diff options
Diffstat (limited to 'tevent/tevent_aio.c')
| -rw-r--r-- | tevent/tevent_aio.c | 567 |
1 files changed, 567 insertions, 0 deletions
diff --git a/tevent/tevent_aio.c b/tevent/tevent_aio.c new file mode 100644 index 000000000..7c3473b9a --- /dev/null +++ b/tevent/tevent_aio.c @@ -0,0 +1,567 @@ +/* + Unix SMB/CIFS implementation. + + main select loop and event handling - aio/epoll hybrid implementation + + Copyright (C) Andrew Tridgell 2006 + + based on events_standard.c + + 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/>. +*/ +/* + this is a very strange beast. The Linux AIO implementation doesn't + yet integrate properly with epoll, but there is a kernel patch that + allows the aio wait primitives to be used to wait for epoll events, + and this can be used to give us a unified event system incorporating + both aio events and epoll events + + this is _very_ experimental code +*/ + +#include "system/filesys.h" +#include "replace.h" +#include "tevent.h" +#include "tevent_internal.h" +#include "tevent_util.h" +#include <sys/epoll.h> +#include <libaio.h> + +#define MAX_AIO_QUEUE_DEPTH 100 +#ifndef IOCB_CMD_EPOLL_WAIT +#define IOCB_CMD_EPOLL_WAIT 9 +#endif + +struct aio_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; + + uint32_t destruction_count; + + io_context_t ioctx; + + struct epoll_event epevent[MAX_AIO_QUEUE_DEPTH]; + + struct iocb *epoll_iocb; + + int epoll_fd; + int is_epoll_set; + pid_t pid; +}; + +struct aio_event { + struct event_context *event_ctx; + struct iocb iocb; + void *private_data; + event_aio_handler_t handler; +}; + +/* + 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 aio_ctx_destructor(struct aio_event_context *aio_ev) +{ + io_queue_release(aio_ev->ioctx); + close(aio_ev->epoll_fd); + aio_ev->epoll_fd = -1; + return 0; +} + +static void epoll_add_event(struct aio_event_context *aio_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 aio_event_context *aio_ev) +{ + struct fd_event *fde; + + if (aio_ev->pid == getpid()) { + return; + } + + close(aio_ev->epoll_fd); + aio_ev->epoll_fd = epoll_create(MAX_AIO_QUEUE_DEPTH); + if (aio_ev->epoll_fd == -1) { + ev_debug(aio_ev->ev, EV_DEBUG_FATAL, "Failed to recreate epoll handle after fork\n"); + return; + } + aio_ev->pid = getpid(); + for (fde=aio_ev->fd_events;fde;fde=fde->next) { + epoll_add_event(aio_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 aio_event_context *aio_ev, struct fd_event *fde) +{ + struct epoll_event event; + if (aio_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 aio_event */ + if (fde->flags == 0) return; + + memset(&event, 0, sizeof(event)); + event.events = epoll_map_flags(fde->flags); + event.data.ptr = fde; + epoll_ctl(aio_ev->epoll_fd, EPOLL_CTL_ADD, fde->fd, &event); + 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 aio_event_context *aio_ev, struct fd_event *fde) +{ + struct epoll_event event; + + DLIST_REMOVE(aio_ev->fd_events, fde); + + if (aio_ev->epoll_fd == -1) return; + + fde->additional_flags &= ~EPOLL_ADDITIONAL_FD_FLAG_REPORT_ERROR; + + /* if there's no aio_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; + epoll_ctl(aio_ev->epoll_fd, EPOLL_CTL_DEL, fde->fd, &event); + + fde->additional_flags &= ~EPOLL_ADDITIONAL_FD_FLAG_HAS_EVENT; +} + +/* + change the epoll event to the given fd_event +*/ +static void epoll_mod_event(struct aio_event_context *aio_ev, struct fd_event *fde) +{ + struct epoll_event event; + if (aio_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; + epoll_ctl(aio_ev->epoll_fd, EPOLL_CTL_MOD, fde->fd, &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; + } +} + +static void epoll_change_event(struct aio_event_context *aio_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 (aio_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(aio_ev, fde); + return; + } + epoll_del_event(aio_ev, fde); + return; + } + + /* there's no aio_event attached to the fde */ + if (want_read || (want_write && !got_error)) { + DLIST_ADD(aio_ev->fd_events, fde); + epoll_add_event(aio_ev, fde); + return; + } +} + +static int setup_epoll_wait(struct aio_event_context *aio_ev) +{ + if (aio_ev->is_epoll_set) { + return 0; + } + memset(aio_ev->epoll_iocb, 0, sizeof(*aio_ev->epoll_iocb)); + aio_ev->epoll_iocb->aio_fildes = aio_ev->epoll_fd; + aio_ev->epoll_iocb->aio_lio_opcode = IOCB_CMD_EPOLL_WAIT; + aio_ev->epoll_iocb->aio_reqprio = 0; + + aio_ev->epoll_iocb->u.c.nbytes = MAX_AIO_QUEUE_DEPTH; + aio_ev->epoll_iocb->u.c.offset = -1; + aio_ev->epoll_iocb->u.c.buf = aio_ev->epevent; + + if (io_submit(aio_ev->ioctx, 1, &aio_ev->epoll_iocb) != 1) { + return -1; + } + aio_ev->is_epoll_set = 1; + + return 0; +} + + +/* + event loop handling using aio/epoll hybrid +*/ +static int aio_event_loop(struct aio_event_context *aio_ev, struct timeval *tvalp) +{ + int ret, i; + uint32_t destruction_count = ++aio_ev->destruction_count; + struct timespec timeout; + struct io_event events[8]; + + if (aio_ev->epoll_fd == -1) return -1; + + if (aio_ev->ev->num_signal_handlers && + common_event_check_signal(aio_ev->ev)) { + return 0; + } + + if (tvalp) { + timeout.tv_sec = tvalp->tv_sec; + timeout.tv_nsec = tvalp->tv_usec; + timeout.tv_nsec *= 1000; + } + + if (setup_epoll_wait(aio_ev) < 0) + return -1; + + ret = io_getevents(aio_ev->ioctx, 1, 8, + events, tvalp?&timeout:NULL); + + if (ret == -EINTR) { + if (aio_ev->ev->num_signal_handlers) { + common_event_check_signal(aio_ev->ev); + } + return 0; + } + + if (ret == 0 && tvalp) { + /* we don't care about a possible delay here */ + common_event_loop_timer_delay(aio_ev->ev); + return 0; + } + + for (i=0;i<ret;i++) { + struct io_event *event = &events[i]; + struct iocb *finished = event->obj; + + switch (finished->aio_lio_opcode) { + case IO_CMD_PWRITE: + case IO_CMD_PREAD: { + struct aio_event *ae = talloc_get_type(finished->data, + struct aio_event); + if (ae) { + talloc_set_destructor(ae, NULL); + ae->handler(ae->event_ctx, ae, + event->res, ae->private_data); + talloc_free(ae); + } + break; + } + case IOCB_CMD_EPOLL_WAIT: { + struct epoll_event *ep = (struct epoll_event *)finished->u.c.buf; + struct fd_event *fde; + uint16_t flags = 0; + int j; + + aio_ev->is_epoll_set = 0; + + for (j=0; j<event->res; j++, ep++) { + fde = talloc_get_type(ep->data.ptr, + struct fd_event); + if (fde == NULL) { + return -1; + } + if (ep->events & (EPOLLHUP|EPOLLERR)) { + fde->additional_flags |= EPOLL_ADDITIONAL_FD_FLAG_GOT_ERROR; + if (!(fde->additional_flags & EPOLL_ADDITIONAL_FD_FLAG_REPORT_ERROR)) { + epoll_del_event(aio_ev, fde); + continue; + } + flags |= EVENT_FD_READ; + } + if (ep->events & EPOLLIN) flags |= EVENT_FD_READ; + if (ep->events & EPOLLOUT) flags |= EVENT_FD_WRITE; + if (flags) { + fde->handler(aio_ev->ev, fde, flags, fde->private_data); + } + } + break; + } + } + if (destruction_count != aio_ev->destruction_count) { + return 0; + } + } + + return 0; +} + +/* + create a aio_event_context structure. +*/ +static int aio_event_context_init(struct event_context *ev) +{ + struct aio_event_context *aio_ev; + + aio_ev = talloc_zero(ev, struct aio_event_context); + if (!aio_ev) return -1; + + aio_ev->ev = ev; + aio_ev->epoll_iocb = talloc(aio_ev, struct iocb); + + if (io_queue_init(MAX_AIO_QUEUE_DEPTH, &aio_ev->ioctx) != 0) { + talloc_free(aio_ev); + return -1; + } + + aio_ev->epoll_fd = epoll_create(MAX_AIO_QUEUE_DEPTH); + if (aio_ev->epoll_fd == -1) { + talloc_free(aio_ev); + return -1; + } + aio_ev->pid = getpid(); + + talloc_set_destructor(aio_ev, aio_ctx_destructor); + + ev->additional_data = aio_ev; + + if (setup_epoll_wait(aio_ev) < 0) { + talloc_free(aio_ev); + return -1; + } + + return 0; +} + +/* + destroy an fd_event +*/ +static int aio_event_fd_destructor(struct fd_event *fde) +{ + struct event_context *ev = fde->event_ctx; + struct aio_event_context *aio_ev = talloc_get_type(ev->additional_data, + struct aio_event_context); + + epoll_check_reopen(aio_ev); + + aio_ev->num_fd_events--; + aio_ev->destruction_count++; + + epoll_del_event(aio_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 *aio_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 aio_event_context *aio_ev = talloc_get_type(ev->additional_data, + struct aio_event_context); + struct fd_event *fde; + + epoll_check_reopen(aio_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; + + aio_ev->num_fd_events++; + talloc_set_destructor(fde, aio_event_fd_destructor); + + DLIST_ADD(aio_ev->fd_events, fde); + epoll_add_event(aio_ev, fde); + + return fde; +} + + +/* + return the fd event flags +*/ +static uint16_t aio_event_get_fd_flags(struct fd_event *fde) +{ + return fde->flags; +} + +/* + set the fd event flags +*/ +static void aio_event_set_fd_flags(struct fd_event *fde, uint16_t flags) +{ + struct event_context *ev; + struct aio_event_context *aio_ev; + + if (fde->flags == flags) return; + + ev = fde->event_ctx; + aio_ev = talloc_get_type(ev->additional_data, struct aio_event_context); + + fde->flags = flags; + + epoll_check_reopen(aio_ev); + + epoll_change_event(aio_ev, fde); +} + +/* + do a single event loop using the events defined in ev +*/ +static int aio_event_loop_once(struct event_context *ev) +{ + struct aio_event_context *aio_ev = talloc_get_type(ev->additional_data, + struct aio_event_context); + struct timeval tval; + + tval = common_event_loop_timer_delay(ev); + if (ev_timeval_is_zero(&tval)) { + return 0; + } + + epoll_check_reopen(aio_ev); + + return aio_event_loop(aio_ev, &tval); +} + +/* + return on failure or (with 0) if all fd events are removed +*/ +static int aio_event_loop_wait(struct event_context *ev) +{ + struct aio_event_context *aio_ev = talloc_get_type(ev->additional_data, + struct aio_event_context); + while (aio_ev->num_fd_events) { + if (aio_event_loop_once(ev) != 0) { + break; + } + } + + return 0; +} + +/* + called when a disk IO event needs to be cancelled +*/ +static int aio_destructor(struct aio_event *ae) +{ + struct event_context *ev = ae->event_ctx; + struct aio_event_context *aio_ev = talloc_get_type(ev->additional_data, + struct aio_event_context); + struct io_event result; + io_cancel(aio_ev->ioctx, &ae->iocb, &result); + /* TODO: handle errors from io_cancel()! */ + return 0; +} + +/* submit an aio disk IO event */ +static struct aio_event *aio_event_add_aio(struct event_context *ev, + TALLOC_CTX *mem_ctx, + struct iocb *iocb, + event_aio_handler_t handler, + void *private_data) +{ + struct aio_event_context *aio_ev = talloc_get_type(ev->additional_data, + struct aio_event_context); + struct iocb *iocbp; + struct aio_event *ae = talloc(mem_ctx?mem_ctx:ev, struct aio_event); + if (ae == NULL) return NULL; + + ae->event_ctx = ev; + ae->iocb = *iocb; + ae->handler = handler; + ae->private_data = private_data; + iocbp = &ae->iocb; + + if (io_submit(aio_ev->ioctx, 1, &iocbp) != 1) { + talloc_free(ae); + return NULL; + } + ae->iocb.data = ae; + talloc_set_destructor(ae, aio_destructor); + + return ae; +} + +static const struct event_ops aio_event_ops = { + .context_init = aio_event_context_init, + .add_fd = aio_event_add_fd, + .add_aio = aio_event_add_aio, + .get_fd_flags = aio_event_get_fd_flags, + .set_fd_flags = aio_event_set_fd_flags, + .add_timed = common_event_add_timed, + .add_signal = common_event_add_signal, + .loop_once = aio_event_loop_once, + .loop_wait = aio_event_loop_wait, +}; + +bool events_aio_init(void) +{ + return event_register_backend("aio", &aio_event_ops); +} + |