public async Task <T> GetOrCreateAsync <T>(string key, Func <ICacheItem, Task <T> > factory, EvictionCallback evictionCallback = null, params string[] dependencyMonikers)
{
if (null != evictionCallback)
{
throw new NotSupportedException("EvictionCallback is not supported for distributed cache.");
}
bool shouldCreateNew = false;
Queue <string> missingDependencyMonikers = new Queue <string>();
DistributedCacheEntry entry = await this.GetAsync(key);
shouldCreateNew = null == entry;
foreach (var dependencyMoniker in dependencyMonikers)
{
var dependencyEntry = await this.GetAsync(dependencyMoniker);
if (null == dependencyEntry)
{
shouldCreateNew = true;
missingDependencyMonikers.Enqueue(dependencyMoniker);
}
}
if (!shouldCreateNew)
{
return(Utilities.SafeDeserialize <T>(entry.Data));
}
long timestamp = DateTime.Now.Ticks;
DistributedCacheEntry newEntry = new DistributedCacheEntry();
T data = await factory.Invoke(newEntry);
newEntry.Data = Utilities.SafeSerialize(data);
newEntry.Timestamp = timestamp;
await this.SetAsync(key, newEntry);
while (missingDependencyMonikers.TryDequeue(out string missingDependencyMoniker))
{
await this.SetAsync(missingDependencyMoniker, new DistributedCacheEntry()
{
Timestamp = timestamp,
AbsoluteExpirationRelativeToNow = TimeSpan.FromDays(7)
});
}
return(Utilities.SafeDeserialize <T>(newEntry.Data));
}
private async Task SetAsync(string key, DistributedCacheEntry entry)
{
if (null == entry)
{
throw new ArgumentNullException(nameof(entry));
}
string json = Utilities.SafeSerialize(entry);
DistributedCacheEntryOptions options = new DistributedCacheEntryOptions()
{
AbsoluteExpiration = entry.AbsoluteExpiration,
AbsoluteExpirationRelativeToNow = entry.AbsoluteExpirationRelativeToNow,
SlidingExpiration = entry.SlidingExpiration
};
await this.Cache.SetStringAsync(key, json, options);
}