676
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1
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2 /*
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3 * Copyright (C) Maxim Dounin
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4 * Copyright (C) Nginx, Inc.
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5 */
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6
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7
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8 #include <ngx_config.h>
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9 #include <ngx_core.h>
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10 #include <ngx_http.h>
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11
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12
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13 typedef struct {
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14 ngx_uint_t *conns;
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15 } ngx_http_upstream_least_conn_conf_t;
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16
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17
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18 typedef struct {
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19 /* the round robin data must be first */
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20 ngx_http_upstream_rr_peer_data_t rrp;
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21
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22 ngx_uint_t *conns;
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23
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24 ngx_event_get_peer_pt get_rr_peer;
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25 ngx_event_free_peer_pt free_rr_peer;
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26 } ngx_http_upstream_lc_peer_data_t;
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27
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28
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29 static ngx_int_t ngx_http_upstream_init_least_conn_peer(ngx_http_request_t *r,
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30 ngx_http_upstream_srv_conf_t *us);
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31 static ngx_int_t ngx_http_upstream_get_least_conn_peer(
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32 ngx_peer_connection_t *pc, void *data);
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33 static void ngx_http_upstream_free_least_conn_peer(ngx_peer_connection_t *pc,
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34 void *data, ngx_uint_t state);
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35 static void *ngx_http_upstream_least_conn_create_conf(ngx_conf_t *cf);
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36 static char *ngx_http_upstream_least_conn(ngx_conf_t *cf, ngx_command_t *cmd,
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37 void *conf);
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38
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39
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40 static ngx_command_t ngx_http_upstream_least_conn_commands[] = {
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41
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42 { ngx_string("least_conn"),
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43 NGX_HTTP_UPS_CONF|NGX_CONF_NOARGS,
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44 ngx_http_upstream_least_conn,
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45 0,
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46 0,
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47 NULL },
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48
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49 ngx_null_command
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50 };
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51
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52
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53 static ngx_http_module_t ngx_http_upstream_least_conn_module_ctx = {
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54 NULL, /* preconfiguration */
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55 NULL, /* postconfiguration */
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56
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57 NULL, /* create main configuration */
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58 NULL, /* init main configuration */
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59
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60 ngx_http_upstream_least_conn_create_conf, /* create server configuration */
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61 NULL, /* merge server configuration */
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62
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63 NULL, /* create location configuration */
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64 NULL /* merge location configuration */
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65 };
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66
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67
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68 ngx_module_t ngx_http_upstream_least_conn_module = {
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69 NGX_MODULE_V1,
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70 &ngx_http_upstream_least_conn_module_ctx, /* module context */
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71 ngx_http_upstream_least_conn_commands, /* module directives */
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72 NGX_HTTP_MODULE, /* module type */
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73 NULL, /* init master */
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74 NULL, /* init module */
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75 NULL, /* init process */
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76 NULL, /* init thread */
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77 NULL, /* exit thread */
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78 NULL, /* exit process */
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79 NULL, /* exit master */
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80 NGX_MODULE_V1_PADDING
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81 };
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82
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83
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84 ngx_int_t
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85 ngx_http_upstream_init_least_conn(ngx_conf_t *cf,
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86 ngx_http_upstream_srv_conf_t *us)
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87 {
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88 ngx_uint_t n;
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89 ngx_http_upstream_rr_peers_t *peers;
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90 ngx_http_upstream_least_conn_conf_t *lcf;
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91
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92 ngx_log_debug0(NGX_LOG_DEBUG_HTTP, cf->log, 0,
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93 "init least conn");
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94
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95 if (ngx_http_upstream_init_round_robin(cf, us) != NGX_OK) {
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96 return NGX_ERROR;
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97 }
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98
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99 peers = us->peer.data;
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100
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101 n = peers->number;
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102
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103 if (peers->next) {
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104 n += peers->next->number;
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105 }
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106
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107 lcf = ngx_http_conf_upstream_srv_conf(us,
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108 ngx_http_upstream_least_conn_module);
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109
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110 lcf->conns = ngx_pcalloc(cf->pool, sizeof(ngx_uint_t) * n);
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111 if (lcf->conns == NULL) {
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112 return NGX_ERROR;
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113 }
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114
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115 us->peer.init = ngx_http_upstream_init_least_conn_peer;
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116
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117 return NGX_OK;
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118 }
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119
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120
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121 static ngx_int_t
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122 ngx_http_upstream_init_least_conn_peer(ngx_http_request_t *r,
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123 ngx_http_upstream_srv_conf_t *us)
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124 {
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125 ngx_http_upstream_lc_peer_data_t *lcp;
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126 ngx_http_upstream_least_conn_conf_t *lcf;
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127
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128 ngx_log_debug0(NGX_LOG_DEBUG_HTTP, r->connection->log, 0,
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129 "init least conn peer");
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130
