util/aio-win32.c

   1 /*
   2  * QEMU aio implementation
   3  *
   4  * Copyright IBM Corp., 2008
   5  * Copyright Red Hat Inc., 2012
   6  *
   7  * Authors:
   8  *  Anthony Liguori   <aliguori@us.ibm.com>
   9  *  Paolo Bonzini     <pbonzini@redhat.com>
  10  *
  11  * This work is licensed under the terms of the GNU GPL, version 2.  See
  12  * the COPYING file in the top-level directory.
  13  *
  14  * Contributions after 2012-01-13 are licensed under the terms of the
  15  * GNU GPL, version 2 or (at your option) any later version.
  16  */
  17
  18 #include "qemu/osdep.h"
  19 #include "qemu-common.h"
  20 #include "block/block.h"
  21 #include "qemu/queue.h"
  22 #include "qemu/sockets.h"
  23 #include "qapi/error.h"
  24 #include "qemu/rcu_queue.h"
  25
  26 struct AioHandler {
  27     EventNotifier *e;
  28     IOHandler *io_read;
  29     IOHandler *io_write;
  30     EventNotifierHandler *io_notify;
  31     GPollFD pfd;
  32     int deleted;
  33     void *opaque;
  34     bool is_external;
  35     QLIST_ENTRY(AioHandler) node;
  36 };
  37
  38 void aio_set_fd_handler(AioContext *ctx,
  39                         int fd,
  40                         bool is_external,
  41                         IOHandler *io_read,
  42                         IOHandler *io_write,
  43                         AioPollFn *io_poll,
  44                         void *opaque)
  45 {
  46     /* fd is a SOCKET in our case */
  47     AioHandler *node;
  48
  49     qemu_lockcnt_lock(&ctx->list_lock);
  50     QLIST_FOREACH(node, &ctx->aio_handlers, node) {
  51         if (node->pfd.fd == fd && !node->deleted) {
  52             break;
  53         }
  54     }
  55
  56     /* Are we deleting the fd handler? */
  57     if (!io_read && !io_write) {
  58         if (node) {
  59             /* If aio_poll is in progress, just mark the node as deleted */
  60             if (qemu_lockcnt_count(&ctx->list_lock)) {
  61                 node->deleted = 1;
  62                 node->pfd.revents = 0;
  63             } else {
  64                 /* Otherwise, delete it for real.  We can't just mark it as
  65                  * deleted because deleted nodes are only cleaned up after
  66                  * releasing the list_lock.
  67                  */
  68                 QLIST_REMOVE(node, node);
  69                 g_free(node);
  70             }
  71         }
  72     } else {
  73         HANDLE event;
  74
  75         if (node == NULL) {
  76             /* Alloc and insert if it's not already there */
  77             node = g_new0(AioHandler, 1);
  78             node->pfd.fd = fd;
  79             QLIST_INSERT_HEAD_RCU(&ctx->aio_handlers, node, node);
  80         }
  81
  82         node->pfd.events = 0;
  83         if (node->io_read) {
  84             node->pfd.events |= G_IO_IN;
  85         }
  86         if (node->io_write) {
  87             node->pfd.events |= G_IO_OUT;
  88         }
  89
  90         node->e = &ctx->notifier;
  91
  92         /* Update handler with latest information */
  93         node->opaque = opaque;
  94         node->io_read = io_read;
  95         node->io_write = io_write;
  96         node->is_external = is_external;
  97
  98         event = event_notifier_get_handle(&ctx->notifier);
  99         WSAEventSelect(node->pfd.fd, event,
 100                        FD_READ | FD_ACCEPT | FD_CLOSE |
 101                        FD_CONNECT | FD_WRITE | FD_OOB);
 102     }
 103
 104     qemu_lockcnt_unlock(&ctx->list_lock);
 105     aio_notify(ctx);
 106 }
 107
 108 void aio_set_fd_poll(AioContext *ctx, int fd,
 109                      IOHandler *io_poll_begin,
 110                      IOHandler *io_poll_end)
 111 {
 112     /* Not implemented */
 113 }
 114
 115 void aio_set_event_notifier(AioContext *ctx,
 116                             EventNotifier *e,
 117                             bool is_external,
 118                             EventNotifierHandler *io_notify,
 119                             AioPollFn *io_poll)
 120 {
 121     AioHandler *node;
 122
 123     qemu_lockcnt_lock(&ctx->list_lock);
 124     QLIST_FOREACH(node, &ctx->aio_handlers, node) {
 125         if (node->e == e && !node->deleted) {
 126             break;
 127         }
 128     }
 129
 130     /* Are we deleting the fd handler? */
 131     if (!io_notify) {
 132         if (node) {
 133             g_source_remove_poll(&ctx->source, &node->pfd);
 134
 135             /* aio_poll is in progress, just mark the node as deleted */
 136             if (qemu_lockcnt_count(&ctx->list_lock)) {
 137                 node->deleted = 1;
 138                 node->pfd.revents = 0;
 139             } else {
 140                 /* Otherwise, delete it for real.  We can't just mark it as
 141                  * deleted because deleted nodes are only cleaned up after
 142                  * releasing the list_lock.
