API Usage - OSCache

Beside the JSP tag library and the CacheFilter you can use OSCache through its straightforward API. You can use the GeneralCacheAdministrator to create, flush and administrate the cache. The GeneralCacheAdministrator has a cache instance and delegates different Cache's methods. Furthermore the GeneralCacheAdministrator is in charge of load the cache.properties and create a cache instance with the properties definded. You have to store an instance of the GeneralCacheAdministrator in a static value or use a singleton pattern to access the same GeneralCacheAdministrator.

Typical use with fail over

String myKey = "myKey";
String myValue;
int myRefreshPeriod = 1000;
try {
    // Get from the cache
    myValue = (String) admin.getFromCache(myKey, myRefreshPeriod);
} catch (NeedsRefreshException nre) {
    try {
        // Get the value (probably from the database)
        myValue = "This is the content retrieved.";
        // Store in the cache
        admin.putInCache(myKey, myValue);
    } catch (Exception ex) {
        // We have the current content if we want fail-over.
        myValue = (String) nre.getCacheContent();
        // It is essential that cancelUpdate is called if the
        // cached content is not rebuilt
        admin.cancelUpdate(myKey);
    }
}

Typical use without fail over

String myKey = "myKey";
String myValue;
int myRefreshPeriod = 1000;
try {
    // Get from the cache
    myValue = (String) admin.getFromCache(myKey, myRefreshPeriod);
} catch (NeedsRefreshException nre) {
    try {
        // Get the value (probably from the database)
        myValue = "This is the content retrieved.";
        // Store in the cache
        admin.putInCache(myKey, myValue);
        updated = true;
    } finally {
        if (!updated) {
            // It is essential that cancelUpdate is called if the
            // cached content could not be rebuilt
            admin.cancelUpdate(myKey);
        }
    }
}

Note

Be Careful

If a NeedsRefreshException is raised you have to invoke admin.putInCache or even admin.cancelUpdate to avoid deadlock situation.