public static bool IfNoneMatch <TRegion>(this HttpRequest request, string cacheKey, ICacheRegion <TRegion> cache,
out byte[] stream, out IActionResult result)
{
var headers = request.GetTypedHeaders();
foreach (var etag in headers.IfNoneMatch)
{
if (etag.IsWeak)
{
if (!etag.Tag.Equals(cacheKey.WeakETag(false, cache)))
{
continue;
}
result = new StatusCodeResult((int)HttpStatusCode.NotModified);
stream = default;
return(false);
}
if (!cache.TryGetValue(cacheKey, out stream) || !etag.Tag.Equals(stream.StrongETag(cache)))
{
continue;
}
result = new StatusCodeResult((int)HttpStatusCode.NotModified);
return(false);
}
result = default;
stream = default;
return(true);
}
public async Task <IActionResult> GetSyndicationFeed([FromRoute] string controller,
[FromHeader(Name = Constants.HeaderNames.Accept)]
string contentType, [FromFilter] Encoding encoding, [FromRoute] string ns, [FromRoute] ulong rs,
[FromQuery(Name = "q")] string query = default)
{
var mediaType = contentType?.ToLowerInvariant().Trim();
var charset = encoding.WebName;
var queryUrl = Request.GetEncodedUrl();
var cacheKey = $"{mediaType}:{charset}:{queryUrl}";
if (!Request.IsContentStale(cacheKey, _feeds, out var stream, out var lastModified, out var result))
{
return(result);
}
if (stream != default || _feeds.TryGetValue(cacheKey, out stream))
{
return(ServeFeed(cacheKey, stream, mediaType, charset, lastModified));
}
var(records, _) = await QueryAsync(controller, ns, rs, query, CancellationToken);
if (!SyndicationGenerator.TryBuildFeedAsync(queryUrl, ns, rs, records, mediaType, encoding, out stream,
out lastModified))
{
return(new UnsupportedMediaTypeResult());
}
_feeds.Set(cacheKey, stream);
_feeds.Set($"{cacheKey}:{HeaderNames.LastModified}", lastModified);
return(ServeFeed(cacheKey, stream, mediaType, charset, lastModified));
}
public static ulong GetSeed <T>(this ICacheRegion <T> cache)
{
if (!cache.TryGetValue(nameof(GetSeed), out ulong seed))
{
cache.Set(nameof(GetSeed), seed = BitConverter.ToUInt64(Encoding.UTF8.GetBytes(typeof(T).Name), 0));
}
return(seed);
}
public static bool IfModifiedSince <TRegion>(this HttpRequest request, string cacheKey,
ICacheRegion <TRegion> cache, out DateTimeOffset?lastModified, out IActionResult result)
{
var headers = request.GetTypedHeaders();
var ifModifiedSince = headers.IfModifiedSince;
if (cache.TryGetValue($"{cacheKey}:{HeaderNames.LastModified}", out lastModified) &&
lastModified <= ifModifiedSince)
{
result = new StatusCodeResult((int)HttpStatusCode.NotModified);
return(false);
}
result = default;
return(true);
}