http_upstream_init_round_robin_peer(r, us) != NGX_OK) {
 108         return NGX_ERROR;
 109     }
 110
 111     r->upstream->peer.get = ngx_http_upstream_get_ip_hash_peer;
 112
 113     /* AF_INET only */
 114     sin = (struct sockaddr_in *) r->connection->sockaddr;
 115     p = (u_char *) &sin->sin_addr.s_addr;
 116     iphp->addr[0] = p[0];
 117     iphp->addr[1] = p[1];
 118     iphp->addr[2] = p[2];
 119
 120     iphp->hash = 89;
 121     iphp->tries = 0;
 122     iphp->get_rr_peer = ngx_http_upstream_get_round_robin_peer;
 123
 124     return NGX_OK;
 125 }
 126
 127
 128 static ngx_int_t
 129 ngx_http_upstream_get_ip_hash_peer(ngx_peer_connection_t *pc, void *data)
 130 {
 131     ngx_http_upstream_ip_hash_peer_data_t  *iphp = data;
 132
 133     time_t                        now;
 134     uintptr_t                     m;
 135     ngx_uint_t                    i, n, p, hash;
 136     ngx_http_upstream_rr_peer_t  *peer;
 137
 138     ngx_log_debug1(NGX_LOG_DEBUG_HTTP, pc->log, 0,
 139                    "get ip hash peer, try: %ui", pc->tries);
 140
 141     /* TODO: cached */
 142
 143     if (iphp->tries > 20 || iphp->rrp.peers->single) {
 144         return iphp->get_rr_peer(pc, &iphp->rrp);
 145     }
 146
 147     now = ngx_time();
 148
 149     pc->cached = 0;
 150     pc->connection = NULL;
 151
 152     hash = iphp->hash;
 153
 154     for ( ;; ) {
 155
 156         for (i = 0; i < 3; i++) {
 157             hash = (hash * 113 + iphp->addr[i]) % 6271;
 158         }
 159
 160         p = hash % iphp->rrp.peers->number;
 161
 162         n = p / (8 * sizeof(uintptr_t));
 163         m = (uintptr_t) 1 << p % (8 * sizeof(uintptr_t));
 164
 165         if (!(iphp->rrp.tried[n] & m)) {
 166
 167             ngx_log_debug2(NGX_LOG_DEBUG_HTTP, pc->log, 0,
 168                            "get ip hash peer, hash: %ui %04XA", p, m);
 169
 170             peer = &iphp->rrp.peers->peer[p];
 171
 172             /* ngx_lock_mutex(iphp->rrp.peers->mutex); */
 173
 174             if (!peer->down) {
 175
 176                 if (peer->max_fails == 0 || peer->fails < peer->max_fails) {
 177                     break;
 178                 }
 179
 180                 if (now - peer->accessed > peer->fail_timeout) {
 181                     peer->fails = 0;
 182                     break;
 183                 }
 184             }
 185
 186             iphp->rrp.tried[n] |= m;
 187
 188             /* ngx_unlock_mutex(iphp->rrp.peers->mutex); */
 189
 190             pc->tries--;
 191         }
 192
 193         if (++iphp->tries >= 20) {
 194             return iphp->get_rr_peer(pc, &iphp->rrp);
 195         }
 196     }
 197
 198     iphp->rrp.current = p;
 199
 200     pc->sockaddr = peer->sockaddr;
 201     pc->socklen = peer->socklen;
 202     pc->name = &peer->name;
 203
 204     /* ngx_unlock_mutex(iphp->rrp.peers->mutex); */
 205
 206     iphp->rrp.tried[n] |= m;
 207     iphp->hash = hash;
 208
 209     return NGX_OK;
 210 }
 211
 212
 213 static char *
 214 ngx_http_upstream_ip_hash(ngx_conf_t *cf, ngx_command_t *cmd, void *conf)
 215 {
 216     ngx_http_upstream_srv_conf_t  *uscf;
 217
 218     uscf = ngx_http_conf_get_module_srv_conf(cf, ngx_http_upstream_module);
 219
 220     uscf->peer.init_upstream = ngx_http_upstream_init_ip_hash;
 221
 222     uscf->flags = NGX_HTTP_UPSTREAM_CREATE
 223                   |NGX_HTTP_UPSTREAM_MAX_FAILS
 224                   |NGX_HTTP_UPSTREAM_FAIL_TIMEOUT
 225                   |NGX_HTTP_UPSTREAM_DOWN;
 226
 227     return NGX_CONF_OK;
 228 }