Re: [Xen-devel] [RFC V6] Libxl Domain Snapshot API Design

["Chun Yan Liu" <cyliu@xxxxxxxx>]

Hi, Ian J. & Ian C.,

Do you have any comments about the new structures and new functions?
Especially libxl_disk_snapshot structure, it's one of the most disputable parts
in last version. If no objection, I'll start writing code.

Thanks,
Chunyan

>>> On 8/27/2014 at 03:22 PM, in message
<1409124146-18249-1-git-send-email-cyliu@xxxxxxxx>, Chunyan Liu
<cyliu@xxxxxxxx> wrote: 
> Since Bamvor left SUSE and turns to work on ARM server, I'd like to continue 
> this work and make progress. Following the discussion about V5, which mainly 
> focused on the API design, here post the updated API design. Thanks for any 
> of your further suggestions! 
>  
> Main changes to V5: 
> * libxl_disk_snapshot: reuse libxl_device_disk rather than specify path, 
>     format separately in the structure. Including two libxl_device_disk 
>     components, one is to indicate the original disk info, one is to 
>     indicate the external snapshot info if it is 'external snapshot'. 
> * define common APIs for domain snapshot creating/deleting/reverting, 
>   rather than a group of functions for disk snapshot operations. 
> * remove those APIs for loading/storing/deleting snapshot config. 
>  
> V5 is here: 
> http://lists.xenproject.org/archives/html/xen-devel/2014-07/msg00893.html 
> V5 about API Design is here: 
> http://lists.xenproject.org/archives/html/xen-devel/2014-07/msg00897.html 
>  
> =========================================================================== 
> Libxl Domain Snapshot API 
>  
> libxl_domain_snapshot = Struct("domain_snapshot",[ 
>     ("name",          string),              /* snapshot name */ 
>     ("description",   string),              /* snapshot description */ 
>     ("creation_time", uint64),              /* creation time, in seconds */ 
>  
>     /* save memory or not. "false" means disk-only snapshot */ 
>     ("memory",        bool), 
>  
>     /* memory state file when snapshot is external */ 
>     ("memory_file",   string), 
>  
>     /* Array to store disk snapshot info. */ 
>     ("disks", Array(libxl_disk_snapshot, "num_disks")), 
>     ]) 
>  
> libxl_disk_snapshot = Struct("disk_snapshot",[ 
>     ("disk",           libxl_device_disk),      /* orignal disk */ 
>     ("name",           string),                 /* snapshot name */ 
>     ("external",       bool),                   /* external snapshot or not  
> */ 
>  
>     /* external snapshot info, including file path and format, etc. 
>      * if "external" is false, this will be "NULL". 
>      */ 
>     ("external_sn",    libxl_device_disk), 
>     ]) 
>  
> enum libxlDomainSnapshotCreateFlags { 
>     /* disk snapshot, not system checkpoint */ 
>     LIBXL_DOMAIN_SNAPSHOT_CREATE_DISK_ONLY    =  1, 
>  
>     /* create the snapshot while the guest is running */ 
>     LIBXL_DOMAIN_SNAPSHOT_CREATE_LIVE         =  2, 
> } 
>  
> enum libxlDomainSnapshotDeleteFlags { 
>     LIBXL_DOMAIN_SNAPSHOT_DELETE_CHILDREN     =  1, /* delete children too */ 
> } 
>  
> enum virDomainSnapshotRevertFlags { 
>     LIBXL_DOMAIN_SNAPSHOT_REVERT_RUNNING        =  1, /* run after revert */ 
>     LIBXL_DOMAIN_SNAPSHOT_REVERT_PAUSED         =  2, /* pause after revert  
> */ 
>     LIBXL_DOMAIN_SNAPSHOT_REVERT_FORCE          =  4, /* force revert */ 
> } 
>  
> int libxl_domain_snapshot_create(libxl_ctx *ctx, const char *domname, 
>                                  libxl_domain_snapshot *snapshot, 
>                                  unsigned int flags); 
>  
>     Creates a new snapshot of a domain based on the snapshot config  
> contained 
>     in @snapshot. 
>  
>     If @flags includes LIBXL_DOMAIN_SNAPSHOT_CREATE_LIVE, then the domain is  
> not 
>     paused while creating the snapshot, like live migration. This increases  
> size 
>     of the memory dump file, but reducess downtime of the guest. Only  
> support 
>     this flag during external checkpoints. 
>  
>     If @flags includes LIBXL_DOMAIN_SNAPSHOT_CREATE_DISK_ONLY, then the  
> snapshot 
>     will be limited to the disks described in @snapshot, and no VM state  
> will 
>     be saved. For an active guest, this is not supported. 
>  
>     ctx: context 
>     domname:  domain name 
>     snapshot: configuration of domain snapshot 
>     flags: bitwise-OR of libxlDomainSnapshotCreateFlags 
>     Returns: 0 on success, -1 on failure 
>  
>  
> int libxl_domain_snapshot_delete(libxl_ctx *ctx, const char *domname, 
>                                  const char *snapshot_name, 
>                                  unsigned int flags); 
>  
>     Delete a snapshot. 
>  
>     If @flags is 0, then just this snapshot is deleted, and changes from  
> this 
>     snapshot are automatically merged into children snapshots. 
>  
>     If @flags includes LIBXL_DOMAIN_SNAPSHOT_DELETE_CHILDREN, then this  
> snapshot 
>     and any descendant snapshots are deleted. 
>  
>     ctx: context 
>     domname: domain name 
>     snapshot_name: snapshot name 
>     flags: bitwise-OR of supported libxlDomainSnapshotDeleteFlags 
>     Returns: 0 on success, -1 on error. 
>  
> int libxl_disk_snapshot_revert(libxl_ctx *ctx, const char *domname, 
>                                const char *snapshot_name, 
>                                unsigned int flags); 
>  
>     Revert the domain to a given snapshot. 
>  
>     Normally, the domain will revert to the same state the domain was in  
> while 
>     the snapshot was taken (whether inactive, running, or paused). 
>  
>     If @flags includes LIBXL_DOMAIN_SNAPSHOT_REVERT_RUNNING, then overrides  
> the 
>     snapshot state to guarantee a running domain after the revert. 
>  
>     If @flags includes LIBXL_DOMAIN_SNAPSHOT_REVERT_PAUSED, then guarantees  
> a 
>     paused domain after the revert. 
>  
>     ctx: context 
>     domname: domain name 
>     snapshot_name: snapshot name 
>     flags: bitwise-OR of supported libxlDomainSnapshotRevertFlags 
>     Returns: 0 on success, -1 on error. 
>  
> _______________________________________________ 
> Xen-devel mailing list 
> Xen-devel@xxxxxxxxxxxxx 
> http://lists.xen.org/xen-devel 
>  
>  


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