/// <summary> Gets the named resource. Returned class type corresponds to specified type (i.e. <code>Template</code> to <code>
/// RESOURCE_TEMPLATE</code>).
///
/// This method is now unsynchronized which requires that ResourceCache
/// implementations be thread safe (as the default is).
///
/// </summary>
/// <param name="resourceName"> The name of the resource to retrieve.
/// </param>
/// <param name="resourceType"> The type of resource (<code>RESOURCE_TEMPLATE</code>, <code>RESOURCE_CONTENT</code>, etc.).
/// </param>
/// <param name="encoding"> The character encoding to use.
///
/// </param>
/// <returns> Resource with the template parsed and ready.
///
/// </returns>
/// <throws> ResourceNotFoundException if template not found from any available source. </throws>
/// <throws> ParseErrorException if template cannot be parsed due to syntax (or other) Error. </throws>
/// <throws> Exception if a problem in parse </throws>
public virtual Resource GetResource(string resourceName, int resourceType, string encoding)
{
/*
* Check to see if the resource was placed in the cache.
* If it was placed in the cache then we will use
* the cached version of the resource. If not we
* will load it.
*
* Note: the type is included in the key to differentiate ContentResource
* (static content from #include) with a Template.
*/
string resourceKey = resourceType + resourceName;
Resource resource = globalCache.Get(resourceKey);
if (resource != null)
{
try
{
// avoids additional method call to refreshResource
if (resource.RequiresChecking())
{
/*
* both loadResource() and refreshResource() now return
* a new Resource instance when they are called
* (Put in the cache when appropriate) in order to allow
* several threads to parse the same template simultaneously.
* It is redundant work and will cause more garbage collection but the
* benefit is that it allows concurrent parsing and processing
* without race conditions when multiple requests try to
* refresh/load the same template at the same time.
*
* Another alternative is to limit template parsing/retrieval
* so that only one thread can parse each template at a time
* but that creates a scalability bottleneck.
*
* See VELOCITY-606, VELOCITY-595 and VELOCITY-24
*/
resource = RefreshResource(resource, encoding);
}
}
catch (ResourceNotFoundException)
{
/*
* something exceptional happened to that resource
* this could be on purpose,
* so clear the cache and try again
*/
globalCache.Remove(resourceKey);
return(GetResource(resourceName, resourceType, encoding));
}
catch (ParseErrorException pee)
{
log.Error("ResourceManager.getResource() exception", pee);
throw pee;
}
catch (System.SystemException re)
{
log.Error("ResourceManager.getResource() exception", re);
throw re;
}
catch (System.Exception e)
{
log.Error("ResourceManager.getResource() exception", e);
throw e;
}
}
else
{
try
{
/*
* it's not in the cache, so load it.
*/
resource = LoadResource(resourceName, resourceType, encoding);
if (resource.ResourceLoader.CachingOn)
{
globalCache.Put(resourceKey, resource);
}
}
catch (ResourceNotFoundException rnfe)
{
log.Error("ResourceManager : unable to find resource '" + resourceName + "' in any resource loader.");
throw rnfe;
}
catch (ParseErrorException pee)
{
log.Error("ResourceManager.getResource() parse exception", pee);
throw pee;
}
catch (System.SystemException re)
{
log.Error("ResourceManager.getResource() load exception", re);
throw re;
}
catch (System.Exception e)
{
log.Error("ResourceManager.getResource() exception new", e);
throw e;
}
}
return(resource);
}
