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Diffstat (limited to 'ctdb/lib/tevent/tevent.c')
| -rw-r--r-- | ctdb/lib/tevent/tevent.c | 669 |
1 files changed, 669 insertions, 0 deletions
diff --git a/ctdb/lib/tevent/tevent.c b/ctdb/lib/tevent/tevent.c new file mode 100644 index 00000000000..be0afd453bb --- /dev/null +++ b/ctdb/lib/tevent/tevent.c @@ -0,0 +1,669 @@ +/* + Unix SMB/CIFS implementation. + main select loop and event handling + Copyright (C) Andrew Tridgell 2003 + Copyright (C) Stefan Metzmacher 2009 + + ** NOTE! The following LGPL license applies to the tevent + ** library. This does NOT imply that all of Samba is released + ** under the LGPL + + This library is free software; you can redistribute it and/or + modify it under the terms of the GNU Lesser General Public + License as published by the Free Software Foundation; either + version 3 of the License, or (at your option) any later version. + + This library 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 + Lesser General Public License for more details. + + You should have received a copy of the GNU Lesser General Public + License along with this library; if not, see <http://www.gnu.org/licenses/>. +*/ + +/* + 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 tevent_context_init(); This returns a + 'struct tevent_context' that you use in all subsequent calls. + + After that you can add/remove events that you are interested in + using tevent_add_*() and talloc_free() + + Finally, you call tevent_loop_wait_once() to block waiting for one of the + events to occor or tevent_loop_wait() which will loop + forever. + +*/ +#include "replace.h" +#include "system/filesys.h" +#define TEVENT_DEPRECATED 1 +#include "tevent.h" +#include "tevent_internal.h" +#include "tevent_util.h" + +struct tevent_ops_list { + struct tevent_ops_list *next, *prev; + const char *name; + const struct tevent_ops *ops; +}; + +/* list of registered event backends */ +static struct tevent_ops_list *tevent_backends = NULL; +static char *tevent_default_backend = NULL; + +/* + register an events backend +*/ +bool tevent_register_backend(const char *name, const struct tevent_ops *ops) +{ + struct tevent_ops_list *e; + + for (e = tevent_backends; e != NULL; e = e->next) { + if (0 == strcmp(e->name, name)) { + /* already registered, skip it */ + return true; + } + } + + e = talloc(NULL, struct tevent_ops_list); + if (e == NULL) return false; + + e->name = name; + e->ops = ops; + DLIST_ADD(tevent_backends, e); + + return true; +} + +/* + set the default event backend + */ +void tevent_set_default_backend(const char *backend) +{ + talloc_free(tevent_default_backend); + tevent_default_backend = talloc_strdup(NULL, backend); +} + +/* + initialise backends if not already done +*/ +static void tevent_backend_init(void) +{ + static bool done; + + if (done) { + return; + } + + done = true; + + tevent_select_init(); + tevent_poll_init(); + tevent_poll_mt_init(); +#ifdef HAVE_EPOLL + tevent_epoll_init(); +#endif + tevent_standard_init(); +} + +_PRIVATE_ const struct tevent_ops *tevent_find_ops_byname(const char *name) +{ + struct tevent_ops_list *e; + + tevent_backend_init(); + + if (name == NULL) { + name = tevent_default_backend; + } + if (name == NULL) { + name = "standard"; + } + + for (e = tevent_backends; e != NULL; e = e->next) { + if (0 == strcmp(e->name, name)) { + return e->ops; + } + } + + return NULL; +} + +/* + list available backends +*/ +const char **tevent_backend_list(TALLOC_CTX *mem_ctx) +{ + const char **list = NULL; + struct tevent_ops_list *e; + + tevent_backend_init(); + + for (e=tevent_backends;e;e=e->next) { + list = ev_str_list_add(list, e->name); + } + + talloc_steal(mem_ctx, list); + + return list; +} + +int tevent_common_context_destructor(struct tevent_context *ev) +{ + struct tevent_fd *fd, *fn; + struct tevent_timer *te, *tn; + struct tevent_immediate *ie, *in; + struct tevent_signal *se, *sn; + + if (ev->pipe_fde) { + talloc_free(ev->pipe_fde); + close(ev->pipe_fds[0]); + close(ev->pipe_fds[1]); + ev->pipe_fde = NULL; + } + + for (fd = ev->fd_events; fd; fd = fn) { + fn = fd->next; + fd->event_ctx = NULL; + DLIST_REMOVE(ev->fd_events, fd); + } + + ev->last_zero_timer = NULL; + for (te = ev->timer_events; te; te = tn) { + tn = te->next; + te->event_ctx = NULL; + DLIST_REMOVE(ev->timer_events, te); + } + + for (ie = ev->immediate_events; ie; ie = in) { + in = ie->next; + ie->event_ctx = NULL; + ie->cancel_fn = NULL; + DLIST_REMOVE(ev->immediate_events, ie); + } + + for (se = ev->signal_events; se; se = sn) { + sn = se->next; + se->event_ctx = NULL; + DLIST_REMOVE(ev->signal_events, se); + /* + * This is important, Otherwise signals + * are handled twice in child. eg, SIGHUP. + * one added in parent, and another one in + * the child. -- BoYang + */ + tevent_cleanup_pending_signal_handlers(se); + } + + /* removing nesting hook or we get an abort when nesting is + * not allowed. -- SSS + * Note that we need to leave the allowed flag at its current + * value, otherwise the use in tevent_re_initialise() will + * leave the event context with allowed forced to false, which + * will break users that expect nesting to be allowed + */ + ev->nesting.level = 0; + ev->nesting.hook_fn = NULL; + ev->nesting.hook_private = NULL; + + return 0; +} + +/* + create a event_context structure for a specific implemementation. + 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. + + This function is for allowing third-party-applications to hook in gluecode + to their own event loop code, so that they can make async usage of our client libs + + NOTE: use tevent_context_init() inside of samba! +*/ +struct tevent_context *tevent_context_init_ops(TALLOC_CTX *mem_ctx, + const struct tevent_ops *ops, + void *additional_data) +{ + struct tevent_context *ev; + int ret; + + ev = talloc_zero(mem_ctx, struct tevent_context); + if (!ev) return NULL; + + talloc_set_destructor(ev, tevent_common_context_destructor); + + ev->ops = ops; + ev->additional_data = additional_data; + + ret = ev->ops->context_init(ev); + if (ret != 0) { + talloc_free(ev); + return NULL; + } + + return ev; +} + +/* + 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 tevent_context *tevent_context_init_byname(TALLOC_CTX *mem_ctx, + const char *name) +{ + const struct tevent_ops *ops; + + ops = tevent_find_ops_byname(name); + if (ops == NULL) { + return NULL; + } + + return tevent_context_init_ops(mem_ctx, ops, NULL); +} + + +/* + 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 tevent_context *tevent_context_init(TALLOC_CTX *mem_ctx) +{ + return tevent_context_init_byname(mem_ctx, NULL); +} + +/* + add a fd based event + return NULL on failure (memory allocation error) +*/ +struct tevent_fd *_tevent_add_fd(struct tevent_context *ev, + TALLOC_CTX *mem_ctx, + int fd, + uint16_t flags, + tevent_fd_handler_t handler, + void *private_data, + const char *handler_name, + const char *location) +{ + return ev->ops->add_fd(ev, mem_ctx, fd, flags, handler, private_data, + handler_name, location); +} + +/* + set a close function on the fd event +*/ +void tevent_fd_set_close_fn(struct tevent_fd *fde, + tevent_fd_close_fn_t close_fn) +{ + if (!fde) return; + if (!fde->event_ctx) return; + fde->event_ctx->ops->set_fd_close_fn(fde, close_fn); +} + +static void tevent_fd_auto_close_fn(struct