source3/lib/fncall.c

   1 /*
   2  * Unix SMB/CIFS implementation.
   3  * Async fn calls
   4  * Copyright (C) Volker Lendecke 2009
   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/util/tevent_unix.h"
  22
  23 #include "lib/pthreadpool/pthreadpool.h"
  24
  25 struct fncall_state {
  26         struct fncall_context *ctx;
  27         int job_id;
  28         bool done;
  29
  30         void *private_parent;
  31         void *job_private;
  32 };
  33
  34 struct fncall_context {
  35         struct pthreadpool *pool;
  36         int next_job_id;
  37         int sig_fd;
  38         struct tevent_req **pending;
  39
  40         struct fncall_state **orphaned;
  41         int num_orphaned;
  42
  43         struct tevent_fd *fde;
  44 };
  45
  46 static void fncall_handler(struct tevent_context *ev, struct tevent_fd *fde,
  47                            uint16_t flags, void *private_data);
  48
  49 static int fncall_context_destructor(struct fncall_context *ctx)
  50 {
  51         while (talloc_array_length(ctx->pending) != 0) {
  52                 /* No TALLOC_FREE here */
  53                 talloc_free(ctx->pending[0]);
  54         }
  55
  56         while (ctx->num_orphaned != 0) {
  57                 /*
  58                  * We've got jobs in the queue for which the tevent_req has
  59                  * been finished already. Wait for all of them to finish.
  60                  */
  61                 fncall_handler(NULL, NULL, TEVENT_FD_READ, ctx);
  62         }
  63
  64         pthreadpool_destroy(ctx->pool);
  65         ctx->pool = NULL;
  66
  67         return 0;
  68 }
  69
  70 struct fncall_context *fncall_context_init(TALLOC_CTX *mem_ctx,
  71                                            int max_threads)
  72 {
  73         struct fncall_context *ctx;
  74         int ret;
  75
  76         ctx = talloc_zero(mem_ctx, struct fncall_context);
  77         if (ctx == NULL) {
  78                 return NULL;
  79         }
  80
  81         ret = pthreadpool_init(max_threads, &ctx->pool);
  82         if (ret != 0) {
  83                 TALLOC_FREE(ctx);
  84                 return NULL;
  85         }
  86         talloc_set_destructor(ctx, fncall_context_destructor);
  87
  88         ctx->sig_fd = pthreadpool_signal_fd(ctx->pool);
  89         if (ctx->sig_fd == -1) {
  90                 TALLOC_FREE(ctx);
  91                 return NULL;
  92         }
  93
  94         return ctx;
  95 }
  96
  97 static int fncall_next_job_id(struct fncall_context *ctx)
  98 {
  99         int num_pending = talloc_array_length(ctx->pending);
 100         int result;
 101
 102         while (true) {
 103                 int i;
 104
 105                 result = ctx->next_job_id++;
 106                 if (result == 0) {
 107                         continue;
 108                 }
 109
 110                 for (i=0; i<num_pending; i++) {
 111                         struct fncall_state *state = tevent_req_data(
 112                                 ctx->pending[i], struct fncall_state);
 113
 114                         if (result == state->job_id) {
 115                                 break;
 116                         }
 117                 }
 118                 if (i == num_pending) {
 119                         return result;
 120                 }
 121         }
 122 }
 123
 124 static void fncall_unset_pending(struct tevent_req *req);
 125 static void fncall_cleanup(struct tevent_req *req,
 126                            enum tevent_req_state req_state);
 127
 128 static bool fncall_set_pending(struct tevent_req *req,
 129                                struct fncall_context *ctx,
 130                                struct tevent_context *ev)
 131 {
 132         struct tevent_req **pending;
 133         int num_pending, orphaned_array_length;
 134
 135         num_pending = talloc_array_length(ctx->pending);
 136
 137         pending = talloc_realloc(ctx, ctx->pending, struct tevent_req *,
 138                                  num_pending+1);
 139         if (pending == NULL) {
 140                 return false;
 141         }
 142         pending[num_pending] = req;
 143         num_pending += 1;
 144         ctx->pending = pending;
 145         tevent_req_set_cleanup_fn(req, fncall_cleanup);
 146
 147         /*
 148          * Make sure that the orphaned array of fncall_state structs has
 149          * enough space. A job can change from pending to orphaned in
 150          * fncall_cleanup, and to fail in a talloc destructor should be
 151          * avoided if possible.
