On Wed, 2010-10-13 at 08:19 +0100, Jiang, Yunhong wrote:
> the xenstore_client.c does not use watch feature at all.
I've occasionally thought that it might be useful to have a
xenstore-watch command for skanky scripting purposes so below is a patch
to add one.
I don't know how useful it is generally but it can be used to shows that
"xenstore-watch -s x" (i.e. xs_daemon_open) does appear to be broken.
Subject: xenstore: add xenstore-watch command line client
# xenstore-watch x | while read w ; do
> echo "watch fired on $w"
> echo "value" $(xenstore-read $w)
> echo
> done
# xenstore-write x/y/z 42
output from while loop:
watch fired on x/t/z
value 42
Signed-off-by: Ian Campbell <ian.campbell@xxxxxxxxxx>
diff -r 0b69bd41cf15 tools/xenstore/Makefile
--- a/tools/xenstore/Makefile Wed Oct 13 13:47:32 2010 +0100
+++ b/tools/xenstore/Makefile Wed Oct 13 13:56:08 2010 +0100
@@ -9,7 +9,7 @@ CFLAGS += $(CFLAGS_libxenctrl)
CFLAGS += $(CFLAGS_libxenctrl)
CLIENTS := xenstore-exists xenstore-list xenstore-read xenstore-rm
xenstore-chmod
-CLIENTS += xenstore-write xenstore-ls
+CLIENTS += xenstore-write xenstore-ls xenstore-watch
XENSTORED_OBJS = xenstored_core.o xenstored_watch.o xenstored_domain.o
xenstored_transaction.o xs_lib.o talloc.o utils.o tdb.o hashtable.o
diff -r 0b69bd41cf15 tools/xenstore/xenstore_client.c
--- a/tools/xenstore/xenstore_client.c Wed Oct 13 13:47:32 2010 +0100
+++ b/tools/xenstore/xenstore_client.c Wed Oct 13 13:56:08 2010 +0100
@@ -36,6 +36,7 @@ enum mode {
MODE_read,
MODE_rm,
MODE_write,
+ MODE_watch,
};
static char *output_buf = NULL;
@@ -95,6 +96,9 @@ usage(enum mode mode, int incl_mode, con
case MODE_chmod:
mstr = incl_mode ? "chmod " : "";
errx(1, "Usage: %s %s[-h] [-u] [-r] [-s] key <mode [modes...]>",
progname, mstr);
+ case MODE_watch:
+ mstr = incl_mode ? "watch " : "";
+ errx(1, "Usage: %s %s[-h] [-n NR] key", progname, mstr);
}
}
@@ -263,9 +267,28 @@ do_chmod(char *path, struct xs_permissio
}
}
+static void
+do_watch(struct xs_handle *xsh, int max_events)
+{
+ int count = 0;
+ char **vec = NULL;
+
+ for ( count = 0; max_events == -1 || count < max_events; count++ ) {
+ unsigned int num;
+
+ vec = xs_read_watch(xsh, &num);
+ if (vec == NULL)
+ continue;
+
+ printf("%s\n", vec[XS_WATCH_PATH]);
+ fflush(stdout);
+ free(vec);
+ }
+}
+
static int
perform(enum mode mode, int optind, int argc, char **argv, struct xs_handle
*xsh,
- xs_transaction_t xth, int prefix, int tidy, int upto, int recurse)
+ xs_transaction_t xth, int prefix, int tidy, int upto, int recurse, int
nr_watches)
{
switch (mode) {
case MODE_ls:
@@ -428,6 +451,15 @@ perform(enum mode mode, int optind, int
do_chmod(path, perms, nperms, upto, recurse, xsh, xth);
break;
}
+ case MODE_watch: {
+ for (; argv[optind]; optind++) {
+ const char *w = argv[optind];
+
+ if (!xs_watch(xsh, w, w))
+ errx(1, "Unable to add watch on %s\n", w);
+ }
+ do_watch(xsh, nr_watches);
+ }
}
}
@@ -452,6 +484,8 @@ static enum mode lookup_mode(const char
return MODE_write;
else if (strcmp(m, "read") == 0)
return MODE_read;
+ else if (strcmp(m, "watch") == 0)
+ return MODE_watch;
errx(1, "unknown mode %s\n", m);
return 0;
@@ -467,6 +501,7 @@ main(int argc, char **argv)
int tidy = 0;
int upto = 0;
int recurse = 0;
+ int nr_watches = -1;
int transaction;
struct winsize ws;
enum mode mode;
@@ -500,10 +535,11 @@ main(int argc, char **argv)
{"tidy", 0, 0, 't'}, /* MODE_rm */
{"upto", 0, 0, 'u'}, /* MODE_chmod */
{"recurse", 0, 0, 'r'}, /* MODE_chmod */
+ {"number", 1, 0, 'n'}, /* MODE_watch */
{0, 0, 0, 0}
};
- c = getopt_long(argc - switch_argv, argv + switch_argv, "hfsptur",
+ c = getopt_long(argc - switch_argv, argv + switch_argv, "hfspturn:",
long_options, &index);
if (c == -1)
break;
@@ -548,6 +584,12 @@ main(int argc, char **argv)
else
usage(mode, switch_argv, argv[0]);
break;
+ case 'n':
+ if ( mode == MODE_watch )
+ nr_watches = atoi(optarg);
+ else
+ usage(mode, switch_argv, argv[0]);
+ break;
}
}
@@ -575,6 +617,7 @@ main(int argc, char **argv)
transaction = (argc - switch_argv - optind) > 2;
break;
case MODE_ls:
+ case MODE_watch:
transaction = 0;
break;
default:
@@ -601,7 +644,7 @@ again:
errx(1, "couldn't start transaction");
}
- ret = perform(mode, optind, argc - switch_argv, argv + switch_argv, xsh,
xth, prefix, tidy, upto, recurse);
+ ret = perform(mode, optind, argc - switch_argv, argv + switch_argv, xsh,
xth, prefix, tidy, upto, recurse, nr_watches);
if (transaction && !xs_transaction_end(xsh, xth, ret)) {
if (ret == 0 && errno == EAGAIN) {
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