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| -rw-r--r-- | lib/tevent/tevent_req.c | 338 |
1 files changed, 338 insertions, 0 deletions
diff --git a/lib/tevent/tevent_req.c b/lib/tevent/tevent_req.c new file mode 100644 index 0000000000..db47bd93ed --- /dev/null +++ b/lib/tevent/tevent_req.c @@ -0,0 +1,338 @@ +/* + Unix SMB/CIFS implementation. + Infrastructure for async requests + Copyright (C) Volker Lendecke 2008 + + 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 "includes.h" +#include "lib/tevent/tevent.h" +#include "lib/talloc/talloc.h" +#include "lib/util/dlinklist.h" +#include "lib/async_req/async_req.h" + +#ifndef TALLOC_FREE +#define TALLOC_FREE(ctx) do { talloc_free(ctx); ctx=NULL; } while(0) +#endif + +/** + * @brief Print an async_req structure + * @param[in] mem_ctx The memory context for the result + * @param[in] req The request to be printed + * @retval Text representation of req + * + * This is a default print function for async requests. Implementations should + * override this with more specific information. + * + * This function should not be used by async API users, this is non-static + * only to allow implementations to easily provide default information in + * their specific functions. + */ + +char *async_req_print(TALLOC_CTX *mem_ctx, struct async_req *req) +{ + return talloc_asprintf(mem_ctx, "async_req: state=%d, error=%d, " + "priv=%s", req->state, (int)req->error, + talloc_get_name(req->private_data)); +} + +/** + * @brief Create an async request + * @param[in] mem_ctx The memory context for the result + * @param[in] ev The event context this async request will be driven by + * @retval A new async request + * + * The new async request will be initialized in state ASYNC_REQ_IN_PROGRESS + */ + +struct async_req *async_req_new(TALLOC_CTX *mem_ctx) +{ + struct async_req *result; + + result = talloc_zero(mem_ctx, struct async_req); + if (result == NULL) { + return NULL; + } + result->state = ASYNC_REQ_IN_PROGRESS; + result->print = async_req_print; + return result; +} + +static void async_req_finish(struct async_req *req, enum async_req_state state) +{ + req->state = state; + if (req->async.fn != NULL) { + req->async.fn(req); + } +} + +/** + * @brief An async request has successfully finished + * @param[in] req The finished request + * + * async_req_done is to be used by implementors of async requests. When a + * request is successfully finished, this function calls the user's completion + * function. + */ + +void async_req_done(struct async_req *req) +{ + async_req_finish(req, ASYNC_REQ_DONE); +} + +/** + * @brief An async request has seen an error + * @param[in] req The request with an error + * @param[in] error The error code + * + * async_req_done is to be used by implementors of async requests. When a + * request can not successfully completed, the implementation should call this + * function with the appropriate status code. + */ + +void async_req_error(struct async_req *req, uint64_t error) +{ + req->error = error; + async_req_finish(req, ASYNC_REQ_USER_ERROR); +} + +/** + * @brief Timed event callback + * @param[in] ev Event context + * @param[in] te The timed event + * @param[in] now zero time + * @param[in] priv The async request to be finished + */ + +static void async_trigger(struct tevent_context *ev, struct tevent_timer *te, + struct timeval now, void *priv) +{ + struct async_req *req = talloc_get_type_abort(priv, struct async_req); + + TALLOC_FREE(te); + if (req->error == 0) { + async_req_done(req); + } + else { + async_req_error(req, req->error); + } +} + +/** + * @brief Helper function for nomem check + * @param[in] p The pointer to be checked + * @param[in] req The request being processed + * + * Convenience helper to easily check alloc failure within a callback + * implementing the next step of an async request. + * + * Call pattern would be + * \code + * p = talloc(mem_ctx, bla); + * if (async_req_ntnomem(p, req)) { + * return; + * } + * \endcode + */ + +bool async_req_nomem(const void *p, struct async_req *req) +{ + if (p != NULL) { + return false; + } + async_req_finish(req, ASYNC_REQ_NO_MEMORY); + return