Mercurial > hg > nginx
view src/http/modules/ngx_http_split_clients_module.c @ 8045:aa28c802409f
Resolver: make TCP write timer event cancelable.
Similar to 70e65bf8dfd7, the change is made to ensure that the ability to
cancel resolver tasks is fully controlled by the caller. As mentioned in the
referenced commit, it is safe to make this timer cancelable because resolve
tasks can have their own timeouts that are not cancelable.
The scenario where this may become a problem is a periodic background resolve
task (not tied to a specific request or a client connection), which receives a
response with short TTL, large enough to warrant fallback to a TCP query.
With each event loop wakeup, we either have a previously set write timer
instance or schedule a new one. The non-cancelable write timer can delay or
block graceful shutdown of a worker even if the ngx_resolver_ctx_t->cancelable
flag is set by the API user, and there are no other tasks or connections.
We use the resolver API in this way to maintain the list of upstream server
addresses specified with the 'resolve' parameter, and there could be third-party
modules implementing similar logic.
author | Aleksei Bavshin <a.bavshin@f5.com> |
---|---|
date | Wed, 01 Jun 2022 20:17:23 -0700 |
parents | b78cf2414fda |
children |
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/* * Copyright (C) Igor Sysoev * Copyright (C) Nginx, Inc. */ #include <ngx_config.h> #include <ngx_core.h> #include <ngx_http.h> typedef struct { uint32_t percent; ngx_http_variable_value_t value; } ngx_http_split_clients_part_t; typedef struct { ngx_http_complex_value_t value; ngx_array_t parts; } ngx_http_split_clients_ctx_t; static char *ngx_conf_split_clients_block(ngx_conf_t *cf, ngx_command_t *cmd, void *conf); static char *ngx_http_split_clients(ngx_conf_t *cf, ngx_command_t *dummy, void *conf); static ngx_command_t ngx_http_split_clients_commands[] = { { ngx_string("split_clients"), NGX_HTTP_MAIN_CONF|NGX_CONF_BLOCK|NGX_CONF_TAKE2, ngx_conf_split_clients_block, NGX_HTTP_MAIN_CONF_OFFSET, 0, NULL }, ngx_null_command }; static ngx_http_module_t ngx_http_split_clients_module_ctx = { NULL, /* preconfiguration */ NULL, /* postconfiguration */ NULL, /* create main configuration */ NULL, /* init main configuration */ NULL, /* create server configuration */ NULL, /* merge server configuration */ NULL, /* create location configuration */ NULL /* merge location configuration */ }; ngx_module_t ngx_http_split_clients_module = { NGX_MODULE_V1, &ngx_http_split_clients_module_ctx, /* module context */ ngx_http_split_clients_commands, /* module directives */ NGX_HTTP_MODULE, /* module type */ NULL, /* init master */ NULL, /* init module */ NULL, /* init process */ NULL, /* init thread */ NULL, /* exit thread */ NULL, /* exit process */ NULL, /* exit master */ NGX_MODULE_V1_PADDING }; static ngx_int_t ngx_http_split_clients_variable(ngx_http_request_t *r, ngx_http_variable_value_t *v, uintptr_t data) { ngx_http_split_clients_ctx_t *ctx = (ngx_http_split_clients_ctx_t *) data; uint32_t hash; ngx_str_t val; ngx_uint_t i; ngx_http_split_clients_part_t *part; *v = ngx_http_variable_null_value; if (ngx_http_complex_value(r, &ctx->value, &val) != NGX_OK) { return NGX_OK; } hash = ngx_murmur_hash2(val.data, val.len); part = ctx->parts.elts; for (i = 0; i < ctx->parts.nelts; i++) { ngx_log_debug2(NGX_LOG_DEBUG_HTTP, r->connection->log, 0, "http split: %uD %uD", hash, part[i].percent); if (hash < part[i].percent || part[i].percent == 0) { *v = part[i].value; return NGX_OK; } } return NGX_OK; } static char * ngx_conf_split_clients_block(ngx_conf_t *cf, ngx_command_t *cmd, void *conf) { char *rv; uint32_t sum, last; ngx_str_t *value, name; ngx_uint_t i; ngx_conf_t save; ngx_http_variable_t *var; ngx_http_split_clients_ctx_t *ctx; ngx_http_split_clients_part_t *part; ngx_http_compile_complex_value_t ccv; ctx = ngx_pcalloc(cf->pool, sizeof(ngx_http_split_clients_ctx_t)); if (ctx == NULL) { return NGX_CONF_ERROR; } value = cf->args->elts; ngx_memzero(&ccv, sizeof(ngx_http_compile_complex_value_t)); ccv.cf = cf; ccv.value = &value[1]; ccv.complex_value = &ctx->value; if (ngx_http_compile_complex_value(&ccv) != NGX_OK) { return NGX_CONF_ERROR; } name = value[2]; if (name.data[0] != '$') { ngx_conf_log_error(NGX_LOG_EMERG, cf, 0, "invalid variable name \"%V\"", &name); return NGX_CONF_ERROR; } name.len--; name.data++; var = ngx_http_add_variable(cf, &name, NGX_HTTP_VAR_CHANGEABLE); if (var == NULL) { return NGX_CONF_ERROR; } var->get_handler = ngx_http_split_clients_variable; var->data = (uintptr_t) ctx; if (ngx_array_init(&ctx->parts, cf->pool, 2, sizeof(ngx_http_split_clients_part_t)) != NGX_OK) { return NGX_CONF_ERROR; } save = *cf; cf->ctx = ctx; cf->handler = ngx_http_split_clients; cf->handler_conf = conf; rv = ngx_conf_parse(cf, NULL); *cf = save; if (rv != NGX_CONF_OK) { return rv; } sum = 0; last = 0; part = ctx->parts.elts; for (i = 0; i < ctx->parts.nelts; i++) { sum = part[i].percent ? sum + part[i].percent : 10000; if (sum > 10000) { ngx_conf_log_error(NGX_LOG_EMERG, cf, 0, "percent total is greater than 100%%"); return NGX_CONF_ERROR; } if (part[i].percent) { last += part[i].percent * (uint64_t) 0xffffffff / 10000; part[i].percent = last; } } return rv; } static char * ngx_http_split_clients(ngx_conf_t *cf, ngx_command_t *dummy, void *conf) { ngx_int_t n; ngx_str_t *value; ngx_http_split_clients_ctx_t *ctx; ngx_http_split_clients_part_t *part; ctx = cf->ctx; value = cf->args->elts; part = ngx_array_push(&ctx->parts); if (part == NULL) { return NGX_CONF_ERROR; } if (value[0].len == 1 && value[0].data[0] == '*') { part->percent = 0; } else { if (value[0].len == 0 || value[0].data[value[0].len - 1] != '%') { goto invalid; } n = ngx_atofp(value[0].data, value[0].len - 1, 2); if (n == NGX_ERROR || n == 0) { goto invalid; } part->percent = (uint32_t) n; } part->value.len = value[1].len; part->value.valid = 1; part->value.no_cacheable = 0; part->value.not_found = 0; part->value.data = value[1].data; return NGX_CONF_OK; invalid: ngx_conf_log_error(NGX_LOG_EMERG, cf, 0, "invalid percent value \"%V\"", &value[0]); return NGX_CONF_ERROR; }