diff options
Diffstat (limited to 'tevent/tevent_epoll.c')
| -rw-r--r-- | tevent/tevent_epoll.c | 482 |
1 files changed, 482 insertions, 0 deletions
diff --git a/tevent/tevent_epoll.c b/tevent/tevent_epoll.c new file mode 100644 index 000000000..1d03b7dbf --- /dev/null +++ b/tevent/tevent_epoll.c @@ -0,0 +1,482 @@ +/* + Unix SMB/CIFS implementation. + + main select loop and event handling - epoll implementation + + Copyright (C) Andrew Tridgell 2003-2005 + Copyright (C) Stefan Metzmacher 2005 + + This program is free software; you can redistribute it and/or modify + it under the terms of the GNU General Public License as published by + the Free Software Foundation; either version 3 of the License, or + (at your option) any later version. + + This program is distributed in the hope that it will be useful, + but WITHOUT ANY WARRANTY; without even the implied warranty of + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + GNU General Public License for more details. + + You should have received a copy of the GNU General Public License + along with this program. If not, see <http://www.gnu.org/licenses/>. +*/ + +#include "replace.h" +#include "system/filesys.h" +#include "system/network.h" +#include "tevent.h" +#include "tevent_internal.h" +#include "tevent_util.h" +#include <sys/epoll.h> + +struct epoll_event_context { + /* a pointer back to the generic event_context */ + struct event_context *ev; + + /* list of filedescriptor events */ + struct fd_event *fd_events; + + /* number of registered fd event handlers */ + int num_fd_events; + + /* this is changed by the destructors for the fd event + type. It is used to detect event destruction by event + handlers, which means the code that is calling the event + handler needs to assume that the linked list is no longer + valid + */ + uint32_t destruction_count; + + /* when using epoll this is the handle from epoll_create */ + int epoll_fd; + + pid_t pid; +}; + +/* + called when a epoll call fails, and we should fallback + to using select +*/ +static void epoll_panic(struct epoll_event_context *epoll_ev, const char *reason) +{ + ev_debug(epoll_ev->ev, EV_DEBUG_FATAL, + "%s (%s) - calling abort()\n", reason, strerror(errno)); + abort(); +} + +/* + map from EVENT_FD_* to EPOLLIN/EPOLLOUT +*/ +static uint32_t epoll_map_flags(uint16_t flags) +{ + uint32_t ret = 0; + if (flags & EVENT_FD_READ) ret |= (EPOLLIN | EPOLLERR | EPOLLHUP); + if (flags & EVENT_FD_WRITE) ret |= (EPOLLOUT | EPOLLERR | EPOLLHUP); + return ret; +} + +/* + free the epoll fd +*/ +static int epoll_ctx_destructor(struct epoll_event_context *epoll_ev) +{ + close(epoll_ev->epoll_fd); + epoll_ev->epoll_fd = -1; + return 0; +} + +/* + init the epoll fd +*/ +static int epoll_init_ctx(struct epoll_event_context *epoll_ev) +{ + epoll_ev->epoll_fd = epoll_create(64); + epoll_ev->pid = getpid(); + talloc_set_destructor(epoll_ev, epoll_ctx_destructor); + if (epoll_ev->epoll_fd == -1) { + return -1; + } + return 0; +} + +static void epoll_add_event(struct epoll_event_context *epoll_ev, struct fd_event *fde); + +/* + reopen the epoll handle when our pid changes + see http://junkcode.samba.org/ftp/unpacked/junkcode/epoll_fork.c for an + demonstration of why this is needed + */ +static void