block: move AioContext, QEMUTimer, main-loop to libqemuutil

AioContext is fairly self contained, the only dependency is QEMUTimer but
that in turn doesn't need anything else.  So move them out of block-obj-y
to avoid introducing a dependency from io/ to block-obj-y.

main-loop and its dependency iohandler also need to be moved, because
later in this series io/ will call iohandler_get_aio_context.

[Changed copyright "the QEMU team" to "other QEMU contributors" as
suggested by Daniel Berrange and agreed by Paolo.
--Stefan]

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Reviewed-by: Fam Zheng <famz@redhat.com>
Message-id: 20170213135235.12274-2-pbonzini@redhat.com
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>

1 files changed, 421 insertions, 0 deletions

diff --git a/util/aio-win32.c b/util/aio-win32.c
new file mode 100644
index 0000000000..900524c9c2
--- /dev/null
+++ b/util/aio-win32.c
@@ -0,0 +1,421 @@
+/*
+ * 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/osdep.h"
+#include "qemu-common.h"
+#include "block/block.h"
+#include "qemu/queue.h"
+#include "qemu/sockets.h"
+#include "qapi/error.h"
+#include "qemu/rcu_queue.h"
+
+struct AioHandler {
+    EventNotifier *e;
+    IOHandler *io_read;
+    IOHandler *io_write;
+    EventNotifierHandler *io_notify;
+    GPollFD pfd;
+    int deleted;
+    void *opaque;
+    bool is_external;
+    QLIST_ENTRY(AioHandler) node;
+};
+
+void aio_set_fd_handler(AioContext *ctx,
+                        int fd,
+                        bool is_external,
+                        IOHandler *io_read,
+                        IOHandler *io_write,
+                        AioPollFn *io_poll,
+                        void *opaque)
+{
+    /* fd is a SOCKET in our case */
+    AioHandler *node;
+
+    qemu_lockcnt_lock(&ctx->list_lock);
+    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 aio_poll is in progress, just mark the node as deleted */
+            if (qemu_lockcnt_count(&ctx->list_lock)) {
+                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 list_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_RCU(&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;
+        node->is_external = is_external;
+
+        event = event_notifier_get_handle(&ctx->notifier);
+        WSAEventSelect(node->pfd.fd, event,
+                       FD_READ | FD_ACCEPT | FD_CLOSE |
+                       FD_CONNECT | FD_WRITE | FD_OOB);
+    }
+
+    qemu_lockcnt_unlock(&ctx->list_lock);
+    aio_notify(ctx);
+}
+
+void aio_set_fd_poll(AioContext *ctx, int fd,
+                     IOHandler *io_poll_begin,
+                     IOHandler *io_poll_end)
+{
+    /* Not implemented */
+}
+
+void aio_set_event_notifier(AioContext *ctx,
+                            EventNotifier *e,
+                            bool is_external,
+                            EventNotifierHandler *io_notify,
+                            AioPollFn *io_poll)
+{
+    AioHandler *node;
+
+    qemu_lockcnt_lock(&ctx->list_lock);
+    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);
+
+            /* aio_poll is in progress, just mark the node as deleted */
+            if (qemu_lockcnt_count(&ctx->list_lock)) {
+                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 list_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;
+            node->is_external = is_external;
+            QLIST_INSERT_HEAD_RCU(&ctx->aio_handlers, node, node);
+
+            g_source_add_poll(&ctx->source, &node->pfd);
+        }
+        /* Update handler with latest information */
+        node->io_notify = io_notify;
+    }
+
+    qemu_lockcnt_unlock(&ctx->list_lock);
+    aio_notify(ctx);
+}
+
+void aio_set_event_notifier_poll(AioContext *ctx,
+                                 EventNotifier *notifier,
+                                 EventNotifierHandler *io_poll_begin,
+                                 EventNotifierHandler *io_poll_end)
+{
+    /* Not implemented */
+}
+
+bool aio_prepare(AioContext *ctx)
+{
+    static struct timeval tv0;
+    AioHandler *node;
+    bool have_select_revents = false;
+    fd_set rfds, wfds;
+
+    /*
+     * We have to walk very carefully in case aio_set_fd_handler is
+     * called while we're walking.
+     */
+    qemu_lockcnt_inc(&ctx->list_lock);
+
+    /* fill fd sets */
+    FD_ZERO(&rfds);
+    FD_ZERO(&wfds);
+    QLIST_FOREACH_RCU(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_RCU(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;
+            }
+        }
+    }
+
+    qemu_lockcnt_dec(&ctx->list_lock);
+    return have_select_revents;
+}
+
+bool aio_pending(AioContext *ctx)
+{
+    AioHandler *node;
+    bool result = false;
+
+    /*
+     * We have to walk very carefully in case aio_set_fd_handler is
+     * called while we're walking.
+     */
+    qemu_lockcnt_inc(&ctx->list_lock);
+    QLIST_FOREACH_RCU(node, &ctx->aio_handlers, node) {
+        if (node->pfd.revents && node->io_notify) {
+            result = true;
+            break;
+        }
+
+        if ((node->pfd.revents & G_IO_IN) && node->io_read) {
+            result = true;
+            break;
+        }
+        if ((node->pfd.revents & G_IO_OUT) && node->io_write) {
+            result = true;
+            break;
+        }
+    }
+
+    qemu_lockcnt_dec(&ctx->list_lock);
+    return result;
+}
+
+static bool aio_dispatch_handlers(AioContext *ctx, HANDLE event)
+{
+    AioHandler *node;
+    bool progress = false;
+    AioHandler *tmp;
+
+    qemu_lockcnt_inc(&ctx->list_lock);
+
+    /*
+     * We have to walk very carefully in case aio_set_fd_handler is
+     * called while we're walking.
+     */
+    QLIST_FOREACH_SAFE_RCU(node, &ctx->aio_handlers, node, tmp) {
+        int revents = node->pfd.revents;
+
+        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;
+                }
+            }
+        }
+
+        if (node->deleted) {
+            if (qemu_lockcnt_dec_if_lock(&ctx->list_lock)) {
+                QLIST_REMOVE(node, node);
+                g_free(node);
+                qemu_lockcnt_inc_and_unlock(&ctx->list_lock);
+            }
+        }
+    }
+
+    qemu_lockcnt_dec(&ctx->list_lock);
+    return progress;
+}
+
+bool aio_dispatch(AioContext *ctx, bool dispatch_fds)
+{
+    bool progress;
+
+    progress = aio_bh_poll(ctx);
+    if (dispatch_fds) {
+        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);
+    }
+
+    qemu_lockcnt_inc(&ctx->list_lock);
+    have_select_revents = aio_prepare(ctx);
+
+    /* fill fd sets */
+    count = 0;
+    QLIST_FOREACH_RCU(node, &ctx->aio_handlers, node) {
+        if (!node->deleted && node->io_notify
+            && aio_node_check(ctx, node->is_external)) {
+            events[count++] = event_notifier_get_handle(node->e);
+        }
+    }
+
+    qemu_lockcnt_dec(&ctx->list_lock);
+    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;
+}
+
+void aio_context_setup(AioContext *ctx)
+{
+}
+
+void aio_context_set_poll_params(AioContext *ctx, int64_t max_ns,
+                                 int64_t grow, int64_t shrink, Error **errp)
+{
+    error_setg(errp, "AioContext polling is not implemented on Windows");
+}