Re: [Qemu-devel] [RFC PATCH v2 03/10] Colo-proxy: add colo-proxy framework

[Dr. David Alan Gilbert]

* Zhang Chen (address@hidden) wrote:
> From: zhangchen <address@hidden>
> 

> +static void colo_proxy_setup(NetFilterState *nf, Error **errp)
> +{
> +    COLOProxyState *s = FILTER_COLO_PROXY(nf);
> +
> +    if (!s->addr) {
> +        error_setg(errp, "filter colo_proxy needs 'addr' property set!");
> +        return;
> +    }
> +
> +    if (nf->direction != NET_FILTER_DIRECTION_ALL) {
> +        error_setg(errp, "colo need queue all packet,"
> +                        "please startup colo-proxy with queue=all\n");
> +        return;
> +    }
> +
> +    s->sockfd = -1;
> +    s->hashtable_size = 0;
> +    colo_do_checkpoint = false;
> +    qemu_event_init(&s->need_compare_ev, false);
> +
> +    s->incoming_queue = qemu_new_net_queue(qemu_netfilter_pass_to_next, nf);

I found that I had to be careful that this queue got flushed.  If the packet
can't be sent immediately, then the packet only gets sent if another
packet is added to the queue later.  I added a state change notifier to
flush it when the VM started running (this is more of a problem in my hybrid
mode case).

Note also that the queue is not protected by locks; so take care since packets
are sent from both the comparison thread and the colo thread (when it flushes)
and I think it's read by the main thread as well potentially as packets are 
sent.

Dave


> +    colo_conn_hash = g_hash_table_new_full(connection_key_hash,
> +                                           connection_key_equal,
> +                                           g_free,
> +                                           connection_destroy);
> +    g_queue_init(&s->conn_list);
> +}
> +
> +static void colo_proxy_class_init(ObjectClass *oc, void *data)
> +{
> +    NetFilterClass *nfc = NETFILTER_CLASS(oc);
> +
> +    nfc->setup = colo_proxy_setup;
> +    nfc->cleanup = colo_proxy_cleanup;
> +    nfc->receive_iov = colo_proxy_receive_iov;
> +}
> +
> +static int colo_proxy_get_mode(Object *obj, Error **errp)
> +{
> +    COLOProxyState *s = FILTER_COLO_PROXY(obj);
> +
> +    return s->colo_mode;
> +}
> +
> +static void
> +colo_proxy_set_mode(Object *obj, int mode, Error **errp)
> +{
> +    COLOProxyState *s = FILTER_COLO_PROXY(obj);
> +
> +    s->colo_mode = mode;
> +}
> +
> +static char *colo_proxy_get_addr(Object *obj, Error **errp)
> +{
> +    COLOProxyState *s = FILTER_COLO_PROXY(obj);
> +
> +    return g_strdup(s->addr);
> +}
> +
> +static void
> +colo_proxy_set_addr(Object *obj, const char *value, Error **errp)
> +{
> +    COLOProxyState *s = FILTER_COLO_PROXY(obj);
> +    g_free(s->addr);
> +    s->addr = g_strdup(value);
> +    if (!s->addr) {
> +        error_setg(errp, "colo_proxy needs 'addr'"
> +                     "property set!");
> +        return;
> +    }
> +}
> +
> +static void colo_proxy_init(Object *obj)
> +{
> +    object_property_add_enum(obj, "mode", "COLOMode", COLOMode_lookup,
> +                             colo_proxy_get_mode, colo_proxy_set_mode, NULL);
> +    object_property_add_str(obj, "addr", colo_proxy_get_addr,
> +                            colo_proxy_set_addr, NULL);
> +}
> +
> +static void colo_proxy_fini(Object *obj)
> +{
> +    COLOProxyState *s = FILTER_COLO_PROXY(obj);
> +    g_free(s->addr);
> +}
> +
> +static const TypeInfo colo_proxy_info = {
> +    .name = TYPE_FILTER_COLO_PROXY,
> +    .parent = TYPE_NETFILTER,
> +    .class_init = colo_proxy_class_init,
> +    .instance_init = colo_proxy_init,
> +    .instance_finalize = colo_proxy_fini,
> +    .instance_size = sizeof(COLOProxyState),
> +};
> +
> +static void register_types(void)
> +{
> +    type_register_static(&colo_proxy_info);
> +}
> +
> +type_init(register_types);
> diff --git a/net/colo-proxy.h b/net/colo-proxy.h
> new file mode 100644
> index 0000000..affc117
> --- /dev/null
> +++ b/net/colo-proxy.h
> @@ -0,0 +1,24 @@
> +/*
> + * COarse-grain LOck-stepping Virtual Machines for Non-stop Service (COLO)
> + * (a.k.a. Fault Tolerance or Continuous Replication)
> + *
> + * Copyright (c) 2015 HUAWEI TECHNOLOGIES CO., LTD.
> + * Copyright (c) 2015 FUJITSU LIMITED
> + * Copyright (c) 2015 Intel Corporation
> + *
> + * Author: Zhang Chen <address@hidden>
> + *
> + * This work is licensed under the terms of the GNU GPL, version 2 or
> + * later.  See the COPYING file in the top-level directory.
> + */
> +
> +
> +#ifndef QEMU_COLO_PROXY_H
> +#define QEMU_COLO_PROXY_H
> +
> +int colo_proxy_start(int mode);
> +void colo_proxy_stop(int mode);
> +int colo_proxy_do_checkpoint(int mode);
> +bool colo_proxy_query_checkpoint(void);
> +
> +#endif /* QEMU_COLO_PROXY_H */
> -- 
> 1.9.1
> 
> 
> 
> 
--
Dr. David Alan Gilbert / address@hidden / Manchester, UK