On Fri, Dec 11, 2009 at 03:26:15PM -0500, Adam Litke wrote:
Use a dynamically sized xdr_array to pass memory stats on the wire. This supports the addition of future memory stats and reduces the message size since only supported statistics are returned. + /* Allocate return buffer. We need 2 slots per stat: the tag and value. */ + if (VIR_ALLOC_N(ret->stats.stats_val, nr_stats * 2) < 0) { + VIR_FREE(stats); + remoteDispatchOOMError(rerr); + return -1; + } + + /* Copy the stats into the xdr return structure */ + for (i = 0; i < nr_stats; i++) { + ret->stats.stats_val[2 * i] = (uint64_t) stats[i].tag; + ret->stats.stats_val[2 * i + 1] = stats[i].val; + } + ret->stats.stats_len = nr_stats * 2;
This is a slightly wierd way to encode the data on the wire. The wire format ought to follow the public API struct format, rather than packing both values into a single array.
+struct remote_domain_memory_stats_args { + remote_nonnull_domain dom; + u_int maxStats; +}; +typedef struct remote_domain_memory_stats_args remote_domain_memory_stats_args; + +struct remote_domain_memory_stats_ret { + struct { + u_int stats_len; + uint64_t *stats_val; + } stats; +};
XDR has a native array type which automatically tracks length. Also for portability to OS-X/Solaris we avoid uint64_t and use hyper instead for 64bit data. The return value structure should thus look like this: const REMOTE_DOMAIN_MEMORY_STATS_MAX = 1024; struct remote_domain_memory_stat { int tag; unsigned hyper val; }; struct remote_domain_memory_stats_ret { remote_domain_memory_stat<REMOTE_DOMAIN_MEMORY_STATS_MAX>; }; NB, the MAX constant there should not be fixed to the public API max. This is just a wire protocol decoder limit to avoid DOS on large arrays. Regards, Daniel -- |: Red Hat, Engineering, London -o- http://people.redhat.com/berrange/ :| |: http://libvirt.org -o- http://virt-manager.org -o- http://ovirt.org :| |: http://autobuild.org -o- http://search.cpan.org/~danberr/ :| |: GnuPG: 7D3B9505 -o- F3C9 553F A1DA 4AC2 5648 23C1 B3DF F742 7D3B 9505 :|