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
  24 struct AioHandler {
  25     EventNotifier *e;
  26     IOHandler *io_read;
  27     IOHandler *io_write;
  28     EventNotifierHandler *io_notify;
  29     GPollFD pfd;
  30     int deleted;
  31     void *opaque;
  32     bool is_external;
  33     QLIST_ENTRY(AioHandler) node;
  34 };
  35
  36 void aio_set_fd_handler(AioContext *ctx,
  37                         int fd,
  38                         bool is_external,
  39                         IOHandler *io_read,
  40                         IOHandler *io_write,
  41                         void *opaque)
  42 {
  43     /* fd is a SOCKET in our case */
  44     AioHandler *node;
  45
  46     QLIST_FOREACH(node, &ctx->aio_handlers, node) {
  47         if (node->pfd.fd == fd && !node->deleted) {
  48             break;
  49         }
  50     }
  51
  52     /* Are we deleting the fd handler? */
  53     if (!io_read && !io_write) {
  54         if (node) {
  55             /* If the lock is held, just mark the node as deleted */
  56             if (ctx->walking_handlers) {
  57                 node->deleted = 1;
  58                 node->pfd.revents = 0;
  59             } else {
  60                 /* Otherwise, delete it for real.  We can't just mark it as
  61                  * deleted because deleted nodes are only cleaned up after
  62                  * releasing the walking_handlers lock.
  63                  */
  64                 QLIST_REMOVE(node, node);
  65                 g_free(node);
  66             }
  67         }
  68     } else {
  69         HANDLE event;
  70
  71         if (node == NULL) {
  72             /* Alloc and insert if it's not already there */
  73             node = g_new0(AioHandler, 1);
  74             node->pfd.fd = fd;
  75             QLIST_INSERT_HEAD(&ctx->aio_handlers, node, node);
  76         }
  77
  78         node->pfd.events = 0;
  79         if (node->io_read) {
  80             node->pfd.events |= G_IO_IN;
  81         }
  82         if (node->io_write) {
  83             node->pfd.events |= G_IO_OUT;
  84         }
  85
  86         node->e = &ctx->notifier;
  87
  88         /* Update handler with latest information */
  89         node->opaque = opaque;
  90         node->io_read = io_read;
  91         node->io_write = io_write;
  92         node->is_external = is_external;
  93
  94         event = event_notifier_get_handle(&ctx->notifier);
  95         WSAEventSelect(node->pfd.fd, event,
  96                        FD_READ | FD_ACCEPT | FD_CLOSE |
  97                        FD_CONNECT | FD_WRITE | FD_OOB);
  98     }
  99
 100     aio_notify(ctx);
 101 }
 102
 103 void aio_set_event_notifier(AioContext *ctx,
 104                             EventNotifier *e,
 105                             bool is_external,
 106                             EventNotifierHandler *io_notify)
 107 {
 108     AioHandler *node;
 109
 110     QLIST_FOREACH(node, &ctx->aio_handlers, node) {
 111         if (node->e == e && !node->deleted) {
 112             break;
 113         }
 114     }
 115
 116     /* Are we deleting the fd handler? */
 117     if (!io_notify) {
 118         if (node) {
 119             g_source_remove_poll(&ctx->source, &node->pfd);
 120
 121             /* If the lock is held, just mark the node as deleted */
 122             if (ctx->walking_handlers) {
 123                 node->deleted = 1;
 124                 node->pfd.revents = 0;
 125             } else {
 126                 /* Otherwise, delete it for real.  We can't just mark it as
 127                  * deleted because deleted nodes are only cleaned up after
 128                  * releasing the walking_handlers lock.
