private async Task HandleCachedAttribute(
CachedAttribute attribute, MethodInfo actionMethod,
ActionExecutingContext context, ActionExecutionDelegate next)
{
if (UserAgentSpecifiedNoCache(context.HttpContext.Request))
{
await next();
return;
}
var scopeValue = _cacheParametersResolver.ResolveScopeValue(attribute.ScopeName, context);
var outputContentType = actionMethod.GetCustomAttribute <ProducesAttribute>()?.ContentTypes.First()
?? RawActionResult.JsonContentType;
var methodParameters = new CacheMethodParameters(
actionMethod.GetUniqueIdentifier(),
attribute.ScopeName,
scopeValue,
context.ActionArguments,
outputContentType,
attribute.ExpireAfterTimeSpan ?? _cacheParametersResolver.DefaultExpiration,
attribute.SlidingExpiration);
var cacheGetResult = await _cacheAdapter.GetOrUpdate(methodParameters, () => OnCacheMiss(next));
if (cacheGetResult.Hit)
{
context.Result = cacheGetResult.ValueFromCache;
}
}
private async Task CacheMethodResult(
CacheMethodParameters parameters, string statusCodeFieldName,
string payloadFieldName, string contentTypeFieldName, IActionResult result)
{
var entries = new List <HashEntry>();
switch (result)
{
// methods that does not return an IActionResult might not have the status code field populated:
case ObjectResult objectResult:
{
var statusCode = objectResult.StatusCode ?? (int)HttpStatusCode.OK;
var contentTypeFormatterId = parameters.OutputContentType.Split(';')[0];
if (objectResult.Value != null)
{
var payload = await _serializationHelper.Serialize(contentTypeFormatterId, objectResult.Value);
entries.Add(new HashEntry(payloadFieldName, payload));
entries.Add(new HashEntry(contentTypeFieldName, parameters.OutputContentType));
}
entries.Add(new HashEntry(statusCodeFieldName, statusCode));
break;
}
case StatusCodeResult statusCodeResult:
{
var statusCode = statusCodeResult.StatusCode;
entries.Add(new HashEntry(statusCodeFieldName, statusCode));
break;
}
default:
throw new UnsupportedContentTypeException("unsupported WebApi method result type!");
}
var key = GetCacheKey(parameters.MethodName, parameters.ScopeName, parameters.ScopeValue);
var database = _redisConnectionMultiplexer.GetDatabase();
await database.HashSetAsync(key, entries.ToArray());
if (parameters.ExpirationTime.HasValue)
{
await database.KeyExpireAsync(key, parameters.ExpirationTime.Value);
}
}
public async Task <CacheGetResult> GetOrUpdate(
CacheMethodParameters parameters, Func <Task <IActionResult> > cacheMissResolver)
{
var database = _redisConnectionMultiplexer.GetDatabase();
var key = GetCacheKey(parameters.MethodName, parameters.ScopeName, parameters.ScopeValue);
var(statusCodeFieldName, payloadFieldName, contentTypeFieldName) =
GetCacheParametersFieldNames(parameters);
var cached = await database.HashGetAsync(key, new RedisValue[]
{
statusCodeFieldName, payloadFieldName, contentTypeFieldName
});
var statusCode = cached[0];
var payload = cached[1];
var contentType = cached[2];
if (!statusCode.HasValue)
{
var newValue = await cacheMissResolver();
if (newValue != null)
{
await CacheMethodResult(parameters, statusCodeFieldName, payloadFieldName, contentTypeFieldName,
newValue);
}
return(new CacheGetResult(false, null));
}
if (parameters.ExpirationTime.HasValue && parameters.IsSlidingExpiration)
{
await database.KeyExpireAsync(key, parameters.ExpirationTime.Value);
}
ActionResult result = new RawActionResult((int)statusCode, payload, contentType,
new Dictionary <string, string>
{
["x-served-from-cache"] = "true"
});
return(new CacheGetResult(true, result));
}
GetCacheParametersFieldNames(CacheMethodParameters parameters)
{
var parametersHash = _serializationHelper.ComputeHash(parameters.Parameters);
return($"{parametersHash}:statusCode", $"{parametersHash}:payload", $"{parametersHash}:contentType");
}
