Mercurial > hg > nginx
view src/event/modules/ngx_devpoll_module.c @ 7583:efd71d49bde0
Events: available bytes calculation via ioctl(FIONREAD).
This makes it possible to avoid looping for a long time while working
with a fast enough peer when data are added to the socket buffer faster
than we are able to read and process them (ticket #1431). This is
basically what we already do on FreeBSD with kqueue, where information
about the number of bytes in the socket buffer is returned by
the kevent() call.
With other event methods rev->available is now set to -1 when the socket
is ready for reading. Later in ngx_recv() and ngx_recv_chain(), if
full buffer is received, real number of bytes in the socket buffer is
retrieved using ioctl(FIONREAD). Reading more than this number of bytes
ensures that even with edge-triggered event methods the event will be
triggered again, so it is safe to stop processing of the socket and
switch to other connections.
Using ioctl(FIONREAD) only after reading a full buffer is an optimization.
With this approach we only call ioctl(FIONREAD) when there are at least
two recv()/readv() calls.
author | Maxim Dounin <mdounin@mdounin.ru> |
---|---|
date | Thu, 17 Oct 2019 16:02:19 +0300 |
parents | fbdaad9b0e7b |
children |
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/* * Copyright (C) Igor Sysoev * Copyright (C) Nginx, Inc. */ #include <ngx_config.h> #include <ngx_core.h> #include <ngx_event.h> #if (NGX_TEST_BUILD_DEVPOLL) /* Solaris declarations */ #ifndef POLLREMOVE #define POLLREMOVE 0x0800 #endif #define DP_POLL 0xD001 #define DP_ISPOLLED 0xD002 struct dvpoll { struct pollfd *dp_fds; int dp_nfds; int dp_timeout; }; #endif typedef struct { ngx_uint_t changes; ngx_uint_t events; } ngx_devpoll_conf_t; static ngx_int_t ngx_devpoll_init(ngx_cycle_t *cycle, ngx_msec_t timer); static void ngx_devpoll_done(ngx_cycle_t *cycle); static ngx_int_t ngx_devpoll_add_event(ngx_event_t *ev, ngx_int_t event, ngx_uint_t flags); static ngx_int_t ngx_devpoll_del_event(ngx_event_t *ev, ngx_int_t event, ngx_uint_t flags); static ngx_int_t ngx_devpoll_set_event(ngx_event_t *ev, ngx_int_t event, ngx_uint_t flags); static ngx_int_t ngx_devpoll_process_events(ngx_cycle_t *cycle, ngx_msec_t timer, ngx_uint_t flags); static void *ngx_devpoll_create_conf(ngx_cycle_t *cycle); static char *ngx_devpoll_init_conf(ngx_cycle_t *cycle, void *conf); static int dp = -1; static struct pollfd *change_list, *event_list; static ngx_uint_t nchanges, max_changes, nevents; static ngx_event_t **change_index; static ngx_str_t devpoll_name = ngx_string("/dev/poll"); static ngx_command_t ngx_devpoll_commands[] = { { ngx_string("devpoll_changes"), NGX_EVENT_CONF|NGX_CONF_TAKE1, ngx_conf_set_num_slot, 0, offsetof(ngx_devpoll_conf_t, changes), NULL }, { ngx_string("devpoll_events"), NGX_EVENT_CONF|NGX_CONF_TAKE1, ngx_conf_set_num_slot, 0, offsetof(ngx_devpoll_conf_t, events), NULL }, ngx_null_command }; static ngx_event_module_t ngx_devpoll_module_ctx = { &devpoll_name, ngx_devpoll_create_conf, /* create configuration */ ngx_devpoll_init_conf, /* init configuration */ { ngx_devpoll_add_event, /* add an event */ ngx_devpoll_del_event, /* delete an event */ ngx_devpoll_add_event, /* enable an event */ ngx_devpoll_del_event, /* disable an event */ NULL, /* add an connection */ NULL, /* delete an connection */ NULL, /* trigger a notify */ ngx_devpoll_process_events, /* process the events */ ngx_devpoll_init, /* init the events */ ngx_devpoll_done, /* done the events */ } }; ngx_module_t ngx_devpoll_module = { NGX_MODULE_V1, &ngx_devpoll_module_ctx, /* module context */ ngx_devpoll_commands, /* 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_devpoll_init(ngx_cycle_t *cycle, ngx_msec_t timer) { size_t n; ngx_devpoll_conf_t *dpcf; dpcf = ngx_event_get_conf(cycle->conf_ctx, ngx_devpoll_module); if (dp == -1) { dp = open("/dev/poll", O_RDWR); if (dp == -1) { ngx_log_error(NGX_LOG_EMERG, cycle->log, ngx_errno, "open(/dev/poll) failed"); return NGX_ERROR; } } if (max_changes < dpcf->changes) { if (nchanges) { n = nchanges * sizeof(struct pollfd); if (write(dp, change_list, n) != (ssize_t) n) { ngx_log_error(NGX_LOG_ALERT, cycle->log, ngx_errno, "write(/dev/poll) failed"); return NGX_ERROR; } nchanges = 0; } if (change_list) { ngx_free(change_list); } change_list = ngx_alloc(sizeof(struct pollfd) * dpcf->changes, cycle->log); if (change_list == NULL) { return NGX_ERROR; } if (change_index) { ngx_free(change_index); } change_index = ngx_alloc(sizeof(ngx_event_t *) * dpcf->changes, cycle->log); if (change_index == NULL) { return NGX_ERROR; } } max_changes = dpcf->changes; if (nevents < dpcf->events) { if (event_list) { ngx_free(event_list); } event_list = ngx_alloc(sizeof(struct pollfd) * dpcf->events, cycle->log); if (event_list == NULL) { return NGX_ERROR; } } nevents = dpcf->events; ngx_io = ngx_os_io; ngx_event_actions = ngx_devpoll_module_ctx.actions; ngx_event_flags = NGX_USE_LEVEL_EVENT|NGX_USE_FD_EVENT; return NGX_OK; } static void ngx_devpoll_done(ngx_cycle_t *cycle) { if (close(dp) == -1) { ngx_log_error(NGX_LOG_ALERT, cycle->log, ngx_errno, "close(/dev/poll) failed"); } dp = -1; ngx_free(change_list); ngx_free(event_list); ngx_free(change_index); change_list = NULL; event_list = NULL; change_index = NULL; max_changes = 0; nchanges = 0; nevents = 0; } static ngx_int_t ngx_devpoll_add_event(ngx_event_t *ev, ngx_int_t event, ngx_uint_t flags) { #if (NGX_DEBUG) ngx_connection_t *c; #endif #if (NGX_READ_EVENT != POLLIN) event = (event == NGX_READ_EVENT) ? POLLIN : POLLOUT; #endif #if (NGX_DEBUG) c = ev->data; ngx_log_debug2(NGX_LOG_DEBUG_EVENT, ev->log, 0, "devpoll add event: fd:%d ev:%04Xi", c->fd, event); #endif ev->active = 1; return ngx_devpoll_set_event(ev, event, 0); } static ngx_int_t ngx_devpoll_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; #if (NGX_READ_EVENT != POLLIN) event = (event == NGX_READ_EVENT) ? POLLIN : POLLOUT; #endif ngx_log_debug2(NGX_LOG_DEBUG_EVENT, ev->log, 0, "devpoll del event: fd:%d ev:%04Xi", c->fd, event); if (ngx_devpoll_set_event(ev, POLLREMOVE, flags) == NGX_ERROR) { return NGX_ERROR; } ev->active = 0; if (flags & NGX_CLOSE_EVENT) { e = (event == POLLIN) ? c->write : c->read; if (e) { e->active = 0; } return NGX_OK; } /* restore the pair event if it exists */ if (event == POLLIN) { e = c->write; event = POLLOUT; } else { e = c->read; event = POLLIN; } if (e && e->active) { return ngx_devpoll_set_event(e, event, 0); } return NGX_OK; } static ngx_int_t ngx_devpoll_set_event(ngx_event_t *ev, ngx_int_t event, ngx_uint_t flags) { size_t n; ngx_connection_t *c; c = ev->data; ngx_log_debug3(NGX_LOG_DEBUG_EVENT, ev->log, 0, "devpoll fd:%d ev:%04Xi fl:%04Xi", c->fd, event, flags); if (nchanges >= max_changes) { ngx_log_error(NGX_LOG_WARN, ev->log, 0, "/dev/pool change list is filled up"); n = nchanges * sizeof(struct pollfd); if (write(dp, change_list, n) != (ssize_t) n) { ngx_log_error(NGX_LOG_ALERT, ev->log, ngx_errno, "write(/dev/poll) failed"); return NGX_ERROR; } nchanges = 0; } change_list[nchanges].fd = c->fd; change_list[nchanges].events = (short) event; change_list[nchanges].revents = 0; change_index[nchanges] = ev; ev->index = nchanges; nchanges++; if (flags & NGX_CLOSE_EVENT) { n = nchanges * sizeof(struct pollfd); if (write(dp, change_list, n) != (ssize_t) n) { ngx_log_error(NGX_LOG_ALERT, ev->log, ngx_errno, "write(/dev/poll) failed"); return NGX_ERROR; } nchanges = 0; } return NGX_OK; } static ngx_int_t ngx_devpoll_process_events(ngx_cycle_t *cycle, ngx_msec_t timer, ngx_uint_t flags) { int events, revents, rc; size_t n; ngx_fd_t fd; ngx_err_t err; ngx_int_t i; ngx_uint_t level, instance; ngx_event_t *rev, *wev; ngx_queue_t *queue; ngx_connection_t *c; struct pollfd pfd; struct dvpoll dvp; /* NGX_TIMER_INFINITE == INFTIM */ ngx_log_debug1(NGX_LOG_DEBUG_EVENT, cycle->log, 0, "devpoll timer: %M", timer); if (nchanges) { n = nchanges * sizeof(struct pollfd); if (write(dp, change_list, n) != (ssize_t) n) { ngx_log_error(NGX_LOG_ALERT, cycle->log, ngx_errno, "write(/dev/poll) failed"); return NGX_ERROR; } nchanges = 0; } dvp.dp_fds = event_list; dvp.dp_nfds = (int) nevents; dvp.dp_timeout = timer; events = ioctl(dp, DP_POLL, &dvp); err = (events == -1) ? ngx_errno : 0; if (flags & NGX_UPDATE_TIME || ngx_event_timer_alarm) { ngx_time_update(); } if (err) { if (err == NGX_EINTR) { if (ngx_event_timer_alarm) { ngx_event_timer_alarm = 0; return NGX_OK; } level = NGX_LOG_INFO; } else { level = NGX_LOG_ALERT; } ngx_log_error(level, cycle->log, err, "ioctl(DP_POLL) failed"); return NGX_ERROR; } if (events == 0) { if (timer != NGX_TIMER_INFINITE) { return NGX_OK; } ngx_log_error(NGX_LOG_ALERT, cycle->log, 0, "ioctl(DP_POLL) returned no events without timeout"); return NGX_ERROR; } for (i = 0; i < events; i++) { fd = event_list[i].fd; revents = event_list[i].revents; c = ngx_cycle->files[fd]; if (c == NULL || c->fd == -1) { pfd.fd = fd; pfd.events = 0; pfd.revents = 0; rc = ioctl(dp, DP_ISPOLLED, &pfd); switch (rc) { case -1: ngx_log_error(NGX_LOG_ALERT, cycle->log, ngx_errno, "ioctl(DP_ISPOLLED) failed for socket %d, event %04Xd", fd, revents); break; case 0: ngx_log_error(NGX_LOG_ALERT, cycle->log, 0, "phantom event %04Xd for closed and removed socket %d", revents, fd); break; default: ngx_log_error(NGX_LOG_ALERT, cycle->log, 0, "unexpected event %04Xd for closed and removed socket %d, " "ioctl(DP_ISPOLLED) returned rc:%d, fd:%d, event %04Xd", revents, fd, rc, pfd.fd, pfd.revents); pfd.fd = fd; pfd.events = POLLREMOVE; pfd.revents = 0; if (write(dp, &pfd, sizeof(struct pollfd)) != (ssize_t) sizeof(struct pollfd)) { ngx_log_error(NGX_LOG_ALERT, cycle->log, ngx_errno, "write(/dev/poll) for %d failed", fd); } if (close(fd) == -1) { ngx_log_error(NGX_LOG_ALERT, cycle->log, ngx_errno, "close(%d) failed", fd); } break; } continue; } ngx_log_debug3(NGX_LOG_DEBUG_EVENT, cycle->log, 0, "devpoll: fd:%d, ev:%04Xd, rev:%04Xd", fd, event_list[i].events, revents); if (revents & (POLLERR|POLLHUP|POLLNVAL)) { ngx_log_debug3(NGX_LOG_DEBUG_EVENT, cycle->log, 0, "ioctl(DP_POLL) error fd:%d ev:%04Xd rev:%04Xd", fd, event_list[i].events, revents); } if (revents & ~(POLLIN|POLLOUT|POLLERR|POLLHUP|POLLNVAL)) { ngx_log_error(NGX_LOG_ALERT, cycle->log, 0, "strange ioctl(DP_POLL) events " "fd:%d ev:%04Xd rev:%04Xd", fd, event_list[i].events, revents); } if (revents & (POLLERR|POLLHUP|POLLNVAL)) { /* * if the error events were returned, add POLLIN and POLLOUT * to handle the events at least in one active handler */ revents |= POLLIN|POLLOUT; } rev = c->read; if ((revents & POLLIN) && rev->active) { rev->ready = 1; rev->available = -1; if (flags & NGX_POST_EVENTS) { queue = rev->accept ? &ngx_posted_accept_events : &ngx_posted_events; ngx_post_event(rev, queue); } else { instance = rev->instance; rev->handler(rev); if (c->fd == -1 || rev->instance != instance) { continue; } } } wev = c->write; if ((revents & POLLOUT) && wev->active) { wev->ready = 1; if (flags & NGX_POST_EVENTS) { ngx_post_event(wev, &ngx_posted_events); } else { wev->handler(wev); } } } return NGX_OK; } static void * ngx_devpoll_create_conf(ngx_cycle_t *cycle) { ngx_devpoll_conf_t *dpcf; dpcf = ngx_palloc(cycle->pool, sizeof(ngx_devpoll_conf_t)); if (dpcf == NULL) { return NULL; } dpcf->changes = NGX_CONF_UNSET; dpcf->events = NGX_CONF_UNSET; return dpcf; } static char * ngx_devpoll_init_conf(ngx_cycle_t *cycle, void *conf) { ngx_devpoll_conf_t *dpcf = conf; ngx_conf_init_uint_value(dpcf->changes, 32); ngx_conf_init_uint_value(dpcf->events, 32); return NGX_CONF_OK; }