[sheepdog] [PATCH v2] sheep: add epoch file recovery

[Hitoshi Mitake]

At Mon, 28 Jul 2014 14:55:20 +0800,
Ruoyu wrote:
> 
> If cluster members change frequently, especially the first two or
> more nodes of the cluster leave and join frequently, the following
> error message will be found in sheep.log
> 
> Failed to find requested tag, remote address: 127.0.0.1:7001,
> op name: GET_EPOCH
> 
> This patch adds epoch recovery to reduce these errors. To achieve
> it, it is better to unify epoch file because rb_node is unused
> in it. And then, we can create a new epoch file as long as the file
> is not found in local node.
> 
> v2 is rebased on the latest master and
> 1. memset's 2nd parameter, use 0 instead of '\0'
> 2. for loop initial declaration
> 
> Signed-off-by: Ruoyu <liangry at ucweb.com>
> ---
>  sheep/group.c | 7 +++++--
>  sheep/store.c | 9 +++++++++
>  2 files changed, 14 insertions(+), 2 deletions(-)

Applied, thanks.
Hitoshi

> 
> diff --git a/sheep/group.c b/sheep/group.c
> index 6b1ec5d..f53ad0f 100644
> --- a/sheep/group.c
> +++ b/sheep/group.c
> @@ -359,7 +359,7 @@ int epoch_log_read_remote(uint32_t epoch, struct sd_node *nodes, int len,
>  	rb_for_each_entry(node, &vinfo->nroot, rb) {
>  		struct sd_req hdr;
>  		struct sd_rsp *rsp = (struct sd_rsp *)&hdr;
> -		int nodes_len;
> +		int nodes_len, nr_nodes;
>  
>  		if (node_is_local(node))
>  			continue;
> @@ -377,7 +377,10 @@ int epoch_log_read_remote(uint32_t epoch, struct sd_node *nodes, int len,
>  		if (timestamp)
>  			memcpy(timestamp, buf + nodes_len, sizeof(*timestamp));
>  
> -		return nodes_len / sizeof(struct sd_node);
> +		nr_nodes = nodes_len / sizeof(struct sd_node);
> +		/* epoch file is missing in local node, try to create one */
> +		update_epoch_log(epoch, nodes, nr_nodes);
> +		return nr_nodes;
>  	}
>  
>  	/*
> diff --git a/sheep/store.c b/sheep/store.c
> index eb42f2c..ea445fc 100644
> --- a/sheep/store.c
> +++ b/sheep/store.c
> @@ -33,6 +33,15 @@ int update_epoch_log(uint32_t epoch, struct sd_node *nodes, size_t nr_nodes)
>  	memcpy(buf, nodes, nodes_len);
>  	memcpy(buf + nodes_len, &t, sizeof(time_t));
>  
> +	/*
> +	 * rb field is unused in epoch file, zero-filling it
> +	 * is good for epoch file recovery because it is unified
> +	 */
> +	for (int i = 0; i < nr_nodes; i++)
> +		memset(buf + i * sizeof(struct sd_node)
> +				+ offsetof(struct sd_node, rb),
> +				0, sizeof(struct rb_node));
> +
>  	snprintf(path, sizeof(path), "%s%08u", epoch_path, epoch);
>  
>  	ret = atomic_create_and_write(path, buf, len, true);
> -- 
> 1.8.3.2
> 
> 
> -- 
> sheepdog mailing list
> sheepdog at lists.wpkg.org
> http://lists.wpkg.org/mailman/listinfo/sheepdog