Mercurial > hg > nginx
view src/event/ngx_event_accept.c @ 9138:a90f79792b5d
QUIC: optimized ACK delay.
Previously ACK was not generated if max_ack_delay was not yet expired and the
number of unacknowledged ack-eliciting packets was less than two, as allowed by
RFC 9000 13.2.1-13.2.2. However this only makes sense to avoid sending ACK-only
packets, as explained by the RFC:
On the other hand, reducing the frequency of packets that carry only
acknowledgments reduces packet transmission and processing cost at both
endpoints.
Now ACK is delayed only if output frame queue is empty. Otherwise ACK is sent
immediately, which significantly improves QUIC performance with certain tests.
author | Roman Arutyunyan <arut@nginx.com> |
---|---|
date | Thu, 27 Jul 2023 16:37:17 +0400 |
parents | e2d07e4ec636 |
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> static ngx_int_t ngx_disable_accept_events(ngx_cycle_t *cycle, ngx_uint_t all); #if (NGX_HAVE_EPOLLEXCLUSIVE) static void ngx_reorder_accept_events(ngx_listening_t *ls); #endif static void ngx_close_accepted_connection(ngx_connection_t *c); void ngx_event_accept(ngx_event_t *ev) { socklen_t socklen; ngx_err_t err; ngx_log_t *log; ngx_uint_t level; ngx_socket_t s; ngx_event_t *rev, *wev; ngx_sockaddr_t sa; ngx_listening_t *ls; ngx_connection_t *c, *lc; ngx_event_conf_t *ecf; #if (NGX_HAVE_ACCEPT4) static ngx_uint_t use_accept4 = 1; #endif if (ev->timedout) { if (ngx_enable_accept_events((ngx_cycle_t *) ngx_cycle) != NGX_OK) { return; } ev->timedout = 0; } ecf = ngx_event_get_conf(ngx_cycle->conf_ctx, ngx_event_core_module); if (!(ngx_event_flags & NGX_USE_KQUEUE_EVENT)) { ev->available = ecf->multi_accept; } lc = ev->data; ls = lc->listening; ev->ready = 0; ngx_log_debug2(NGX_LOG_DEBUG_EVENT, ev->log, 0, "accept on %V, ready: %d", &ls->addr_text, ev->available); do { socklen = sizeof(ngx_sockaddr_t); #if (NGX_HAVE_ACCEPT4) if (use_accept4) { s = accept4(lc->fd, &sa.sockaddr, &socklen, SOCK_NONBLOCK); } else { s = accept(lc->fd, &sa.sockaddr, &socklen); } #else s = accept(lc->fd, &sa.sockaddr, &socklen); #endif if (s == (ngx_socket_t) -1) { err = ngx_socket_errno; if (err == NGX_EAGAIN) { ngx_log_debug0(NGX_LOG_DEBUG_EVENT, ev->log, err, "accept() not ready"); return; } level = NGX_LOG_ALERT; if (err == NGX_ECONNABORTED) { level = NGX_LOG_ERR; } else if (err == NGX_EMFILE || err == NGX_ENFILE) { level = NGX_LOG_CRIT; } #if (NGX_HAVE_ACCEPT4) ngx_log_error(level, ev->log, err, use_accept4 ? "accept4() failed" : "accept() failed"); if (use_accept4 && err == NGX_ENOSYS) { use_accept4 = 0; ngx_inherited_nonblocking = 0; continue; } #else ngx_log_error(level, ev->log, err, "accept() failed"); #endif if (err == NGX_ECONNABORTED) { if (ngx_event_flags & NGX_USE_KQUEUE_EVENT) { ev->available--; } if (ev->available) { continue; } } if (err == NGX_EMFILE || err == NGX_ENFILE) { if (ngx_disable_accept_events((ngx_cycle_t *) ngx_cycle, 1) != NGX_OK) { return; } if (ngx_use_accept_mutex) { if (ngx_accept_mutex_held) { ngx_shmtx_unlock(&ngx_accept_mutex); ngx_accept_mutex_held = 0; } ngx_accept_disabled = 1; } else { ngx_add_timer(ev, ecf->accept_mutex_delay); } } return; } #if (NGX_STAT_STUB) (void) ngx_atomic_fetch_add(ngx_stat_accepted, 1); #endif ngx_accept_disabled = ngx_cycle->connection_n / 8 - ngx_cycle->free_connection_n; c = ngx_get_connection(s, ev->log); if (c == NULL) { if (ngx_close_socket(s) == -1) { ngx_log_error(NGX_LOG_ALERT, ev->log, ngx_socket_errno, ngx_close_socket_n " failed"); } return; } c->type = SOCK_STREAM; #if (NGX_STAT_STUB) (void) ngx_atomic_fetch_add(ngx_stat_active, 