[PATCH v2 2/2] tools/xenstore: simplify xenstored main loop

[Juergen Gross <jgross@suse.com>]

The main loop of xenstored is rather complicated due to different
handling of socket and ring-page interfaces. Unify that handling by
introducing interface type specific functions can_read() and
can_write().

Signed-off-by: Juergen Gross <jgross@suse.com>
---
V2:
- split off function vector introduction (Julien Grall)
---
 tools/xenstore/xenstored_core.c   | 77 +++++++++++++++----------------
 tools/xenstore/xenstored_core.h   |  2 +
 tools/xenstore/xenstored_domain.c |  2 +
 3 files changed, 41 insertions(+), 40 deletions(-)

diff --git a/tools/xenstore/xenstored_core.c b/tools/xenstore/xenstored_core.c
index 856f518075..883a1a582a 100644
--- a/tools/xenstore/xenstored_core.c
+++ b/tools/xenstore/xenstored_core.c
@@ -1659,9 +1659,34 @@ static int readfd(struct connection *conn, void *data, unsigned int len)
 	return rc;
 }
 
+static bool socket_can_process(struct connection *conn, int mask)
+{
+	if (conn->pollfd_idx == -1)
+		return false;
+
+	if (fds[conn->pollfd_idx].revents & ~(POLLIN | POLLOUT)) {
+		talloc_free(conn);
+		return false;
+	}
+
+	return (fds[conn->pollfd_idx].revents & mask) && !conn->is_ignored;
+}
+
+static bool socket_can_write(struct connection *conn)
+{
+	return socket_can_process(conn, POLLOUT);
+}
+
+static bool socket_can_read(struct connection *conn)
+{
+	return socket_can_process(conn, POLLIN);
+}
+
 const struct interface_funcs socket_funcs = {
 	.write = writefd,
 	.read = readfd,
+	.can_write = socket_can_write,
+	.can_read = socket_can_read,
 };
 
 static void accept_connection(int sock)
@@ -2296,47 +2321,19 @@ int main(int argc, char *argv[])
 			if (&next->list != &connections)
 				talloc_increase_ref_count(next);
 
-			if (conn->domain) {
-				if (domain_can_read(conn))
-					handle_input(conn);
-				if (talloc_free(conn) == 0)
-					continue;
-
-				talloc_increase_ref_count(conn);
-				if (domain_can_write(conn) &&
-				    !list_empty(&conn->out_list))
-					handle_output(conn);
-				if (talloc_free(conn) == 0)
-					continue;
-			} else {
-				if (conn->pollfd_idx != -1) {
-					if (fds[conn->pollfd_idx].revents
-					    & ~(POLLIN|POLLOUT))
-						talloc_free(conn);
-					else if ((fds[conn->pollfd_idx].revents
-						  & POLLIN) &&
-						 !conn->is_ignored)
-						handle_input(conn);
-				}
-				if (talloc_free(conn) == 0)
-					continue;
-
-				talloc_increase_ref_count(conn);
-
-				if (conn->pollfd_idx != -1) {
-					if (fds[conn->pollfd_idx].revents
-					    & ~(POLLIN|POLLOUT))
-						talloc_free(conn);
-					else if ((fds[conn->pollfd_idx].revents
-						  & POLLOUT) &&
-						 !conn->is_ignored)
-						handle_output(conn);
-				}
-				if (talloc_free(conn) == 0)
-					continue;
+			if (conn->funcs->can_read(conn))
+				handle_input(conn);
+			if (talloc_free(conn) == 0)
+				continue;
 
-				conn->pollfd_idx = -1;
-			}
+			talloc_increase_ref_count(conn);
+
+			if (conn->funcs->can_write(conn))
+				handle_output(conn);
+			if (talloc_free(conn) == 0)
+				continue;
+
+			conn->pollfd_idx = -1;
 		}
 
 		if (delayed_requests) {
diff --git a/tools/xenstore/xenstored_core.h b/tools/xenstore/xenstored_core.h
index 021e41076d..c6e04c0708 100644
--- a/tools/xenstore/xenstored_core.h
+++ b/tools/xenstore/xenstored_core.h
@@ -90,6 +90,8 @@ struct connection;
 struct interface_funcs {
 	int (*write)(struct connection *, const void *, unsigned int);
 	int (*read)(struct connection *, void *, unsigned int);
+	bool (*can_write)(struct connection *);
+	bool (*can_read)(struct connection *);
 };
 
 struct connection
diff --git a/tools/xenstore/xenstored_domain.c b/tools/xenstore/xenstored_domain.c
index f3cd56050e..708bf68af0 100644
--- a/tools/xenstore/xenstored_domain.c
+++ b/tools/xenstore/xenstored_domain.c
@@ -175,6 +175,8 @@ static int readchn(struct connection *conn, void *data, unsigned int len)
 static const struct interface_funcs domain_funcs = {
 	.write = writechn,
 	.read = readchn,
+	.can_write = domain_can_write,
+	.can_read = domain_can_read,
 };
 
 static void *map_interface(domid_t domid)
-- 
2.26.2