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
  22 #if WITH_PTHREADPOOL
  23
  24 #include "pthreadpool.h"
  25
  26 struct fncall_state {
  27         struct fncall_context *ctx;
  28         int job_id;
  29         bool done;
  30
  31         void *private_parent;
  32         void *job_private;
  33 };
  34
  35 struct fncall_context {
  36         struct pthreadpool *pool;
  37         int next_job_id;
  38         int sig_fd;
  39         struct tevent_req **pending;
  40
  41         struct fncall_state **orphaned;
  42         int num_orphaned;
  43
  44         struct fd_event *fde;
  45 };
  46
  47 static void fncall_handler(struct tevent_context *ev, struct tevent_fd *fde,
  48                            uint16_t flags, void *private_data);
  49
  50 static int fncall_context_destructor(struct fncall_context *ctx)
  51 {
  52         while (talloc_array_length(ctx->pending) != 0) {
  53                 /* No TALLOC_FREE here */
  54                 talloc_free(ctx->pending[0]);
  55         }
  56
  57         while (ctx->num_orphaned != 0) {
  58                 /*
  59                  * We've got jobs in the queue for which the tevent_req has
  60                  * been finished already. Wait for all of them to finish.
  61                  */
  62                 fncall_handler(NULL, NULL, TEVENT_FD_READ, ctx);
  63         }
  64
  65         pthreadpool_destroy(ctx->pool);
  66         ctx->pool = NULL;
  67
  68         return 0;
  69 }
  70
  71 struct fncall_context *fncall_context_init(TALLOC_CTX *mem_ctx,
  72                                            int max_threads)
  73 {
  74         struct fncall_context *ctx;
  75         int ret;
  76
  77         ctx = talloc_zero(mem_ctx, struct fncall_context);
  78         if (ctx == NULL) {
  79                 return NULL;
  80         }
  81
  82         ret = pthreadpool_init(max_threads, &ctx->pool);
  83         if (ret != 0) {
  84                 TALLOC_FREE(ctx);
  85                 return NULL;
  86         }
  87         talloc_set_destructor(ctx, fncall_context_destructor);
  88
  89         ctx->sig_fd = pthreadpool_sig_fd(ctx->pool);
  90         if (ctx->sig_fd == -1) {
  91                 TALLOC_FREE(ctx);
  92                 return NULL;
  93         }
  94
  95         return ctx;
  96 }
  97
  98 static int fncall_next_job_id(struct fncall_context *ctx)
  99 {
 100         int num_pending = talloc_array_length(ctx->pending);
 101         int result;
 102
 103         while (true) {
 104                 int i;
 105
 106                 result = ctx->next_job_id++;
 107                 if (result == 0) {
 108                         continue;
 109                 }
 110
 111                 for (i=0; i<num_pending; i++) {
 112                         struct fncall_state *state = tevent_req_data(
 113                                 ctx->pending[i], struct fncall_state);
 114
 115                         if (result == state->job_id) {
 116                                 break;
 117                         }
 118                 }
 119                 if (i == num_pending) {
 120                         return result;
 121                 }
 122         }
 123 }
 124
 125 static void fncall_unset_pending(struct tevent_req *req);
 126 static int fncall_destructor(struct tevent_req *req);
 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         talloc_set_destructor(req, fncall_destructor);
 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_destructor, 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         if (num_pending == 1) {
 189                 TALLOC_FREE(ctx->fde);
 190                 TALLOC_FREE(ctx->pending);
 191                 return;
 192         }
 193
 194         for (i=0; i<num_pending; i++) {
 195                 if (req == ctx->pending[i]) {
 196                         break;
 197                 }
 198         }
 199         if (i == num_pending) {
 200                 return;
 201         }
 202         if (num_pending > 1) {
 203                 ctx->pending[i] = ctx->pending[num_pending-1];
 204         }
 205         ctx->pending = talloc_realloc(NULL, ctx->pending, struct tevent_req *,
 206                                       num_pending - 1);
 207 }
 208
 209 static int fncall_destructor(struct tevent_req *req)
 210 {
 211         struct fncall_state *state = tevent_req_data(
 212                 req, struct fncall_state);
 213         struct fncall_context *ctx = state->ctx;
 214
 215         fncall_unset_pending(req);
 216
 217         if (state->done) {
 218                 return 0;
 219         }
 220
 221         /*
 222          * Keep around the state of the deleted request until the request has
 223          * finished in the helper thread. fncall_handler will destroy it.