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131 lcf = ngx_http_conf_upstream_srv_conf(us,
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132 ngx_http_upstream_least_conn_module);
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133
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134 lcp = ngx_palloc(r->pool, sizeof(ngx_http_upstream_lc_peer_data_t));
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135 if (lcp == NULL) {
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136 return NGX_ERROR;
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137 }
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138
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139 lcp->conns = lcf->conns;
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140
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141 r->upstream->peer.data = &lcp->rrp;
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142
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143 if (ngx_http_upstream_init_round_robin_peer(r, us) != NGX_OK) {
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144 return NGX_ERROR;
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145 }
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146
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147 r->upstream->peer.get = ngx_http_upstream_get_least_conn_peer;
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148 r->upstream->peer.free = ngx_http_upstream_free_least_conn_peer;
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149
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150 lcp->get_rr_peer = ngx_http_upstream_get_round_robin_peer;
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151 lcp->free_rr_peer = ngx_http_upstream_free_round_robin_peer;
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152
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153 return NGX_OK;
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154 }
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155
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156
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157 static ngx_int_t
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158 ngx_http_upstream_get_least_conn_peer(ngx_peer_connection_t *pc, void *data)
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159 {
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160 ngx_http_upstream_lc_peer_data_t *lcp = data;
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161
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162 time_t now;
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163 uintptr_t m;
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164 ngx_int_t rc, total;
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165 ngx_uint_t i, n, p, many;
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166 ngx_http_upstream_rr_peer_t *peer, *best;
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167 ngx_http_upstream_rr_peers_t *peers;
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168
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169 ngx_log_debug1(NGX_LOG_DEBUG_HTTP, pc->log, 0,
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170 "get least conn peer, try: %ui", pc->tries);
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171
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172 if (lcp->rrp.peers->single) {
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173 return lcp->get_rr_peer(pc, &lcp->rrp);
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174 }
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175
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176 pc->cached = 0;
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177 pc->connection = NULL;
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178
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179 now = ngx_time();
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180
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181 peers = lcp->rrp.peers;
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182
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183 best = NULL;
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184 total = 0;
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185
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186 #if (NGX_SUPPRESS_WARN)
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187 many = 0;
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188 p = 0;
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189 #endif
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190
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191 for (i = 0; i < peers->number; i++) {
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192
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193 n = i / (8 * sizeof(uintptr_t));
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194 m = (uintptr_t) 1 << i % (8 * sizeof(uintptr_t));
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195
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196 if (lcp->rrp.tried[n] & m) {
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197 continue;
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198 }
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199
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200 peer = &peers->peer[i];
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201
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202 if (peer->down) {
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203 continue;
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204 }
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205
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206 if (peer->max_fails
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207 && peer->fails >= peer->max_fails
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208 && now - peer->checked <= peer->fail_timeout)
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209 {
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210 continue;
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211 }
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212
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213 /*
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214 * select peer with least number of connections; if there are
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215 * multiple peers with the same number of connections, select
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216 * based on round-robin
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217 */
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218
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219 if (best == NULL
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220 || lcp->conns[i] * best->weight < lcp->conns[p] * peer->weight)
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221 {
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222 best = peer;
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223 many = 0;
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224 p = i;
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225
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226 } else if (lcp->conns[i] * best->weight
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227 == lcp->conns[p] * peer->weight)
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228 {
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229 many = 1;
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230 }
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231 }
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232
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233 if (best == NULL) {
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234 ngx_log_debug0(NGX_LOG_DEBUG_HTTP, pc->log, 0,
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235 "get least conn peer, no peer found");
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236
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237 goto failed;
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238 }
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239
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240 if (many) {
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241 ngx_log_debug0(NGX_LOG_DEBUG_HTTP, pc->log, 0,
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242 "get least conn peer, many");
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243
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244 for (i = p; i < peers->number; i++) {
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245
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246 n = i / (8 * sizeof(uintptr_t));
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247 m = (uintptr_t) 1 << i % (8 * sizeof(uintptr_t));
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248
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249 if (lcp->rrp.tried[n] & m) {
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250 continue;
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251 }
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252
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253 peer = &peers->peer[i];
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254
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255 if (peer->down) {
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256 continue;
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257 }
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258
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259 if (lcp->conns[i] * best->weight != lcp->conns[p] * peer->weight) {
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260 continue;
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261 }
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262
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263 if (peer->max_fails
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264 && peer->fails >= peer->max_fails
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265 && now - peer->checked <= peer->fail_timeout)
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266 {
