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-rw-r--r--aio-win32.c209
1 files changed, 209 insertions, 0 deletions
diff --git a/aio-win32.c b/aio-win32.c
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+++ b/aio-win32.c
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+/*
+ * QEMU aio implementation
+ *
+ * Copyright IBM Corp., 2008
+ * Copyright Red Hat Inc., 2012
+ *
+ * Authors:
+ * Anthony Liguori <aliguori@us.ibm.com>
+ * Paolo Bonzini <pbonzini@redhat.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 {
+ EventNotifier *e;
+ EventNotifierHandler *io_notify;
+ AioFlushEventNotifierHandler *io_flush;
+ GPollFD pfd;
+ int deleted;
+ QLIST_ENTRY(AioHandler) node;
+};
+
+void aio_set_event_notifier(AioContext *ctx,
+ EventNotifier *e,
+ EventNotifierHandler *io_notify,
+ AioFlushEventNotifierHandler *io_flush)
+{
+ AioHandler *node;
+
+ QLIST_FOREACH(node, &ctx->aio_handlers, node) {
+ if (node->e == e && !node->deleted) {
+ break;
+ }
+ }
+
+ /* Are we deleting the fd handler? */
+ if (!io_notify) {
+ 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->e = e;
+ node->pfd.fd = (uintptr_t)event_notifier_get_handle(e);
+ node->pfd.events = G_IO_IN;
+ QLIST_INSERT_HEAD(&ctx->aio_handlers, node, node);
+ }
+ /* Update handler with latest information */
+ node->io_notify = io_notify;
+ node->io_flush = io_flush;
+ }
+}
+
+bool aio_pending(AioContext *ctx)
+{
+ AioHandler *node;
+
+ QLIST_FOREACH(node, &ctx->aio_handlers, node) {
+ if (node->pfd.revents && node->io_notify) {
+ return true;
+ }
+ }
+
+ return false;
+}
+
+bool aio_poll(AioContext *ctx, bool blocking)
+{
+ AioHandler *node;
+ HANDLE events[MAXIMUM_WAIT_OBJECTS + 1];
+ bool busy, progress;
+ int count;
+
+ 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;
+
+ ctx->walking_handlers++;
+
+ if (node->pfd.revents && node->io_notify) {
+ node->pfd.revents = 0;
+ node->io_notify(node->e);
+ 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++;
+
+ /* fill fd sets */
+ busy = false;
+ count = 0;
+ 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->e) == 0) {
+ continue;
+ }
+ busy = true;
+ }
+ if (!node->deleted && node->io_notify) {
+ events[count++] = event_notifier_get_handle(node->e);
+ }
+ }
+
+ ctx->walking_handlers--;
+
+ /* No AIO operations? Get us out of here */
+ if (!busy) {
+ return progress;
+ }
+
+ /* wait until next event */
+ for (;;) {
+ int timeout = blocking ? INFINITE : 0;
+ int ret = WaitForMultipleObjects(count, events, FALSE, timeout);
+
+ /* if we have any signaled events, dispatch event */
+ if ((DWORD) (ret - WAIT_OBJECT_0) >= count) {
+ break;
+ }
+
+ blocking = false;
+
+ /* 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 &&
+ event_notifier_get_handle(node->e) == events[ret - WAIT_OBJECT_0] &&
+ node->io_notify) {
+ node->io_notify(node->e);
+ 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;
+}