ngx_http_split_clients_module.c revision e18a033b
1
2/*
3 * Copyright (C) Igor Sysoev
4 * Copyright (C) Nginx, Inc.
5 */
6
7
8#include <ngx_config.h>
9#include <ngx_core.h>
10#include <ngx_http.h>
11
12
13typedef struct {
14    uint32_t                    percent;
15    ngx_http_variable_value_t   value;
16} ngx_http_split_clients_part_t;
17
18
19typedef struct {
20    ngx_http_complex_value_t    value;
21    ngx_array_t                 parts;
22} ngx_http_split_clients_ctx_t;
23
24
25static char *ngx_conf_split_clients_block(ngx_conf_t *cf, ngx_command_t *cmd,
26    void *conf);
27static char *ngx_http_split_clients(ngx_conf_t *cf, ngx_command_t *dummy,
28    void *conf);
29
30static ngx_command_t  ngx_http_split_clients_commands[] = {
31
32    { ngx_string("split_clients"),
33      NGX_HTTP_MAIN_CONF|NGX_CONF_BLOCK|NGX_CONF_TAKE2,
34      ngx_conf_split_clients_block,
35      NGX_HTTP_MAIN_CONF_OFFSET,
36      0,
37      NULL },
38
39      ngx_null_command
40};
41
42
43static ngx_http_module_t  ngx_http_split_clients_module_ctx = {
44    NULL,                                  /* preconfiguration */
45    NULL,                                  /* postconfiguration */
46
47    NULL,                                  /* create main configuration */
48    NULL,                                  /* init main configuration */
49
50    NULL,                                  /* create server configuration */
51    NULL,                                  /* merge server configuration */
52
53    NULL,                                  /* create location configuration */
54    NULL                                   /* merge location configuration */
55};
56
57
58ngx_module_t  ngx_http_split_clients_module = {
59    NGX_MODULE_V1,
60    &ngx_http_split_clients_module_ctx,    /* module context */
61    ngx_http_split_clients_commands,       /* module directives */
62    NGX_HTTP_MODULE,                       /* module type */
63    NULL,                                  /* init master */
64    NULL,                                  /* init module */
65    NULL,                                  /* init process */
66    NULL,                                  /* init thread */
67    NULL,                                  /* exit thread */
68    NULL,                                  /* exit process */
69    NULL,                                  /* exit master */
70    NGX_MODULE_V1_PADDING
71};
72
73
74static ngx_int_t
75ngx_http_split_clients_variable(ngx_http_request_t *r,
76    ngx_http_variable_value_t *v, uintptr_t data)
77{
78    ngx_http_split_clients_ctx_t *ctx = (ngx_http_split_clients_ctx_t *) data;
79
80    uint32_t                        hash;
81    ngx_str_t                       val;
82    ngx_uint_t                      i;
83    ngx_http_split_clients_part_t  *part;
84
85    *v = ngx_http_variable_null_value;
86
87    if (ngx_http_complex_value(r, &ctx->value, &val) != NGX_OK) {
88        return NGX_OK;
89    }
90
91    hash = ngx_murmur_hash2(val.data, val.len);
92
93    part = ctx->parts.elts;
94
95    for (i = 0; i < ctx->parts.nelts; i++) {
96
97        ngx_log_debug2(NGX_LOG_DEBUG_HTTP, r->connection->log, 0,
98                       "http split: %uD %uD", hash, part[i].percent);
99
100        if (hash < part[i].percent || part[i].percent == 0) {
101            *v = part[i].value;
102            return NGX_OK;
103        }
104    }
105
106    return NGX_OK;
107}
108
109
110static char *
111ngx_conf_split_clients_block(ngx_conf_t *cf, ngx_command_t *cmd, void *conf)
112{
113    char                                *rv;
114    uint32_t                             sum, last;
