# HG changeset patch
# User Ian Campbell <ian.campbell@xxxxxxxxxx>
# Date 1207658379 -3600
# Node ID 46073fa39b7bc6cb914a1bc4b4ec2397f9018374
# Parent  40310b53f5d0a456f12302aa07b592fd27736cb5
xenstore: re-enable watch support when threading is disabled.

The caller can select on the watch fd in the normal way.

This patch is only build tested.

diff -r 40310b53f5d0 -r 46073fa39b7b tools/xenstore/xs.c
--- a/tools/xenstore/xs.c	Tue Apr 08 13:39:36 2008 +0100
+++ b/tools/xenstore/xs.c	Tue Apr 08 13:39:39 2008 +0100
@@ -118,7 +118,13 @@ struct xs_handle {
 struct xs_handle {
 	int fd;
 	struct list_head reply_list;
+	struct list_head watch_list;
+	/* Clients can select() on this pipe to wait for a watch to fire. */
+	int watch_pipe[2];
 };
+
+static void watch_mutex_lock(struct xs_handle *h) {}
+static void watch_mutex_unlock(struct xs_handle *h) {}
 
 static void request_mutex_lock(struct xs_handle *h) {}
 static void request_mutex_unlock(struct xs_handle *h) {}
@@ -130,7 +136,6 @@ static void reply_mutex_unlock(struct xs
 
 static int read_message(struct xs_handle *h);
 
-#ifdef USE_PTHREAD
 int xs_fileno(struct xs_handle *h)
 {
 	char c = 0;
@@ -148,7 +153,6 @@ int xs_fileno(struct xs_handle *h)
 
 	return h->watch_pipe[0];
 }
-#endif
 
 static int get_socket(const char *connect_to)
 {
@@ -215,12 +219,12 @@ static struct xs_handle *get_handle(cons
 	h->fd = fd;
 
 	INIT_LIST_HEAD(&h->reply_list);
-
-#ifdef USE_PTHREAD
+	INIT_LIST_HEAD(&h->watch_list);
+
 	/* Watch pipe is allocated on demand in xs_fileno(). */
 	h->watch_pipe[0] = h->watch_pipe[1] = -1;
 
-	INIT_LIST_HEAD(&h->watch_list);
+#ifdef USE_PTHREAD
 	pthread_mutex_init(&h->watch_mutex, NULL);
 	pthread_cond_init(&h->watch_condvar, NULL);
 
@@ -269,21 +273,21 @@ void xs_daemon_close(struct xs_handle *h
 		free(msg);
 	}
 
-#ifdef USE_PTHREAD
 	list_for_each_entry_safe(msg, tmsg, &h->watch_list, list) {
 		free(msg->body);
 		free(msg);
 	}
 
+#ifdef USE_PTHREAD
 	request_mutex_unlock(h);
 	reply_mutex_unlock(h);
 	watch_mutex_unlock(h);
+#endif
 
 	if (h->watch_pipe[0] != -1) {
 		close(h->watch_pipe[0]);
 		close(h->watch_pipe[1]);
 	}
-#endif
 
 	close(h->fd);
 
@@ -612,7 +616,6 @@ unwind:
 	return false;
 }
 
-#ifdef USE_PTHREAD
 /* Watch a node for changes (poll on fd to detect, or call read_watch()).
  * When the node (or any child) changes, fd will become readable.
  * Token is returned when watch is read, to allow matching.
@@ -622,6 +625,7 @@ bool xs_watch(struct xs_handle *h, const
 {
 	struct iovec iov[2];
 
+#ifdef USE_PTHREAD
 	/* We dynamically create a reader thread on demand. */
 	request_mutex_lock(h);
 	if (!h->read_thr_exists) {
@@ -632,6 +636,7 @@ bool xs_watch(struct xs_handle *h, const
 		h->read_thr_exists = 1;
 	}
 	request_mutex_unlock(h);
+#endif
 
 	iov[0].iov_base = (void *)path;
 	iov[0].iov_len = strlen(path) + 1;
@@ -656,7 +661,11 @@ char **xs_read_watch(struct xs_handle *h
 
 	/* Wait on the condition variable for a watch to fire. */
 	while (list_empty(&h->watch_list))
+#ifdef USE_PTHREAD
 		pthread_cond_wait(&h->watch_condvar, &h->watch_mutex);
+#else
+		read_message(h);
+#endif
 	msg = list_top(&h->watch_list, struct xs_stored_msg, list);
 	list_del(&msg->list);
 
@@ -708,7 +717,6 @@ bool xs_unwatch(struct xs_handle *h, con
 	return xs_bool(xs_talkv(h, XBT_NULL, XS_UNWATCH, iov,
 				ARRAY_SIZE(iov), NULL));
 }
-#endif
 
 /* Start a transaction: changes by others will not be seen during this
  * transaction, and changes will not be visible to others until end.
@@ -868,7 +876,6 @@ static int read_message(struct xs_handle
 	body[msg->hdr.len] = '\0';
 
 	if (msg->hdr.type == XS_WATCH_EVENT) {
-#ifdef USE_PTHREAD
 		watch_mutex_lock(h);
 
 		/* Kick users out of their select() loop. */
@@ -878,14 +885,12 @@ static int read_message(struct xs_handle
 				continue;
 
 		list_add_tail(&msg->list, &h->watch_list);
+
+#ifdef USE_PTHREAD
 		pthread_cond_signal(&h->watch_condvar);
+#endif
 
 		watch_mutex_unlock(h);
-#else
-		/* Cannot handle this event, but should never have been registered. */
-		errno = -EIO;
-		goto error;
-#endif
 	} else {
 		reply_mutex_lock(h);