protected override SessionItem GetSessionItem(string sessionId)
{
SessionItem result = null;
var data = namedCache.Retrieve(sessionId, false) as SessionItemEx;
if (data != null)
{
result = data.GetSessionItem();
}
return(result);
}
/// <summary>
/// Event handler for expiring objects in a ScaleOut named cache.
/// </summary>
private void HandleObjectExpired(object sender, NamedCacheObjExpiredEventArgs eventArgs)
{
try
{
// TODO: custom event handling logic:
var expiringkey = eventArgs.CachedObjectId;
object obj = _nc.Retrieve(expiringkey, acquireLock: false);
_traceSource.TraceEvent(TraceEventType.Verbose, 101, obj.ToString());
// Allow the expiring object to be removed from the store. (Or, set to
// NamedCacheObjDisposition.Save for objects that should not be removed.)
eventArgs.NamedCacheObjDisposition = NamedCacheObjDisposition.Remove;
// Trace successful completion.
_traceSource.TraceEvent(TraceEventType.Verbose, 3, "Handled expiration event successfully.");
}
catch (Exception ex)
{
_traceSource.TraceEvent(TraceEventType.Warning, 4, $"Error handling expiration event:\n{ex}");
}
}
/// <summary>
/// Entry point to the application
/// </summary>
static void Main(string[] args)
{
SampleObject obj = null;
int objectKey = 12345;
int iteration = 0;
string[] counting = { "one", "two", "three", "four", "five", "six", "seven", "eight", "nine", "ten" };
int objectTimeoutInSeconds = counting.Length; // 10 seconds
NamedCache cache = CacheFactory.GetCache(Configuration.CACHE_NAME);
// Unlike read-through and write-through operations (which are enabled on an entire NamedCache through the backingStorePolicy parameter),
// the asynchronous write-behind and refresh-ahead operations must be enabled on an object-by-object basis when they are first created
// in the ScaleOut StateServer cache. We use the BackingStoreMode property below to enable write-behind operation for an object.
// We're setting this property on the DefaultCreatePolicy level, so all objects added to this named cache will inherit this setting.
// Note that the BackingStoreInterval property controls the interval between asynchronous backing store events.
cache.DefaultCreatePolicy.BackingStoreMode = BackingStoreAsyncPolicy.WriteBehind;
cache.DefaultCreatePolicy.BackingStoreInterval = TimeSpan.FromSeconds(5);
cache.DefaultCreatePolicy.Timeout = TimeSpan.FromSeconds(objectTimeoutInSeconds);
cache.DefaultCreatePolicy.IsAbsoluteTimeout = true;
// Perform a few add/read operations
while (iteration < 4)
{
int year = DateTime.Now.Year + iteration;
double fraction = (DateTime.Now.Month < 10) ? ((double)DateTime.Now.Month / 10) : ((double)DateTime.Now.Month / 100);
obj = new SampleObject(year, ((double)year + fraction), $"iteration {iteration}");
// Add or Update object to the store
cache.Insert(objectKey.ToString(), obj, cache.DefaultCreatePolicy, updateIfExists: true, lockAfterInsert: false);
Thread.Sleep(2000);
// Reading object from the store
obj = cache.Retrieve(objectKey.ToString(), false) as SampleObject;
if (obj != null)
{
Console.WriteLine($"Added and retrieved the sample object {obj.ToString()} with key {objectKey}");
}
Thread.Sleep(2000);
iteration++;
}
// Waiting for our test object to expire
Console.WriteLine($"Wait for {objectTimeoutInSeconds} seconds to make sure the object is expired, counting...");
foreach (var countItem in counting)
{
Console.WriteLine(countItem);
Thread.Sleep(1000);
}
Console.WriteLine("Reading object from the store:");
obj = cache.Retrieve(objectKey.ToString(), acquireLock: false) as SampleObject;
if (obj == null)
{
Console.WriteLine("\tObject is null as expected, re-adding it back.");
}
else
{
Console.WriteLine($"\tObject is still present, key: {obj.ToString()}, updating it.");
}
// Final step - re-adding it back to observe a pair of write-behind events associated with the object (store and erase) one more time
obj = new SampleObject(2019, 2019.10, $"October, 2019");
cache.Insert(objectKey.ToString(), obj, cache.DefaultCreatePolicy, updateIfExists: true, lockAfterInsert: false);
Console.WriteLine($"\nThe sample object {obj.ToString()} was re-added back to the cache.");
Console.WriteLine($"You should still observe 2 backing store events fired:\n one is for adding object back and another one is for removing it due to its expiration in {objectTimeoutInSeconds} seconds.");
Console.WriteLine("\nPress Enter to finish the application.");
Console.ReadLine();
}
private object GetItem(string name)
{
return(namedCache.Retrieve(keyPrefix + name, false));
}