src/http/modules/ngx_http_split_clients_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     uint32_t                    percent;
  14     ngx_http_variable_value_t   value;
  15 } ngx_http_split_clients_part_t;
  16
  17
  18 typedef struct {
  19     ngx_http_complex_value_t    value;
  20     ngx_array_t                 parts;
  21 } ngx_http_split_clients_ctx_t;
  22
  23
  24 static char *ngx_conf_split_clients_block(ngx_conf_t *cf, ngx_command_t *cmd,
  25     void *conf);
  26 static char *ngx_http_split_clients(ngx_conf_t *cf, ngx_command_t *dummy,
  27     void *conf);
  28
  29 static ngx_command_t  ngx_http_split_clients_commands[] = {
  30
  31     { ngx_string("split_clients"),
  32       NGX_HTTP_MAIN_CONF|NGX_CONF_BLOCK|NGX_CONF_TAKE2,
  33       ngx_conf_split_clients_block,
  34       NGX_HTTP_MAIN_CONF_OFFSET,
  35       0,
  36       NULL },
  37
  38       ngx_null_command
  39 };
  40
  41
  42 static ngx_http_module_t  ngx_http_split_clients_module_ctx = {
  43     NULL,                                  /* preconfiguration */
  44     NULL,                                  /* postconfiguration */
  45
  46     NULL,                                  /* create main configuration */
  47     NULL,                                  /* init main configuration */
  48
  49     NULL,                                  /* create server configuration */
  50     NULL,                                  /* merge server configuration */
  51
  52     NULL,                                  /* create location configuration */
  53     NULL                                   /* merge location configuration */
  54 };
  55
  56
  57 ngx_module_t  ngx_http_split_clients_module = {
  58     NGX_MODULE_V1,
  59     &ngx_http_split_clients_module_ctx,    /* module context */
  60     ngx_http_split_clients_commands,       /* module directives */
  61     NGX_HTTP_MODULE,                       /* module type */
  62     NULL,                                  /* init master */
  63     NULL,                                  /* init module */
  64     NULL,                                  /* init process */
  65     NULL,                                  /* init thread */
  66     NULL,                                  /* exit thread */
  67     NULL,                                  /* exit process */
  68     NULL,                                  /* exit master */
  69     NGX_MODULE_V1_PADDING
  70 };
  71
  72
  73 static ngx_int_t
  74 ngx_http_split_clients_variable(ngx_http_request_t *r,
  75     ngx_http_variable_value_t *v, uintptr_t data)
  76 {
  77     ngx_http_split_clients_ctx_t *ctx = (ngx_http_split_clients_ctx_t *) data;
  78
  79     uint32_t                        hash;
  80     ngx_str_t                       val;
  81     ngx_uint_t                      i;
  82     ngx_http_split_clients_part_t  *part;
  83
  84     *v = ngx_http_variable_null_value;
  85
  86     if (ngx_http_complex_value(r, &ctx->value, &val) != NGX_OK) {
  87         return NGX_OK;
  88     }
  89
  90     hash = ngx_murmur_hash2(val.data, val.len);
  91
  92     part = ctx->parts.elts;
  93
  94     for (i = 0; i < ctx->parts.nelts; i++) {
  95
  96         ngx_log_debug2(NGX_LOG_DEBUG_HTTP, r->connection->log, 0,
  97                        "http split: %uD %uD", hash, part[i].percent);
  98
  99         if (hash < part[i].percent) {
 100             *v = part[i].value;
 101             return NGX_OK;
 102         }
 103     }
 104
 105     return NGX_OK;
 106 }
 107
 108
 109 static char *
 110 ngx_conf_split_clients_block(ngx_conf_t *cf, ngx_command_t *cmd, void *conf)
 111 {
 112     char                                *rv;
 113     ngx_str_t                           *value, name;
