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Diffstat (limited to 'source4/lib/events/events_standard.c')
| -rw-r--r-- | source4/lib/events/events_standard.c | 540 |
1 files changed, 540 insertions, 0 deletions
diff --git a/source4/lib/events/events_standard.c b/source4/lib/events/events_standard.c new file mode 100644 index 0000000000..9783603759 --- /dev/null +++ b/source4/lib/events/events_standard.c @@ -0,0 +1,540 @@ +/* + Unix SMB/CIFS implementation. + main select loop and event handling + Copyright (C) Andrew Tridgell 2003 + + 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 2 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, write to the Free Software + Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. +*/ + +/* + PLEASE READ THIS BEFORE MODIFYING! + + This module is a general abstraction for the main select loop and + event handling. Do not ever put any localised hacks in here, instead + register one of the possible event types and implement that event + somewhere else. + + There are 2 types of event handling that are handled in this module: + + 1) a file descriptor becoming readable or writeable. This is mostly + used for network sockets, but can be used for any type of file + descriptor. You may only register one handler for each file + descriptor/io combination or you will get unpredictable results + (this means that you can have a handler for read events, and a + separate handler for write events, but not two handlers that are + both handling read events) + + 2) a timed event. You can register an event that happens at a + specific time. You can register as many of these as you + like. They are single shot - add a new timed event in the event + handler to get another event. + + To setup a set of events you first need to create a event_context + structure using the function event_context_init(); This returns a + 'struct event_context' that you use in all subsequent calls. + + After that you can add/remove events that you are interested in + using event_add_*() and talloc_free() + + Finally, you call event_loop_wait() to block waiting for one of the + events to occor. In normal operation event_loop_wait() will loop + forever. + +*/ + +#include "includes.h" +#include "system/time.h" +#include "system/select.h" +#include "system/filesys.h" +#include "dlinklist.h" +#include "lib/events/events.h" + +/* use epoll if it is available */ +#if defined(HAVE_EPOLL_CREATE) && defined(HAVE_SYS_EPOLL_H) +#define WITH_EPOLL 1 +#endif + +#if WITH_EPOLL +#include <sys/epoll.h> +#endif + +struct event_context { + /* list of filedescriptor events */ + struct fd_event { + struct event_context *event_ctx; + struct fd_event *next, *prev; + int fd; + uint16_t flags; /* see EVENT_FD_* flags */ + event_fd_handler_t handler; + void *private; + } *fd_events; + + /* list of timed events */ + struct timed_event { + struct event_context *event_ctx; + struct timed_event *next, *prev; + struct timeval next_event; + event_timed_handler_t handler; + void *private; + } *timed_events; + + /* the maximum file descriptor number in fd_events */ + int maxfd; + + /* information for exiting from the event loop */ + int exit_code; + + /* 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; + +#if WITH_EPOLL + /* when using epoll this is the handle from epoll_create */ + int epoll_fd; +#endif +}; + + +/* + destroy an event context +*/ +static int event_context_destructor(void *ptr) +{ +#if WITH_EPOLL + struct event_context *ev = talloc_get_type(ptr, struct event_context); + if (ev->epoll_fd != -1) { + close(ev->epoll_fd); + ev->epoll_fd = -1; + } +#endif + return 0; +} + +/* + create a event_context structure. This must be the first events + call, and all subsequent calls pass this event_context as the first + element. Event handlers also receive this as their first argument. +*/ +struct event_context *event_context_init(TALLOC_CTX *mem_ctx) +{ + struct event_context *ev; + + ev = talloc_zero(mem_ctx, struct event_context); + if (!ev) return NULL; + +#if WITH_EPOLL + ev->epoll_fd = epoll_create(64); +#endif + + talloc_set_destructor(ev, event_context_destructor); + + return ev; +} + + +/* + recalculate