 143                  */
 144                 QLIST_REMOVE(node, node);
 145                 g_free(node);
 146             }
 147         }
 148     } else {
 149         if (node == NULL) {
 150             /* Alloc and insert if it's not already there */
 151             node = g_new0(AioHandler, 1);
 152             node->e = e;
 153             node->pfd.fd = (uintptr_t)event_notifier_get_handle(e);
 154             node->pfd.events = G_IO_IN;
 155             node->is_external = is_external;
 156             QLIST_INSERT_HEAD_RCU(&ctx->aio_handlers, node, node);
 157
 158             g_source_add_poll(&ctx->source, &node->pfd);
 159         }
 160         /* Update handler with latest information */
 161         node->io_notify = io_notify;
 162     }
 163
 164     qemu_lockcnt_unlock(&ctx->list_lock);
 165     aio_notify(ctx);
 166 }
 167
 168 void aio_set_event_notifier_poll(AioContext *ctx,
 169                                  EventNotifier *notifier,
 170                                  EventNotifierHandler *io_poll_begin,
 171                                  EventNotifierHandler *io_poll_end)
 172 {
 173     /* Not implemented */
 174 }
 175
 176 bool aio_prepare(AioContext *ctx)
 177 {
 178     static struct timeval tv0;
 179     AioHandler *node;
 180     bool have_select_revents = false;
 181     fd_set rfds, wfds;
 182
 183     /*
 184      * We have to walk very carefully in case aio_set_fd_handler is
 185      * called while we're walking.
 186      */
 187     qemu_lockcnt_inc(&ctx->list_lock);
 188
 189     /* fill fd sets */
 190     FD_ZERO(&rfds);
 191     FD_ZERO(&wfds);
 192     QLIST_FOREACH_RCU(node, &ctx->aio_handlers, node) {
 193         if (node->io_read) {
 194             FD_SET ((SOCKET)node->pfd.fd, &rfds);
 195         }
 196         if (node->io_write) {
 197             FD_SET ((SOCKET)node->pfd.fd, &wfds);
 198         }
 199     }
 200
 201     if (select(0, &rfds, &wfds, NULL, &tv0) > 0) {
 202         QLIST_FOREACH_RCU(node, &ctx->aio_handlers, node) {
 203             node->pfd.revents = 0;
 204             if (FD_ISSET(node->pfd.fd, &rfds)) {
 205                 node->pfd.revents |= G_IO_IN;
 206                 have_select_revents = true;
 207             }
 208
 209             if (FD_ISSET(node->pfd.fd, &wfds)) {
 210                 node->pfd.revents |= G_IO_OUT;
 211                 have_select_revents = true;
 212             }
 213         }
 214     }
 215
 216     qemu_lockcnt_dec(&ctx->list_lock);
 217     return have_select_revents;
 218 }
 219
 220 bool aio_pending(AioContext *ctx)
 221 {
 222     AioHandler *node;
 223     bool result = false;
 224
 225     /*
 226      * We have to walk very carefully in case aio_set_fd_handler is
 227      * called while we're walking.
 228      */
 229     qemu_lockcnt_inc(&ctx->list_lock);
 230     QLIST_FOREACH_RCU(node, &ctx->aio_handlers, node) {
 231         if (node->pfd.revents && node->io_notify) {
 232             result = true;
 233             break;
 234         }
 235
 236         if ((node->pfd.revents & G_IO_IN) && node->io_read) {
 237             result = true;
 238             break;
 239         }
 240         if ((node->pfd.revents & G_IO_OUT) && node->io_write) {
 241             result = true;
 242             break;
 243         }
 244     }
 245
 246     qemu_lockcnt_dec(&ctx->list_lock);
 247     return result;
 248 }
 249
 250 static bool aio_dispatch_handlers(AioContext *ctx, HANDLE event)
 251 {
 252     AioHandler *node;
 253     bool progress = false;
 254     AioHandler *tmp;
 255
 256     qemu_lockcnt_inc(&ctx->list_lock);
 257
 258     /*
 259      * We have to walk very carefully in case aio_set_fd_handler is
 260      * called while we're walking.