 114     ngx_uint_t                           i, sum, last;
 115     ngx_conf_t                           save;
 116     ngx_http_variable_t                 *var;
 117     ngx_http_split_clients_ctx_t        *ctx;
 118     ngx_http_split_clients_part_t       *part;
 119     ngx_http_compile_complex_value_t     ccv;
 120
 121     ctx = ngx_pcalloc(cf->pool, sizeof(ngx_http_split_clients_ctx_t));
 122     if (ctx == NULL) {
 123         return NGX_CONF_ERROR;
 124     }
 125
 126     value = cf->args->elts;
 127
 128     ngx_memzero(&ccv, sizeof(ngx_http_compile_complex_value_t));
 129
 130     ccv.cf = cf;
 131     ccv.value = &value[1];
 132     ccv.complex_value = &ctx->value;
 133
 134     if (ngx_http_compile_complex_value(&ccv) != NGX_OK) {
 135         return NGX_CONF_ERROR;
 136     }
 137
 138     name = value[2];
 139     name.len--;
 140     name.data++;
 141
 142     var = ngx_http_add_variable(cf, &name, NGX_HTTP_VAR_CHANGEABLE);
 143     if (var == NULL) {
 144         return NGX_CONF_ERROR;
 145     }
 146
 147     var->get_handler = ngx_http_split_clients_variable;
 148     var->data = (uintptr_t) ctx;
 149
 150     if (ngx_array_init(&ctx->parts, cf->pool, 2,
 151                        sizeof(ngx_http_split_clients_part_t))
 152         != NGX_OK)
 153     {
 154         return NGX_CONF_ERROR;
 155     }
 156
 157     save = *cf;
 158     cf->ctx = ctx;
 159     cf->handler = ngx_http_split_clients;
 160     cf->handler_conf = conf;
 161
 162     rv = ngx_conf_parse(cf, NULL);
 163
 164     *cf = save;
 165
 166     if (rv != NGX_CONF_OK) {
 167         return rv;
 168     }
 169
 170     sum = 0;
 171     last = 0;
 172     part = ctx->parts.elts;
 173
 174     for (i = 0; i < ctx->parts.nelts; i++) {
 175         sum = part[i].percent ? sum + part[i].percent : 10000;
 176         if (sum > 10000) {
 177            ngx_conf_log_error(NGX_LOG_EMERG, cf, 0,
 178                               "percent sum is more than 100%%");
 179            return NGX_CONF_ERROR;
 180         }
 181
 182         if (part[i].percent) {
 183             part[i].percent = (uint32_t)
 184                                  (last + 0xffffffff / 10000 * part[i].percent);
 185         } else {
 186             part[i].percent = 0xffffffff;
 187         }
 188
 189         last = part[i].percent;
 190     }
 191
 192     return rv;
 193 }
 194
 195
 196 static char *
 197 ngx_http_split_clients(ngx_conf_t *cf, ngx_command_t *dummy, void *conf)
 198 {
 199     ngx_int_t                       n;
 200     ngx_str_t                      *value;
 201     ngx_http_split_clients_ctx_t   *ctx;
 202     ngx_http_split_clients_part_t  *part;
 203
 204     ctx = cf->ctx;
 205     value = cf->args->elts;
 206
 207     part = ngx_array_push(&ctx->parts);
 208     if (part == NULL) {
 209         return NGX_CONF_ERROR;
 210     }
 211
 212     if (value[0].len == 1 && value[0].data[0] == '*') {
 213         part->percent = 0;
 214
 215     } else {
 216         if (value[0].data[value[0].len - 1] != '%') {
 217             goto invalid;
 218         }
 219
 220         n = ngx_atofp(value[0].data, value[0].len - 1, 2);
 221         if (n == NGX_ERROR || n == 0) {
 222             goto invalid;
 223         }
 224
 225         part->percent = (uint32_t) n;
 226     }
 227
 228     part->value.len = value[1].len;
 229     part->value.valid = 1;
 230     part->value.no_cacheable = 0;
 231     part->value.not_found = 0;
 232     part->value.data = value[1].data;
 233
 234     return NGX_CONF_OK;
 235
 236 invalid:
 237
 238     ngx_conf_log_error(NGX_LOG_EMERG, cf, 0,
 239                        "invalid percent value \"%V\"", &value[0]);
 240     return NGX_CONF_ERROR;
 241 }