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6115
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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_stream.h>
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11
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12
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13 static ngx_int_t ngx_stream_upstream_init_least_conn_peer(
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14 ngx_stream_session_t *s, ngx_stream_upstream_srv_conf_t *us);
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15 static ngx_int_t ngx_stream_upstream_get_least_conn_peer(
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16 ngx_peer_connection_t *pc, void *data);
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17 static char *ngx_stream_upstream_least_conn(ngx_conf_t *cf, ngx_command_t *cmd,
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18 void *conf);
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19
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20
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21 static ngx_command_t ngx_stream_upstream_least_conn_commands[] = {
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22
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23 { ngx_string("least_conn"),
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24 NGX_STREAM_UPS_CONF|NGX_CONF_NOARGS,
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25 ngx_stream_upstream_least_conn,
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26 0,
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27 0,
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28 NULL },
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29
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30 ngx_null_command
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31 };
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32
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33
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34 static ngx_stream_module_t ngx_stream_upstream_least_conn_module_ctx = {
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35 NULL, /* create main configuration */
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36 NULL, /* init main configuration */
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37
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38 NULL, /* create server configuration */
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39 NULL, /* merge server configuration */
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40 };
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41
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42
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43 ngx_module_t ngx_stream_upstream_least_conn_module = {
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44 NGX_MODULE_V1,
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45 &ngx_stream_upstream_least_conn_module_ctx, /* module context */
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46 ngx_stream_upstream_least_conn_commands, /* module directives */
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47 NGX_STREAM_MODULE, /* module type */
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48 NULL, /* init master */
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49 NULL, /* init module */
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50 NULL, /* init process */
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51 NULL, /* init thread */
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52 NULL, /* exit thread */
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53 NULL, /* exit process */
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54 NULL, /* exit master */
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55 NGX_MODULE_V1_PADDING
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56 };
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57
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58
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59 static ngx_int_t
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60 ngx_stream_upstream_init_least_conn(ngx_conf_t *cf,
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61 ngx_stream_upstream_srv_conf_t *us)
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62 {
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63 ngx_log_debug0(NGX_LOG_DEBUG_STREAM, cf->log, 0,
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64 "init least conn");
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65
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66 if (ngx_stream_upstream_init_round_robin(cf, us) != NGX_OK) {
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67 return NGX_ERROR;
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68 }
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69
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70 us->peer.init = ngx_stream_upstream_init_least_conn_peer;
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71
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72 return NGX_OK;
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73 }
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74
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75
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76 static ngx_int_t
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77 ngx_stream_upstream_init_least_conn_peer(ngx_stream_session_t *s,
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78 ngx_stream_upstream_srv_conf_t *us)
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79 {
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80 ngx_log_debug0(NGX_LOG_DEBUG_STREAM, s->connection->log, 0,
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81 "init least conn peer");
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82
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83 if (ngx_stream_upstream_init_round_robin_peer(s, us) != NGX_OK) {
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84 return NGX_ERROR;
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85 }
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86
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87 s->upstream->peer.get = ngx_stream_upstream_get_least_conn_peer;
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88
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89 return NGX_OK;
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90 }
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91
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92
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93 static ngx_int_t
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94 ngx_stream_upstream_get_least_conn_peer(ngx_peer_connection_t *pc, void *data)
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95 {
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96 ngx_stream_upstream_rr_peer_data_t *rrp = data;
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97
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98 time_t now;
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99 uintptr_t m;
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100 ngx_int_t rc, total;
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101 ngx_uint_t i, n, p, many;
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102 ngx_stream_upstream_rr_peer_t *peer, *best;
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103 ngx_stream_upstream_rr_peers_t *peers;
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104
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105 ngx_log_debug1(NGX_LOG_DEBUG_STREAM, pc->log, 0,
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106 "get least conn peer, try: %ui", pc->tries);
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107
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108 if (rrp->peers->single) {
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109 return ngx_stream_upstream_get_round_robin_peer(pc, rrp);
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110 }
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111
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112 pc->connection = NULL;
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113
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114 now = ngx_time();
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115
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116 peers = rrp->peers;
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117
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118 ngx_stream_upstream_rr_peers_wlock(peers);
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119
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120 best = NULL;
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121 total = 0;
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122
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123 #if (NGX_SUPPRESS_WARN)
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124 many = 0;
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125 p = 0;
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126 #endif
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127
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128 for (peer = peers->peer, i = 0;
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129 peer;
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130 peer = peer->next, i++)
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131 {
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132
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133 n = i / (8 * sizeof(uintptr_t));
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134 m = (uintptr_t) 1 << i % (8 * sizeof(uintptr_t));
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135
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136 if (rrp->tried[n] & m) {
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137 continue;
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138 }
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139
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140 if (peer->down) {
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141 continue;
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142 }
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143
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144 if (peer->max_fails
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145 && peer->fails >= peer->max_fails
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146 && now - peer->checked <= peer->fail_timeout)
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147 {
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148 continue;
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149 }
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150
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151 /*
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152 * select peer with least number of connections; if there are
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153 * multiple peers with the same number of connections, select
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154 * based on round-robin
