[Sheepdog] [PATCH] sheep: abstract out 'all or nothing' write operation

[MORITA Kazutaka]

At Wed, 21 Dec 2011 16:48:26 +0800,
Liu Yuan wrote:
> 
> From: Liu Yuan <tailai.ly at taobao.com>
> 
> In recovery, sheep needs to atomically write the object to the store
> that is being recovered. This operation assume underlying store layout,
> so we need to abstract it out.
> 
> Signed-off-by: Liu Yuan <tailai.ly at taobao.com>
> ---
>  sheep/sheep_priv.h   |    1 +
>  sheep/simple_store.c |   41 +++++++++++++++++++++++++++++++++++++++++
>  sheep/store.c        |   36 ++++++------------------------------
>  3 files changed, 48 insertions(+), 30 deletions(-)
> 
> diff --git a/sheep/sheep_priv.h b/sheep/sheep_priv.h
> index 29ffd74..8a39d1b 100644
> --- a/sheep/sheep_priv.h
> +++ b/sheep/sheep_priv.h
> @@ -175,6 +175,7 @@ struct store_driver {
>  	/* Operations in recovery */
>  	int (*get_objlist)(struct siocb *);
>  	int (*link)(uint64_t oid, struct siocb *, int tgt_epoch);
> +	int (*atomic_put)(uint64_t oid, struct siocb *);
>  };
>  
>  extern void register_store_driver(struct store_driver *);
> diff --git a/sheep/simple_store.c b/sheep/simple_store.c
> index 36c45b3..ec77a8d 100644
> --- a/sheep/simple_store.c
> +++ b/sheep/simple_store.c
> @@ -198,6 +198,46 @@ static int simple_store_link(uint64_t oid, struct siocb *iocb, int tgt_epoch)
>         return SD_RES_EIO;
>  }
>  
> +static int simple_store_atomic_put(uint64_t oid, struct siocb *iocb)
> +{
> +	char path[PATH_MAX], tmp_path[PATH_MAX];
> +	int flags = O_DSYNC | O_RDWR | O_CREAT;
> +	int ret = SD_RES_EIO, epoch = iocb->epoch, fd;
> +	uint32_t len = iocb->length;
> +
> +	snprintf(path, sizeof(path), "%s%08u/%016" PRIx64, obj_path,
> +		 epoch, oid);
> +	snprintf(tmp_path, sizeof(tmp_path), "%s%08u/%016" PRIx64 ".tmp",
> +		 obj_path, epoch, oid);
> +
> +	fd = open(tmp_path, flags, def_fmode);
> +	if (fd < 0) {
> +		eprintf("failed to open %s: %m\n", tmp_path);
> +		goto out;
> +	}
> +
> +	ret = write(fd, iocb->buf, len);
> +	if (ret != len) {
> +		eprintf("failed to write object. %m\n");
> +		ret = SD_RES_EIO;
> +		goto out_close;
> +	}
> +
> +
> +	ret = rename(tmp_path, path);
> +	if (ret < 0) {
> +		eprintf("failed to rename %s to %s: %m\n", tmp_path, path);
> +		ret = SD_RES_EIO;
> +		goto out_close;
> +	}
> +	dprintf("%"PRIx64"\n", oid);
> +	ret = SD_RES_SUCCESS;
> +out_close:
> +	close(fd);
> +out:
> +	return ret;
> +}
> +
>  struct store_driver store = {
>  	.driver_name = "simple",
>  	.init = simple_store_init,
> @@ -207,6 +247,7 @@ struct store_driver store = {
>  	.close = simple_store_close,
>  	.get_objlist = simple_store_get_objlist,
>  	.link = simple_store_link,
> +	.atomic_put = simple_store_atomic_put,
>  };
>  
>  void register_store_driver(struct store_driver *driver)
> diff --git a/sheep/store.c b/sheep/store.c
> index 4adae51..8c857f9 100644
> --- a/sheep/store.c
> +++ b/sheep/store.c
> @@ -1186,6 +1186,7 @@ static int recover_object_from_replica(uint64_t oid,
>  	unsigned wlen = 0, rlen;
>  	int fd, ret;
>  	void *buf;
> +	struct siocb iocb = { 0 };
>  
>  	buf = alloc_buffer_for(oid);
>  	if (!buf) {
> @@ -1194,8 +1195,6 @@ static int recover_object_from_replica(uint64_t oid,
>  	}
>  
>  	if (is_myself(entry->addr, entry->port)) {
> -		struct siocb iocb = { 0 };
> -
>  		iocb.epoch = epoch;
>  		ret = store.link(oid, &iocb, tgt_epoch);
>  		if (ret == SD_RES_SUCCESS) {
> @@ -1242,34 +1241,11 @@ static int recover_object_from_replica(uint64_t oid,
>  	rsp = (struct sd_obj_rsp *)&hdr;
>  
>  	if (rsp->result == SD_RES_SUCCESS) {
> -		char path[PATH_MAX], tmp_path[PATH_MAX];
> -		int flags = O_DSYNC | O_RDWR | O_CREAT;
> -
> -		snprintf(path, sizeof(path), "%s%08u/%016" PRIx64, obj_path,
> -				epoch, oid);
> -		snprintf(tmp_path, sizeof(tmp_path), "%s%08u/%016" PRIx64 ".tmp",
> -				obj_path, epoch, oid);
> -
> -		fd = open(tmp_path, flags, def_fmode);
> -		if (fd < 0) {
> -			eprintf("failed to open %s: %m\n", tmp_path);
> -			ret = -1;
> -			goto out;
> -		}
> -
> -		ret = write(fd, buf, rlen);
> -		if (ret != rlen) {
> -			eprintf("failed to write object\n");
> -			ret = -1;
> -			goto out;
> -		}
> -
> -		close(fd);
> -
> -		dprintf("rename %s to %s\n", tmp_path, path);
> -		ret = rename(tmp_path, path);
> -		if (ret < 0) {
> -			eprintf("failed to rename %s to %s: %m\n", tmp_path, path);
> +		iocb.epoch = epoch;
> +		iocb.length = rlen;
> +		iocb.buf = buf;
> +		ret = store.atomic_put(oid, &iocb);
> +		if (ret!= SD_RES_SUCCESS) {

Missing a space before '!='.

I've applied after fixing this.

Thanks,

Kazutaka