lib/async_req/async_req.c

   1 /*
   2    Unix SMB/CIFS implementation.
   3    Infrastructure for async requests
   4    Copyright (C) Volker Lendecke 2008
   5
   6    This program is free software; you can redistribute it and/or modify
   7    it under the terms of the GNU General Public License as published by
   8    the Free Software Foundation; either version 3 of the License, or
   9    (at your option) any later version.
  10
  11    This program is distributed in the hope that it will be useful,
  12    but WITHOUT ANY WARRANTY; without even the implied warranty of
  13    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14    GNU General Public License for more details.
  15
  16    You should have received a copy of the GNU General Public License
  17    along with this program.  If not, see <http://www.gnu.org/licenses/>.
  18 */
  19
  20 #include "includes.h"
  21 #include "lib/tevent/tevent.h"
  22 #include "lib/talloc/talloc.h"
  23 #include "lib/util/dlinklist.h"
  24 #include "lib/async_req/async_req.h"
  25
  26 #ifndef TALLOC_FREE
  27 #define TALLOC_FREE(ctx) do { talloc_free(ctx); ctx=NULL; } while(0)
  28 #endif
  29
  30 /**
  31  * @brief Print an async_req structure
  32  * @param[in] mem_ctx   The memory context for the result
  33  * @param[in] req       The request to be printed
  34  * @retval              Text representation of req
  35  *
  36  * This is a default print function for async requests. Implementations should
  37  * override this with more specific information.
  38  *
  39  * This function should not be used by async API users, this is non-static
  40  * only to allow implementations to easily provide default information in
  41  * their specific functions.
  42  */
  43
  44 char *async_req_print(TALLOC_CTX *mem_ctx, struct async_req *req)
  45 {
  46         return talloc_asprintf(mem_ctx, "async_req: state=%d, error=%d, "
  47                                "priv=%s", req->state, (int)req->error,
  48                                talloc_get_name(req->private_data));
  49 }
  50
  51 /**
  52  * @brief Create an async request
  53  * @param[in] mem_ctx   The memory context for the result
  54  * @param[in] ev        The event context this async request will be driven by
  55  * @retval              A new async request
  56  *
  57  * The new async request will be initialized in state ASYNC_REQ_IN_PROGRESS
  58  */
  59
  60 struct async_req *async_req_new(TALLOC_CTX *mem_ctx)
  61 {
  62         struct async_req *result;
  63
  64         result = talloc_zero(mem_ctx, struct async_req);
  65         if (result == NULL) {
  66                 return NULL;
  67         }
  68         result->state = ASYNC_REQ_IN_PROGRESS;
  69         result->print = async_req_print;
  70         return result;
  71 }
  72
  73 /**
  74  * @brief An async request has successfully finished
  75  * @param[in] req       The finished request
  76  *
  77  * async_req_done is to be used by implementors of async requests. When a
  78  * request is successfully finished, this function calls the user's completion
  79  * function.
  80  */
  81
  82 void async_req_done(struct async_req *req)
  83 {
  84         req->error = 0;
  85         req->state = ASYNC_REQ_DONE;
  86         if (req->async.fn != NULL) {
  87                 req->async.fn(req);
  88         }
  89 }
  90
  91 /**
  92  * @brief An async request has seen an error
  93  * @param[in] req       The request with an error
  94  * @param[in] status    The error code
  95  *
  96  * async_req_done is to be used by implementors of async requests. When a
  97  * request can not successfully completed, the implementation should call this
  98  * function with the appropriate status code.
  99  */
 100
 101 void async_req_error(struct async_req *req, uint32_t error)
 102 {
 103         req->error = error;
 104         req->state = ASYNC_REQ_ERROR;
 105         if (req->async.fn != NULL) {
 106                 req->async.fn(req);
 107         }
 108 }
 109
 110 /**
 111  * @brief Timed event callback
 112  * @param[in] ev        Event context
 113  * @param[in] te        The timed event
 114  * @param[in] now       zero time
 115  * @param[in] priv      The async request to be finished
 116  */
 117
 118 static void async_trigger(struct tevent_context *ev, struct tevent_timer *te,
 119                           struct timeval now, void *priv)
 120 {
 121         struct async_req *req = talloc_get_type_abort(priv, struct async_req);
 122
 123         TALLOC_FREE(te);
 124         if (req->error == 0) {
 125                 async_req_done(req);
 126         }
 127         else {
 128                 async_req_error(req, req->error);
 129         }
 130 }
 131
 132 /**
 133  * @brief Finish a request before it started processing
 134  * @param[in] req       The finished request
 135  * @param[in] status    The success code
 136  *
 137  * An implementation of an async request might find that it can either finish
 138  * the request without waiting for an external event, or it can't even start
 139  * the engine. To present the illusion of a callback to the user of the API,
 140  * the implementation can call this helper function which triggers an
 141  * immediate timed event. This way the caller can use the same calling
 142  * conventions, independent of whether the request was actually deferred.
