On Sep 22, 2012, at 7:18 AM, calugaru.cristi <
[hidden email]> wrote:
> Hi,
>
> We have a Grails Web App, and we wanted to add a cache layer for some of the
> more expensive-computation calls.
> We settled to the base grails cache plugin, plus the redis cache
> implementation.
>
> How do you configure the cache as an optional layer? If a request comes, and
> does not find the cache being "up"(for ex the redis process is down, or the
> cache machine is not accessible) it automatically fails over to the database
> and does the query? I see the cache as just an optional layer which if
> exists, should be used, but it should not make the web app fully dependent
> on it (which seems to be the default behavior with the cache plugin).
>
> Is there a convenient way to do this?
>
> Thanks for any suggestions.
>
>
You could have 2 code paths to retrieve the data, a caching path and a non caching path. You could invoke the caching path and if it fails then invoke the non caching path. You have to decide what "fails" means. For example, if you attempt to retrieve data from the cache and the data isn't there, is that a failure or does that just mean the requested data doesn't exist (in the cache or anywhere else)?
There may be important details about your application and environment that need to be factored in here but a simplistic approach if your failures manifest with an exception might look something like this pseudo code…
class MyService {
def dataService
def getData() {
def data
try {
data = dataService.getDataFromCache()
} catch (SomeExceptionType e) {
data = dataService.getDataFromDatabase()
}
data
}
}
jsb
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Jeff Brown
[hidden email]
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