Mercurial > hg > nginx
view src/event/modules/ngx_win32_select_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 | efd71d49bde0 |
children |
line wrap: on
line source
/* * Copyright (C) Igor Sysoev * Copyright (C) Nginx, Inc. */ #include <ngx_config.h> #include <ngx_core.h> #include <ngx_event.h> static ngx_int_t ngx_select_init(ngx_cycle_t *cycle, ngx_msec_t timer); static void ngx_select_done(ngx_cycle_t *cycle); static ngx_int_t ngx_select_add_event(ngx_event_t *ev, ngx_int_t event, ngx_uint_t flags); static ngx_int_t ngx_select_del_event(ngx_event_t *ev, ngx_int_t event, ngx_uint_t flags); static ngx_int_t ngx_select_process_events(ngx_cycle_t *cycle, ngx_msec_t timer, ngx_uint_t flags); static void ngx_select_repair_fd_sets(ngx_cycle_t *cycle); static char *ngx_select_init_conf(ngx_cycle_t *cycle, void *conf); static fd_set master_read_fd_set; static fd_set master_write_fd_set; static fd_set work_read_fd_set; static fd_set work_write_fd_set; static fd_set work_except_fd_set; static ngx_uint_t max_read; static ngx_uint_t max_write; static ngx_uint_t nevents; static ngx_event_t **event_index; static ngx_str_t select_name = ngx_string("select"); static ngx_event_module_t ngx_select_module_ctx = { &select_name, NULL, /* create configuration */ ngx_select_init_conf, /* init configuration */ { ngx_select_add_event, /* add an event */ ngx_select_del_event, /* delete an event */ ngx_select_add_event, /* enable an event */ ngx_select_del_event, /* disable an event */ NULL, /* add an connection */ NULL, /* delete an connection */ NULL, /* trigger a notify */ ngx_select_process_events, /* process the events */ ngx_select_init, /* init the events */ ngx_select_done /* done the events */ } }; ngx_module_t ngx_select_module = { NGX_MODULE_V1, &ngx_select_module_ctx, /* module context */ NULL, /* module directives */ NGX_EVENT_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_select_init(ngx_cycle_t *cycle, ngx_msec_t timer) { ngx_event_t **index; if (event_index == NULL) { FD_ZERO(&master_read_fd_set); FD_ZERO(&master_write_fd_set); nevents = 0; } if (ngx_process >= NGX_PROCESS_WORKER || cycle->old_cycle == NULL || cycle->old_cycle->connection_n < cycle->connection_n) { index = ngx_alloc(sizeof(ngx_event_t *) * 2 * cycle->connection_n, cycle->log); if (index == NULL) { return NGX_ERROR; } if (event_index) { ngx_memcpy(index, event_index, sizeof(ngx_event_t *) * nevents); ngx_free(event_index); } event_index = index; } ngx_io = ngx_os_io; ngx_event_actions = ngx_select_module_ctx.actions; ngx_event_flags = NGX_USE_LEVEL_EVENT; max_read = 0; max_write = 0; return NGX_OK; } static void ngx_select_done(ngx_cycle_t *cycle) { ngx_free(event_index); event_index = NULL; } static ngx_int_t ngx_select_add_event(ngx_event_t *ev, ngx_int_t event, ngx_uint_t flags) { ngx_connection_t *c; c = ev->data; ngx_log_debug2(NGX_LOG_DEBUG_EVENT, ev->log, 0, "select add event fd:%d ev:%i", c->fd, event); if (ev->index != NGX_INVALID_INDEX) { ngx_log_error(NGX_LOG_ALERT, ev->log, 0, "select event fd:%d ev:%i is already set", c->fd, event); return NGX_OK; } if ((event == NGX_READ_EVENT && ev->write) || (event == NGX_WRITE_EVENT && !ev->write)) { ngx_log_error(NGX_LOG_ALERT, ev->log, 0, "invalid select %s event fd:%d ev:%i", ev->write ? "write" : "read", c->fd, event); return NGX_ERROR; } if ((event == NGX_READ_EVENT && max_read >= FD_SETSIZE) || (event == NGX_WRITE_EVENT && max_write >= FD_SETSIZE)) { ngx_log_error(NGX_LOG_ERR, ev->log, 0, "maximum number of descriptors " "supported by select() is %d", FD_SETSIZE); return NGX_ERROR; } if (event == NGX_READ_EVENT) { FD_SET(c->fd, &master_read_fd_set); max_read++; } else if (event == NGX_WRITE_EVENT) { FD_SET(c->fd, &master_write_fd_set); max_write++; } ev->active = 1; event_index[nevents] = ev; ev->index = nevents; nevents++; return NGX_OK; } static ngx_int_t ngx_select_del_event(ngx_event_t *ev, ngx_int_t event, ngx_uint_t flags) { ngx_event_t *e; ngx_connection_t *c; c = ev->data; ev->active = 0; if (ev->index == NGX_INVALID_INDEX) { return NGX_OK; } ngx_log_debug2(NGX_LOG_DEBUG_EVENT, ev->log, 0, "select del event fd:%d ev:%i", c->fd, event); if (event == NGX_READ_EVENT) { FD_CLR(c->fd, &master_read_fd_set); max_read--; } else if (event == NGX_WRITE_EVENT) { FD_CLR(c->fd, &master_write_fd_set); max_write--; } if (ev->index < --nevents) { e = event_index[nevents]; event_index[ev->index] = e; e->index = ev->index; } ev->index = NGX_INVALID_INDEX; return NGX_OK; } static ngx_int_t ngx_select_process_events(ngx_cycle_t *cycle, ngx_msec_t timer, ngx_uint_t flags) { int ready, nready; ngx_err_t err; ngx_uint_t i, found; ngx_event_t *ev; ngx_queue_t *queue; struct timeval tv, *tp; ngx_connection_t *c; #if (NGX_DEBUG) if (cycle->log->log_level & NGX_LOG_DEBUG_ALL) { for (i = 0; i < nevents; i++) { ev = event_index[i]; c = ev->data; ngx_log_debug2(NGX_LOG_DEBUG_EVENT, cycle->log, 0, "select event: fd:%d wr:%d", c->fd, ev->write); } } #endif if (timer == NGX_TIMER_INFINITE) { tp = NULL; } else { tv.tv_sec = (long) (timer / 1000); tv.tv_usec = (long) ((timer % 1000) * 1000); tp = &tv; } ngx_log_debug1(NGX_LOG_DEBUG_EVENT, cycle->log, 0, "select timer: %M", timer); work_read_fd_set = master_read_fd_set; work_write_fd_set = master_write_fd_set; work_except_fd_set = master_write_fd_set; if (max_read || max_write) { ready = select(0, &work_read_fd_set, &work_write_fd_set, &work_except_fd_set, tp); } else { /* * Winsock select() requires that at least one descriptor set must be * be non-null, and any non-null descriptor set must contain at least * one handle to a socket. Otherwise select() returns WSAEINVAL. */ ngx_msleep(timer); ready = 0; } err = (ready == -1) ? ngx_socket_errno : 0; if (flags & NGX_UPDATE_TIME) { ngx_time_update(); } ngx_log_debug1(NGX_LOG_DEBUG_EVENT, cycle->log, 0, "select ready %d", ready); if (err) { ngx_log_error(NGX_LOG_ALERT, cycle->log, err, "select() failed"); if (err == WSAENOTSOCK) { ngx_select_repair_fd_sets(cycle); } return NGX_ERROR; } if (ready == 0) { if (timer != NGX_TIMER_INFINITE) { return NGX_OK; } ngx_log_error(NGX_LOG_ALERT, cycle->log, 0, "select() returned no events without timeout"); return NGX_ERROR; } nready = 0; for (i = 0; i < nevents; i++) { ev = event_index[i]; c = ev->data; found = 0; if (ev->write) { if (FD_ISSET(c->fd, &work_write_fd_set)) { found++; ngx_log_debug1(NGX_LOG_DEBUG_EVENT, cycle->log, 0, "select write %d", c->fd); } if (FD_ISSET(c->fd, &work_except_fd_set)) { found++; ngx_log_debug1(NGX_LOG_DEBUG_EVENT, cycle->log, 0, "select except %d", c->fd); } } else { if (FD_ISSET(c->fd, &work_read_fd_set)) { found++; ngx_log_debug1(NGX_LOG_DEBUG_EVENT, cycle->log, 0, "select read %d", c->fd); } } if (found) { ev->ready = 1; ev->available = -1; queue = ev->accept ? &ngx_posted_accept_events : &ngx_posted_events; ngx_post_event(ev, queue); nready += found; } } if (ready != nready) { ngx_log_error(NGX_LOG_ALERT, cycle->log, 0, "select ready != events: %d:%d", ready, nready); ngx_select_repair_fd_sets(cycle); } return NGX_OK; } static void ngx_select_repair_fd_sets(ngx_cycle_t *cycle) { int n; u_int i; socklen_t len; ngx_err_t err; ngx_socket_t s; for (i = 0; i < master_read_fd_set.fd_count; i++) { s = master_read_fd_set.fd_array[i]; len = sizeof(int); if (getsockopt(s, SOL_SOCKET, SO_TYPE, (char *) &n, &len) == -1) { err = ngx_socket_errno; ngx_log_error(NGX_LOG_ALERT, cycle->log, err, "invalid descriptor #%d in read fd_set", s); FD_CLR(s, &master_read_fd_set); } } for (i = 0; i < master_write_fd_set.fd_count; i++) { s = master_write_fd_set.fd_array[i]; len = sizeof(int); if (getsockopt(s, SOL_SOCKET, SO_TYPE, (char *) &n, &len) == -1) { err = ngx_socket_errno; ngx_log_error(NGX_LOG_ALERT, cycle->log, err, "invalid descriptor #%d in write fd_set", s); FD_CLR(s, &master_write_fd_set); } } } static char * ngx_select_init_conf(ngx_cycle_t *cycle, void *conf) { ngx_event_conf_t *ecf; ecf = ngx_event_get_conf(cycle->conf_ctx, ngx_event_core_module); if (ecf->use != ngx_select_module.ctx_index) { return NGX_CONF_OK; } return NGX_CONF_OK; }