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267 continue;
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268 }
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269
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270 peer->current_weight += peer->effective_weight;
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271 total += peer->effective_weight;
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272
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273 if (peer->effective_weight < peer->weight) {
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274 peer->effective_weight++;
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275 }
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276
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277 if (peer->current_weight > best->current_weight) {
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278 best = peer;
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279 p = i;
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280 }
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281 }
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282 }
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283
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284 best->current_weight -= total;
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285 best->checked = now;
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286
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287 pc->sockaddr = best->sockaddr;
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288 pc->socklen = best->socklen;
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289 pc->name = &best->name;
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290
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291 lcp->rrp.current = p;
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292
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293 n = p / (8 * sizeof(uintptr_t));
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294 m = (uintptr_t) 1 << p % (8 * sizeof(uintptr_t));
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295
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296 lcp->rrp.tried[n] |= m;
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297 lcp->conns[p]++;
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298
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299 if (pc->tries == 1 && peers->next) {
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300 pc->tries += peers->next->number;
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301 }
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302
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303 return NGX_OK;
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304
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305 failed:
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306
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307 if (peers->next) {
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308 ngx_log_debug0(NGX_LOG_DEBUG_HTTP, pc->log, 0,
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309 "get least conn peer, backup servers");
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310
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311 lcp->conns += peers->number;
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312
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313 lcp->rrp.peers = peers->next;
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314 pc->tries = lcp->rrp.peers->number;
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315
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316 n = lcp->rrp.peers->number / (8 * sizeof(uintptr_t)) + 1;
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317 for (i = 0; i < n; i++) {
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318 lcp->rrp.tried[i] = 0;
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319 }
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320
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321 rc = ngx_http_upstream_get_least_conn_peer(pc, lcp);
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322
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323 if (rc != NGX_BUSY) {
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324 return rc;
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325 }
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326 }
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327
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328 /* all peers failed, mark them as live for quick recovery */
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329
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330 for (i = 0; i < peers->number; i++) {
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331 peers->peer[i].fails = 0;
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332 }
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333
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334 pc->name = peers->name;
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335
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336 return NGX_BUSY;
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337 }
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338
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339
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340 static void
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341 ngx_http_upstream_free_least_conn_peer(ngx_peer_connection_t *pc,
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342 void *data, ngx_uint_t state)
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343 {
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344 ngx_http_upstream_lc_peer_data_t *lcp = data;
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345
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346 ngx_log_debug2(NGX_LOG_DEBUG_HTTP, pc->log, 0,
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347 "free least conn peer %ui %ui", pc->tries, state);
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348
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349 if (lcp->rrp.peers->single) {
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350 lcp->free_rr_peer(pc, &lcp->rrp, state);
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351 return;
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352 }
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353
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354 if (state == 0 && pc->tries == 0) {
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355 return;
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356 }
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357
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358 lcp->conns[lcp->rrp.current]--;
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359
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360 lcp->free_rr_peer(pc, &lcp->rrp, state);
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361 }
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362
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363
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364 static void *
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365 ngx_http_upstream_least_conn_create_conf(ngx_conf_t *cf)
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366 {
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367 ngx_http_upstream_least_conn_conf_t *conf;
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368
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369 conf = ngx_pcalloc(cf->pool,
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370 sizeof(ngx_http_upstream_least_conn_conf_t));
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371 if (conf == NULL) {
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372 return NULL;
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373 }
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374
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375 /*
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376 * set by ngx_pcalloc():
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377 *
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378 * conf->conns = NULL;
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379 */
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380
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381 return conf;
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382 }
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383
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384
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385 static char *
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386 ngx_http_upstream_least_conn(ngx_conf_t *cf, ngx_command_t *cmd, void *conf)
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387 {
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388 ngx_http_upstream_srv_conf_t *uscf;
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389
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390 uscf = ngx_http_conf_get_module_srv_conf(cf, ngx_http_upstream_module);
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391
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392 uscf->peer.init_upstream = ngx_http_upstream_init_least_conn;
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393
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394 uscf->flags = NGX_HTTP_UPSTREAM_CREATE
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395 |NGX_HTTP_UPSTREAM_WEIGHT
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396 |NGX_HTTP_UPSTREAM_MAX_FAILS
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397 |NGX_HTTP_UPSTREAM_FAIL_TIMEOUT
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398 |NGX_HTTP_UPSTREAM_DOWN
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399 |NGX_HTTP_UPSTREAM_BACKUP;
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400
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401 return NGX_CONF_OK;
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402 }
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