public TzdbDownload?GetRelease(string name)
{
var releasesByName = (cache.Value ?? FetchReleases()).ReleasesByName;
if (releasesByName.TryGetValue(name, out var value))
{
return(value);
}
// We don't know about the requested release from the last cache refresh. See whether
// it's *possibly* a real release, and if so try to fetch the object metadata.
// If that succeeds, serve that (and remember it) until we next refresh the cache.
if (!PlausibleReleaseName.IsMatch(name))
{
return(null);
}
var onDemandCache = cache.Value?.OnDemandReleasesByName ?? new ConcurrentDictionary <string, TzdbDownload>();
if (onDemandCache.TryGetValue(name, out value))
{
return(value);
}
string objectName = $"tzdb/{name}";
try
{
storage.GetObject(objectName);
}
catch (GoogleApiException)
{
// If we can't get the metadata entry for *any* reason, just return that it's not been found.
return(null);
}
value = new TzdbDownload(storage, objectName);
onDemandCache[name] = value;
return(value);
}
private string GetDownloadUrl(TzdbDownload download) =>
$"{Request.Scheme}://{Request.Host}/tzdb/{download.Name}";
