CP-54072: Define new MIRROR.send_start function

The `send_start` function is a subroutine inside the
`Storage_migrate.start` function, which takes the mirror prepared by the
`receive_start` and initiates mirroring to the remote VDI.

This commit only defines the interface, which means this function is
currently unused.

Signed-off-by: Vincent Liu <shuntian.liu2@cloud.com>

Author: incipit0

ocaml/xapi-idl/storage/storage_interface.ml

@@ -1027,8 +1027,43 @@ module StorageAPI (R : RPC) = struct
         )
 
     module MIRROR = struct
+      let mirror_vm_p = Param.mk ~name:"mirror_vm" Vm.t
+
+      let copy_vm_p = Param.mk ~name:"copy_vm" Vm.t
+
+      let live_vm_p = Param.mk ~name:"live_vm" Vm.t
+
       let id_p = Param.mk ~name:"id" Mirror.id
 
+      (** [send_start dbg dp task src_sr vdi mirror_vm mirror_id local_vdi copy_vm 
+      live_vm url remote_mirror dest_sr verify_dest]
+      takes the remote mirror [remote_mirror] prepared by the destination host 
+      and initiates the mirroring of [vdi] from the source *)
+      let send_start =
+        let recv_result_p =
+          Param.mk ~name:"recv_result" Mirror.mirror_receive_result
+        in
+        let local_vdi_p = Param.mk ~name:"local_vdi" vdi_info in
+        let src_sr_p = Param.mk ~name:"src_sr" Sr.t in
+        let dest_sr_p = Param.mk ~name:"dest_sr" Sr.t in
+        declare "DATA.MIRROR.send_start" []
+          (dbg_p
+          @-> dp_p
+          @-> task_id_p
+          @-> src_sr_p
+          @-> vdi_p
+          @-> mirror_vm_p
+          @-> id_p
+          @-> local_vdi_p
+          @-> copy_vm_p
+          @-> live_vm_p
+          @-> url_p
+          @-> recv_result_p
+          @-> dest_sr_p
+          @-> verify_dest_p
+          @-> returning unit_p err
+          )
+
       (** Called on the receiving end 
         @deprecated This function is deprecated, and is only here to keep backward 
         compatibility with old xapis that call Remote.DATA.MIRROR.receive_start during SXM. 
@@ -1130,6 +1165,24 @@ end
 module type MIRROR = sig
   type context = unit
 
+  val send_start :
+       context
+    -> dbg:debug_info
+    -> task_id:Task.id
+    -> dp:dp
+    -> sr:sr
+    -> vdi:vdi
+    -> mirror_vm:vm
+    -> mirror_id:Mirror.id
+    -> local_vdi:vdi_info
+    -> copy_vm:vm
+    -> live_vm:vm
+    -> url:string
+    -> remote_mirror:Mirror.mirror_receive_result
+    -> dest_sr:sr
+    -> verify_dest:bool
+    -> unit
+
   val receive_start :
        context
     -> dbg:debug_info
@@ -1586,6 +1639,27 @@ module Server (Impl : Server_impl) () = struct
     S.DATA.copy (fun dbg sr vdi vm url dest verify_dest ->
         Impl.DATA.copy () ~dbg ~sr ~vdi ~vm ~url ~dest ~verify_dest
     ) ;
+    S.DATA.MIRROR.send_start
+      (fun
+        dbg
+        task_id
+        dp
+        sr
+        vdi
+        mirror_vm
+        mirror_id
+        local_vdi
+        copy_vm
+        live_vm
+        url
+        remote_mirror
+        dest_sr
+        verify_dest
+      ->
+        Impl.DATA.MIRROR.send_start () ~dbg ~task_id ~dp ~sr ~vdi ~mirror_vm
+          ~mirror_id ~local_vdi ~copy_vm ~live_vm ~url ~remote_mirror ~dest_sr
+          ~verify_dest
+    ) ;
     S.DATA.MIRROR.receive_start (fun dbg sr vdi_info id similar ->
         Impl.DATA.MIRROR.receive_start () ~dbg ~sr ~vdi_info ~id ~similar
     ) ;

ocaml/xapi-idl/storage/storage_skeleton.ml

@@ -162,6 +162,10 @@ module DATA = struct
   module MIRROR = struct
     type context = unit
 