 129                  */
 130                 QLIST_REMOVE(node, node);
 131                 g_free(node);
 132             }
 133         }
 134     } else {
 135         if (node == NULL) {
 136             /* Alloc and insert if it's not already there */
 137             node = g_new0(AioHandler, 1);
 138             node->e = e;
 139             node->pfd.fd = (uintptr_t)event_notifier_get_handle(e);
 140             node->pfd.events = G_IO_IN;
 141             node->is_external = is_external;
 142             QLIST_INSERT_HEAD(&ctx->aio_handlers, node, node);
 143
 144             g_source_add_poll(&ctx->source, &node->pfd);
 145         }
 146         /* Update handler with latest information */
 147         node->io_notify = io_notify;
 148     }
 149
 150     aio_notify(ctx);
 151 }
 152
 153 bool aio_prepare(AioContext *ctx)
 154 {
 155     static struct timeval tv0;
 156     AioHandler *node;
 157     bool have_select_revents = false;
 158     fd_set rfds, wfds;
 159
 160     /* fill fd sets */
 161     FD_ZERO(&rfds);
 162     FD_ZERO(&wfds);
 163     QLIST_FOREACH(node, &ctx->aio_handlers, node) {
 164         if (node->io_read) {
 165             FD_SET ((SOCKET)node->pfd.fd, &rfds);
 166         }
 167         if (node->io_write) {
 168             FD_SET ((SOCKET)node->pfd.fd, &wfds);
 169         }
 170     }
 171
 172     if (select(0, &rfds, &wfds, NULL, &tv0) > 0) {
 173         QLIST_FOREACH(node, &ctx->aio_handlers, node) {
 174             node->pfd.revents = 0;
 175             if (FD_ISSET(node->pfd.fd, &rfds)) {
 176                 node->pfd.revents |= G_IO_IN;
 177                 have_select_revents = true;
 178             }
 179
 180             if (FD_ISSET(node->pfd.fd, &wfds)) {
 181                 node->pfd.revents |= G_IO_OUT;
 182                 have_select_revents = true;
 183             }
 184         }
 185     }
 186
 187     return have_select_revents;
 188 }
 189
 190 bool aio_pending(AioContext *ctx)
 191 {
 192     AioHandler *node;
 193
 194     QLIST_FOREACH(node, &ctx->aio_handlers, node) {
 195         if (node->pfd.revents && node->io_notify) {
 196             return true;
 197         }
 198
 199         if ((node->pfd.revents & G_IO_IN) && node->io_read) {
 200             return true;
 201         }
 202         if ((node->pfd.revents & G_IO_OUT) && node->io_write) {
 203             return true;
 204         }
 205     }
 206
 207     return false;
 208 }
 209
 210 static bool aio_dispatch_handlers(AioContext *ctx, HANDLE event)
 211 {
 212     AioHandler *node;
 213     bool progress = false;
 214
 215     /*
 216      * We have to walk very carefully in case aio_set_fd_handler is
 217      * called while we're walking.
 218      */
 219     node = QLIST_FIRST(&ctx->aio_handlers);
 220     while (node) {
 221         AioHandler *tmp;
 222         int revents = node->pfd.revents;
 223
 224         ctx->walking_handlers++;
 225
 226         if (!node->deleted &&
 227             (revents || event_notifier_get_handle(node->e) == event) &&
 228             node->io_notify) {
 229             node->pfd.revents = 0;
 230             node->io_notify(node->e);
 231
 232             /* aio_notify() does not count as progress */
 233             if (node->e != &ctx->notifier) {
 234                 progress = true;
 235             }
 236         }
 237
 238         if (!node->deleted &&
 239             (node->io_read || node->io_write)) {
 240             node->pfd.revents = 0;
 241             if ((revents & G_IO_IN) && node->io_read) {
 242                 node->io_read(node->opaque);
 243                 progress = true;
 244             }
 245             if ((revents & G_IO_OUT) && node->io_write) {
 246                 node->io_write(node->opaque);
 247                 progress = true;
 248             }
 249
 250             /* if the next select() will return an event, we have progressed */
 251             if (event == event_notifier_get_handle(&ctx->notifier)) {
