Adds table-open-cache charm config option, as per lp1402586.

Also increases the default for table_open_cache to 2048, as the default
of 512 is a bit too low (and there is no repercussions with using larger
table cache).

Note: table_cache got renamed to table_open_cache in MySQL 5.1.3, but 
mysql-common didn't address that. Change is made in the charm now so
that future upgrades (from 5.5 to 5.6) can be smooth.

config.yaml

@@ -68,6 +68,11 @@ options:
       InnoDB table into separate .idb file. Existing InnoDB tables will remain
       in ibdata1 file - full dump/import is needed to get rid of large
       ibdata1 file
+  table-open-cache:
+    type: int
+    default: 2048
+    description:
+      Sets table_open_cache (formerly known as table_cache) to mysql.
   lp1366997-workaround:
     type: boolean
     default: False

hooks/percona_hooks.py

@@ -113,11 +113,10 @@ def render_config(clustered=False, hosts=[], mysql_password=None):
         'sst_method': 'xtrabackup',
         'sst_password': mysql_password,
         'innodb_file_per_table': config('innodb-file-per-table'),
+        'table_open_cache': config('table-open-cache'),
         'lp1366997_workaround': config('lp1366997-workaround')
     }
 
-    print config
-
     if config('prefer-ipv6'):
         # NOTE(hopem): this is a kludge to get percona working with ipv6.
         # See lp 1380747 for more info. This is intended as a stop gap until

templates/my.cnf

@@ -61,7 +61,7 @@ max_connections = {{ max_connections }}
 
 # Fine tuning
 key_buffer_size = {{ key_buffer }}
-table_cache = 512
+table_open_cache = {{ table_open_cache }}
 max_allowed_packet = 16M
 
 # InnoDB buffer should consume 100% of the bytes of the dataset size