Merge lp:~clint-fewbar/charms/precise/mysql/dynamic-memory into lp:charms/mysql

[Clint Byrum]

Makes RAM dynamic based on available system memory. This should fix mysql not starting up on HP Cloud which only has 800MB of RAM for the default instance type.

[lp:~clint-fewbar/charms/precise/mysql/dynamic-memory]

78. By Clint Byrum on 2012-08-21

bumping rev for new memory changes

[Marco Ceppi (marcoceppi)]

LGTM!

review: Approve

=== modified file 'config.yaml'
--- config.yaml	2012-04-25 07:20:11 +0000
+++ config.yaml	2012-08-21 21:15:23 +0000
@@ -1,7 +1,7 @@
 options:
     dataset-size:
-        default: 1G
-        description: How much data do you want to keep in memory in the DB. This will be used to tune settings in the database server appropriately. Any more specific settings will override these defaults though. This currently sets innodb_buffer_pool_size or key_cache_size depending on the setting in preferred-storage-engine. If query-cache-type is set to 'ON' or 'DEMAND' 10% of this is given to query-cache-size.
+        default: '80%'
+        description: How much data do you want to keep in memory in the DB. This will be used to tune settings in the database server appropriately. Any more specific settings will override these defaults though. This currently sets innodb_buffer_pool_size or key_cache_size depending on the setting in preferred-storage-engine. If query-cache-type is set to 'ON' or 'DEMAND' 20% of this is given to query-cache-size. Suffix this value with 'K','M','G', or 'T' to get the relevant kilo/mega/etc. bytes. If suffixed with %, one will get that percentage of RAM devoted to dataset and (if enabled) query cache.
         type: string
     preferred-storage-engine:
         default: InnoDB

=== modified file 'hooks/config-changed'
--- hooks/config-changed	2012-08-01 23:39:18 +0000
+++ hooks/config-changed	2012-08-21 21:15:23 +0000
@@ -6,11 +6,26 @@
 import re
 import hashlib
 import os
+from string import upper
 
 num_re = re.compile('^[0-9]+$')
 
+# Going for the biggest page size to avoid wasted bytes. InnoDB page size is
+# 16MB
+PAGE_SIZE = 16*1024*1024
+
 configs=json.loads(check_output(['config-get','--format=json']))
 
+def get_memtotal():
+    with open('/proc/meminfo') as meminfo_file:
+        meminfo = {}
+        for line in meminfo_file:
+            (key, mem) = line.split(':', 2)
+            if key == 'MemTotal':
+                (mtot, modifier) = mem.strip().split(' ')
+                return '%s%s' % (mtot, upper(modifier[0]))
+
+
 # There should be a library for this
 def human_to_bytes(human):
     if num_re.match(human):
@@ -19,14 +34,23 @@
     modifier=human[-1]
     if modifier in factors:
         return int(human[:-1]) * factors[modifier]
-    raise Exception("Can only convert K,M,G, or T")
+    if modifier == '%':
+        total_ram = human_to_bytes(get_memtotal())
+        factor = int(human[:-1]) * 0.01
+        pctram = total_ram * factor
+        return int(pctram - (pctram % PAGE_SIZE))
+    raise ValueError("Can only convert K,M,G, or T")
 
 # smart-calc stuff in the configs
 dataset_bytes = human_to_bytes(configs['dataset-size'])
 
+check_call(['juju-log','-l','INFO','dataset size in bytes: %d' % dataset_bytes])
+
 if configs['query-cache-size'] == -1 and configs['query-cache-type'] in ['ON','DEMAND']:
-    configs['query-cache-size'] = int(dataset_bytes * 0.20)
-    dataset_bytes -= configs['query-cache-size']
+    qcache_bytes = (dataset_bytes * 0.20)
+    qcache_bytes = int(qcache_bytes - (qcache_bytes % PAGE_SIZE))
+    configs['query-cache-size'] = qcache_bytes
+    dataset_bytes -= qcache_bytes
 
 # 5.5 allows the words, but not 5.1
 if configs['query-cache-type'] == 'ON':

=== modified file 'revision'
--- revision	2012-08-21 00:07:19 +0000
+++ revision	2012-08-21 21:15:23 +0000
@@ -1,1 +1,1 @@
-146
+147