public async Task TestExpiration()
{
var expiration = TimeSpan.FromSeconds(1);
var cache = new AsyncValueCache<char>(defaultExpiration: expiration);
Func<char, Task<char>> asyncValueProvisioning = async character =>
{
await Task.Delay(200);
return character;
};
await cache.GetOrAdd('x', asyncValueProvisioning);
var lastAccessDate1 = cache['x'].LastAccessDate;
var expirationDate1 = cache['x'].ExpirationDate;
cache.HandleExpiration(); // not expired
await cache.GetOrAdd('x', asyncValueProvisioning);
var lastAccessDate2 = cache['x'].LastAccessDate;
var expirationDate2 = cache['x'].ExpirationDate;
Assert.AreEqual(expirationDate1, expirationDate2);
Assert.AreNotEqual(lastAccessDate1, lastAccessDate2);
await Task.Delay(expiration);
cache.HandleExpiration(); // expired
await cache.GetOrAdd('x', asyncValueProvisioning);
var lastAccessDate3 = cache['x'].LastAccessDate;
var expirationDate3 = cache['x'].ExpirationDate;
Assert.AreNotEqual(expirationDate2, expirationDate3);
Assert.AreNotEqual(lastAccessDate2, lastAccessDate3);
for (var i = 0; i < 10; i++)
{
await cache.GetOrAdd('x', asyncValueProvisioning);
await Task.Delay(1);
}
cache.HandleExpiration(); // not expired
var lastAccessDate4 = cache['x'].LastAccessDate;
var expirationDate4 = cache['x'].ExpirationDate;
Assert.AreEqual(expirationDate3, expirationDate4);
Assert.AreNotEqual(lastAccessDate3, lastAccessDate4);
}
public async Task TestDemo()
{
Func<string, Task<int>> temperatureProvisioning = async city => await GetTemperatureAsync(city);
var cities = new[] {"London", "Paris", "London", "Berlin"};
var cache = new AsyncValueCache<string>();
foreach (var city in cities)
{
var temperature = await cache.GetOrAdd(city, temperatureProvisioning, expiration: TimeSpan.FromHours(1));
Assert.AreEqual(city.Length, temperature);
await Task.Delay(1);
}
Assert.IsTrue(cache["London"].ExpirationDate < cache["Paris"].ExpirationDate, "cache item created before");
Assert.IsTrue(cache["London"].LastAccessDate > cache["Paris"].LastAccessDate, "cache item accessed again");
}
public async Task TestIndividualItemExpiration()
{
var cache = new AsyncValueCache<int>();
var counter = 0;
Func<int, Task<int>> asyncValueProvisioning = _ => Task.FromResult(Interlocked.Increment(ref counter));
Assert.AreEqual(1, await cache.GetOrAdd(1, asyncValueProvisioning, TimeSpan.FromMilliseconds(10)),
"1 as new item is created");
Assert.AreEqual(2, await cache.GetOrAdd(2, asyncValueProvisioning, TimeSpan.FromMilliseconds(50)),
"2 as new item is created");
await Task.Delay(30); // 2 expired
cache.HandleExpiration();
Assert.AreEqual(3, await cache.GetOrAdd(1, asyncValueProvisioning), "3 as new item is created");
Assert.AreEqual(2, await cache.GetOrAdd(2, asyncValueProvisioning), "2 as cached item is used");
}
public async Task TestLRU(int maxItems)
{
var cache = new AsyncValueCache<string>(maxItems);
var counter = 0;
Func<string, Task<int>> asyncValueProvisioning = _ => Task.FromResult(Interlocked.Increment(ref counter));
for (var i = 1; i <= maxItems + 1; i++)
{
var key = Convert.ToString(i);
Assert.AreEqual(i, await cache.GetOrAdd(key, asyncValueProvisioning), key + " as new item is created");
Assert.AreEqual(i, await cache.GetOrAdd(key, asyncValueProvisioning), key + " as cached item is used");
await Task.Delay(30);
}
cache.HandleExpiration();
Assert.AreEqual(maxItems, await cache.GetOrAdd(Convert.ToString(maxItems), asyncValueProvisioning),
maxItems + " as cached item is used");
Assert.AreEqual(maxItems + 1, await cache.GetOrAdd(Convert.ToString(maxItems + 1), asyncValueProvisioning),
maxItems + 1 + " as cached item is used");
Assert.AreNotEqual(1, await cache.GetOrAdd(Convert.ToString(1), asyncValueProvisioning),
"not " + 1 + " as new item is created");
}