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-common.h"
  19 #include "block/block.h"
  20 #include "qemu/queue.h"
  21 #include "qemu/sockets.h"
  22
  23 struct AioHandler {
  24     EventNotifier *e;
  25     IOHandler *io_read;
  26     IOHandler *io_write;
  27     EventNotifierHandler *io_notify;
  28     GPollFD pfd;
  29     int deleted;
  30     void *opaque;
  31     QLIST_ENTRY(AioHandler) node;
  32 };
  33
  34 void aio_set_fd_handler(AioContext *ctx,
  35                         int fd,
  36                         IOHandler *io_read,
  37                         IOHandler *io_write,
  38                         void *opaque)
  39 {
  40     /* fd is a SOCKET in our case */
  41     AioHandler *node;
  42
  43     QLIST_FOREACH(node, &ctx->aio_handlers, node) {
  44         if (node->pfd.fd == fd && !node->deleted) {
  45             break;
  46         }
  47     }
  48
  49     /* Are we deleting the fd handler? */
  50     if (!io_read && !io_write) {
  51         if (node) {
  52             /* If the lock is held, just mark the node as deleted */
  53             if (ctx->walking_handlers) {
  54                 node->deleted = 1;
  55                 node->pfd.revents = 0;
  56             } else {
  57                 /* Otherwise, delete it for real.  We can't just mark it as
  58                  * deleted because deleted nodes are only cleaned up after
  59                  * releasing the walking_handlers lock.
  60                  */
  61                 QLIST_REMOVE(node, node);
  62                 g_free(node);
  63             }
  64         }
  65     } else {
  66         HANDLE event;
  67
  68         if (node == NULL) {
  69             /* Alloc and insert if it's not already there */
  70             node = g_new0(AioHandler, 1);
  71             node->pfd.fd = fd;
  72             QLIST_INSERT_HEAD(&ctx->aio_handlers, node, node);
  73         }
  74
  75         node->pfd.events = 0;
  76         if (node->io_read) {
  77             node->pfd.events |= G_IO_IN;
  78         }
  79         if (node->io_write) {
  80             node->pfd.events |= G_IO_OUT;
  81         }
  82
  83         node->e = &ctx->notifier;
  84
  85         /* Update handler with latest information */
  86         node->opaque = opaque;
  87         node->io_read = io_read;
  88         node->io_write = io_write;
  89
  90         event = event_notifier_get_handle(&ctx->notifier);
  91         WSAEventSelect(node->pfd.fd, event,
  92                        FD_READ | FD_ACCEPT | FD_CLOSE |
  93                        FD_CONNECT | FD_WRITE | FD_OOB);
  94     }
  95
  96     aio_notify(ctx);
  97 }
  98
  99 void aio_set_event_notifier(AioContext *ctx,
 100                             EventNotifier *e,
 101                             EventNotifierHandler *io_notify)
 102 {
 103     AioHandler *node;
 104
 105     QLIST_FOREACH(node, &ctx->aio_handlers, node) {
 106         if (node->e == e && !node->deleted) {
 107             break;
 108         }
 109     }
 110
 111     /* Are we deleting the fd handler? */
 112     if (!io_notify) {
 113         if (node) {
 114             g_source_remove_poll(&ctx->source, &node->pfd);
 115
 116             /* If the lock is held, just mark the node as deleted */
 117             if (ctx->walking_handlers) {
 118                 node->deleted = 1;
 119                 node->pfd.revents = 0;
 120             } else {
 121                 /* Otherwise, delete it for real.  We can't just mark it as
 122                  * deleted because deleted nodes are only cleaned up after
 123                  * releasing the walking_handlers lock.
