--- /dev/null
+/*
+ * 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/block.h"
+#include "qemu/queue.h"
+#include "qemu/sockets.h"
+
+struct AioHandler {
+ EventNotifier *e;
+ IOHandler *io_read;
+ IOHandler *io_write;
+ EventNotifierHandler *io_notify;
+ GPollFD pfd;
+ int deleted;
+ void *opaque;
+ QLIST_ENTRY(AioHandler) node;
+};
+
+void aio_set_fd_handler(AioContext *ctx,
+ int fd,
+ IOHandler *io_read,
+ IOHandler *io_write,
+ void *opaque)
+{
+ /* fd is a SOCKET in our case */
+ AioHandler *node;
+
+ QLIST_FOREACH(node, &ctx->aio_handlers, node) {
+ if (node->pfd.fd == fd && !node->deleted) {
+ break;
+ }
+ }
+
+ /* 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 {
+ HANDLE event;
+
+ if (node == NULL) {
+ /* Alloc and insert if it's not already there */
+ node = g_new0(AioHandler, 1);
+ node->pfd.fd = fd;
+ QLIST_INSERT_HEAD(&ctx->aio_handlers, node, node);
+ }
+
+ node->pfd.events = 0;
+ if (node->io_read) {
+ node->pfd.events |= G_IO_IN;
+ }
+ if (node->io_write) {
+ node->pfd.events |= G_IO_OUT;
+ }
+
+ node->e = &ctx->notifier;
+
+ /* Update handler with latest information */
+ node->opaque = opaque;
+ node->io_read = io_read;
+ node->io_write = io_write;
+
+ event = event_notifier_get_handle(&ctx->notifier);
+ WSAEventSelect(node->pfd.fd, event,
+ FD_READ | FD_ACCEPT | FD_CLOSE |
+ FD_CONNECT | FD_WRITE | FD_OOB);
+ }
+
+ aio_notify(ctx);
+}
+
+void aio_set_event_notifier(AioContext *ctx,
+ EventNotifier *e,
+ EventNotifierHandler *io_notify)
+{
+ 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) {
+ g_source_remove_poll(&ctx->source, &node->pfd);
+
+ /* 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_new0(AioHandler, 1);
+ 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);
+
+ g_source_add_poll(&ctx->source, &node->pfd);
+ }
+ /* Update handler with latest information */
+ node->io_notify = io_notify;
+ }
+
+ aio_notify(ctx);
+}
+
+bool aio_prepare(AioContext *ctx)
+{
+ static struct timeval tv0;
+ AioHandler *node;
+ bool have_select_revents = false;
+ fd_set rfds, wfds;
+
+ /* fill fd sets */
+ FD_ZERO(&rfds);
+ FD_ZERO(&wfds);
+ QLIST_FOREACH(node, &ctx->aio_handlers, node) {
+ if (node->io_read) {
+ FD_SET ((SOCKET)node->pfd.fd, &rfds);
+ }
+ if (node->io_write) {
+ FD_SET ((SOCKET)node->pfd.fd, &wfds);
+ }
+ }
+
+ if (select(0, &rfds, &wfds, NULL, &tv0) > 0) {
+ QLIST_FOREACH(node, &ctx->aio_handlers, node) {
+ node->pfd.revents = 0;
+ if (FD_ISSET(node->pfd.fd, &rfds)) {
+ node->pfd.revents |= G_IO_IN;
+ have_select_revents = true;
+ }
+
+ if (FD_ISSET(node->pfd.fd, &wfds)) {
+ node->pfd.revents |= G_IO_OUT;
+ have_select_revents = true;
+ }
+ }
+ }
+
+ return have_select_revents;
+}
+
+bool aio_pending(AioContext *ctx)
+{
+ AioHandler *node;
+
+ QLIST_FOREACH(node, &ctx->aio_handlers, node) {
+ if (node->pfd.revents && node->io_notify) {
+ return true;
+ }
+
+ if ((node->pfd.revents & G_IO_IN) && node->io_read) {
+ return true;
+ }
+ if ((node->pfd.revents & G_IO_OUT) && node->io_write) {
+ return true;
+ }
+ }
+
+ return false;
+}
+
+static bool aio_dispatch_handlers(AioContext *ctx, HANDLE event)
+{
+ AioHandler *node;
+ bool progress = false;
+
+ /*
+ * We have to walk very carefully in case aio_set_fd_handler is
+ * called while we're walking.
