[PATCH v3 7/9] oxenstored: only process domain connections that notify us by events

[Zheng Li <dev@zheng.li>]

Currently, upon receiving an event, oxenstored will always scan/process all
the domain connections (xs rings), disregarding which domain sent that event.
This is rather costy and inefficient. It also shadows and indulges client
for not correctly communicating with us on message/space availability.

With this patch, oxenstore will only scan/process the domain connections
that have correctly notified us by events or have IO actions leftover from
previous communication.

Signed-off-by: Zheng Li <dev@zheng.li>
---
 tools/ocaml/xenstored/connection.ml  |  4 ++++
 tools/ocaml/xenstored/connections.ml |  9 ++++-----
 tools/ocaml/xenstored/xenstored.ml   | 13 ++++++++++---
 3 files changed, 18 insertions(+), 8 deletions(-)

diff --git a/tools/ocaml/xenstored/connection.ml b/tools/ocaml/xenstored/connection.ml
index 47695f8..807fc00 100644
--- a/tools/ocaml/xenstored/connection.ml
+++ b/tools/ocaml/xenstored/connection.ml
@@ -223,10 +223,14 @@ let pop_in con = Xenbus.Xb.get_in_packet con.xb
 let has_more_input con = Xenbus.Xb.has_more_input con.xb
 
 let has_output con = Xenbus.Xb.has_output con.xb
+let has_old_output con = Xenbus.Xb.has_old_output con.xb
 let has_new_output con = Xenbus.Xb.has_new_output con.xb
 let peek_output con = Xenbus.Xb.peek_output con.xb
 let do_output con = Xenbus.Xb.output con.xb
 
+let has_more_work con =
+	has_more_input con || not (has_old_output con) && has_new_output con
+
 let incr_ops con = con.stat_nb_ops <- con.stat_nb_ops + 1
 
 let mark_symbols con =
diff --git a/tools/ocaml/xenstored/connections.ml b/tools/ocaml/xenstored/connections.ml
index 1c8d911..f9bc225 100644
--- a/tools/ocaml/xenstored/connections.ml
+++ b/tools/ocaml/xenstored/connections.ml
@@ -98,11 +98,10 @@ let iter cons fct =
 	iter_domains cons fct; iter_anonymous cons fct
 
 let has_more_work cons =
-	Hashtbl.fold (fun id con acc ->
-		if Connection.has_more_input con then
-			con :: acc
-		else
-			acc) cons.domains []
+	Hashtbl.fold
+		(fun id con acc ->
+		 if Connection.has_more_work con then con :: acc else acc)
+		cons.domains []
 
 let key_of_str path =
 	if path.[0] = '@'
diff --git a/tools/ocaml/xenstored/xenstored.ml b/tools/ocaml/xenstored/xenstored.ml
index ea1a08f..b13393c 100644
--- a/tools/ocaml/xenstored/xenstored.ml
+++ b/tools/ocaml/xenstored/xenstored.ml
@@ -57,7 +57,10 @@ let process_domains store cons domains =
 			let con = Connections.find_domain cons (Domain.get_id domain) in
 				Process.do_input store cons domains con;
 				Process.do_output store cons domains con in
-	Domains.iter domains do_io_domain
+	List.iter
+		(fun c ->
+		 match Connection.get_domain c with
+		 | Some d -> do_io_domain d | _ -> ())
 
 let sigusr1_handler store =
 	try
@@ -305,6 +308,7 @@ let _ =
 			Connections.add_anonymous cons cfd can_write
 		and handle_eventchn fd =
 			let port = Event.pending eventchn in
+			debug "pending port %d" (Xeneventchn.to_int port);
 			finally (fun () ->
 				if Some port = eventchn.Event.virq_port then (
 					let (notify, deaddom) = Domains.cleanup xc domains in
@@ -312,7 +316,10 @@ let _ =
 					if deaddom <> [] || notify then
 						Connections.fire_spec_watches cons "@releaseDomain"
 				)
-			) (fun () -> Event.unmask eventchn port);
+				else
+					let c = Connections.find_domain_by_port cons port in
+					process_domains store cons domains [c]
+				) (fun () -> Event.unmask eventchn port)
 		and do_if_set fd set fct =
 			if List.mem fd set then
 				fct fd in
@@ -382,7 +389,7 @@ let _ =
 			process_special_fds sfds;
 		if List.length cfds > 0 || List.length wset > 0 then
 			process_connection_fds store cons domains cfds wset;
-		process_domains store cons domains
+		process_domains store cons domains mw
 		in
 
 	while not !quit
-- 
2.1.1