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From f8083d52b6314f92718316f160eea47fef47988e Mon Sep 17 00:00:00 2001
From: Jonathan Davies <jonathan.davies@citrix.com>
Date: Thu, 23 Mar 2017 14:20:33 +0000
Subject: [PATCH 08/15] oxenstored: only record operations with side-effects in
history
There is no need to record "read" operations as they will never cause another
transaction to fail.
Reported-by: Juergen Gross <jgross@suse.com>
Signed-off-by: Jonathan Davies <jonathan.davies@citrix.com>
Reviewed-by: Thomas Sanders <thomas.sanders@citrix.com>
---
tools/ocaml/xenstored/process.ml | 47 ++++++++++++++++++++++++++++++++++++----
1 file changed, 43 insertions(+), 4 deletions(-)
diff --git a/tools/ocaml/xenstored/process.ml b/tools/ocaml/xenstored/process.ml
index 964c044..b435a4a 100644
--- a/tools/ocaml/xenstored/process.ml
+++ b/tools/ocaml/xenstored/process.ml
@@ -450,6 +450,37 @@ let function_of_type ty =
| _ -> function_of_type_simple_op ty
(**
+ * Determines which individual (non-transactional) operations we want to retain.
+ * We only want to retain operations that have side-effects in the store since
+ * these can be the cause of transactions failing.
+ *)
+let retain_op_in_history ty =
+ match ty with
+ | Xenbus.Xb.Op.Write
+ | Xenbus.Xb.Op.Mkdir
+ | Xenbus.Xb.Op.Rm
+ | Xenbus.Xb.Op.Setperms -> true
+ | Xenbus.Xb.Op.Debug
+ | Xenbus.Xb.Op.Directory
+ | Xenbus.Xb.Op.Read
+ | Xenbus.Xb.Op.Getperms
+ | Xenbus.Xb.Op.Watch
+ | Xenbus.Xb.Op.Unwatch
+ | Xenbus.Xb.Op.Transaction_start
+ | Xenbus.Xb.Op.Transaction_end
+ | Xenbus.Xb.Op.Introduce
+ | Xenbus.Xb.Op.Release
+ | Xenbus.Xb.Op.Getdomainpath
+ | Xenbus.Xb.Op.Watchevent
+ | Xenbus.Xb.Op.Error
+ | Xenbus.Xb.Op.Isintroduced
+ | Xenbus.Xb.Op.Resume
+ | Xenbus.Xb.Op.Set_target
+ | Xenbus.Xb.Op.Restrict
+ | Xenbus.Xb.Op.Reset_watches
+ | Xenbus.Xb.Op.Invalid -> false
+
+(**
* Nothrow guarantee.
*)
let process_packet ~store ~cons ~doms ~con ~req =
@@ -465,10 +496,18 @@ let process_packet ~store ~cons ~doms ~con ~req =
Connection.get_transaction con tid
in
- let before = Store.copy store in
- let response = input_handle_error ~cons ~doms ~fct ~con ~t ~req in
- let after = Store.copy store in
- if tid = Transaction.none then record_commit ~con ~tid ~before ~after;
+ let execute () = input_handle_error ~cons ~doms ~fct ~con ~t ~req in
+
+ let response =
+ (* Note that transactions are recorded in history separately. *)
+ if tid = Transaction.none && retain_op_in_history ty then begin
+ let before = Store.copy store in
+ let response = execute () in
+ let after = Store.copy store in
+ record_commit ~con ~tid ~before ~after;
+ response
+ end else execute ()
+ in
let response = try
if tid <> Transaction.none then
--
2.1.4
|
