How to, Flush data stored in TreeCache to disk?

[sjeevan]

Hi,

I am using JE BerkleyDB implementation of JBossTreeCache (org.jboss.cache.TreeCache) in my application for storing some information.

A sniipet out of the constructor:

public final Fqn CREATED_DATE_FQN;
private static final String CREATED_DATE = "CreatedDate";
....

this.cache = new TreeCache();
cache.setClusterName(name);
cache.setCacheMode("local");
cache.setCacheLoaderConfiguration(getSingleCacheLoaderConfig("",
 BdbjeCacheLoader.class.getName(), "location="
 + f.getAbsolutePath(), false, true, false));
cache.startService();
cache.put(CREATED_DATE_FQN, CREATED_DATE, new Timestamp(new Date().getTime()));
cache.load(name);//Load existing data if any
...
cache.startService(); /// required before the cache can be used!
...

To store data I use:

cache.put(MAX_ID_FQN, MAX_ID, eventId);

But what I have observed is that the cache is not flushed to disk.
I have discovered a workaround (but unacceptable for production) is, after every put;

cache.put(MAX_ID_FQN, MAX_ID, eventId);
// stopService & startSerivice of cache, to flush the data just added to disk
cache.stopService();
cache.startService();

I tried commit() after the put

cache.put(MAX_ID_FQN, MAX_ID, eventId);
cache.commit(cache.getCurrentTransaction(true)); //commit to disk, but this throws an exception

but that throws a
java.lang.UnsupportedOperationException::commit() should not be called on TreeCache directly.

Any clues will be appreciated.

~g1
PS: To build I use maven with jboss-cache-1.4.0.SP1.jar, jboss-system-4.0.3.jar, jboss-jmx-4.0.3.jar & jboss-common-4.0.3.jar

[manik]

The code you have above, the getSingleCacheLoaderConfig() method generates a block of XML corresponding to a cache loader config (see the chapter on cache loaders in the docs).

Make sure you generate XML that sets __async__ to false. If async is true, flushes will not happen in realtime and will be deferred to a queue and processed by a separate thread. Perhaps you could check the XML that getSingleCacheLoaderConfig() generates?

[sjeevan]

Manik,

Thank you.
My problem has been resolved but in a different way.

I checked the code you pointed out and the xml used to configure the CacheLoader is as

#DEBUG 15:35:02 [recovery.LedgerImpl] (main) Cache loader
 configuration XML=
 <config>
 <passivation>false</passivation>
 <preload></preload>
 <cacheloader>
 <class>org.jboss.cache.loader.bdbje.BdbjeCacheLoader</class>
 <properties>location=C:\DOCUME~1\124872\LOCALS~1\Temp\dev\Ledgers\INTTEST2</properties>
 <async>false</async>
 <shared>false</shared>
 <fetchPersistentState>true</fetchPersistentState>
 <purgeOnStartup>false</purgeOnStartup>
 </cacheloader>
 </config>

As pointed out the value of __async__ is false, but that did not help in acheiving flush to disk.

Anyways I discovered that by setting the TransactionManager of the TreeCache I could achieve flushing to disk.

this.cache = new TreeCache();
cache.setClusterName(eventSourceName);
cache.setCacheMode("local");

//set the Transaction Manager to enable flushing of cache to disk
 cache.setTransactionManagerLookupClass(DummyTransactionManagerLookup.class.getName());

cache.setCacheLoaderConfiguration(getSingleCacheLoaderConfig("",
 BdbjeCacheLoader.class.getName(), "location="
 + f.getAbsolutePath(), false, true, false));

thank u
~g1