private static string BuildEndpointDiscoveryCacheKey(EndpointOperationContextBase context)
{
var cacheKeyBuilder = new StringBuilder();
cacheKeyBuilder.Append(context.CustomerCredentials);
var identifiers = context.EndpointDiscoveryData.Identifiers;
if (identifiers != null && identifiers.Count > 0)
{
cacheKeyBuilder.Append(string.Format(CultureInfo.InvariantCulture, ".{0}", context.OperationName));
foreach (var identifier in identifiers)
{
cacheKeyBuilder.Append(string.Format(CultureInfo.InvariantCulture, ".{0}", identifier.Value));
}
}
return(cacheKeyBuilder.ToString());
}
/// <summary>
/// Method that performs endpoint discovery for the current operation
/// </summary>
/// <param name="context">Context information used in calculations for endpoint discovery</param>
/// <param name="InvokeEndpointOperation">The operation to fetch endpoints from the server</param>
/// <returns></returns>
public virtual IEnumerable <DiscoveryEndpointBase> ResolveEndpoints(EndpointOperationContextBase context, Func <IList <DiscoveryEndpointBase> > InvokeEndpointOperation)
{
//Build the cacheKey
var cacheKey = BuildEndpointDiscoveryCacheKey(context);
//Evict cache keys that more than 1 hour old.
_cache.EvictExpiredLRUListItems(_cacheKeyValidityInSeconds);
//Check / cleanup the cache
var refreshCache = false;
IEnumerable <DiscoveryEndpointBase> endpoints = ProcessEndpointCache(cacheKey, context.EvictCacheKey, context.EvictUri, out refreshCache);
if (endpoints != null)
{
if (refreshCache)
{
//Async fetch new endpoints because one or more of the endpoints in the cache have expired.
#if AWS_ASYNC_API
// Task only exists in framework 4.5 and up, and Standard.
System.Threading.Tasks.Task.Run(() =>
{
ProcessInvokeEndpointOperation(cacheKey, InvokeEndpointOperation, false);
});
#else
// ThreadPool only exists in 3.5 and below. These implementations do not have the Task library.
System.Threading.ThreadPool.QueueUserWorkItem((state) =>
{
ProcessInvokeEndpointOperation(cacheKey, InvokeEndpointOperation, false);
});
#endif
}
return(endpoints);
}
if (context.EvictCacheKey)
{
return(null);
}
//Determine if we are required to get an endpoint or if we can defer it to an async call
if (context.EndpointDiscoveryData.Required)
{
//Must find an endpoint or error for this operation
endpoints = ProcessInvokeEndpointOperation(cacheKey, InvokeEndpointOperation, true);
}
else if (_config.EndpointDiscoveryEnabled)
{
//Optionally find and endpoint for this supported operation async
#if AWS_ASYNC_API
// Task only exists in framework 4.5 and up, and Standard.
System.Threading.Tasks.Task.Run(() =>
{
ProcessInvokeEndpointOperation(cacheKey, InvokeEndpointOperation, false);
});
#else
// ThreadPool only exists in 3.5 and below. These implementations do not have the Task library.
System.Threading.ThreadPool.QueueUserWorkItem((state) =>
{
ProcessInvokeEndpointOperation(cacheKey, InvokeEndpointOperation, false);
});
#endif
return(null);
}
//else not required or endpoint discovery has been disabled so fall through to normal regional endpoint
return(endpoints);
}
