internal Func <HttpRequestMessage, Task <HttpResponseMessage> > PutIfMatch()
{
return(request =>
{
if (request.Method != HttpMethod.Put)
{
return null;
}
ICollection <EntityTagHeaderValue> matchTags = request.Headers.IfMatch;
if (matchTags == null || matchTags.Count == 0)
{
return null;
}
IEnumerable <KeyValuePair <string, IEnumerable <string> > > headers =
request.Headers.Where(h => _varyByHeaders.Any(v => v.Equals(h.Key, StringComparison.CurrentCultureIgnoreCase)));
string resource = UriTrimmer(request.RequestUri);
EntityTagKey entityTagKey = EntityTagKeyGenerator(resource, headers);
TimedEntityTagHeaderValue actualEtag;
bool matchFound = false;
if (_entityTagStore.TryGetValue(entityTagKey, out actualEtag))
{
if (matchTags.Any(etag => etag.Tag == actualEtag.Tag))
{
matchFound = true;
}
}
return matchFound
? null
: new HttpResponseMessage(HttpStatusCode.PreconditionFailed).ToTask();
});
}
/// <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
IEnumerable <string> linkedUrls = LinkedRoutePatternProvider(uri, request.Method);
foreach (string linkedUrl in linkedUrls)
{
_entityTagStore.RemoveAllByRoutePattern(linkedUrl);
}
});
}
internal Func <HttpRequestMessage, Task <HttpResponseMessage> > PutIfUnmodifiedSince()
{
return(request =>
{
if (request.Method != HttpMethod.Put)
{
return null;
}
DateTimeOffset?ifUnmodifiedSince = request.Headers.IfUnmodifiedSince;
if (ifUnmodifiedSince == null)
{
return null;
}
DateTimeOffset modifiedInQuestion = ifUnmodifiedSince.Value;
IEnumerable <KeyValuePair <string, IEnumerable <string> > > headers =
request.Headers.Where(h => _varyByHeaders.Any(v => v.Equals(h.Key, StringComparison.CurrentCultureIgnoreCase)));
string resource = UriTrimmer(request.RequestUri);
EntityTagKey entityTagKey = EntityTagKeyGenerator(resource, headers);
TimedEntityTagHeaderValue actualEtag;
bool isModified = false;
if (_entityTagStore.TryGetValue(entityTagKey, out actualEtag))
{
isModified = actualEtag.LastModified > modifiedInQuestion;
}
return isModified
? new HttpResponseMessage(HttpStatusCode.PreconditionFailed).ToTask()
: null;
});
}
protected void ExecuteCacheAdditionRules(EntityTagKey entityTagKey,
HttpRequestMessage request,
HttpResponseMessage response,
IEnumerable <KeyValuePair <string, IEnumerable <string> > > varyHeaders)
{
new[]
{
AddCaching(entityTagKey, request, response, varyHeaders), // general caching
}
.Chain()();
}
protected void ExecuteCacheInvalidationRules(EntityTagKey entityTagKey,
HttpRequestMessage request,
HttpResponseMessage response)
{
new[]
{
InvalidateCache(entityTagKey, request, response), // general invalidation
PostInvalidationRule(entityTagKey, request, response)
}
.Chain()();
}
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);
});
}
/// <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
(() =>
{
CacheControlHeaderValue 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());
}
});
}
internal Func <HttpRequestMessage, Task <HttpResponseMessage> > GetIfMatchNoneMatch()
{
return((request) =>
{
if (request.Method != HttpMethod.Get)
{
return null;
}
ICollection <EntityTagHeaderValue> noneMatchTags = request.Headers.IfNoneMatch;
ICollection <EntityTagHeaderValue> matchTags = request.Headers.IfMatch;
if (matchTags.Count == 0 && noneMatchTags.Count == 0)
{
return null; // no etag
}
if (matchTags.Count > 0 && noneMatchTags.Count > 0) // both if-match and if-none-match exist
{
return new HttpResponseMessage(HttpStatusCode.BadRequest).ToTask();
}
bool isNoneMatch = noneMatchTags.Count > 0;
ICollection <EntityTagHeaderValue> etags = isNoneMatch ? noneMatchTags : matchTags;
string resource = UriTrimmer(request.RequestUri);
IEnumerable <KeyValuePair <string, IEnumerable <string> > > headers =
request.Headers.Where(h => _varyByHeaders.Any(v => v.Equals(h.Key, StringComparison.CurrentCultureIgnoreCase)));
EntityTagKey entityTagKey = EntityTagKeyGenerator(resource, headers);
// compare the Etag with the one in the cache
// do conditional get.
TimedEntityTagHeaderValue actualEtag = null;
bool matchFound = false;
if (_entityTagStore.TryGetValue(entityTagKey, out actualEtag))
{
if (etags.Any(etag => etag.Tag == actualEtag.Tag))
{
matchFound = true;
}
}
return matchFound ^ isNoneMatch ? null : new NotModifiedResponse(actualEtag.ToEntityTagHeaderValue()).ToTask();
});
}
internal Func <HttpRequestMessage, Task <HttpResponseMessage> > GetIfModifiedUnmodifiedSince()
{
return((request) =>
{
if (request.Method != HttpMethod.Get && request.Headers != null)
{
return null;
}
DateTimeOffset?ifModifiedSince = request.Headers.IfModifiedSince;
DateTimeOffset?ifUnmodifiedSince = request.Headers.IfUnmodifiedSince;
if (ifModifiedSince == null && ifUnmodifiedSince == null)
{
return null; // no etag
}
if (ifModifiedSince != null && ifUnmodifiedSince != null) // both exist
{
return new HttpResponseMessage(HttpStatusCode.BadRequest).ToTask();
}
bool ifModified = (ifUnmodifiedSince == null);
DateTimeOffset modifiedInQuestion = ifModified ? ifModifiedSince.Value : ifUnmodifiedSince.Value;
IEnumerable <KeyValuePair <string, IEnumerable <string> > > headers =
request.Headers.Where(h => _varyByHeaders.Any(v => v.Equals(h.Key, StringComparison.CurrentCultureIgnoreCase)));
string resource = UriTrimmer(request.RequestUri);
EntityTagKey entityTagKey = EntityTagKeyGenerator(resource, headers);
TimedEntityTagHeaderValue actualEtag;
bool isModified = false;
if (_entityTagStore.TryGetValue(entityTagKey, out actualEtag))
{
isModified = actualEtag.LastModified > modifiedInQuestion;
}
return isModified ^ ifModified
? new NotModifiedResponse(actualEtag.ToEntityTagHeaderValue()).ToTask()
: null;
});
}
/// <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());
}
});
}
internal Func <Task <HttpResponseMessage>, HttpResponseMessage> GetCachingContinuation(HttpRequestMessage request)
{
return(task =>
{
HttpResponseMessage response = task.Result;
int statusCode = (int)response.StatusCode;
if (statusCode >= 300 || statusCode < 200) // only if successful carry on processing
{
return response;
}
string uri = UriTrimmer(request.RequestUri);
IEnumerable <KeyValuePair <string, IEnumerable <string> > > varyHeaders = request.Headers.Where(h =>
_varyByHeaders.Any(v => v.Equals(h.Key, StringComparison.CurrentCultureIgnoreCase)));
EntityTagKey eTagKey = EntityTagKeyGenerator(uri, varyHeaders);
ExecuteCacheInvalidationRules(eTagKey, request, response);
ExecuteCacheAdditionRules(eTagKey, request, response, varyHeaders);
return response;
});
}
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));
}