diff options
Diffstat (limited to 'aio-posix.c')
| -rw-r--r-- | aio-posix.c | 262 |
1 files changed, 262 insertions, 0 deletions
diff --git a/aio-posix.c b/aio-posix.c new file mode 100644 index 0000000000..44247224e2 --- /dev/null +++ b/aio-posix.c @@ -0,0 +1,262 @@ +/* + * QEMU aio implementation + * + * Copyright IBM, Corp. 2008 + * + * Authors: + * Anthony Liguori <aliguori@us.ibm.com> + * + * This work is licensed under the terms of the GNU GPL, version 2. See + * the COPYING file in the top-level directory. + * + * Contributions after 2012-01-13 are licensed under the terms of the + * GNU GPL, version 2 or (at your option) any later version. + */ + +#include "qemu-common.h" +#include "block.h" +#include "qemu-queue.h" +#include "qemu_socket.h" + +struct AioHandler +{ + GPollFD pfd; + IOHandler *io_read; + IOHandler *io_write; + AioFlushHandler *io_flush; + int deleted; + void *opaque; + QLIST_ENTRY(AioHandler) node; +}; + +static AioHandler *find_aio_handler(AioContext *ctx, int fd) +{ + AioHandler *node; + + QLIST_FOREACH(node, &ctx->aio_handlers, node) { + if (node->pfd.fd == fd) + if (!node->deleted) + return node; + } + + return NULL; +} + +void aio_set_fd_handler(AioContext *ctx, + int fd, + IOHandler *io_read, + IOHandler *io_write, + AioFlushHandler *io_flush, + void *opaque) +{ + AioHandler *node; + + node = find_aio_handler(ctx, fd); + + /* Are we deleting the fd handler? */ + if (!io_read && !io_write) { + if (node) { + /* If the lock is held, just mark the node as deleted */ + if (ctx->walking_handlers) { + node->deleted = 1; + node->pfd.revents = 0; + } else { + /* Otherwise, delete it for real. We can't just mark it as + * deleted because deleted nodes are only cleaned up after + * releasing the walking_handlers lock. + */ + QLIST_REMOVE(node, node); + g_free(node); + } + } + } else { + if (node == NULL) { + /* Alloc and insert if it's not already there */ + node = g_malloc0(sizeof(AioHandler)); + node->pfd.fd = fd; + QLIST_INSERT_HEAD(&ctx->aio_handlers, node, node); + } + /* Update handler with latest information */ + node->io_read = io_read; + node->io_write = io_write; + node->io_flush = io_flush; + node->opaque = opaque; + + node->pfd.events = (io_read ? G_IO_IN | G_IO_HUP : 0); + node->pfd.events |= (io_write ? G_IO_OUT : 0); + } +} + +void aio_set_event_notifier(AioContext *ctx, + EventNotifier *notifier, + EventNotifierHandler *io_read, + AioFlushEventNotifierHandler *io_flush) +{ + aio_set_fd_handler(ctx, event_notifier_get_fd(notifier), + (IOHandler *)io_read, NULL, + (AioFlushHandler *)io_flush, notifier); +} + +bool aio_pending(AioContext *ctx) +{ + AioHandler *node; + + QLIST_FOREACH(node, &ctx->aio_handlers, node) { + int revents; + + /* + * FIXME: right now we cannot get G_IO_HUP and G_IO_ERR because + * main-loop.c is still select based (due to the slirp legacy). + * If main-loop.c ever switches to poll, G_IO_ERR should be + * tested too. Dispatching G_IO_ERR to both handlers should be + * okay, since handlers need to be ready for spurious wakeups. + */ + revents = node->pfd.revents & node->pfd.events; + if (revents & (G_IO_IN | G_IO_HUP | G_IO_ERR) && node->io_read) { + return true; + } + if (revents & (G_IO_OUT | G_IO_ERR) && node->io_write) { + return true; + } + } + + return false; +} + +bool aio_poll(AioContext *ctx, bool blocking) +{ + static struct timeval tv0; + AioHandler *node; + fd_set rdfds, wrfds; + int max_fd = -1; + int ret; + bool busy, progress; + + progress = false; + + /* + * If there are callbacks left that have been queued, we need to call then. + * Do not call select in this case, because it is possible that the caller + * does not need a complete flush (as is the case for qemu_aio_wait loops). + */ + if (aio_bh_poll(ctx)) { + blocking = false; + progress = true; + } + + /* + * Then dispatch any pending callbacks from the GSource. + * + * We have to walk very carefully in case qemu_aio_set_fd_handler is + * called while we're walking. + */ + node = QLIST_FIRST(&ctx->aio_handlers); + while (node) { + AioHandler *tmp; + int revents; + + ctx->walking_handlers++; + + revents = node->pfd.revents & node->pfd.events; + node->pfd.revents = 0; + + /* See comment in aio_pending. */ + if (revents & (G_IO_IN | G_IO_HUP | G_IO_ERR) && node->io_read) { + node->io_read(node->opaque); + progress = true; + } + if (revents & (G_IO_OUT | G_IO_ERR) && node->io_write) { + node->io_write(node->opaque); + progress = true; + } + + tmp = node; + node = QLIST_NEXT(node, node); + + ctx->walking_handlers--; + + if (!ctx->walking_handlers && tmp->deleted) { + QLIST_REMOVE(tmp, node); + g_free(tmp); + } + } + + if (progress && !blocking) { + return true; + } + + ctx->walking_handlers++; + + FD_ZERO(&rdfds); + FD_ZERO(&wrfds); + + /* fill fd sets */ + busy = false; + QLIST_FOREACH(node, &ctx->aio_handlers, node) { + /* If there aren't pending AIO operations, don't invoke callbacks. + * Otherwise, if there are no AIO requests, qemu_aio_wait() would + * wait indefinitely. + */ + if (!node->deleted && node->io_flush) { + if (node->io_flush(node->opaque) == 0) { + continue; + } + busy = true; + } + if (!node->deleted && node->io_read) { + FD_SET(node->pfd.fd, &rdfds); + max_fd = MAX(max_fd, node->pfd.fd + 1); + } + if (!node->deleted && node->io_write) { + FD_SET(node->pfd.fd, &wrfds); + max_fd = MAX(max_fd, node->pfd.fd + 1); + } + } + + ctx->walking_handlers--; + + /* No AIO operations? Get us out of here */ + if (!busy) { + return progress; + } + + /* wait until next event */ + ret = select(max_fd, &rdfds, &wrfds, NULL, blocking ? NULL : &tv0); + + /* if we have any readable fds, dispatch event */ + if (ret > 0) { + /* we have to walk very carefully in case + * qemu_aio_set_fd_handler is called while we're walking */ + node = QLIST_FIRST(&ctx->aio_handlers); + while (node) { + AioHandler *tmp; + + ctx->walking_handlers++; + + if (!node->deleted && + FD_ISSET(node->pfd.fd, &rdfds) && + node->io_read) { + node->io_read(node->opaque); + progress = true; + } + if (!node->deleted && + FD_ISSET(node->pfd.fd, &wrfds) && + node->io_write) { + node->io_write(node->opaque); + progress = true; + } + + tmp = node; + node = QLIST_NEXT(node, node); + + ctx->walking_handlers--; + + if (!ctx->walking_handlers && tmp->deleted) { + QLIST_REMOVE(tmp, node); + g_free(tmp); + } + } + } + + return progress; +} |