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https://issues.apache.org/jira/browse/CAMEL-3686?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13029489#comment-13029489
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Piotr Klimczak commented on CAMEL-3686:
---------------------------------------
Things have change a litle since february.
Let's start from cache sharing across bundles problem. It will not work as
default. This is because CacheManager in DefaultCacheManagerFactory class is
created like (since always):
{code}
protected CacheManager createCacheManagerInstance() {
return CacheManager.create(
getClass().getResourceAsStream("/ehcache.xml"));
}
{code}
Then take a look at CacheManager.create method:
{code}
/**
* The Singleton Instance.
*/
private static volatile CacheManager singleton;
//some code...
public static CacheManager create(InputStream inputStream) throws
CacheException {
if (singleton != null) {
return singleton;
}
synchronized (CacheManager.class) {
if (singleton == null) {
LOG.debug("Creating new CacheManager with InputStream");
singleton = new CacheManager(inputStream);
}
return singleton;
}
}
{code}
As you can see CacheManager is creating its own instance as a singleton stored
in static field. This is good for one bundle. But remember that each bundle is
running in separate ClassLoader. It means that static fields of one bundle are
not visible straight to any other. This is fine for daily usage as cache have
to be separated by default.
Please also note, that CacheManager instance is as default disposed/destroyed
during bundle shutdown. So stopping one bundle will close your default
CacheManager which is implemented in DefaultCacheManagerFactory of camel-cache
component:
{code}
@Override
protected void doStop() throws Exception {
// shutdown cache manager when stopping
if (cacheManager != null) {
cacheManager.shutdown();
}
}
{code}
Please note that due to my last changes to camel-cache component, cache is not
deleted from CacheManager during route shutdown anymore as it was before (which
was extremely bad for people like you and me).
So in my opinion the best what you can do is to create a separate bundle where
you can instantiate the CacheManager and expose it under some getter method of
your own interface through OSGi service.
As you have your own CacheManager singleton accesible through OSGi service
reference, you can implement (for each bundle using that cache) your own
CacheManagerFactory with constructor which expect to get that referenced
CachemManager as a parameter, like this:
{code}
public class YourCacheManagerFactory extends CacheManagerFactory {
private CacheManager cacheManager;
public YourCacheManagerFactory(CacheManager cacheManager) {
if (cacheManager == null) {
throw new RuntimeCamelException("cacheManager should never be
null");
}
this.cacheManager = cacheManager;
}
@Override
protected synchronized CacheManager createCacheManagerInstance() {
return cacheManager;
}
{code}
Then it could be referenced to the endpoint like this:
{code:xml}
<camelContext xmlns="http://camel.apache.org/schema/spring";>
<endpoint id="fooCache"
uri="cache:foo?cacheManagerFactory=#yourReferencedCacheManagerFactory" />
</camelContext>
{code}
This should solve all your problems.
Please let me know if it works fine for you. If not, then i will do my best to
help you.
Have a FUN! :)
> Allow to share cache between bundles, and only clear cache when no more
> bundles access that cache
> -------------------------------------------------------------------------------------------------
>
> Key: CAMEL-3686
> URL: https://issues.apache.org/jira/browse/CAMEL-3686
> Project: Camel
> Issue Type: Improvement
> Components: camel-cache
> Affects Versions: 2.4.0
> Environment: camel-cache 2.4.0-fuse-01-00
> Reporter: Justas
> Fix For: 2.8.0
>
> Attachments: camel-cache.zip, diff.txt
>
>
> I am using camel-cache component in serviceMix. Cache endpoint uri is
> "cache://elements?maxElementsInMemory=2&memoryStoreEvictionPolicy=MemoryStoreEvictionPolicy.FIFO&overflowToDisk=false&eternal=false&timeToLiveSeconds=800"
>
> I have 2 bundles (core.jar, services.jar). Inside those bundles I use
> @EndpointInject(uri = Constants.CACHE_URI)
> ProducerTemplate cacheTemplate;
> cacheTemplate.requestBodyAndHeaders(...)
> core.jar puts and reads elements from cache.
> services.jar only reads elements from cache.
> After deploying both bundles it works fine, but if i uninstall services.jar,
> cache is "destroyed". core.jar (and all others) can't put objects into cache
> anymore.
> How could I make all bundles to "share" the same cache?
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