oxenstored: enable domain connection indexing based on eventchn port

Currently in xenstore connection database,  we use a hash table of
(domid -> connection) to store domain connections. This allows fast indexing
based on dom ids.

This patch adds another dimention of fast indexing that is based on eventchn
port number. This is useful when doing selective connection processing
based on the port numbers of incoming events.

Reported-by: Juergen Gross <jgross@suse.com>
Signed-off-by: Zheng Li <dev@zheng.li>
Reviewed-by: David Scott <dave.scott@citrix.com>

tools/ocaml/xenstored/connections.ml

@@ -20,10 +20,16 @@ let debug fmt = Logging.debug "connections" fmt
 type t = {
 	anonymous: (Unix.file_descr, Connection.t) Hashtbl.t;
 	domains: (int, Connection.t) Hashtbl.t;
+	ports: (Xeneventchn.t, Connection.t) Hashtbl.t;
 	mutable watches: (string, Connection.watch list) Trie.t;
 }
 
-let create () = { anonymous = Hashtbl.create 37; domains = Hashtbl.create 37; watches = Trie.create () }
+let create () = {
+	anonymous = Hashtbl.create 37;
+	domains = Hashtbl.create 37;
+	ports = Hashtbl.create 37;
+	watches = Trie.create ()
+}
 
 let add_anonymous cons fd can_write =
 	let xbcon = Xenbus.Xb.open_fd fd in
@@ -33,7 +39,10 @@ let add_anonymous cons fd can_write =
 let add_domain cons dom =
 	let xbcon = Xenbus.Xb.open_mmap (Domain.get_interface dom) (fun () -> Domain.notify dom) in
 	let con = Connection.create xbcon (Some dom) in
-	Hashtbl.add cons.domains (Domain.get_id dom) con
+	Hashtbl.add cons.domains (Domain.get_id dom) con;
+	match Domain.get_port dom with
+	| Some p -> Hashtbl.add cons.ports p con;
+	| None -> ()
 
 let select cons =
 	Hashtbl.fold
@@ -45,8 +54,11 @@ let select cons =
 let find cons =
 	Hashtbl.find cons.anonymous
 
-let find_domain cons id =
-	Hashtbl.find cons.domains id
+let find_domain cons =
+	Hashtbl.find cons.domains
+
+let find_domain_by_port cons port =
+	Hashtbl.find cons.ports port
 
 let del_watches_of_con con watches =
 	match List.filter (fun w -> Connection.get_con w != con) watches with
@@ -65,6 +77,12 @@ let del_domain cons id =
 	try
 		let con = find_domain cons id in
 		Hashtbl.remove cons.domains id;
+		(match Connection.get_domain con with
+		 | Some d ->
+		   (match Domain.get_port d with
+		    | Some p -> Hashtbl.remove cons.ports p
+		    | None -> ())
+		 | None -> ());
 		cons.watches <- Trie.map (del_watches_of_con con) cons.watches;
 		Connection.close con
 	with exn ->

tools/ocaml/xenstored/domain.ml

@@ -35,6 +35,7 @@ let get_id domain = domain.id
 let get_interface d = d.interface
 let get_mfn d = d.mfn
 let get_remote_port d = d.remote_port
+let get_port d = d.port
 
 let is_bad_domain domain = domain.bad_client
 let mark_as_bad domain = domain.bad_client <- true