epoll_check_reopen(struct epoll_event_context *epoll_ev) +{ + struct fd_event *fde; + + if (epoll_ev->pid == getpid()) { + return; + } + + close(epoll_ev->epoll_fd); + epoll_ev->epoll_fd = epoll_create(64); + if (epoll_ev->epoll_fd == -1) { + ev_debug(epoll_ev->ev, EV_DEBUG_FATAL, + "Failed to recreate epoll handle after fork\n"); + return; + } + epoll_ev->pid = getpid(); + for (fde=epoll_ev->fd_events;fde;fde=fde->next) { + epoll_add_event(epoll_ev, fde); + } +} + +#define EPOLL_ADDITIONAL_FD_FLAG_HAS_EVENT (1<<0) +#define EPOLL_ADDITIONAL_FD_FLAG_REPORT_ERROR (1<<1) +#define EPOLL_ADDITIONAL_FD_FLAG_GOT_ERROR (1<<2) + +/* + add the epoll event to the given fd_event +*/ +static void epoll_add_event(struct epoll_event_context *epoll_ev, struct fd_event *fde) +{ + struct epoll_event event; + + if (epoll_ev->epoll_fd == -1) return; + + fde->additional_flags &= ~EPOLL_ADDITIONAL_FD_FLAG_REPORT_ERROR; + + /* if we don't want events yet, don't add an epoll_event */ + if (fde->flags == 0) return; + + ZERO_STRUCT(event); + event.events = epoll_map_flags(fde->flags); + event.data.ptr = fde; + if (epoll_ctl(epoll_ev->epoll_fd, EPOLL_CTL_ADD, fde->fd, &event) != 0) { + epoll_panic(epoll_ev, "EPOLL_CTL_ADD failed"); + } + fde->additional_flags |= EPOLL_ADDITIONAL_FD_FLAG_HAS_EVENT; + + /* only if we want to read we want to tell the event handler about errors */ + if (fde->flags & EVENT_FD_READ) { + fde->additional_flags |= EPOLL_ADDITIONAL_FD_FLAG_REPORT_ERROR; + } +} + +/* + delete the epoll event for given fd_event +*/ +static void epoll_del_event(struct epoll_event_context *epoll_ev, struct fd_event *fde) +{ + struct epoll_event event; + + if (epoll_ev->epoll_fd == -1) return; + + fde->additional_flags &= ~EPOLL_ADDITIONAL_FD_FLAG_REPORT_ERROR; + + /* if there's no epoll_event, we don't need to delete it */ + if (!(fde->additional_flags & EPOLL_ADDITIONAL_FD_FLAG_HAS_EVENT)) return; + + ZERO_STRUCT(event); + event.events = epoll_map_flags(fde->flags); + event.data.ptr = fde; + if (epoll_ctl(epoll_ev->epoll_fd, EPOLL_CTL_DEL, fde->fd, &event) != 0) { + ev_debug(epoll_ev->ev, EV_DEBUG_FATAL, + "epoll_del_event failed! probable early close bug (%s)\n", + strerror(errno)); + } + fde->additional_flags &= ~EPOLL_ADDITIONAL_FD_FLAG_HAS_EVENT; +} + +/* + change the epoll event to the given fd_event +*/ +static void epoll_mod_event(struct epoll_event_context *epoll_ev, struct fd_event *fde) +{ + struct epoll_event event; + if (epoll_ev->epoll_fd == -1) return; + + fde->additional_flags &= ~EPOLL_ADDITIONAL_FD_FLAG_REPORT_ERROR; + + ZERO_STRUCT(event); + event.events = epoll_map_flags(fde->flags); + event.data.ptr = fde; + if (epoll_ctl(epoll_ev->epoll_fd, EPOLL_CTL_MOD, fde->fd, &event) != 0) { + epoll_panic(epoll_ev, "EPOLL_CTL_MOD failed"); + } + + /* only if we want to read we want to tell the event handler about errors */ + if (fde->flags & EVENT_FD_READ) { + fde->additional_flags |= EPOLL_ADDITIONAL_FD_FLAG_REPORT_ERROR; + } +} + +static void epoll_change_event(struct epoll_event_context *epoll_ev, struct fd_event *fde) +{ + bool got_error = (fde->additional_flags & EPOLL_ADDITIONAL_FD_FLAG_GOT_ERROR); + bool want_read = (fde->flags & EVENT_FD_READ); + bool want_write= (fde->flags & EVENT_FD_WRITE); + + if (epoll_ev->epoll_fd == -1) return; + + fde->additional_flags &= ~EPOLL_ADDITIONAL_FD_FLAG_REPORT_ERROR; + + /* there's already an event */ + if (fde->additional_flags & EPOLL_ADDITIONAL_FD_FLAG_HAS_EVENT) { + if (want_read || (want_write && !got_error)) { + epoll_mod_event(epoll_ev, fde); + return; + } + /* + * if we want to match the select behavior, we need to remove the epoll_event + * when the caller isn't interested in events. + * + * this is because epoll reports EPOLLERR and EPOLLHUP, even without asking for them + */ + epoll_del_event(epoll_ev, fde); + return; + } + + /* there's no epoll_event attached to the fde */ + if (want_read || (want_write && !got_error)) { + epoll_add_event(epoll_ev, fde); + return; + } +} + +/* + event loop handling using epoll +*/ +static int epoll_event_loop(struct epoll_event_context *epoll_ev, struct timeval *tvalp) +{ + int ret, i; +#define MAXEVENTS 32 + struct epoll_event events[MAXEVENTS]; + uint32_t destruction_count = ++epoll_ev->destruction_count; + int timeout = -1; + + if (epoll_ev->epoll_fd == -1) return -1; + + if (tvalp) { + /* it's better to trigger timed events a bit later than to early */ + timeout = ((tvalp->tv_usec+999) / 1000) + (tvalp->tv_sec*1000); + } + + if (epoll_ev->ev->num_signal_handlers && + common_event_check_signal(epoll_ev->ev)) { + return 0; + } + + ret = epoll_wait(epoll_ev->epoll_fd, events, MAXEVENTS, timeout); + + if (ret == -1 && errno == EINTR && epoll_ev->ev->num_signal_handlers) { + if (common_event_check_signal(epoll_ev->ev)) { + return 0; + } + } + + if (ret == -1 && errno != EINTR) { + epoll_panic(epoll_ev, "epoll_wait() failed"); + return -1; + } + + if (ret == 0 && tvalp) { + /* we don't care about a possible delay here */ + common_event_loop_timer_delay(epoll_ev->ev); + return 0; + } + + for (i=0;i<ret;i++) { + struct fd_event *fde = talloc_get_type(events[i].data.ptr, + struct fd_event); + uint16_t flags = 0; + + if (fde == NULL) { + epoll_panic(epoll_ev, "epoll_wait() gave bad data"); + return -1; + } + if (events[i].events & (EPOLLHUP|EPOLLERR)) { + fde->additional_flags |= EPOLL_ADDITIONAL_FD_FLAG_GOT_ERROR; + /* + * if we only wait for EVENT_FD_WRITE, we should not tell the + * event handler about it, and remove the epoll_event, + * as we only report errors when waiting for read events, + * to match the select() behavior + */ + if (!(fde->additional_flags & EPOLL_ADDITIONAL_FD_FLAG_REPORT_ERROR)) { + epoll_del_event(epoll_ev, fde); + continue; + } + flags |= EVENT_FD_READ; + } + if (events[i].events & EPOLLIN) flags |= EVENT_FD_READ; + if (events[i].events & EPOLLOUT) flags |= EVENT_FD_WRITE; + if (flags) { + fde->handler(epoll_ev->ev, fde, flags, fde->private_data); + if (destruction_count != epoll_ev->destruction_count) { + break; + } + } + } + + return 0; +} + +/* + create a epoll_event_context structure. +*/ +static int epoll_event_context_init(struct event_context *ev) +{ + int ret; + struct epoll_event_context *epoll_ev; + + epoll_ev = talloc_zero(ev, struct epoll_event_context); + if (!epoll_ev) return -1; + epoll_ev->ev = ev; + epoll_ev->epoll_fd = -1; + + ret = epoll_init_ctx(epoll_ev); + if (ret != 0) { + talloc_free(epoll_ev); + return ret; + } + + ev->additional_data = epoll_ev; + return 0; +} + +/* + destroy an fd_event +*/ +static int epoll_event_fd_destructor(struct fd_event *fde) +{ + struct event_context *ev = fde->event_ctx; + struct epoll_event_context *epoll_ev = talloc_get_type(ev->additional_data, + struct epoll_event_context); + + epoll_check_reopen(epoll_ev); + + epoll_ev->num_fd_events--; + epoll_ev->destruction_count++; + + DLIST_REMOVE(epoll_ev->fd_events, fde); + + epoll_del_event(epoll_ev, fde); + + if (fde->flags & EVENT_FD_AUTOCLOSE) { + close(fde->fd); + fde->fd = -1; + } + + return 0; +} + +/* + add a fd based event + return NULL on failure (memory allocation error) +*/ +static struct fd_event *epoll_event_add_fd(struct event_context *ev, TALLOC_CTX *mem_ctx, + int fd, uint16_t flags, + event_fd_handler_t handler, + void *private_data) +{ + struct epoll_event_context *epoll_ev = talloc_get_type(ev->additional_data, + struct epoll_event_context); + struct fd_event *fde; + + epoll_check_reopen(epoll_ev); + + fde = talloc(mem_ctx?mem_ctx:ev, struct fd_event); + if (!fde) return NULL; + + fde->event_ctx = ev; + fde->fd = fd; + fde->flags = flags; + fde->handler = handler; + fde->private_data = private_data; + fde->additional_flags = 0; + fde->additional_data = NULL; + + epoll_ev->num_fd_events++; + talloc_set_destructor(fde, epoll_event_fd_destructor); + + DLIST_ADD(epoll_ev->fd_events, fde); + epoll_add_event(epoll_ev, fde); + + return fde; +} + + +/* + return the fd event flags +*/ +static uint16_t epoll_event_get_fd_flags(struct fd_event *fde) +{ + return fde->flags; +} + +/* + set the fd event flags +*/ +static void epoll_event_set_fd_flags(struct fd_event *fde, uint16_t flags) +{ + struct event_context *ev; + struct epoll_event_context *epoll_ev; + + if (fde->flags == flags) return; + + ev = fde->event_ctx; + epoll_ev = talloc_get_type(ev->additional_data, struct epoll_event_context); + + fde->flags = flags; + + epoll_check_reopen(epoll_ev); + + epoll_change_event(epoll_ev, fde); +} + +/* + do a single event loop using the events defined in ev +*/ +static int epoll_event_loop_once(struct event_context *ev) +{ + struct epoll_event_context *epoll_ev = talloc_get_type(ev->additional_data, + struct epoll_event_context); + struct timeval tval; + + tval = common_event_loop_timer_delay(ev); + if (ev_timeval_is_zero(&tval)) { + return 0; + } + + epoll_check_reopen(epoll_ev); + + return epoll_event_loop(epoll_ev, &tval); +} + +/* + return on failure or (with 0) if all fd events are removed +*/ +static int epoll_event_loop_wait(struct event_context *ev) +{ + struct epoll_event_context *epoll_ev = talloc_get_type(ev->additional_data, + struct epoll_event_context); + while (epoll_ev->num_fd_events) { + if (epoll_event_loop_once(ev) != 0) { + break; + } + } + + return 0; +} + +static const struct event_ops epoll_event_ops = { + .context_init = epoll_event_context_init, + .add_fd = epoll_event_add_fd, + .get_fd_flags = epoll_event_get_fd_flags, + .set_fd_flags = epoll_event_set_fd_flags, + .add_timed = common_event_add_timed, + .add_signal = common_event_add_signal, + .loop_once = epoll_event_loop_once, + .loop_wait = epoll_event_loop_wait, +}; + +bool events_epoll_init(void) +{ + return event_register_backend("epoll", &epoll_event_ops); +} |