public AutoCompleteResourceV3(HttpSource client, ServiceIndexResourceV3 serviceIndex, RegistrationResourceV3 regResource)
: base()
{
_regResource = regResource;
_serviceIndex = serviceIndex;
_client = client;
}
public override async Task <Tuple <bool, INuGetResource> > TryCreate(SourceRepository source, CancellationToken token)
{
ServiceIndexResourceV3 index = null;
ServiceIndexCacheInfo cacheInfo = null;
var url = source.PackageSource.Source;
// the file type can easily rule out if we need to request the url
if (source.PackageSource.ProtocolVersion == 3 ||
(source.PackageSource.IsHttp &&
url.EndsWith(".json", StringComparison.OrdinalIgnoreCase)))
{
var utcNow = DateTime.UtcNow;
var entryValidCutoff = utcNow.Subtract(MaxCacheDuration);
// check the cache before downloading the file
if (!_cache.TryGetValue(url, out cacheInfo) ||
entryValidCutoff > cacheInfo.CachedTime)
{
// Track if the semaphore needs to be released
var release = false;
try
{
await _semaphore.WaitAsync(token);
release = true;
token.ThrowIfCancellationRequested();
// check the cache again, another thread may have finished this one waited for the lock
if (!_cache.TryGetValue(url, out cacheInfo) ||
entryValidCutoff > cacheInfo.CachedTime)
{
index = await GetServiceIndexResourceV3(source, utcNow, NullLogger.Instance, token);
// cache the value even if it is null to avoid checking it again later
var cacheEntry = new ServiceIndexCacheInfo
{
CachedTime = utcNow,
Index = index
};
// If the cache entry has expired it will already exist
_cache.AddOrUpdate(url, cacheEntry, (key, value) => cacheEntry);
}
}
finally
{
if (release)
{
_semaphore.Release();
}
}
}
}
if (index == null && cacheInfo != null)
{
index = cacheInfo.Index;
}
return(new Tuple <bool, INuGetResource>(index != null, index));
}