1); #endif c->pool = ngx_create_pool(ls->pool_size, ev->log); if (c->pool == NULL) { ngx_close_accepted_connection(c); return; } if (socklen > (socklen_t) sizeof(ngx_sockaddr_t)) { socklen = sizeof(ngx_sockaddr_t); } c->sockaddr = ngx_palloc(c->pool, socklen); if (c->sockaddr == NULL) { ngx_close_accepted_connection(c); return; } ngx_memcpy(c->sockaddr, &sa, socklen); log = ngx_palloc(c->pool, sizeof(ngx_log_t)); if (log == NULL) { ngx_close_accepted_connection(c); return; } /* set a blocking mode for iocp and non-blocking mode for others */ if (ngx_inherited_nonblocking) { if (ngx_event_flags & NGX_USE_IOCP_EVENT) { if (ngx_blocking(s) == -1) { ngx_log_error(NGX_LOG_ALERT, ev->log, ngx_socket_errno, ngx_blocking_n " failed"); ngx_close_accepted_connection(c); return; } } } else { if (!(ngx_event_flags & NGX_USE_IOCP_EVENT)) { if (ngx_nonblocking(s) == -1) { ngx_log_error(NGX_LOG_ALERT, ev->log, ngx_socket_errno, ngx_nonblocking_n " failed"); ngx_close_accepted_connection(c); return; } } } *log = ls->log; c->recv = ngx_recv; c->send = ngx_send; c->recv_chain = ngx_recv_chain; c->send_chain = ngx_send_chain; c->log = log; c->pool->log = log; c->socklen = socklen; c->listening = ls; c->local_sockaddr = ls->sockaddr; c->local_socklen = ls->socklen; #if (NGX_HAVE_UNIX_DOMAIN) if (c->sockaddr->sa_family == AF_UNIX) { c->tcp_nopush = NGX_TCP_NOPUSH_DISABLED; c->tcp_nodelay = NGX_TCP_NODELAY_DISABLED; #if (NGX_SOLARIS) /* Solaris's sendfilev() supports AF_NCA, AF_INET, and AF_INET6 */ c->sendfile = 0; #endif } #endif rev = c->read; wev = c->write; wev->ready = 1; if (ngx_event_flags & NGX_USE_IOCP_EVENT) { rev->ready = 1; } if (ev->deferred_accept) { rev->ready = 1; #if (NGX_HAVE_KQUEUE || NGX_HAVE_EPOLLRDHUP) rev->available = 1; #endif } rev->log = log; wev->log = log; /* * TODO: MT: - ngx_atomic_fetch_add() * or protection by critical section or light mutex * * TODO: MP: - allocated in a shared memory * - ngx_atomic_fetch_add() * or protection by critical section or light mutex */ c->number = ngx_atomic_fetch_add(ngx_connection_counter, 1); c->start_time = ngx_current_msec; #if (NGX_STAT_STUB) (void) ngx_atomic_fetch_add(ngx_stat_handled, 1); #endif if (ls->addr_ntop) { c->addr_text.data = ngx_pnalloc(c->pool, ls->addr_text_max_len); if (c->addr_text.data == NULL) { ngx_close_accepted_connection(c); return; } c->addr_text.len = ngx_sock_ntop(c->sockaddr, c->socklen, c->addr_text.data, ls->addr_text_max_len, 0); if (c->addr_text.len == 0) { ngx_close_accepted_connection(c); return; } } #if (NGX_DEBUG) { ngx_str_t addr; u_char text[NGX_SOCKADDR_STRLEN]; ngx_debug_accepted_connection(ecf, c); if (log->log_level & NGX_LOG_DEBUG_EVENT) { addr.data = text; addr.len = ngx_sock_ntop(c->sockaddr, c->socklen, text, NGX_SOCKADDR_STRLEN, 1); ngx_log_debug3(NGX_LOG_DEBUG_EVENT, log, 0, "*%uA accept: %V fd:%d", c->number, &addr, s); } } #endif if (ngx_add_conn && (ngx_event_flags & NGX_USE_EPOLL_EVENT) == 0) { if (ngx_add_conn(c) == NGX_ERROR) { ngx_close_accepted_connection(c); return; } } log->data = NULL; log->handler = NULL; ls->handler(c); if (ngx_event_flags & NGX_USE_KQUEUE_EVENT) { ev->available--; } } while (ev->available); #if (NGX_HAVE_EPOLLEXCLUSIVE) ngx_reorder_accept_events(ls); #endif } ngx_int_t ngx_trylock_accept_mutex(ngx_cycle_t *cycle) { if (ngx_shmtx_trylock(&ngx_accept_mutex)) { ngx_log_debug0(NGX_LOG_DEBUG_EVENT, cycle->log, 0, "accept mutex locked"); if (ngx_accept_mutex_held && ngx_accept_events == 0) { return NGX_OK; } if (ngx_enable_accept_events(cycle) == NGX_ERROR) { ngx_shmtx_unlock(&ngx_accept_mutex); return