the maxfd +*/ +static void calc_maxfd(struct event_context *ev) +{ + struct fd_event *e; + ev->maxfd = 0; + for (e=ev->fd_events; e; e=e->next) { + if (e->fd > ev->maxfd) { + ev->maxfd = e->fd; + } + } +} + + +/* to mark the ev->maxfd invalid + * this means we need to recalculate it + */ +#define EVENT_INVALID_MAXFD (-1) + + +#if WITH_EPOLL +/* + called when a epoll call fails, and we should fallback + to using select +*/ +static void epoll_fallback_to_select(struct event_context *ev, const char *reason) +{ + DEBUG(0,("%s (%s) - falling back to select()\n", reason, strerror(errno))); + close(ev->epoll_fd); + ev->epoll_fd = -1; +} +#endif + + +#if WITH_EPOLL +/* + 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; + if (flags & EVENT_FD_WRITE) ret |= EPOLLOUT; + return ret; +} +#endif + +/* + destroy an fd_event +*/ +static int event_fd_destructor(void *ptr) +{ + struct fd_event *fde = talloc_get_type(ptr, struct fd_event); + struct event_context *ev = fde->event_ctx; + + if (ev->maxfd == fde->fd) { + ev->maxfd = EVENT_INVALID_MAXFD; + } + DLIST_REMOVE(ev->fd_events, fde); + ev->destruction_count++; +#if WITH_EPOLL + if (ev->epoll_fd != -1) { + struct epoll_event event; + ZERO_STRUCT(event); + event.events = epoll_map_flags(fde->flags); + event.data.ptr = fde; + epoll_ctl(ev->epoll_fd, EPOLL_CTL_DEL, fde->fd, &event); + } +#endif + return 0; +} + +/* + add a fd based event + return NULL on failure (memory allocation error) +*/ +struct fd_event *event_add_fd(struct event_context *ev, TALLOC_CTX *mem_ctx, + int fd, uint16_t flags, event_fd_handler_t handler, + void *private) +{ + struct fd_event *e = talloc(ev, struct fd_event); + if (!e) return NULL; + + e->event_ctx = ev; + e->fd = fd; + e->flags = flags; + e->handler = handler; + e->private = private; + + DLIST_ADD(ev->fd_events, e); + + if (e->fd > ev->maxfd) { + ev->maxfd = e->fd; + } + + talloc_set_destructor(e, event_fd_destructor); + if (mem_ctx) { + talloc_steal(mem_ctx, e); + } + +#if WITH_EPOLL + if (ev->epoll_fd != -1) { + struct epoll_event event; + ZERO_STRUCT(event); + event.events = epoll_map_flags(flags); + event.data.ptr = e; + if (epoll_ctl(ev->epoll_fd, EPOLL_CTL_ADD, e->fd, &event) != 0) { + epoll_fallback_to_select(ev, "EPOLL_CTL_ADD failed"); + } + } +#endif + + return e; +} + + +/* + return the fd event flags +*/ +uint16_t event_fd_flags(struct fd_event *fde) +{ + return fde?fde->flags:0; +} + +/* + set the fd event flags +*/ +void event_fd_setflags(struct fd_event *fde, uint16_t flags) +{ +#if WITH_EPOLL + struct event_context *ev; + if (fde == NULL || + fde->flags == flags) { + return; + } + ev = fde->event_ctx; + if (ev->epoll_fd != -1) { + struct epoll_event event; + ZERO_STRUCT(event); + event.events = epoll_map_flags(flags); + event.data.ptr = fde; + if (epoll_ctl(ev->epoll_fd, EPOLL_CTL_MOD, fde->fd, &event) != 0) { + epoll_fallback_to_select(ev, "EPOLL_CTL_MOD failed"); + } + } +#endif + if (fde) { + fde->flags = flags; + } +} + +/* + destroy a timed event +*/ +static int event_timed_destructor(void *ptr) +{ + struct timed_event *te = talloc_get_type(ptr, struct timed_event); + DLIST_REMOVE(te->event_ctx->timed_events, te); + return 0; +} + +/* + add a timed event + return NULL on failure (memory allocation error) +*/ +struct timed_event *event_add_timed(struct event_context *ev, TALLOC_CTX *mem_ctx, + struct timeval next_event, + event_timed_handler_t handler, + void *private) +{ + struct timed_event *te, *e; + + e = talloc(mem_ctx?mem_ctx:ev, struct timed_event); + if (e == NULL) return NULL; + + e->event_ctx = ev; + e->next_event = next_event; + e->handler = handler; + e->private = private; + + /* keep the list ordered */ + if (ev->timed_events == NULL || + timeval_compare(&e->next_event, &ev->timed_events->next_event) > 0) { + DLIST_ADD(ev->timed_events, e); + } else { + for (te=ev->timed_events;te && te->next;te=te->next) { + if (!timeval_is_zero(&te->next->next_event) && + timeval_compare(&te->next->next_event, &e->next_event) < 0) { + break; + } + } + DLIST_ADD_AFTER(ev->timed_events, e, te); + } + + talloc_set_destructor(e, event_timed_destructor); + + return e; +} + +/* + a timer has gone