+ */
+ node = QLIST_FIRST(&ctx->aio_handlers);
+ while (node) {
+ AioHandler *tmp;
+ int revents = node->pfd.revents;
+
+ ctx->walking_handlers++;
+
+ if (!node->deleted &&
+ (revents || event_notifier_get_handle(node->e) == event) &&
+ node->io_notify) {
+ node->pfd.revents = 0;
+ node->io_notify(node->e);
+
+ /* aio_notify() does not count as progress */
+ if (node->e != &ctx->notifier) {
+ progress = true;
+ }
+ }
+
+ if (!node->deleted &&
+ (node->io_read || node->io_write)) {
+ node->pfd.revents = 0;
+ if ((revents & G_IO_IN) && node->io_read) {
+ node->io_read(node->opaque);
+ progress = true;
+ }
+ if ((revents & G_IO_OUT) && node->io_write) {
+ node->io_write(node->opaque);
+ progress = true;
+ }
+
+ /* if the next select() will return an event, we have progressed */
+ if (event == event_notifier_get_handle(&ctx->notifier)) {
+ WSANETWORKEVENTS ev;
+ WSAEnumNetworkEvents(node->pfd.fd, event, &ev);
+ if (ev.lNetworkEvents) {
+ 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;
+}
+
+bool aio_dispatch(AioContext *ctx)
+{
+ bool progress;
+
+ progress = aio_bh_poll(ctx);
+ progress |= aio_dispatch_handlers(ctx, INVALID_HANDLE_VALUE);
+ progress |= timerlistgroup_run_timers(&ctx->tlg);
+ return progress;
+}
+
+bool aio_poll(AioContext *ctx, bool blocking)
+{
+ AioHandler *node;
+ HANDLE events[MAXIMUM_WAIT_OBJECTS + 1];
+ bool progress, have_select_revents, first;
+ int count;
+ int timeout;
+
+ aio_context_acquire(ctx);
+ progress = false;
+
+ /* aio_notify can avoid the expensive event_notifier_set if
+ * everything (file descriptors, bottom halves, timers) will
+ * be re-evaluated before the next blocking poll(). This is
+ * already true when aio_poll is called with blocking == false;
+ * if blocking == true, it is only true after poll() returns,
+ * so disable the optimization now.
+ */
+ if (blocking) {
+ atomic_add(&ctx->notify_me, 2);
+ }
+
+ have_select_revents = aio_prepare(ctx);
+
+ ctx->walking_handlers++;
+
+ /* fill fd sets */
+ count = 0;
+ QLIST_FOREACH(node, &ctx->aio_handlers, node) {
+ if (!node->deleted && node->io_notify) {
+ events[count++] = event_notifier_get_handle(node->e);
+ }
+ }
+
+ ctx->walking_handlers--;
+ first = true;
+
+ /* ctx->notifier is always registered. */
+ assert(count > 0);
+
+ /* Multiple iterations, all of them non-blocking except the first,
+ * may be necessary to process all pending events. After the first
+ * WaitForMultipleObjects call ctx->notify_me will be decremented.
+ */
+ do {
+ HANDLE event;
+ int ret;
+
+ timeout = blocking && !have_select_revents
+ ? qemu_timeout_ns_to_ms(aio_compute_timeout(ctx)) : 0;
+ if (timeout) {
+ aio_context_release(ctx);
+ }
+ ret = WaitForMultipleObjects(count, events, FALSE, timeout);
+ if (blocking) {
+ assert(first);
+ atomic_sub(&ctx->notify_me, 2);
+ }
+ if (timeout) {
+ aio_context_acquire(ctx);
+ }
+
+ if (first) {
+ aio_notify_accept(ctx);
+ progress |= aio_bh_poll(ctx);
+ first = false;
+ }
+
+ /* if we have any signaled events, dispatch event */
+ event = NULL;
+ if ((DWORD) (ret - WAIT_OBJECT_0) < count) {
+ event = events[ret - WAIT_OBJECT_0];
+ events[ret - WAIT_OBJECT_0] = events[--count];
+ } else if (!have_select_revents) {
+ break;
+ }
+
+ have_select_revents = false;
+ blocking = false;
+
+ progress |= aio_dispatch_handlers(ctx, event);
+ } while (count > 0);
+
+ progress |= timerlistgroup_run_timers(&ctx->tlg);
+
+ aio_context_release(ctx);
+ return progress;
+}
Code Review / kvmfornfv.git / blobdiff