Reviewed-by: Steven Dake <sdake@xxxxxxxxxx>
On 01/10/2012 02:23 AM, Fabio M. Di Nitto wrote:
> From: "Fabio M. Di Nitto" <fdinitto@xxxxxxxxxx>
>
> this flag (0|1) can be configured via quorum.auto_tie_breaker and when
> enabled, support for perfect even split is on.
>
> In case of a 50% of votes loss in one single transition, the partition
> with the node that has the lowest node id will remain quorate.
>
> Signed-off-by: Fabio M. Di Nitto <fdinitto@xxxxxxxxxx>
> ---
> :100644 100644 abbd512... c088bb3... M exec/coroparse.c
> :100644 100644 3ba5978... a11b9b3... M services/votequorum.c
> exec/coroparse.c | 1 +
> services/votequorum.c | 52 +++++++++++++++++++++++++++++++++++++++++++++++++
> 2 files changed, 53 insertions(+), 0 deletions(-)
>
> diff --git a/exec/coroparse.c b/exec/coroparse.c
> index abbd512..c088bb3 100644
> --- a/exec/coroparse.c
> +++ b/exec/coroparse.c
> @@ -369,6 +369,7 @@ static int main_config_parser_cb(const char *path,
> if ((strcmp(path, "quorum.disallowed") == 0) ||
> (strcmp(path, "quorum.two_node") == 0) ||
> (strcmp(path, "quorum.wait_for_all") == 0) ||
> + (strcmp(path, "quorum.auto_tie_breaker") == 0) ||
> (strcmp(path, "quorum.quorate") == 0)) {
> i = atoi(value);
> icmap_set_uint8(path, i);
> diff --git a/services/votequorum.c b/services/votequorum.c
> index 3ba5978..a11b9b3 100644
> --- a/services/votequorum.c
> +++ b/services/votequorum.c
> @@ -125,6 +125,8 @@ static int first_trans = 1;
> static unsigned int quorumdev_poll = DEFAULT_QDEV_POLL;
> static unsigned int leaving_timeout = DEFAULT_LEAVE_TMO;
> static uint8_t wait_for_all = 0;
> +static uint8_t auto_tie_breaker = 0;
> +static int lowest_node_id = -1;
>
> static struct cluster_node *us;
> static struct cluster_node *quorum_device = NULL;
> @@ -387,6 +389,16 @@ static void votequorum_init(struct corosync_api_v1 *api,
> set_quorum = report;
>
> icmap_get_uint8("quorum.wait_for_all", &wait_for_all);
> + icmap_get_uint8("quorum.auto_tie_breaker", &auto_tie_breaker);
> +
> + /*
> + * TODO: we need to know the lowest node-id in the cluster
> + * current lack of node list with node-id's requires us to see all nodes
> + * to determine which is the lowest.
> + */
> + if (auto_tie_breaker) {
> + wait_for_all = 1;
> + }
>
> /* Load the library-servicing part of this module */
> api->service_link_and_init(api, "corosync_votequorum_iface", 0);
> @@ -606,6 +618,39 @@ static void send_expectedvotes_notification(void)
> }
> }
>
> +static void get_lowest_node_id(void)
> +{
> + struct cluster_node *node = NULL;
> + struct list_head *tmp;
> +
> + lowest_node_id = us->node_id;
> +
> + list_iterate(tmp, &cluster_members_list) {
> + node = list_entry(tmp, struct cluster_node, list);
> + if (node->node_id < lowest_node_id)
> + lowest_node_id = node->node_id;
> + }
> + log_printf(LOGSYS_LEVEL_DEBUG, "lowest node id: %d us: %d\n", lowest_node_id, us->node_id);
> +}
> +
> +static int check_low_node_id_partition(void)
> +{
> + struct cluster_node *node = NULL;
> + struct list_head *tmp;
> + int found = 0;
> +
> + list_iterate(tmp, &cluster_members_list) {
> + node = list_entry(tmp, struct cluster_node, list);
> + if (node->state == NODESTATE_MEMBER) {
> + if (node->node_id == lowest_node_id) {
> + found = 1;
> + }
> + }
> + }
> +
> + return found;
> +}
> +
> static void set_quorate(int total_votes)
> {
> int quorate;
> @@ -626,6 +671,7 @@ static void set_quorate(int total_votes)
> return;
> }
> wait_for_all = 0;
> + get_lowest_node_id();
> }
>
> if (quorum > total_votes) {
> @@ -635,6 +681,12 @@ static void set_quorate(int total_votes)
> quorate = 1;
> }
>
> + if ((auto_tie_breaker) &&
> + (total_votes == (us->expected_votes / 2)) &&
> + (check_low_node_id_partition() == 1)) {
> + quorate = 1;
> + }
> +
> if (cluster_is_quorate && !quorate)
> log_printf(LOGSYS_LEVEL_INFO, "quorum lost, blocking activity\n");
> if (!cluster_is_quorate && quorate)
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