diff options
Diffstat (limited to 'aio.c')
| -rw-r--r-- | aio.c | 194 |
1 files changed, 0 insertions, 194 deletions
@@ -1,194 +0,0 @@ -/* - * 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" - -typedef struct AioHandler AioHandler; - -/* The list of registered AIO handlers */ -static QLIST_HEAD(, AioHandler) aio_handlers; - -/* This is a simple lock used to protect the aio_handlers list. Specifically, - * it's used to ensure that no callbacks are removed while we're walking and - * dispatching callbacks. - */ -static int walking_handlers; - -struct AioHandler -{ - int fd; - IOHandler *io_read; - IOHandler *io_write; - AioFlushHandler *io_flush; - int deleted; - void *opaque; - QLIST_ENTRY(AioHandler) node; -}; - -static AioHandler *find_aio_handler(int fd) -{ - AioHandler *node; - - QLIST_FOREACH(node, &aio_handlers, node) { - if (node->fd == fd) - if (!node->deleted) - return node; - } - - return NULL; -} - -int qemu_aio_set_fd_handler(int fd, - IOHandler *io_read, - IOHandler *io_write, - AioFlushHandler *io_flush, - void *opaque) -{ - AioHandler *node; - - node = find_aio_handler(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 (walking_handlers) - node->deleted = 1; - 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->fd = fd; - QLIST_INSERT_HEAD(&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; - } - - qemu_set_fd_handler2(fd, NULL, io_read, io_write, opaque); - - return 0; -} - -void qemu_aio_flush(void) -{ - while (qemu_aio_wait()); -} - -bool qemu_aio_wait(void) -{ - AioHandler *node; - fd_set rdfds, wrfds; - int max_fd = -1; - int ret; - bool busy; - - /* - * 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 (qemu_bh_poll()) { - return true; - } - - walking_handlers++; - - FD_ZERO(&rdfds); - FD_ZERO(&wrfds); - - /* fill fd sets */ - busy = false; - QLIST_FOREACH(node, &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->io_flush) { - if (node->io_flush(node->opaque) == 0) { - continue; - } - busy = true; - } - if (!node->deleted && node->io_read) { - FD_SET(node->fd, &rdfds); - max_fd = MAX(max_fd, node->fd + 1); - } - if (!node->deleted && node->io_write) { - FD_SET(node->fd, &wrfds); - max_fd = MAX(max_fd, node->fd + 1); - } - } - - walking_handlers--; - - /* No AIO operations? Get us out of here */ - if (!busy) { - return false; - } - - /* wait until next event */ - ret = select(max_fd, &rdfds, &wrfds, NULL, NULL); - - /* 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(&aio_handlers); - while (node) { - AioHandler *tmp; - - walking_handlers++; - - if (!node->deleted && - FD_ISSET(node->fd, &rdfds) && - node->io_read) { - node->io_read(node->opaque); - } - if (!node->deleted && - FD_ISSET(node->fd, &wrfds) && - node->io_write) { - node->io_write(node->opaque); - } - - tmp = node; - node = QLIST_NEXT(node, node); - - walking_handlers--; - - if (!walking_handlers && tmp->deleted) { - QLIST_REMOVE(tmp, node); - g_free(tmp); - } - } - } - - return true; -} |
