protected async Task TryGetRevalidatedResult(IHandlerContextWithResult handlerContext, HttpRequestMessage request, HttpResponseMessage response)
{
if (!Enabled)
{
return;
}
var context = GetContext(handlerContext);
var result = (CacheEntry)context.Items["CacheHandlerCachedItem"];
var meta = CachingHelpers.CreateResponseMetadata(result, request, response, context);
if (result == null || !context.RevalidateValidator(context, meta))
{
return;
}
if (!result.IsEmpty && result.Value != null)
{
result.UpdateResponseMetadata(request, response, context);
context.ResultInspector?.Invoke(result);
}
else
{
result = CacheEntry.Empty;
}
if (result.IsEmpty)
{
var missedResult = await context.HandlerRegister.OnMiss(context);
if (missedResult.IsDirty)
{
result = new CacheEntry(missedResult.Value, null);
}
}
if (!result.IsEmpty)
{
var hitResult = await context.HandlerRegister.OnHit(context, result.Value);
if (hitResult.IsDirty && !(bool)hitResult.Value)
{
handlerContext.Result = result.Value;
}
}
context.Items["CacheHandlerCachedItem"] = result;
}
protected async Task TryGetFromCache(IHandlerContextWithResult handlerContext)
{
if (!Enabled)
{
return;
}
var context = GetContext(handlerContext);
var requestValidation = context.RequestValidator(context);
if (requestValidation != RequestValidationResult.OK)
{
await ExpireResult(context, requestValidation);
return;
}
var result = await _cacheManager.Get(context);
var responseValidation = ResponseValidationResult.NotExist;
if (!result.IsEmpty)
{
context.ResultInspector?.Invoke(result);
responseValidation = context.ResponseValidator(context, result.Metadata);
}
// TODO: Determine the need for conditional put - if so, that logic would go here
if (responseValidation == ResponseValidationResult.Stale && !context.AllowStaleResultValidator(context, result.Metadata))
{
responseValidation = ResponseValidationResult.MustRevalidate;
}
if (responseValidation == ResponseValidationResult.MustRevalidate && context.Request != null)
{
if (result.Metadata.ETag != null)
{
context.Request.Headers.Add("If-None-Match", result.Metadata.ETag);
}
else if (result.Metadata.LastModified != null)
{
context.Request.Headers.Add("If-Modified-Since", result.Metadata.LastModified.Value.ToString("r"));
}
//hang on to this we are going to need it in a sec. We could try to get it from cache store, but it may have expired by then
context.Items["CacheHandlerCachedItem"] = result;
return;
}
if (result.IsEmpty)
{
var missedResult = await context.HandlerRegister.OnMiss(context);
if (missedResult.IsDirty)
{
result = new CacheEntry(missedResult.Value, null);
}
}
if (!result.IsEmpty)
{
var hitResult = await context.HandlerRegister.OnHit(context, result.Value);
if (!hitResult.IsDirty || !(bool)hitResult.Value)
{
handlerContext.Result = result.Value;
}
}
context.Items["CacheHandlerCachedItem"] = result;
}
