private AsyncLazy <TValue> GetOrAddExpirableAsyncLazy <TKey, TValue>(
VolatileMap <TKey, AsyncLazy <TValue> > map,
TKey key,
TimeSpan timeToLive,
Func <Task <TValue> > func)
{
AsyncLazy <TValue> asyncLazyValue;
while (!map.TryGetValue(key, out asyncLazyValue))
{
bool invalidate()
{
map.Invalidate(key);
return(false);
}
asyncLazyValue = new AsyncLazy <TValue>(async() =>
{
try
{
return(await func());
}
catch (Exception) when(invalidate())
{
// This should never be reached.
// Using Exception filter to invalidate entry on exception
// and preserve stack trace
throw;
}
});
map.TryAdd(key, asyncLazyValue, timeToLive);
}
return(asyncLazyValue);
}
public async Task <X509Certificate2> GetCertificateAsync(string certificateName)
{
if (_cachedCertificates.TryGetValue(certificateName, out var certificate))
{
return(certificate);
}
var client = new SecretClient(_uri, _azureCreds);
IcmCallsCounter.Increment();
var certResponse = await client.GetSecretAsync(certificateName);
var bytes = Convert.FromBase64String(certResponse.Value.Value);
var cert = new X509Certificate2(bytes);
var added = _cachedCertificates.TryAdd(certificateName, cert, _cacheTimeToLive, replaceIfExists: true);
Contract.Assert(added, "Failed to add certificate to cache.");
return(cert);
}