public static async Task <string> GetTestDataWithCachingAsync(string key, CacheItemPolicy overrideCacheItemPolicy = null)
{
return(await TestCacheFacade.GetCachedDataAsync(new TestCacheParams(key, overrideCacheItemPolicy), async() =>
{
return await SomeLongRunningMethodAsync(DateTime.Now);
}));
}
public static async Task <string> GetTestDataWithCachingAndTTLAsync(string key, int secondsTTL)
{
return(await TestCacheFacade.GetCachedDataAsync(
new TestCacheParams(key, secondsTTL),
async() =>
{
string result = await SomeLongRunningMethodAsync(DateTime.Now);
return result;
}
));
}
public async Task TestCacheThreadSafetyWithLazyInitializationAsync()
{
string key = $"CachedDataWithSameKey[{nameof(TestCacheThreadSafetyWithLazyInitializationAsync)}]";
int secondsTTL = 300;
int threadCount = 20;
var globalCount = 0;
var timer = Stopwatch.StartNew();
var tasks = new List <Task <string> >();
for (int x = 0; x < threadCount; x++)
{
//Simulated MANY threads running at the same time attempting to get the same data for the same Cache key!!!
tasks.Add(Task.Run(async() =>
{
//THIS RUNS ON IT'S OWN THREAD, but the Lazy Cache initialization will ensure that the Value Factory Function
// is only executed by the FIRST thread, and all other threads will immediately benefit from the result!
return(await TestCacheFacade.GetCachedDataAsync(new TestCacheParams(key, secondsTTL), async() =>
{
//TEST that this Code ONLY ever runs ONE TIME by ONE THREAD via Lazy<> initialization!
// meaning globalCount is only ever incremented 1 time!
Interlocked.Increment(ref globalCount);
//TEST that the cached data is never re-generated so only ONE Value is ever created!
var longTaskResult = await SomeLongRunningMethodAsync(DateTime.Now);
return longTaskResult;
}));
}));
}
//Allow all threads to complete and get the results...
var results = await Task.WhenAll(tasks.ToArray());
var distinctCount = results.Distinct().Count();
timer.Stop();
//TEST that this Code ONLY ever runs ONE TIME by ONE THREAD via Lazy<> initialization!
// meaning globalCount is only ever incremented 1 time!
Assert.AreEqual(1, globalCount);
//Ensure ONLY ONE item was ever generated and ALL other's were identical from Cache!
Assert.AreEqual(1, distinctCount);
//Ensure that the Total time takes barely longer than one iteration of the Long Running Task!
Assert.IsTrue(timer.ElapsedMilliseconds < (LongRunningTaskMillis * 2));
}