Add check for speed (takes 33 minutes on my laptop, OUCH!)

Make xenstored use tdb, transactions can soft-fail (EAGAIN)
Transactions no longer take root dir, no longer lock & block: commit can fail spuriously with EAGAIN, not ETIMEDOUT.
Speeds up transactions by over 1000 times, should be NFS safe.
New program: xs_tdb_dump to dump raw TDB contents.
Don't do failure testing: we are no longer robust against all ENOMEM 8(
Introduce "struct node" which contains perms, children and data.
Make struct xs_permissions unpadded, so we can write to tdb w/o valgrind complaints.
Gently modify TDB to use talloc, not do alloc on tdb_delete.

Fix up transaction users for new semantics.
Don't need a transaction around a single read in xen/i386/kernel/smpboot.c.
Python: transaction_start() returns True/False rather than raising exception on EAGAIN.
Fix usage comment on xs_transaction_end().
Include stdarg to xs_tdb_dump so it compiles.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>

1 files changed, 7 insertions, 4 deletions

diff --git a/tools/xenstore/xenstore_client.c b/tools/xenstore/xenstore_client.c
index 8b6ed4a245..ef428f9acb 100644
--- a/tools/xenstore/xenstore_client.c
+++ b/tools/xenstore/xenstore_client.c
@@ -14,6 +14,7 @@
 #include <stdlib.h>
 #include <string.h>
 #include <xs.h>
+#include <errno.h>
 
 static void
 usage(const char *progname)
@@ -82,8 +83,8 @@ main(int argc, char **argv)
     }
 #endif
 
-    /* XXX maybe find longest common prefix */
-    success = xs_transaction_start(xsh, "/");
+  again:
+    success = xs_transaction_start(xsh);
     if (!success)
 	errx(1, "couldn't start transaction");
 
@@ -145,8 +146,10 @@ main(int argc, char **argv)
 
  out:
     success = xs_transaction_end(xsh, ret ? true : false);
-    if (!success)
+    if (!success) {
+	if (ret == 0 && errno == EAGAIN)
+	    goto again;
 	errx(1, "couldn't end transaction");
-
+    }
     return ret;
 }