memcached_stats plugin only returns statistics if all servers are available in list

[Joe Daly]

To use the memcached_stats plugin you need to set the global variable memcached_stats_servers to point to valid memcached instances. If one of the servers in the list is not available no results are returned, it does not matter which server is killed off in the list. I ran into this problem when I ported over the plugin to use data_dictionary, so the problem will still exist when that goes into trunk.

For instance:

drizzle> set global memcached_stats_servers = 'localhost:12000, localhost:12050';
Query OK, 0 rows affected (0 sec)

drizzle> select * from MEMCACHED_STATS;
+-----------+-------------+------------+--------+------------+---------+--------------+-------------+---------------+---------------+-------------+-------+---------------------+-------------------+-----------------------+------+------+------+--------+-----------+------------+---------------+----------------+---------+
| NAME | PORT_NUMBER | PROCESS_ID | UPTIME | TIME | VERSION | POINTER_SIZE | RUSAGE_USER | RUSAGE_SYSTEM | CURRENT_ITEMS | TOTAL_ITEMS | BYTES | CURRENT_CONNECTIONS | TOTAL_CONNECTIONS | CONNECTION_STRUCTURES | GETS | SETS | HITS | MISSES | EVICTIONS | BYTES_READ | BYTES_WRITTEN | LIMIT_MAXBYTES | THREADS |
+-----------+-------------+------------+--------+------------+---------+--------------+-------------+---------------+---------------+-------------+-------+---------------------+-------------------+-----------------------+------+------+------+--------+-----------+------------+---------------+----------------+---------+
| localhost | 12000 | 2185 | 79355 | 1266282950 | 1.4.1 | 64 | 0 | 0 | 0 | 0 | 0 | 10 | 18 | 11 | 0 | 0 | 0 | 0 | 0 | 105 | 5126 | 67108864 | 5 |
| localhost | 12050 | 3068 | 79295 | 1266282949 | 1.4.1 | 64 | 1 | 1 | 0 | 0 | 0 | 10 | 13 | 11 | 0 | 0 | 0 | 0 | 0 | 35 | 1460 | 67108864 | 5 |
+-----------+-------------+------------+--------+------------+---------+--------------+-------------+---------------+---------------+-------------+-------+---------------------+-------------------+-----------------------+------+------+------+--------+-----------+------------+---------------+----------------+---------+
2 rows in set (0.01 sec)

************* At this point I killed off one of the memcached servers, but one in the list is still running ********************

drizzle> select * from MEMCACHED_STATS;
ERROR 1105 (HY000): Unable get stats from memcached server localhost. Got error from memcached_stat_servername().
drizzle>