 143  */
 144
 145 bool async_post_error(struct async_req *req, struct tevent_context *ev,
 146                       uint32_t error)
 147 {
 148         req->error = error;
 149
 150         if (tevent_add_timer(ev, req, timeval_zero(),
 151                             async_trigger, req) == NULL) {
 152                 return false;
 153         }
 154         return true;
 155 }
 156
 157 bool async_req_is_error(struct async_req *req, uint32_t *error)
 158 {
 159         if (req->state < ASYNC_REQ_DONE) {
 160                 return true;
 161         }
 162         if (req->state == ASYNC_REQ_ERROR) {
 163                 *error = req->error;
 164                 return true;
 165         }
 166         return false;
 167 }
 168
 169 static void async_req_timedout(struct tevent_context *ev,
 170                                struct tevent_timer *te,
 171                                struct timeval now,
 172                                void *priv)
 173 {
 174         struct async_req *req = talloc_get_type_abort(
 175                 priv, struct async_req);
 176         TALLOC_FREE(te);
 177         async_req_nterror(req, NT_STATUS_IO_TIMEOUT);
 178 }
 179
 180 bool async_req_set_timeout(struct async_req *req, struct tevent_context *ev,
 181                            struct timeval to)
 182 {
 183         return (tevent_add_timer(ev, req,
 184                                 timeval_current_ofs(to.tv_sec, to.tv_usec),
 185                                 async_req_timedout, req)
 186                 != NULL);
 187 }
 188
 189 struct async_req *async_wait_send(TALLOC_CTX *mem_ctx,
 190                                   struct tevent_context *ev,
 191                                   struct timeval to)
 192 {
 193         struct async_req *result;
 194
 195         result = async_req_new(mem_ctx);
 196         if (result == NULL) {
 197                 return result;
 198         }
 199         if (!async_req_set_timeout(result, ev, to)) {
 200                 TALLOC_FREE(result);
 201                 return NULL;
 202         }
 203         return result;
 204 }
 205
 206 bool async_wait_recv(struct async_req *req)
 207 {
 208         return true;
 209 }
 210
 211 struct async_queue_entry {
 212         struct async_queue_entry *prev, *next;
 213         struct async_req_queue *queue;
 214         struct async_req *req;
 215         void (*trigger)(struct async_req *req);
 216 };
 217
 218 struct async_req_queue {
 219         struct async_queue_entry *queue;
 220 };
 221
 222 struct async_req_queue *async_req_queue_init(TALLOC_CTX *mem_ctx)
 223 {
 224         return talloc_zero(mem_ctx, struct async_req_queue);
 225 }
 226
 227 static int async_queue_entry_destructor(struct async_queue_entry *e)
 228 {
 229         struct async_req_queue *queue = e->queue;
 230
 231         DLIST_REMOVE(queue->queue, e);
 232
 233         if (queue->queue != NULL) {
 234                 queue->queue->trigger(queue->queue->req);
 235         }
 236
 237         return 0;
 238 }
 239
 240 static void async_req_immediate_trigger(struct tevent_context *ev,
 241                                         struct tevent_timer *te,
 242                                         struct timeval now,
 243                                         void *priv)
 244 {
 245         struct async_queue_entry *e = talloc_get_type_abort(
 246                 priv, struct async_queue_entry);
 247
 248         TALLOC_FREE(te);
 249         e->trigger(e->req);
 250 }
 251
 252 bool async_req_enqueue(struct async_req_queue *queue, struct tevent_context *ev,
 253                        struct async_req *req,
 254                        void (*trigger)(struct async_req *req))
 255 {
 256         struct async_queue_entry *e;
 257         bool busy;
 258
 259         busy = (queue->queue != NULL);
 260
 261         e = talloc(req, struct async_queue_entry);
 262         if (e == NULL) {
 263                 return false;
 264         }
 265
 266         e->req = req;
 267         e->trigger = trigger;
 268         e->queue = queue;
 269
 270         DLIST_ADD_END(queue->queue, e, struct async_queue_entry *);
 271         talloc_set_destructor(e, async_queue_entry_destructor);
 272
 273         if (!busy) {
 274                 struct tevent_timer *te;
 275
 276                 te = tevent_add_timer(ev, e, timeval_zero(),
 277                                      async_req_immediate_trigger,
 278                                      e);
 279                 if (te == NULL) {
 280                         TALLOC_FREE(e);
 281                         return false;
 282                 }
 283         }
 284
 285         return true;
 286 }
 287
 288 bool _async_req_setup(TALLOC_CTX *mem_ctx, struct async_req **preq,
 289                       void *pstate, size_t state_size, const char *typename)
 290 {
 291         struct async_req *req;
 292         void **ppstate = (void **)pstate;
 293         void *state;
 294
 295         req = async_req_new(mem_ctx);
 296         if (req == NULL) {
 297                 return false;
 298         }
 299         state = talloc_size(req, state_size);
 300         if (state == NULL) {
 301                 TALLOC_FREE(req);
 302                 return false;
 303         }
 304         talloc_set_name_const(state, typename);
 305         req->private_data = state;
 306
 307         *preq = req;
 308         *ppstate = state;
 309
 310         return true;
 311 }