off - call it +*/ +static void event_loop_timer(struct event_context *ev) +{ + struct timeval t = timeval_current(); + struct timed_event *te = ev->timed_events; + + te->next_event = timeval_zero(); + + te->handler(ev, te, t, te->private); + + /* note the care taken to prevent referencing a event + that could have been freed by the handler */ + if (ev->timed_events && timeval_is_zero(&ev->timed_events->next_event)) { + talloc_free(ev->timed_events); + } +} + +#if WITH_EPOLL +/* + event loop handling using epoll +*/ +static int event_loop_epoll(struct event_context *ev, struct timeval *tvalp) +{ + int ret, i; + const int maxevents = 8; + struct epoll_event events[maxevents]; + uint32_t destruction_count = ev->destruction_count; + int timeout = -1; + + if (tvalp) { + timeout = (tvalp->tv_usec / 1000) + (tvalp->tv_sec*1000); + } + + ret = epoll_wait(ev->epoll_fd, events, maxevents, timeout); + + if (ret == -1 && errno != EINTR) { + epoll_fallback_to_select(ev, "epoll_wait() failed"); + return -1; + } + + if (ret == 0 && tvalp) { + event_loop_timer(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_fallback_to_select(ev, "epoll_wait() gave bad data"); + return -1; + } + if (events[i].events & (EPOLLIN|EPOLLHUP|EPOLLERR)) + flags |= EVENT_FD_READ; + if (events[i].events & EPOLLOUT) flags |= EVENT_FD_WRITE; + if (flags) { + fde->handler(ev, fde, flags, fde->private); + if (destruction_count != ev->destruction_count) { + break; + } + } + } + + return 0; +} +#endif + +/* + event loop handling using select() +*/ +static int event_loop_select(struct event_context *ev, struct timeval *tvalp) +{ + fd_set r_fds, w_fds; + int selrtn; + uint32_t destruction_count = ev->destruction_count; + struct fd_event *fe; + + /* we maybe need to recalculate the maxfd */ + if (ev->maxfd == EVENT_INVALID_MAXFD) { + calc_maxfd(ev); + } + + FD_ZERO(&r_fds); + FD_ZERO(&w_fds); + + /* setup any fd events */ + for (fe=ev->fd_events; fe; ) { + struct fd_event *next = fe->next; + if (fe->flags & EVENT_FD_READ) { + FD_SET(fe->fd, &r_fds); + } + if (fe->flags & EVENT_FD_WRITE) { + FD_SET(fe->fd, &w_fds); + } + fe = next; + } + + selrtn = select(ev->maxfd+1, &r_fds, &w_fds, NULL, tvalp); + + if (selrtn == -1 && errno == EBADF) { + /* the socket is dead! this should never + happen as the socket should have first been + made readable and that should have removed + the event, so this must be a bug. This is a + fatal error. */ + DEBUG(0,("ERROR: EBADF on event_loop_once\n")); + ev->exit_code = EBADF; + return -1; + } + + if (selrtn == 0 && tvalp) { + event_loop_timer(ev); + return 0; + } + + if (selrtn > 0) { + /* at least one file descriptor is ready - check + which ones and call the handler, being careful to allow + the handler to remove itself when called */ + for (fe=ev->fd_events; fe; fe=fe->next) { + uint16_t flags = 0; + if (FD_ISSET(fe->fd, &r_fds)) flags |= EVENT_FD_READ; + if (FD_ISSET(fe->fd, &w_fds)) flags |= EVENT_FD_WRITE; + if (flags) { + fe->handler(ev, fe, flags, fe->private); + if (destruction_count != ev->destruction_count) { + break; + } + } + } + } + + return 0; +} + +/* + do a single event loop using the events defined in ev +*/ +int event_loop_once(struct event_context *ev) +{ + struct timeval tval, *tvalp; + + tvalp = NULL; + + /* work out the right timeout for all timed events */ + if (ev->timed_events) { + struct timeval t = timeval_current(); + tval = timeval_diff(&ev->timed_events->next_event, &t); + tvalp = &tval; + if (timeval_is_zero(tvalp)) { + event_loop_timer(ev); + return 0; + } + } + +#if WITH_EPOLL + if (ev->epoll_fd != -1) { + if (event_loop_epoll(ev, tvalp) == 0) { + return 0; + } + } +#endif + + return event_loop_select(ev, tvalp); +} + +/* + go into an event loop using the events defined in ev this function + will return with the specified code if one of the handlers calls + event_loop_exit() + + also return (with code 0) if all fd events are removed +*/ +int event_loop_wait(struct event_context *ev) +{ + ev->exit_code = 0; + ev->maxfd = EVENT_INVALID_MAXFD; + + while (ev->fd_events && ev->exit_code == 0) { + if (event_loop_once(ev) != 0) { + break; + } + } + + return ev->exit_code; +} |