 124                  */
 125                 QLIST_REMOVE(node, node);
 126                 g_free(node);
 127             }
 128         }
 129     } else {
 130         if (node == NULL) {
 131             /* Alloc and insert if it's not already there */
 132             node = g_new0(AioHandler, 1);
 133             node->e = e;
 134             node->pfd.fd = (uintptr_t)event_notifier_get_handle(e);
 135             node->pfd.events = G_IO_IN;
 136             QLIST_INSERT_HEAD(&ctx->aio_handlers, node, node);
 137
 138             g_source_add_poll(&ctx->source, &node->pfd);
 139         }
 140         /* Update handler with latest information */
 141         node->io_notify = io_notify;
 142     }
 143
 144     aio_notify(ctx);
 145 }
 146
 147 bool aio_prepare(AioContext *ctx)
 148 {
 149     static struct timeval tv0;
 150     AioHandler *node;
 151     bool have_select_revents = false;
 152     fd_set rfds, wfds;
 153
 154     /* fill fd sets */
 155     FD_ZERO(&rfds);
 156     FD_ZERO(&wfds);
 157     QLIST_FOREACH(node, &ctx->aio_handlers, node) {
 158         if (node->io_read) {
 159             FD_SET ((SOCKET)node->pfd.fd, &rfds);
 160         }
 161         if (node->io_write) {
 162             FD_SET ((SOCKET)node->pfd.fd, &wfds);
 163         }
 164     }
 165
 166     if (select(0, &rfds, &wfds, NULL, &tv0) > 0) {
 167         QLIST_FOREACH(node, &ctx->aio_handlers, node) {
 168             node->pfd.revents = 0;
 169             if (FD_ISSET(node->pfd.fd, &rfds)) {
 170                 node->pfd.revents |= G_IO_IN;
 171                 have_select_revents = true;
 172             }
 173
 174             if (FD_ISSET(node->pfd.fd, &wfds)) {
 175                 node->pfd.revents |= G_IO_OUT;
 176                 have_select_revents = true;
 177             }
 178         }
 179     }
 180
 181     return have_select_revents;
 182 }
 183
 184 bool aio_pending(AioContext *ctx)
 185 {
 186     AioHandler *node;
 187
 188     QLIST_FOREACH(node, &ctx->aio_handlers, node) {
 189         if (node->pfd.revents && node->io_notify) {
 190             return true;
 191         }
 192
 193         if ((node->pfd.revents & G_IO_IN) && node->io_read) {
 194             return true;
 195         }
 196         if ((node->pfd.revents & G_IO_OUT) && node->io_write) {
 197             return true;
 198         }
 199     }
 200
 201     return false;
 202 }
 203
 204 static bool aio_dispatch_handlers(AioContext *ctx, HANDLE event)
 205 {
 206     AioHandler *node;
 207     bool progress = false;
 208
 209     /*
 210      * We have to walk very carefully in case aio_set_fd_handler is
 211      * called while we're walking.
 212      */
 213     node = QLIST_FIRST(&ctx->aio_handlers);
 214     while (node) {
 215         AioHandler *tmp;
 216         int revents = node->pfd.revents;
 217
 218         ctx->walking_handlers++;
 219
 220         if (!node->deleted &&
 221             (revents || event_notifier_get_handle(node->e) == event) &&
 222             node->io_notify) {
 223             node->pfd.revents = 0;
 224             node->io_notify(node->e);
 225
 226             /* aio_notify() does not count as progress */
 227             if (node->e != &ctx->notifier) {
 228                 progress = true;
 229             }
 230         }
 231
 232         if (!node->deleted &&
 233             (node->io_read || node->io_write)) {
 234             node->pfd.revents = 0;
 235             if ((revents & G_IO_IN) && node->io_read) {
 236                 node->io_read(node->opaque);
 237                 progress = true;
 238             }
 239             if ((revents & G_IO_OUT) && node->io_write) {
 240                 node->io_write(node->opaque);
 241                 progress = true;
 242             }
 243
 244             /* if the next select() will return an event, we have progressed */