 224          */
 225         ctx->orphaned[ctx->num_orphaned] = talloc_move(ctx->orphaned, &state);
 226         ctx->num_orphaned += 1;
 227
 228         return 0;
 229 }
 230
 231 struct tevent_req *fncall_send(TALLOC_CTX *mem_ctx, struct tevent_context *ev,
 232                                struct fncall_context *ctx,
 233                                void (*fn)(void *private_data),
 234                                void *private_data)
 235 {
 236         struct tevent_req *req;
 237         struct fncall_state *state;
 238         int ret;
 239
 240         req = tevent_req_create(mem_ctx, &state, struct fncall_state);
 241         if (req == NULL) {
 242                 return NULL;
 243         }
 244         state->ctx = ctx;
 245         state->job_id = fncall_next_job_id(state->ctx);
 246         state->done = false;
 247
 248         /*
 249          * We need to keep the private data we handed out to the thread around
 250          * as long as the job is not finished. This is a bit of an abstraction
 251          * violation, because the "req->state1->subreq->state2" (we're
 252          * "subreq", "req" is the request our caller creates) is broken to
 253          * "ctx->state2->state1", but we are right now in the destructor for
 254          * "subreq2", so what can we do. We need to keep state1 around,
 255          * otherwise the helper thread will have no place to put its results.
 256          */
 257
 258         state->private_parent = talloc_parent(private_data);
 259         state->job_private = talloc_move(state, &private_data);
 260
 261         ret = pthreadpool_add_job(state->ctx->pool, state->job_id, fn,
 262                                   state->job_private);
 263         if (ret == -1) {
 264                 tevent_req_error(req, errno);
 265                 return tevent_req_post(req, ev);
 266         }
 267         if (!fncall_set_pending(req, state->ctx, ev)) {
 268                 tevent_req_nomem(NULL, req);
 269                 return tevent_req_post(req, ev);
 270         }
 271         return req;
 272 }
 273
 274 static void fncall_handler(struct tevent_context *ev, struct tevent_fd *fde,
 275                            uint16_t flags, void *private_data)
 276 {
 277         struct fncall_context *ctx = talloc_get_type_abort(
 278                 private_data, struct fncall_context);
 279         int i, num_pending;
 280         int job_id;
 281
 282         job_id = pthreadpool_finished_job(ctx->pool);
 283         if (job_id <= 0) {
 284                 return;
 285         }
 286
 287         num_pending = talloc_array_length(ctx->pending);
 288
 289         for (i=0; i<num_pending; i++) {
 290                 struct fncall_state *state = tevent_req_data(
 291                         ctx->pending[i], struct fncall_state);
 292
 293                 if (job_id == state->job_id) {
 294                         state->done = true;
 295                         talloc_move(state->private_parent,
 296                                     &state->job_private);
 297                         tevent_req_done(ctx->pending[i]);
 298                         return;
 299                 }
 300         }
 301
 302         for (i=0; i<ctx->num_orphaned; i++) {
 303                 if (job_id == ctx->orphaned[i]->job_id) {
 304                         break;
 305                 }
 306         }
 307         if (i == ctx->num_orphaned) {
 308                 return;
 309         }
 310
 311         TALLOC_FREE(ctx->orphaned[i]);
 312
 313         if (i < ctx->num_orphaned-1) {
 314                 ctx->orphaned[i] = ctx->orphaned[ctx->num_orphaned-1];
 315         }
 316         ctx->num_orphaned -= 1;
 317 }
 318
 319 int fncall_recv(struct tevent_req *req, int *perr)
 320 {
 321         if (tevent_req_is_unix_error(req, perr)) {
 322                 return -1;
 323         }
 324         return 0;
 325 }
 326
 327 #else  /* WITH_PTHREADPOOL */
 328
 329 struct fncall_context {
 330         uint8_t dummy;
 331 };
 332
 333 struct fncall_context *fncall_context_init(TALLOC_CTX *mem_ctx,
 334                                            int max_threads)
 335 {
 336         return talloc(mem_ctx, struct fncall_context);
 337 }
 338
 339 struct fncall_state {
 340         uint8_t dummy;
 341 };
 342
 343 struct tevent_req *fncall_send(TALLOC_CTX *mem_ctx, struct tevent_context *ev,
 344                                struct fncall_context *ctx,
 345                                void (*fn)(void *private_data),
 346                                void *private_data)
 347 {
 348         struct tevent_req *req;
 349         struct fncall_state *state;
 350
 351         req = tevent_req_create(mem_ctx, &state, struct fncall_state);
 352         if (req == NULL) {
 353                 return NULL;
 354         }
 355         fn(private_data);
 356         tevent_req_post(req, ev);
 357         return req;
 358 }
 359
 360 int fncall_recv(struct tevent_req *req, int *perr)
 361 {
 362         return 0;
 363 }
 364
 365 #endif