tevent_context *ev, + struct tevent_fd *fde, + int fd, + void *private_data) +{ + close(fd); +} + +void tevent_fd_set_auto_close(struct tevent_fd *fde) +{ + tevent_fd_set_close_fn(fde, tevent_fd_auto_close_fn); +} + +/* + return the fd event flags +*/ +uint16_t tevent_fd_get_flags(struct tevent_fd *fde) +{ + if (!fde) return 0; + if (!fde->event_ctx) return 0; + return fde->event_ctx->ops->get_fd_flags(fde); +} + +/* + set the fd event flags +*/ +void tevent_fd_set_flags(struct tevent_fd *fde, uint16_t flags) +{ + if (!fde) return; + if (!fde->event_ctx) return; + fde->event_ctx->ops->set_fd_flags(fde, flags); +} + +bool tevent_signal_support(struct tevent_context *ev) +{ + if (ev->ops->add_signal) { + return true; + } + return false; +} + +static void (*tevent_abort_fn)(const char *reason); + +void tevent_set_abort_fn(void (*abort_fn)(const char *reason)) +{ + tevent_abort_fn = abort_fn; +} + +static void tevent_abort(struct tevent_context *ev, const char *reason) +{ + tevent_debug(ev, TEVENT_DEBUG_FATAL, + "abort: %s\n", reason); + + if (!tevent_abort_fn) { + abort(); + } + + tevent_abort_fn(reason); +} + +/* + add a timer event + return NULL on failure +*/ +struct tevent_timer *_tevent_add_timer(struct tevent_context *ev, + TALLOC_CTX *mem_ctx, + struct timeval next_event, + tevent_timer_handler_t handler, + void *private_data, + const char *handler_name, + const char *location) +{ + return ev->ops->add_timer(ev, mem_ctx, next_event, handler, private_data, + handler_name, location); +} + +/* + allocate an immediate event + return NULL on failure (memory allocation error) +*/ +struct tevent_immediate *_tevent_create_immediate(TALLOC_CTX *mem_ctx, + const char *location) +{ + struct tevent_immediate *im; + + im = talloc(mem_ctx, struct tevent_immediate); + if (im == NULL) return NULL; + + im->prev = NULL; + im->next = NULL; + im->event_ctx = NULL; + im->create_location = location; + im->handler = NULL; + im->private_data = NULL; + im->handler_name = NULL; + im->schedule_location = NULL; + im->cancel_fn = NULL; + im->additional_data = NULL; + + return im; +} + +/* + schedule an immediate event +*/ +void _tevent_schedule_immediate(struct tevent_immediate *im, + struct tevent_context *ev, + tevent_immediate_handler_t handler, + void *private_data, + const char *handler_name, + const char *location) +{ + ev->ops->schedule_immediate(im, ev, handler, private_data, + handler_name, location); +} + +/* + add a signal event + + sa_flags are flags to sigaction(2) + + return NULL on failure +*/ +struct tevent_signal *_tevent_add_signal(struct tevent_context *ev, + TALLOC_CTX *mem_ctx, + int signum, + int sa_flags, + tevent_signal_handler_t handler, + void *private_data, + const char *handler_name, + const char *location) +{ + return ev->ops->add_signal(ev, mem_ctx, signum, sa_flags, handler, private_data, + handler_name, location); +} + +void tevent_loop_allow_nesting(struct tevent_context *ev) +{ + ev->nesting.allowed = true; +} + +void tevent_loop_set_nesting_hook(struct tevent_context *ev, + tevent_nesting_hook hook, + void *private_data) +{ + if (ev->nesting.hook_fn && + (ev->nesting.hook_fn != hook || + ev->nesting.hook_private != private_data)) { + /* the way the nesting hook code is currently written + we cannot support two different nesting hooks at the + same time. */ + tevent_abort(ev, "tevent: Violation of nesting hook rules\n"); + } + ev->nesting.hook_fn = hook; + ev->nesting.hook_private = private_data; +} + +static void tevent_abort_nesting(struct tevent_context *ev, const char *location) +{ + const char *reason; + + reason = talloc_asprintf(NULL, "tevent_loop_once() nesting at %s", + location); + if (!reason) { + reason = "tevent_loop_once() nesting"; + } + + tevent_abort(ev, reason); +} + +/* + do a single event loop using the events defined in ev +*/ +int _tevent_loop_once(struct tevent_context *ev, const char *location) +{ + int ret; + void *nesting_stack_ptr = NULL; + + ev->nesting.level++; + + if (ev->nesting.level > 1) { + if (!ev->nesting.allowed) { + tevent_abort_nesting(ev, location); + errno = ELOOP; + return -1; + } + } + if (ev->nesting.level > 0) { + if (ev->nesting.hook_fn) { + int ret2; + ret2 = ev->nesting.hook_fn(ev, + ev->nesting.hook_private, + ev->nesting.level, + true, + (void *)&nesting_stack_ptr, + location); + if (ret2 != 0) { + ret = ret2; + goto done; + } + } + } + + tevent_trace_point_callback(ev, TEVENT_TRACE_BEFORE_LOOP_ONCE); + ret = ev->ops->loop_once(ev, location); + tevent_trace_point_callback(ev, TEVENT_TRACE_AFTER_LOOP_ONCE); + + if (ev->nesting.level > 0) { + if (ev->nesting.hook_fn) { + int ret2; + ret2 = ev->nesting.hook_fn(ev, + ev->nesting.hook_private, + ev->nesting.level, + false, + (void *)&nesting_stack_ptr, + location); + if (ret2 != 0) { + ret = ret2; + goto done; + } + } + } + +done: + ev->nesting.level--; + return ret; +} + +/* + this is a performance optimization for the samba4 nested event loop problems +*/ +int _tevent_loop_until(struct tevent_context *ev, + bool (*finished)(void *private_data), + void *private_data, + const char *location) +{ + int ret = 0; + void *nesting_stack_ptr = NULL; + + ev->nesting.level++; + + if (ev->nesting.level > 1) { + if (!ev->nesting.allowed) { + tevent_abort_nesting(ev, location); + errno = ELOOP; + return -1; + } + } + if (ev->nesting.level > 0) { + if (ev->nesting.hook_fn) { + int ret2; + ret2 = ev->nesting.hook_fn(ev, + ev->nesting.hook_private, + ev->nesting.level, + true, + (void *)&nesting_stack_ptr, + location); + if (ret2 != 0) { + ret = ret2; + goto done; + } + } + } + + while (!finished(private_data)) { + tevent_trace_point_callback(ev, TEVENT_TRACE_BEFORE_LOOP_ONCE); + ret = ev->ops->loop_once(ev, location); + tevent_trace_point_callback(ev, TEVENT_TRACE_AFTER_LOOP_ONCE); + if (ret != 0) { + break; + } + } + + if (ev->nesting.level > 0) { + if (ev->nesting.hook_fn) { + int ret2; + ret2 = ev->nesting.hook_fn(ev, + ev->nesting.hook_private, + ev->nesting.level, + false, + (void *)&nesting_stack_ptr, + location); + if (ret2 != 0) { + ret = ret2; + goto done; + } + } + } + +done: + ev->nesting.level--; + return ret; +} + +/* + return on failure or (with 0) if all fd events are removed +*/ +int tevent_common_loop_wait(struct tevent_context *ev, + const char *location) +{ + /* + * loop as long as we have events pending + */ + while (ev->fd_events || + ev->timer_events || + ev->immediate_events || + ev->signal_events) { + int ret; + ret = _tevent_loop_once(ev, location); + if (ret != 0) { + tevent_debug(ev, TEVENT_DEBUG_FATAL, + "_tevent_loop_once() failed: %d - %s\n", + ret, strerror(errno)); + return ret; + } + } + + tevent_debug(ev, TEVENT_DEBUG_WARNING, + "tevent_common_loop_wait() out of events\n"); + return 0; +} + +/* + return on failure or (with 0) if all fd events are removed +*/ +int _tevent_loop_wait(struct tevent_context *ev, const char *location) +{ + return ev->ops->loop_wait(ev, location); +} + + +/* + re-initialise a tevent context. This leaves you with the same + event context, but all events are wiped and the structure is + re-initialised. This is most useful after a fork() + + zero is returned on success, non-zero on failure +*/ +int tevent_re_initialise(struct tevent_context *ev) +{ + tevent_common_context_destructor(ev); + + return ev->ops->context_init(ev); +} |