 245             if (event == event_notifier_get_handle(&ctx->notifier)) {
 246                 WSANETWORKEVENTS ev;
 247                 WSAEnumNetworkEvents(node->pfd.fd, event, &ev);
 248                 if (ev.lNetworkEvents) {
 249                     progress = true;
 250                 }
 251             }
 252         }
 253
 254         tmp = node;
 255         node = QLIST_NEXT(node, node);
 256
 257         ctx->walking_handlers--;
 258
 259         if (!ctx->walking_handlers && tmp->deleted) {
 260             QLIST_REMOVE(tmp, node);
 261             g_free(tmp);
 262         }
 263     }
 264
 265     return progress;
 266 }
 267
 268 bool aio_dispatch(AioContext *ctx)
 269 {
 270     bool progress;
 271
 272     progress = aio_bh_poll(ctx);
 273     progress |= aio_dispatch_handlers(ctx, INVALID_HANDLE_VALUE);
 274     progress |= timerlistgroup_run_timers(&ctx->tlg);
 275     return progress;
 276 }
 277
 278 bool aio_poll(AioContext *ctx, bool blocking)
 279 {
 280     AioHandler *node;
 281     HANDLE events[MAXIMUM_WAIT_OBJECTS + 1];
 282     bool progress, have_select_revents, first;
 283     int count;
 284     int timeout;
 285
 286     aio_context_acquire(ctx);
 287     progress = false;
 288
 289     /* aio_notify can avoid the expensive event_notifier_set if
 290      * everything (file descriptors, bottom halves, timers) will
 291      * be re-evaluated before the next blocking poll().  This is
 292      * already true when aio_poll is called with blocking == false;
 293      * if blocking == true, it is only true after poll() returns,
 294      * so disable the optimization now.
 295      */
 296     if (blocking) {
 297         atomic_add(&ctx->notify_me, 2);
 298     }
 299
 300     have_select_revents = aio_prepare(ctx);
 301
 302     ctx->walking_handlers++;
 303
 304     /* fill fd sets */
 305     count = 0;
 306     QLIST_FOREACH(node, &ctx->aio_handlers, node) {
 307         if (!node->deleted && node->io_notify) {
 308             events[count++] = event_notifier_get_handle(node->e);
 309         }
 310     }
 311
 312     ctx->walking_handlers--;
 313     first = true;
 314
 315     /* ctx->notifier is always registered.  */
 316     assert(count > 0);
 317
 318     /* Multiple iterations, all of them non-blocking except the first,
 319      * may be necessary to process all pending events.  After the first
 320      * WaitForMultipleObjects call ctx->notify_me will be decremented.
 321      */
 322     do {
 323         HANDLE event;
 324         int ret;
 325
 326         timeout = blocking && !have_select_revents
 327             ? qemu_timeout_ns_to_ms(aio_compute_timeout(ctx)) : 0;
 328         if (timeout) {
 329             aio_context_release(ctx);
 330         }
 331         ret = WaitForMultipleObjects(count, events, FALSE, timeout);
 332         if (blocking) {
 333             assert(first);
 334             atomic_sub(&ctx->notify_me, 2);
 335         }
 336         if (timeout) {
 337             aio_context_acquire(ctx);
 338         }
 339
 340         if (first) {
 341             aio_notify_accept(ctx);
 342             progress |= aio_bh_poll(ctx);
 343             first = false;
 344         }
 345
 346         /* if we have any signaled events, dispatch event */
 347         event = NULL;
 348         if ((DWORD) (ret - WAIT_OBJECT_0) < count) {
 349             event = events[ret - WAIT_OBJECT_0];
 350             events[ret - WAIT_OBJECT_0] = events[--count];
 351         } else if (!have_select_revents) {
 352             break;
 353         }
 354
 355         have_select_revents = false;
 356         blocking = false;
 357
 358         progress |= aio_dispatch_handlers(ctx, event);
 359     } while (count > 0);
 360
 361     progress |= timerlistgroup_run_timers(&ctx->tlg);
 362
 363     aio_context_release(ctx);
 364     return progress;
 365 }