 152          */
 153
 154         orphaned_array_length = talloc_array_length(ctx->orphaned);
 155         if (num_pending > orphaned_array_length) {
 156                 struct fncall_state **orphaned;
 157
 158                 orphaned = talloc_realloc(ctx, ctx->orphaned,
 159                                           struct fncall_state *,
 160                                           orphaned_array_length + 1);
 161                 if (orphaned == NULL) {
 162                         fncall_unset_pending(req);
 163                         return false;
 164                 }
 165                 ctx->orphaned = orphaned;
 166         }
 167
 168         if (ctx->fde != NULL) {
 169                 return true;
 170         }
 171
 172         ctx->fde = tevent_add_fd(ev, ctx->pending, ctx->sig_fd, TEVENT_FD_READ,
 173                                  fncall_handler, ctx);
 174         if (ctx->fde == NULL) {
 175                 fncall_unset_pending(req);
 176                 return false;
 177         }
 178         return true;
 179 }
 180
 181 static void fncall_unset_pending(struct tevent_req *req)
 182 {
 183         struct fncall_state *state = tevent_req_data(req, struct fncall_state);
 184         struct fncall_context *ctx = state->ctx;
 185         int num_pending = talloc_array_length(ctx->pending);
 186         int i;
 187
 188         tevent_req_set_cleanup_fn(req, NULL);
 189
 190         if (num_pending == 1) {
 191                 TALLOC_FREE(ctx->fde);
 192                 TALLOC_FREE(ctx->pending);
 193                 return;
 194         }
 195
 196         for (i=0; i<num_pending; i++) {
 197                 if (req == ctx->pending[i]) {
 198                         break;
 199                 }
 200         }
 201         if (i == num_pending) {
 202                 return;
 203         }
 204         if (num_pending > 1) {
 205                 ctx->pending[i] = ctx->pending[num_pending-1];
 206         }
 207         ctx->pending = talloc_realloc(NULL, ctx->pending, struct tevent_req *,
 208                                       num_pending - 1);
 209 }
 210
 211 static void fncall_cleanup(struct tevent_req *req,
 212                            enum tevent_req_state req_state)
 213 {
 214         struct fncall_state *state = tevent_req_data(
 215                 req, struct fncall_state);
 216         struct fncall_context *ctx = state->ctx;
 217
 218         switch (req_state) {
 219         case TEVENT_REQ_RECEIVED:
 220                 break;
 221         default:
 222                 return;
 223         }
 224
 225         fncall_unset_pending(req);
 226
 227         if (state->done) {
 228                 return;
 229         }
 230
 231         /*
 232          * Keep around the state of the deleted request until the request has
 233          * finished in the helper thread. fncall_handler will destroy it.
 234          */
 235         ctx->orphaned[ctx->num_orphaned] = talloc_move(ctx->orphaned, &state);
 236         ctx->num_orphaned += 1;
 237 }
 238
 239 struct tevent_req *fncall_send(TALLOC_CTX *mem_ctx, struct tevent_context *ev,
 240                                struct fncall_context *ctx,
 241                                void (*fn)(void *private_data),
 242                                void *private_data)
 243 {
 244         struct tevent_req *req;
 245         struct fncall_state *state;
 246         int ret;
 247
 248         req = tevent_req_create(mem_ctx, &state, struct fncall_state);
 249         if (req == NULL) {
 250                 return NULL;
 251         }
 252         state->ctx = ctx;
 253         state->job_id = fncall_next_job_id(state->ctx);
 254         state->done = false;
 255
 256         /*
 257          * We need to keep the private data we handed out to the thread around
 258          * as long as the job is not finished. This is a bit of an abstraction
 259          * violation, because the "req->state1->subreq->state2" (we're
 260          * "subreq", "req" is the request our caller creates) is broken to
 261          * "ctx->state2->state1", but we are right now in the destructor for
 262          * "subreq2", so what can we do. We need to keep state1 around,
 263          * otherwise the helper thread will have no place to put its results.
 264          */
 265
 266         state->private_parent = talloc_parent(private_data);
 267         state->job_private = talloc_move(state, &private_data);
 268
 269         ret = pthreadpool_add_job(state->ctx->pool, state->job_id, fn,
 270                                   state->job_private);
 271         if (ret == -1) {
 272                 tevent_req_error(req, errno);
 273                 return tevent_req_post(req, ev);
 274         }
 275         if (!fncall_set_pending(req, state->ctx, ev)) {
 276                 tevent_req_oom(req);
 277                 return tevent_req_post(req, ev);
 278         }
 279         return req;
 280 }
 281
 282 static void fncall_handler(struct tevent_context *ev, struct tevent_fd *fde,
 283                            uint16_t flags, void *private_data)
 284 {
 285         struct fncall_context *ctx = talloc_get_type_abort(
 286                 private_data, struct fncall_context);
 287         int i, num_pending;
 288         int job_id;
 289
 290         if (pthreadpool_finished_jobs(ctx->pool, &job_id, 1) < 0) {
 291                 return;
 292         }
 293
 294         num_pending = talloc_array_length(ctx->pending);
 295
 296         for (i=0; i<num_pending; i++) {
 297                 struct fncall_state *state = tevent_req_data(
 298                         ctx->pending[i], struct fncall_state);
 299
 300                 if (job_id == state->job_id) {
 301                         state->done = true;
 302                         talloc_move(state->private_parent,
 303                                     &state->job_private);
 304                         tevent_req_done(ctx->pending[i]);
 305                         return;
 306                 }
 307         }
 308
 309         for (i=0; i<ctx->num_orphaned; i++) {
 310                 if (job_id == ctx->orphaned[i]->job_id) {
 311                         break;
 312                 }
 313         }
 314         if (i == ctx->num_orphaned) {
 315                 return;
 316         }
 317
 318         TALLOC_FREE(ctx->orphaned[i]);
 319
 320         if (i < ctx->num_orphaned-1) {
 321                 ctx->orphaned[i] = ctx->orphaned[ctx->num_orphaned-1];
 322         }
 323         ctx->num_orphaned -= 1;
 324 }
 325
 326 int fncall_recv(struct tevent_req *req, int *perr)
 327 {
 328         if (tevent_req_is_unix_error(req, perr)) {
 329                 return -1;
 330         }
 331         return 0;
 332 }