NGX_ERROR; } ngx_accept_events = 0; ngx_accept_mutex_held = 1; return NGX_OK; } ngx_log_debug1(NGX_LOG_DEBUG_EVENT, cycle->log, 0, "accept mutex lock failed: %ui", ngx_accept_mutex_held); if (ngx_accept_mutex_held) { if (ngx_disable_accept_events(cycle, 0) == NGX_ERROR) { return NGX_ERROR; } ngx_accept_mutex_held = 0; } return NGX_OK; } ngx_int_t ngx_enable_accept_events(ngx_cycle_t *cycle) { ngx_uint_t i; ngx_listening_t *ls; ngx_connection_t *c; ls = cycle->listening.elts; for (i = 0; i < cycle->listening.nelts; i++) { c = ls[i].connection; if (c == NULL || c->read->active) { continue; } if (ngx_add_event(c->read, NGX_READ_EVENT, 0) == NGX_ERROR) { return NGX_ERROR; } } return NGX_OK; } static ngx_int_t ngx_disable_accept_events(ngx_cycle_t *cycle, ngx_uint_t all) { ngx_uint_t i; ngx_listening_t *ls; ngx_connection_t *c; ls = cycle->listening.elts; for (i = 0; i < cycle->listening.nelts; i++) { c = ls[i].connection; if (c == NULL || !c->read->active) { continue; } #if (NGX_HAVE_REUSEPORT) /* * do not disable accept on worker's own sockets * when disabling accept events due to accept mutex */ if (ls[i].reuseport && !all) { continue; } #endif if (ngx_del_event(c->read, NGX_READ_EVENT, NGX_DISABLE_EVENT) == NGX_ERROR) { return NGX_ERROR; } } return NGX_OK; } #if (NGX_HAVE_EPOLLEXCLUSIVE) static void ngx_reorder_accept_events(ngx_listening_t *ls) { ngx_connection_t *c; /* * Linux with EPOLLEXCLUSIVE usually notifies only the process which * was first to add the listening socket to the epoll instance. As * a result most of the connections are handled by the first worker * process. To fix this, we re-add the socket periodically, so other * workers will get a chance to accept connections. */ if (!ngx_use_exclusive_accept) { return; } #if (NGX_HAVE_REUSEPORT) if (ls->reuseport) { return; } #endif c = ls->connection; if (c->requests++ % 16 != 0 && ngx_accept_disabled <= 0) { return; } if (ngx_del_event(c->read, NGX_READ_EVENT, NGX_DISABLE_EVENT) == NGX_ERROR) { return; } if (ngx_add_event(c->read, NGX_READ_EVENT, NGX_EXCLUSIVE_EVENT) == NGX_ERROR) { return; } } #endif static void ngx_close_accepted_connection(ngx_connection_t *c) { ngx_socket_t fd; ngx_free_connection(c); fd = c->fd; c->fd = (ngx_socket_t) -1; if (ngx_close_socket(fd) == -1) { ngx_log_error(NGX_LOG_ALERT, c->log, ngx_socket_errno, ngx_close_socket_n " failed"); } if (c->pool) { ngx_destroy_pool(c->pool); } #if (NGX_STAT_STUB) (void) ngx_atomic_fetch_add(ngx_stat_active, -1); #endif } u_char * ngx_accept_log_error(ngx_log_t *log, u_char *buf, size_t len) { return ngx_snprintf(buf, len, " while accepting new connection on %V", log->data); } #if (NGX_DEBUG) void ngx_debug_accepted_connection(ngx_event_conf_t *ecf, ngx_connection_t *c) { struct sockaddr_in *sin; ngx_cidr_t *cidr; ngx_uint_t i; #if (NGX_HAVE_INET6) struct sockaddr_in6 *sin6; ngx_uint_t n; #endif cidr = ecf->debug_connection.elts; for (i = 0; i < ecf->debug_connection.nelts; i++) { if (cidr[i].family != (ngx_uint_t) c->sockaddr->sa_family) { goto next; } switch (cidr[i].family) { #if (NGX_HAVE_INET6) case AF_INET6: sin6 = (struct sockaddr_in6 *) c->sockaddr; for (n = 0; n < 16; n++) { if ((sin6->sin6_addr.s6_addr[n] & cidr[i].u.in6.mask.s6_addr[n]) != cidr[i].u.in6.addr.s6_addr[n]) { goto next; } } break; #endif #if (NGX_HAVE_UNIX_DOMAIN) case AF_UNIX: break; #endif default: /* AF_INET */ sin = (struct sockaddr_in *) c->sockaddr; if ((sin->sin_addr.s_addr & cidr[i].u.in.mask) != cidr[i].u.in.addr) { goto next; } break; } c->log->log_level = NGX_LOG_DEBUG_CONNECTION|NGX_LOG_DEBUG_ALL; break; next: continue; } } #endif