public void GetETagTest()
{
var tag = "etag";
//Saves the cache and pass it a timespan for expiration
barrel.Add(key: url, data: json, expireIn: TimeSpan.FromDays(1), eTag: tag);
var cached = barrel.GetETag(url);
Assert.AreEqual(cached, tag);
}
/// <summary>
/// Send a cached requests
/// </summary>
/// <param name="http">Http client ot use</param>
/// <param name="barrel">Barrel to use for cache</param>
/// <param name="req">request to send</param>
/// <param name="expireIn">expire in</param>
/// <param name="forceUpdate">If we should force the update or not</param>
/// <param name="throttled">If throttled or not</param>
/// <returns>The new or cached response.</returns>
public static async Task <string> SendCachedAsync(this HttpClient http, IBarrel barrel, HttpRequestMessage req, TimeSpan expireIn, bool forceUpdate = false, bool throttled = true)
{
var url = req.RequestUri.ToString();
var contents = barrel.Get <string>(url);
var eTag = barrel.GetETag(url);
if (!forceUpdate && !string.IsNullOrEmpty(contents) && !barrel.IsExpired(url))
{
return(contents);
}
var etag = eTag ?? null;
if (throttled)
{
await getThrottle.WaitAsync();
}
HttpResponseMessage r;
string c = null;
try {
if (!forceUpdate && !string.IsNullOrEmpty(etag) && !string.IsNullOrEmpty(contents))
{
req.Headers.IfNoneMatch.Clear();
req.Headers.IfNoneMatch.Add(new EntityTagHeaderValue(etag));
}
r = await http.SendAsync(req);
if (r.StatusCode == HttpStatusCode.NotModified)
{
if (string.IsNullOrEmpty(contents))
{
throw new IndexOutOfRangeException($"Cached value missing for HTTP request: {url}");
}
return(contents);
}
c = await r.Content.ReadAsStringAsync();
} finally {
if (throttled)
{
getThrottle.Release();
}
}
if (r.StatusCode == HttpStatusCode.OK)
{
// Cache it?
var newEtag = r.Headers.ETag != null ? r.Headers.ETag.Tag : null;
if (!string.IsNullOrEmpty(newEtag) && newEtag != etag)
{
barrel.Add(url, c, expireIn, newEtag);
}
return(c);
}
else
{
throw new HttpCacheRequestException(r.StatusCode, "HTTP Cache Request Failed");
}
}