true; +} + +/** + * @brief Finish a request before it started processing + * @param[in] req The finished request + * @param[in] status The success code + * + * An implementation of an async request might find that it can either finish + * the request without waiting for an external event, or it can't even start + * the engine. To present the illusion of a callback to the user of the API, + * the implementation can call this helper function which triggers an + * immediate timed event. This way the caller can use the same calling + * conventions, independent of whether the request was actually deferred. + */ + +bool async_post_error(struct async_req *req, struct tevent_context *ev, + uint64_t error) +{ + req->error = error; + + if (tevent_add_timer(ev, req, timeval_zero(), + async_trigger, req) == NULL) { + return false; + } + return true; +} + +bool async_req_is_error(struct async_req *req, enum async_req_state *state, + uint64_t *error) +{ + if (req->state == ASYNC_REQ_DONE) { + return false; + } + if (req->state == ASYNC_REQ_USER_ERROR) { + *error = req->error; + } + *state = req->state; + return true; +} + +static void async_req_timedout(struct tevent_context *ev, + struct tevent_timer *te, + struct timeval now, + void *priv) +{ + struct async_req *req = talloc_get_type_abort(priv, struct async_req); + TALLOC_FREE(te); + async_req_finish(req, ASYNC_REQ_TIMED_OUT); +} + +bool async_req_set_timeout(struct async_req *req, struct tevent_context *ev, + struct timeval to) +{ + return (tevent_add_timer( + ev, req, timeval_current_ofs(to.tv_sec, to.tv_usec), + async_req_timedout, req) + != NULL); +} + +struct async_req *async_wait_send(TALLOC_CTX *mem_ctx, + struct tevent_context *ev, + struct timeval to) +{ + struct async_req *result; + + result = async_req_new(mem_ctx); + if (result == NULL) { + return result; + } + if (!async_req_set_timeout(result, ev, to)) { + TALLOC_FREE(result); + return NULL; + } + return result; +} + +bool async_wait_recv(struct async_req *req) +{ + return true; +} + +struct async_queue_entry { + struct async_queue_entry *prev, *next; + struct async_req_queue *queue; + struct async_req *req; + void (*trigger)(struct async_req *req); +}; + +struct async_req_queue { + struct async_queue_entry *queue; +}; + +struct async_req_queue *async_req_queue_init(TALLOC_CTX *mem_ctx) +{ + return talloc_zero(mem_ctx, struct async_req_queue); +} + +static int async_queue_entry_destructor(struct async_queue_entry *e) +{ + struct async_req_queue *queue = e->queue; + + DLIST_REMOVE(queue->queue, e); + + if (queue->queue != NULL) { + queue->queue->trigger(queue->queue->req); + } + + return 0; +} + +static void async_req_immediate_trigger(struct tevent_context *ev, + struct tevent_timer *te, + struct timeval now, + void *priv) +{ + struct async_queue_entry *e = talloc_get_type_abort( + priv, struct async_queue_entry); + + TALLOC_FREE(te); + e->trigger(e->req); +} + +bool async_req_enqueue(struct async_req_queue *queue, struct tevent_context *ev, + struct async_req *req, + void (*trigger)(struct async_req *req)) +{ + struct async_queue_entry *e; + bool busy; + + busy = (queue->queue != NULL); + + e = talloc(req, struct async_queue_entry); + if (e == NULL) { + return false; + } + + e->req = req; + e->trigger = trigger; + e->queue = queue; + + DLIST_ADD_END(queue->queue, e, struct async_queue_entry *); + talloc_set_destructor(e, async_queue_entry_destructor); + + if (!busy) { + struct tevent_timer *te; + + te = tevent_add_timer(ev, e, timeval_zero(), + async_req_immediate_trigger, + e); + if (te == NULL) { + TALLOC_FREE(e); + return false; + } + } + + return true; +} + +bool _async_req_setup(TALLOC_CTX *mem_ctx, struct async_req **preq, + void *pstate, size_t state_size, const char *typename) +{ + struct async_req *req; + void **ppstate = (void **)pstate; + void *state; + + req = async_req_new(mem_ctx); + if (req == NULL) { + return false; + } + state = talloc_size(req, state_size); + if (state == NULL) { + TALLOC_FREE(req); + return false; + } + talloc_set_name_const(state, typename); + req->private_data = state; + + *preq = req; + *ppstate = state; + + return true; +} |