On Fri, Apr 16, 2021 at 11:08:55AM +0300, Vladimir Sementsov-Ogievskiy wrote:
> Add an option for thread to retry connection until success. We'll use
> nbd/client-connection both for reconnect and for initial connection in
> nbd_open(), so we need a possibility to use same NBDClientConnection
> instance to connect once in nbd_open() and then use retry semantics for
> reconnect.
>
> Signed-off-by: Vladimir Sementsov-Ogievskiy <vsement...@virtuozzo.com>
> ---
> include/block/nbd.h | 2 ++
> nbd/client-connection.c | 55 +++++++++++++++++++++++++++++------------
> 2 files changed, 41 insertions(+), 16 deletions(-)
>
> diff --git a/include/block/nbd.h b/include/block/nbd.h
> index 5d86e6a393..5bb54d831c 100644
> --- a/include/block/nbd.h
> +++ b/include/block/nbd.h
> @@ -409,6 +409,8 @@ const char *nbd_err_lookup(int err);
> /* nbd/client-connection.c */
> typedef struct NBDClientConnection NBDClientConnection;
>
> +void nbd_client_connection_enable_retry(NBDClientConnection *conn);
> +
> NBDClientConnection *nbd_client_connection_new(const SocketAddress *saddr,
> bool do_negotiation,
> const char *export_name,
> diff --git a/nbd/client-connection.c b/nbd/client-connection.c
> index ae4a77f826..002bd91f42 100644
> --- a/nbd/client-connection.c
> +++ b/nbd/client-connection.c
> @@ -36,6 +36,8 @@ struct NBDClientConnection {
> NBDExportInfo initial_info;
> bool do_negotiation;
>
> + bool do_retry;
> +
> /*
> * Result of last attempt. Valid in FAIL and SUCCESS states.
> * If you want to steal error, don't forget to set pointer to NULL.
> @@ -52,6 +54,15 @@ struct NBDClientConnection {
> Coroutine *wait_co; /* nbd_co_establish_connection() wait in yield() */
> };
>
> +/*
> + * The function isn't protected by any mutex, so call it when thread is not
> + * running.
> + */
> +void nbd_client_connection_enable_retry(NBDClientConnection *conn)
> +{
> + conn->do_retry = true;
> +}
> +
> NBDClientConnection *nbd_client_connection_new(const SocketAddress *saddr,
> bool do_negotiation,
> const char *export_name,
> @@ -144,24 +155,37 @@ static void *connect_thread_func(void *opaque)
> NBDClientConnection *conn = opaque;
> bool do_free;
> int ret;
> + uint64_t timeout = 1;
> + uint64_t max_timeout = 16;
> +
> + while (true) {
> + conn->sioc = qio_channel_socket_new();
> +
> + error_free(conn->err);
> + conn->err = NULL;
> + conn->updated_info = conn->initial_info;
> +
> + ret = nbd_connect(conn->sioc, conn->saddr,
> + conn->do_negotiation ? &conn->updated_info : NULL,
> + conn->tlscreds, &conn->ioc, &conn->err);
> + conn->updated_info.x_dirty_bitmap = NULL;
> + conn->updated_info.name = NULL;
> +
> + if (ret < 0) {
> + object_unref(OBJECT(conn->sioc));
> + conn->sioc = NULL;
> + if (conn->do_retry) {
> + sleep(timeout);
> + if (timeout < max_timeout) {
> + timeout *= 2;
> + }
> + continue;
> + }
> + }
How is it supposed to get canceled?
Roman.
> - conn->sioc = qio_channel_socket_new();
> -
> - error_free(conn->err);
> - conn->err = NULL;
> - conn->updated_info = conn->initial_info;
> -
> - ret = nbd_connect(conn->sioc, conn->saddr,
> - conn->do_negotiation ? &conn->updated_info : NULL,
> - conn->tlscreds, &conn->ioc, &conn->err);
> - if (ret < 0) {
> - object_unref(OBJECT(conn->sioc));
> - conn->sioc = NULL;
> + break;
> }
>
> - conn->updated_info.x_dirty_bitmap = NULL;
> - conn->updated_info.name = NULL;
> -
> WITH_QEMU_LOCK_GUARD(&conn->mutex) {
> assert(conn->running);
> conn->running = false;
> @@ -172,7 +196,6 @@ static void *connect_thread_func(void *opaque)
> do_free = conn->detached;
> }
>
> -
> if (do_free) {
> nbd_client_connection_do_free(conn);
> }
> --
> 2.29.2
>