115    ngx_str_t                           *value, name;
116    ngx_uint_t                           i;
117    ngx_conf_t                           save;
118    ngx_http_variable_t                 *var;
119    ngx_http_split_clients_ctx_t        *ctx;
120    ngx_http_split_clients_part_t       *part;
121    ngx_http_compile_complex_value_t     ccv;
122
123    ctx = ngx_pcalloc(cf->pool, sizeof(ngx_http_split_clients_ctx_t));
124    if (ctx == NULL) {
125        return NGX_CONF_ERROR;
126    }
127
128    value = cf->args->elts;
129
130    ngx_memzero(&ccv, sizeof(ngx_http_compile_complex_value_t));
131
132    ccv.cf = cf;
133    ccv.value = &value[1];
134    ccv.complex_value = &ctx->value;
135
136    if (ngx_http_compile_complex_value(&ccv) != NGX_OK) {
137        return NGX_CONF_ERROR;
138    }
139
140    name = value[2];
141
142    if (name.data[0] != '$') {
143        ngx_conf_log_error(NGX_LOG_EMERG, cf, 0,
144                           "invalid variable name \"%V\"", &name);
145        return NGX_CONF_ERROR;
146    }
147
148    name.len--;
149    name.data++;
150
151    var = ngx_http_add_variable(cf, &name, NGX_HTTP_VAR_CHANGEABLE);
152    if (var == NULL) {
153        return NGX_CONF_ERROR;
154    }
155
156    var->get_handler = ngx_http_split_clients_variable;
157    var->data = (uintptr_t) ctx;
158
159    if (ngx_array_init(&ctx->parts, cf->pool, 2,
160                       sizeof(ngx_http_split_clients_part_t))
161        != NGX_OK)
162    {
163        return NGX_CONF_ERROR;
164    }
165
166    save = *cf;
167    cf->ctx = ctx;
168    cf->handler = ngx_http_split_clients;
169    cf->handler_conf = conf;
170
171    rv = ngx_conf_parse(cf, NULL);
172
173    *cf = save;
174
175    if (rv != NGX_CONF_OK) {
176        return rv;
177    }
178
179    sum = 0;
180    last = 0;
181    part = ctx->parts.elts;
182
183    for (i = 0; i < ctx->parts.nelts; i++) {
184        sum = part[i].percent ? sum + part[i].percent : 10000;
185        if (sum > 10000) {
186            ngx_conf_log_error(NGX_LOG_EMERG, cf, 0,
187                               "percent total is greater than 100%%");
188            return NGX_CONF_ERROR;
189        }
190
191        if (part[i].percent) {
192            last += part[i].percent * (uint64_t) 0xffffffff / 10000;
193            part[i].percent = last;
194        }
195    }
196
197    return rv;
198}
199
200
201static char *
202ngx_http_split_clients(ngx_conf_t *cf, ngx_command_t *dummy, void *conf)
203{
204    ngx_int_t                       n;
205    ngx_str_t                      *value;
206    ngx_http_split_clients_ctx_t   *ctx;
207    ngx_http_split_clients_part_t  *part;
208
209    ctx = cf->ctx;
210    value = cf->args->elts;
211
212    part = ngx_array_push(&ctx->parts);
213    if (part == NULL) {
214        return NGX_CONF_ERROR;
215    }
216
217    if (value[0].len == 1 && value[0].data[0] == '*') {
218        part->percent = 0;
219
220    } else {
221        if (value[0].len == 0 || value[0].data[value[0].len - 1] != '%') {
222            goto invalid;
223        }
224
225        n = ngx_atofp(value[0].data, value[0].len - 1, 2);
226        if (n == NGX_ERROR || n == 0) {
227            goto invalid;
228        }
229
230        part->percent = (uint32_t) n;
231    }
232
233    part->value.len = value[1].len;
234    part->value.valid = 1;
235    part->value.no_cacheable = 0;
236    part->value.not_found = 0;
237    part->value.data = value[1].data;
238
239    return NGX_CONF_OK;
240
241invalid:
242
243    ngx_conf_log_error(NGX_LOG_EMERG, cf, 0,
244                       "invalid percent value \"%V\"", &value[0]);
245    return NGX_CONF_ERROR;
246}
247