CP-48676: Don't check resuable pool session validity by default

Add a new flag validate-reusable-pool-session to xapi globs which skips
the reusable pool session validity check if it is false. This saves time
as we are no longer calling pool.get_all for each session.

Signed-off-by: Steven Woods <[email protected]>

ocaml/xapi/xapi_globs.ml

@@ -1074,6 +1074,9 @@ let disable_webserver = ref false
 let reuse_pool_sessions = ref true
 (* Enables the reuse of pool sessions, speeding up intrapool communication *)
 
+let validate_reusable_pool_session = ref false
+(* Validate a reusable session before each use. This is slower and should not be required *)
+
 let test_open = ref 0
 
 let tgroups_enabled = ref false
@@ -1713,6 +1716,11 @@ let other_options =
     , (fun () -> string_of_bool !reuse_pool_sessions)
     , "Enable the reuse of pool sessions"
     )
+  ; ( "validate-reusable-pool-session"
+    , Arg.Set validate_reusable_pool_session
+    , (fun () -> string_of_bool !validate_reusable_pool_session)
+    , "Enable validation of reusable pool sessions before use"
+    )
   ]
 
 (* The options can be set with the variable xapiflags in /etc/sysconfig/xapi.

ocaml/xapi/xapi_session.ml

@@ -681,7 +681,10 @@ let login_no_password_common ~__context ~uname ~originator ~host ~pool
         debug "Invalid session: %s" err ;
         false
     in
-    session_id <> Ref.null || is_valid_session session_id
+    session_id <> Ref.null
+    && ((not !Xapi_globs.validate_reusable_pool_session)
+       || is_valid_session session_id
+       )
   in
   let create_session () =
     let new_session_id =