public void AddOrUpdate(EntityTagKey key, TimedEntityTagHeaderValue eTag)
{
_eTagCache.AddOrUpdate(key, eTag, (theKey, oldValue) => eTag);
_routePatternCache.AddOrUpdate(key.RoutePattern, new HashSet<EntityTagKey>() { key },
(routePattern, hashSet) =>
{
hashSet.Add(key);
return hashSet;
});
}
protected void ExecuteCacheInvalidationRules(EntityTagKey entityTagKey,
HttpRequestMessage request,
HttpResponseMessage response)
{
new[]
{
InvalidateCache(entityTagKey, request, response), // general invalidation
PostInvalidationRule(entityTagKey, request, response)
}
.Chain()();
}
protected void ExecuteCacheAdditionRules(EntityTagKey entityTagKey,
HttpRequestMessage request,
HttpResponseMessage response,
IEnumerable<KeyValuePair<string, IEnumerable<string>>> varyHeaders)
{
new[]
{
AddCaching(entityTagKey, request, response, varyHeaders), // general caching
}
.Chain()();
}
/// <summary>
/// This is a scenario where we have a POST to a resource
/// and it needs to invalidate the cache to that resource
/// and all its linked URLs
///
/// For example:
/// POST /api/cars => invalidate /api/cars
/// also it might invalidate /api/cars/fastest in which case
/// /api/cars/fastest must be one of the linked URLs
/// </summary>
/// <param name="entityTagKey">entityTagKey</param>
/// <param name="request">request</param>
/// <param name="response">response</param>
/// <returns>returns the function to execute</returns>
internal Action PostInvalidationRule(
EntityTagKey entityTagKey,
HttpRequestMessage request,
HttpResponseMessage response)
{
return () =>
{
if(request.Method!=HttpMethod.Post)
return;
// if location header is set (for newly created resource), invalidate cache for it
// this normally should not be necessary as the item is new and should not be in the cache
// but releasing a non-existent item from cache should not have a big overhead
if (response.Headers.Location != null)
{
_entityTagStore.RemoveAllByRoutePattern(response.Headers.Location.ToString());
}
};
}
/// <summary>
/// This invalidates the resource based on routePattern
/// for methods POST, PUT and DELETE.
/// It also removes for all linked URLs
/// </summary>
/// <param name="entityTagKey"></param>
/// <param name="request"></param>
/// <param name="response"></param>
/// <returns></returns>
internal Action InvalidateCache(
EntityTagKey entityTagKey,
HttpRequestMessage request,
HttpResponseMessage response)
{
return
() =>
{
if (!request.Method.Method.IsIn("PUT", "DELETE", "POST"))
return;
string uri = UriTrimmer(request.RequestUri);
// remove pattern
_entityTagStore.RemoveAllByRoutePattern(entityTagKey.RoutePattern);
// remove all related URIs
var linkedUrls = LinkedRoutePatternProvider(uri, request.Method);
foreach (var linkedUrl in linkedUrls)
_entityTagStore.RemoveAllByRoutePattern(linkedUrl);
};
}
/// <summary>
/// Adds caching for GET and PUT if
/// cache control provided is not null
/// With PUT, since cache has been alreay invalidated,
/// we provide the new ETag (old one has been cleared in invalidation phase)
/// </summary>
/// <param name="entityTagKey"></param>
/// <param name="request"></param>
/// <param name="response"></param>
/// <param name="varyHeaders"></param>
/// <returns></returns>
internal Action AddCaching(
EntityTagKey entityTagKey,
HttpRequestMessage request,
HttpResponseMessage response,
IEnumerable<KeyValuePair<string, IEnumerable<string>>> varyHeaders)
{
return
() =>
{
var cacheControlHeaderValue = CacheControlHeaderProvider(request);
if (cacheControlHeaderValue == null)
return;
TimedEntityTagHeaderValue eTagValue;
string uri = UriTrimmer(request.RequestUri);
// in case of GET and no ETag
// in case of PUT, we should return the new ETag of the resource
// NOTE: No need to check if it is in the cache. If it were, it would not get
// here
if (request.Method == HttpMethod.Get || request.Method == HttpMethod.Put)
{
// create new ETag only if it does not already exist
if (!_entityTagStore.TryGetValue(entityTagKey, out eTagValue))
{
eTagValue = new TimedEntityTagHeaderValue(ETagValueGenerator(uri, varyHeaders));
_entityTagStore.AddOrUpdate(entityTagKey, eTagValue);
}
// set ETag
response.Headers.ETag = eTagValue.ToEntityTagHeaderValue();
// set last-modified
if (AddLastModifiedHeader && response.Content != null && !response.Content.Headers.Any(x => x.Key.Equals(HttpHeaderNames.LastModified,
StringComparison.CurrentCultureIgnoreCase)))
{
response.Content.Headers.Add(HttpHeaderNames.LastModified, eTagValue.LastModified.ToString("r"));
}
// set Vary
if (AddVaryHeader && _varyByHeaders != null && _varyByHeaders.Length > 0)
{
response.Headers.Add(HttpHeaderNames.Vary, _varyByHeaders);
}
response.Headers.TryAddWithoutValidation(HttpHeaderNames.CacheControl, cacheControlHeaderValue.ToString());
}
};
}
public bool TryRemove(EntityTagKey key)
{
TimedEntityTagHeaderValue entityTagHeaderValue;
return _eTagCache.TryRemove(key, out entityTagHeaderValue);
}
public bool TryGetValue(EntityTagKey key, out TimedEntityTagHeaderValue eTag)
{
return _eTagCache.TryGetValue(key, out eTag);
}