+    let send_start ctx ~dbg ~task_id ~dp ~sr ~vdi ~mirror_vm ~mirror_id
+        ~local_vdi ~copy_vm ~live_vm ~url ~remote_mirror ~dest_sr ~verify_dest =
+      u "DATA.MIRROR.send_start"
+
     let receive_start ctx ~dbg ~sr ~vdi_info ~id ~similar =
       u "DATA.MIRROR.receive_start"
 

ocaml/xapi-storage-script/main.ml

@@ -1920,6 +1920,7 @@ let bind ~volume_script_dir =
   S.VDI.similar_content (u "VDI.similar_content") ;
   S.DATA.copy (u "DATA.copy") ;
   S.DP.stat_vdi (u "DP.stat_vdi") ;
+  S.DATA.MIRROR.send_start (u "DATA.MIRROR.send_start") ;
   S.DATA.MIRROR.receive_start (u "DATA.MIRROR.receive_start") ;
   S.DATA.MIRROR.receive_start2 (u "DATA.MIRROR.receive_start2") ;
   S.DATA.MIRROR.receive_finalize (u "DATA.MIRROR.receive_finalize") ;

ocaml/xapi/storage_mux.ml

@@ -760,6 +760,13 @@ module Mux = struct
     module MIRROR = struct
       type context = unit
 
+      let u x = raise Storage_interface.(Storage_error (Errors.Unimplemented x))
+
+      let send_start _ctx ~dbg:_ ~task_id:_ ~dp:_ ~sr:_ ~vdi:_ ~mirror_vm:_
+          ~mirror_id:_ ~local_vdi:_ ~copy_vm:_ ~live_vm:_ ~url:_
+          ~remote_mirror:_ ~dest_sr:_ ~verify_dest:_ =
+        u "DATA.MIRROR.send_start" (* see storage_smapi{v1,v3}_migrate.ml *)
+
       let receive_start () ~dbg ~sr ~vdi_info ~id ~similar =
         with_dbg ~name:"DATA.MIRROR.receive_start" ~dbg @@ fun di ->
         info "%s dbg: %s sr: %s vdi_info: %s mirror_id: %s similar: %s"

ocaml/xapi/storage_smapiv1.ml

@@ -1219,6 +1219,11 @@ module SMAPIv1 : Server_impl = struct
     module MIRROR = struct
       type context = unit
 
+      let send_start _ctx ~dbg:_ ~task_id:_ ~dp:_ ~sr:_ ~vdi:_ ~mirror_vm:_
+          ~mirror_id:_ ~local_vdi:_ ~copy_vm:_ ~live_vm:_ ~url:_
+          ~remote_mirror:_ ~dest_sr:_ ~verify_dest:_ =
+        assert false
+
       let receive_start _context ~dbg:_ ~sr:_ ~vdi_info:_ ~id:_ ~similar:_ =
         assert false
 

ocaml/xapi/storage_smapiv1_wrapper.ml

@@ -1186,6 +1186,14 @@ functor
       module MIRROR = struct
         type context = unit
 
+        let u x =
+          raise Storage_interface.(Storage_error (Errors.Unimplemented x))
+
+        let send_start _ctx ~dbg:_ ~task_id:_ ~dp:_ ~sr:_ ~vdi:_ ~mirror_vm:_
+            ~mirror_id:_ ~local_vdi:_ ~copy_vm:_ ~live_vm:_ ~url:_
+            ~remote_mirror:_ ~dest_sr:_ ~verify_dest:_ =
+          u "DATA.MIRROR.send_start"
+
         let receive_start context ~dbg ~sr ~vdi_info ~id ~similar =
           info "DATA.MIRROR.receive_start dbg:%s sr:%s id:%s similar:[%s]" dbg
             (s_of_sr sr) id