[sheepdog] [disscuss] Design of Libsheepdog

[MORITA Kazutaka]

At Wed, 26 Jun 2013 10:51:26 +0800,
Kai Zhang wrote:
> 
> /* connection */
> int sd_init(char *addr, const sd_t *sd);

I think the syntax of addr needs discussion:
 - How to specify a port number?
 - How to connect to a unix domain socket?

> int sd_close(sd_t *sd);
> 
> /* vdi */
> int sd_vdi_create(sd_t sd, const char *name, size_t size, int copies,
> 		  bool prealloc, const sd_vdi_t *vdi);
> int sd_vdi_clone(sd_t sd, const sd_vdi_t src_vdi, const char *dst_name,
> 		 int copies, const sd_vdi_t *dst_vdi);

The source vdi must be snapshot, so I think we need more arguments to
specify the snapshot tag or index.

> int sd_vdi_open(sd_t sd, const char *name, const sd_vdi_t *vdi);
> int sd_vdi_close(const sd_vdi_t *vdi);
> 
> int sd_vdi_read(sd_t sd, const sd_vdi_t vdi, void *data, size_t size,
> 		size_t offset);

off_t offset?

> int sd_vdi_write(sd_t sd, const sd_vdi_t vdi, void *data, size_t size,
> 		 size_t offset, bool writeback);

Note that we have 3 modes to control cache usage:
 - writethough
 - writeback
 - none (or directsync)
'none' is used to bypass object cache.

> int sd_vdi_resize(sd_t sd, const sd_vdi_t vdi, size_t size);
> int sd_vdi_delete(sd_t sd, const char *name);
> int sd_vdi_setattr(sd_t sd, const char *name, const char *key, void *value,
> 		   size_t value_len);
> int sd_vdi_getattr(sd_t sd, const char *name, const char *key, void *value,
> 		   size_t value_len);

How to delete vdi attributes?

> int sd_vdi_list(sd_t sd, string_iterator *si);
> 
> /* snapshot */
> int sd_vdi_snap_create(sd_t sd, const sd_vdi_t vdi, const char *tag,
> 		       const sd_vdi_t snap_vdi);
> int sd_vdi_snap_open(sd_t sd, const char *name, const char *tag, int idx,
> 		     const sd_vdi_t *snap_vdi);
> int sd_vdi_snap_rollback(sd_t sd, const sd_vdi_t vdi);
> int sd_vdi_snap_read(sd_t sd, const sd_vdi_t vdi, void *data, size_t size,
> 		     size_t offset);

sd_snapshot_*() looks simpler?

Thanks,

Kazutaka