 261      */
 262     QLIST_FOREACH_SAFE_RCU(node, &ctx->aio_handlers, node, tmp) {
 263         int revents = node->pfd.revents;
 264
 265         if (!node->deleted &&
 266             (revents || event_notifier_get_handle(node->e) == event) &&
 267             node->io_notify) {
 268             node->pfd.revents = 0;
 269             node->io_notify(node->e);
 270
 271             /* aio_notify() does not count as progress */
 272             if (node->e != &ctx->notifier) {
 273                 progress = true;
 274             }
 275         }
 276
 277         if (!node->deleted &&
 278             (node->io_read || node->io_write)) {
 279             node->pfd.revents = 0;
 280             if ((revents & G_IO_IN) && node->io_read) {
 281                 node->io_read(node->opaque);
 282                 progress = true;
 283             }
 284             if ((revents & G_IO_OUT) && node->io_write) {
 285                 node->io_write(node->opaque);
 286                 progress = true;
 287             }
 288
 289             /* if the next select() will return an event, we have progressed */
 290             if (event == event_notifier_get_handle(&ctx->notifier)) {
 291                 WSANETWORKEVENTS ev;
 292                 WSAEnumNetworkEvents(node->pfd.fd, event, &ev);
 293                 if (ev.lNetworkEvents) {
 294                     progress = true;
 295                 }
 296             }
 297         }
 298
 299         if (node->deleted) {
 300             if (qemu_lockcnt_dec_if_lock(&ctx->list_lock)) {
 301                 QLIST_REMOVE(node, node);
 302                 g_free(node);
 303                 qemu_lockcnt_inc_and_unlock(&ctx->list_lock);
 304             }
 305         }
 306     }
 307
 308     qemu_lockcnt_dec(&ctx->list_lock);
 309     return progress;
 310 }
 311
 312 void aio_dispatch(AioContext *ctx)
 313 {
 314     aio_bh_poll(ctx);
 315     aio_dispatch_handlers(ctx, INVALID_HANDLE_VALUE);
 316     timerlistgroup_run_timers(&ctx->tlg);
 317 }
 318
 319 bool aio_poll(AioContext *ctx, bool blocking)
 320 {
 321     AioHandler *node;
 322     HANDLE events[MAXIMUM_WAIT_OBJECTS + 1];
 323     bool progress, have_select_revents, first;
 324     int count;
 325     int timeout;
 326
 327     progress = false;
 328
 329     /* aio_notify can avoid the expensive event_notifier_set if
 330      * everything (file descriptors, bottom halves, timers) will
 331      * be re-evaluated before the next blocking poll().  This is
 332      * already true when aio_poll is called with blocking == false;
 333      * if blocking == true, it is only true after poll() returns,
 334      * so disable the optimization now.
 335      */
 336     if (blocking) {
 337         atomic_add(&ctx->notify_me, 2);
 338     }
 339
 340     qemu_lockcnt_inc(&ctx->list_lock);
 341     have_select_revents = aio_prepare(ctx);
 342
 343     /* fill fd sets */
 344     count = 0;
 345     QLIST_FOREACH_RCU(node, &ctx->aio_handlers, node) {
 346         if (!node->deleted && node->io_notify
 347             && aio_node_check(ctx, node->is_external)) {
 348             events[count++] = event_notifier_get_handle(node->e);
 349         }
 350     }
 351
 352     qemu_lockcnt_dec(&ctx->list_lock);
 353     first = true;
 354
 355     /* ctx->notifier is always registered.  */
 356     assert(count > 0);
 357
 358     /* Multiple iterations, all of them non-blocking except the first,
 359      * may be necessary to process all pending events.  After the first
 360      * WaitForMultipleObjects call ctx->notify_me will be decremented.
 361      */
 362     do {
 363         HANDLE event;
 364         int ret;
 365
 366         timeout = blocking && !have_select_revents
 367             ? qemu_timeout_ns_to_ms(aio_compute_timeout(ctx)) : 0;
 368         ret = WaitForMultipleObjects(count, events, FALSE, timeout);
 369         if (blocking) {
 370             assert(first);
 371             atomic_sub(&ctx->notify_me, 2);
 372         }
 373
 374         if (first) {
 375             aio_notify_accept(ctx);
 376             progress |= aio_bh_poll(ctx);
 377             first = false;
 378         }
 379
 380         /* if we have any signaled events, dispatch event */
 381         event = NULL;
 382         if ((DWORD) (ret - WAIT_OBJECT_0) < count) {
 383             event = events[ret - WAIT_OBJECT_0];
 384             events[ret - WAIT_OBJECT_0] = events[--count];
 385         } else if (!have_select_revents) {
 386             break;
 387         }
 388
 389         have_select_revents = false;
 390         blocking = false;
 391
 392         progress |= aio_dispatch_handlers(ctx, event);
 393     } while (count > 0);
 394
 395     progress |= timerlistgroup_run_timers(&ctx->tlg);
 396     return progress;
 397 }
 398
 399 void aio_context_setup(AioContext *ctx)
 400 {
 401 }
 402
 403 void aio_context_set_poll_params(AioContext *ctx, int64_t max_ns,
 404                                  int64_t grow, int64_t shrink, Error **errp)
 405 {
 406     error_setg(errp, "AioContext polling is not implemented on Windows");
 407 }