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155 */
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156
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157 if (best == NULL
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158 || peer->conns * best->weight < best->conns * peer->weight)
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159 {
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160 best = peer;
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161 many = 0;
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162 p = i;
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163
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164 } else if (peer->conns * best->weight == best->conns * peer->weight) {
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165 many = 1;
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166 }
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167 }
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168
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169 if (best == NULL) {
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170 ngx_log_debug0(NGX_LOG_DEBUG_STREAM, pc->log, 0,
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171 "get least conn peer, no peer found");
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172
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173 goto failed;
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174 }
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175
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176 if (many) {
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177 ngx_log_debug0(NGX_LOG_DEBUG_STREAM, pc->log, 0,
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178 "get least conn peer, many");
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179
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180 for (peer = best, i = p;
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181 peer;
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182 peer = peer->next, i++)
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183 {
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184 n = i / (8 * sizeof(uintptr_t));
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185 m = (uintptr_t) 1 << i % (8 * sizeof(uintptr_t));
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186
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187 if (rrp->tried[n] & m) {
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188 continue;
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189 }
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190
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191 if (peer->down) {
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192 continue;
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193 }
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194
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195 if (peer->conns * best->weight != best->conns * peer->weight) {
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196 continue;
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197 }
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198
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199 if (peer->max_fails
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200 && peer->fails >= peer->max_fails
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201 && now - peer->checked <= peer->fail_timeout)
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202 {
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203 continue;
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204 }
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205
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206 peer->current_weight += peer->effective_weight;
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207 total += peer->effective_weight;
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208
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209 if (peer->effective_weight < peer->weight) {
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210 peer->effective_weight++;
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211 }
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212
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213 if (peer->current_weight > best->current_weight) {
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214 best = peer;
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215 p = i;
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216 }
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217 }
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218 }
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219
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220 best->current_weight -= total;
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221
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222 if (now - best->checked > best->fail_timeout) {
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223 best->checked = now;
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224 }
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225
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226 pc->sockaddr = best->sockaddr;
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227 pc->socklen = best->socklen;
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228 pc->name = &best->name;
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229
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230 best->conns++;
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231
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232 rrp->current = best;
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233
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234 n = p / (8 * sizeof(uintptr_t));
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235 m = (uintptr_t) 1 << p % (8 * sizeof(uintptr_t));
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236
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237 rrp->tried[n] |= m;
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238
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239 ngx_stream_upstream_rr_peers_unlock(peers);
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240
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241 return NGX_OK;
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242
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243 failed:
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244
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245 if (peers->next) {
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246 ngx_log_debug0(NGX_LOG_DEBUG_STREAM, pc->log, 0,
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247 "get least conn peer, backup servers");
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248
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249 rrp->peers = peers->next;
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250
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251 n = (rrp->peers->number + (8 * sizeof(uintptr_t) - 1))
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252 / (8 * sizeof(uintptr_t));
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253
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254 for (i = 0; i < n; i++) {
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255 rrp->tried[i] = 0;
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256 }
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257
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258 ngx_stream_upstream_rr_peers_unlock(peers);
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259
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260 rc = ngx_stream_upstream_get_least_conn_peer(pc, rrp);
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261
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262 if (rc != NGX_BUSY) {
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263 return rc;
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264 }
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265
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266 ngx_stream_upstream_rr_peers_wlock(peers);
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267 }
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268
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269 /* all peers failed, mark them as live for quick recovery */
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270
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271 for (peer = peers->peer; peer; peer = peer->next) {
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272 peer->fails = 0;
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273 }
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274
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275 ngx_stream_upstream_rr_peers_unlock(peers);
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276
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277 pc->name = peers->name;
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278
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279 return NGX_BUSY;
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280 }
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281
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282
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283 static char *
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284 ngx_stream_upstream_least_conn(ngx_conf_t *cf, ngx_command_t *cmd, void *conf)
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285 {
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286 ngx_stream_upstream_srv_conf_t *uscf;
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287
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288 uscf = ngx_stream_conf_get_module_srv_conf(cf, ngx_stream_upstream_module);
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289
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290 if (uscf->peer.init_upstream) {
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291 ngx_conf_log_error(NGX_LOG_WARN, cf, 0,
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292 "load balancing method redefined");
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293 }
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294
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295 uscf->peer.init_upstream = ngx_stream_upstream_init_least_conn;
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296
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297 uscf->flags = NGX_STREAM_UPSTREAM_CREATE
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298 |NGX_STREAM_UPSTREAM_WEIGHT
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299 |NGX_STREAM_UPSTREAM_MAX_FAILS
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300 |NGX_STREAM_UPSTREAM_FAIL_TIMEOUT
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301 |NGX_STREAM_UPSTREAM_DOWN
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302 |NGX_STREAM_UPSTREAM_BACKUP;
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303
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304 return NGX_CONF_OK;
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305 }
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