 252                 WSANETWORKEVENTS ev;
 253                 WSAEnumNetworkEvents(node->pfd.fd, event, &ev);
 254                 if (ev.lNetworkEvents) {
 255                     progress = true;
 256                 }
 257             }
 258         }
 259
 260         tmp = node;
 261         node = QLIST_NEXT(node, node);
 262
 263         ctx->walking_handlers--;
 264
 265         if (!ctx->walking_handlers && tmp->deleted) {
 266             QLIST_REMOVE(tmp, node);
 267             g_free(tmp);
 268         }
 269     }
 270
 271     return progress;
 272 }
 273
 274 bool aio_dispatch(AioContext *ctx)
 275 {
 276     bool progress;
 277
 278     progress = aio_bh_poll(ctx);
 279     progress |= aio_dispatch_handlers(ctx, INVALID_HANDLE_VALUE);
 280     progress |= timerlistgroup_run_timers(&ctx->tlg);
 281     return progress;
 282 }
 283
 284 bool aio_poll(AioContext *ctx, bool blocking)
 285 {
 286     AioHandler *node;
 287     HANDLE events[MAXIMUM_WAIT_OBJECTS + 1];
 288     bool progress, have_select_revents, first;
 289     int count;
 290     int timeout;
 291
 292     aio_context_acquire(ctx);
 293     progress = false;
 294
 295     /* aio_notify can avoid the expensive event_notifier_set if
 296      * everything (file descriptors, bottom halves, timers) will
 297      * be re-evaluated before the next blocking poll().  This is
 298      * already true when aio_poll is called with blocking == false;
 299      * if blocking == true, it is only true after poll() returns,
 300      * so disable the optimization now.
 301      */
 302     if (blocking) {
 303         atomic_add(&ctx->notify_me, 2);
 304     }
 305
 306     have_select_revents = aio_prepare(ctx);
 307
 308     ctx->walking_handlers++;
 309
 310     /* fill fd sets */
 311     count = 0;
 312     QLIST_FOREACH(node, &ctx->aio_handlers, node) {
 313         if (!node->deleted && node->io_notify
 314             && aio_node_check(ctx, node->is_external)) {
 315             events[count++] = event_notifier_get_handle(node->e);
 316         }
 317     }
 318
 319     ctx->walking_handlers--;
 320     first = true;
 321
 322     /* ctx->notifier is always registered.  */
 323     assert(count > 0);
 324
 325     /* Multiple iterations, all of them non-blocking except the first,
 326      * may be necessary to process all pending events.  After the first
 327      * WaitForMultipleObjects call ctx->notify_me will be decremented.
 328      */
 329     do {
 330         HANDLE event;
 331         int ret;
 332
 333         timeout = blocking && !have_select_revents
 334             ? qemu_timeout_ns_to_ms(aio_compute_timeout(ctx)) : 0;
 335         if (timeout) {
 336             aio_context_release(ctx);
 337         }
 338         ret = WaitForMultipleObjects(count, events, FALSE, timeout);
 339         if (blocking) {
 340             assert(first);
 341             atomic_sub(&ctx->notify_me, 2);
 342         }
 343         if (timeout) {
 344             aio_context_acquire(ctx);
 345         }
 346
 347         if (first) {
 348             aio_notify_accept(ctx);
 349             progress |= aio_bh_poll(ctx);
 350             first = false;
 351         }
 352
 353         /* if we have any signaled events, dispatch event */
 354         event = NULL;
 355         if ((DWORD) (ret - WAIT_OBJECT_0) < count) {
 356             event = events[ret - WAIT_OBJECT_0];
 357             events[ret - WAIT_OBJECT_0] = events[--count];
 358         } else if (!have_select_revents) {
 359             break;
 360         }
 361
 362         have_select_revents = false;
 363         blocking = false;
 364
 365         progress |= aio_dispatch_handlers(ctx, event);
 366     } while (count > 0);
 367
 368     progress |= timerlistgroup_run_timers(&ctx->tlg);
 369
 370     aio_context_release(ctx);
 371     return progress;
 372 }
 373
 374 void aio_context_setup(AioContext *ctx)
 375 {
 376 }