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authorPaolo Bonzini <pbonzini@redhat.com>2012-06-09 04:01:51 +0200
committerPaolo Bonzini <pbonzini@redhat.com>2012-10-30 09:30:53 +0100
commitf42b22077bc63a482d7a8755b54e33475ab78541 (patch)
tree33f248df458d15ca3a816be0f2ef24ffa8af17a7 /aio-posix.c
parentcd9ba1ebcf0439457f22b75b38533f6634f23c5f (diff)
downloadqemu-arm-f42b22077bc63a482d7a8755b54e33475ab78541.tar.gz
aio: add Win32 implementation
The Win32 implementation will only accept EventNotifiers, thus a few drivers are disabled under Windows. EventNotifiers are a good match for the GSource implementation, too, because the Win32 port of glib allows to place their HANDLEs in a GPollFD. Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Diffstat (limited to 'aio-posix.c')
-rw-r--r--aio-posix.c262
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;
+}