/// <summary>
/// Gets the cache region for the specified invocation.
/// </summary>
/// <param name="invocation"></param>
/// <returns></returns>
private static string GetCacheRegion(IInvocation invocation)
{
string region;
var strategy = ResponseDataCachingStrategy.Get(invocation.Method);
if (strategy != null)
{
region = strategy.GetCacheRegion();
if (!String.IsNullOrEmpty(region))
{
return(region);
}
}
region = string.Format("{0}.{1}", invocation.InvocationTarget.GetType().FullName, invocation.Method.Name);
return(region);
}
/// <summary>
/// Called from subclasses within the intercept method to process the invocation, adding caching as appropriate.
/// </summary>
/// <param name="invocation"></param>
/// <param name="cacheId"></param>
protected void ProcessInvocation(IInvocation invocation, string cacheId)
{
using (var cacheClient = Cache.CreateClient(cacheId))
{
var region = GetCacheRegion(invocation);
var request = invocation.Arguments[0];
// check for a cached response, unless it is being explicity bypassed
// must do this even if this operation does not support caching, because have no way of knowing
// whether it does or does not support caching
if (ResponseCacheBypassScope.BypassCount == 0 && GetCachedResponse(invocation, request, cacheClient, region))
{
return;
}
// invoke the operation
invocation.Proceed();
// Regardless of caching directives, just remove anything the strategy says to when we actually call the method.
var strategy = ResponseDataCachingStrategy.Get(invocation.Method);
var cacheKeysToRemove = strategy.GetCacheKeysToRemove(request, invocation.ReturnValue);
if (cacheKeysToRemove != null && cacheKeysToRemove.Length > 0)
{
foreach (var cacheKey in cacheKeysToRemove)
{
cacheClient.Remove(cacheKey, new CacheRemoveOptions(region));
}
}
// get cache directive
var directive = GetCachingDirective(invocation);
// cache the response if directed
if (directive != null && directive.EnableCaching && directive.TimeToLive > TimeSpan.Zero)
{
CacheResponse(invocation, request, cacheClient, region, directive);
}
}
}
/// <summary>
/// Puts the invocation response in the specified cache.
/// </summary>
/// <param name="invocation"></param>
/// <param name="cacheClient"></param>
/// <param name="request"> </param>
/// <param name="region"></param>
/// <param name="directive"></param>
protected static void PutResponseInCache(IInvocation invocation, object request, ICacheClient cacheClient, string region, ResponseCachingDirective directive)
{
// bail if the directive does not tell us to cache anything
if (directive == null || !directive.EnableCaching || directive.TimeToLive == TimeSpan.Zero)
{
return;
}
var strategy = ResponseDataCachingStrategy.Get(invocation.Method);
var data = strategy.GetCacheDataToPut(request, invocation.ReturnValue);
if (data == null || data.Length == 0)
{
throw new InvalidOperationException(
string.Format("{0} is cacheable but the caching strategy didn't return any data to put in the cache.", invocation.GetType().FullName));
}
foreach (var item in data)
{
cacheClient.Put(item.CacheKey, item.Data, new CachePutOptions(region, directive.TimeToLive, false));
}
}
/// <summary>
/// Tries to get a previously cached response for the specified invocation, returning false if not found.
/// </summary>
/// <param name="invocation"></param>
/// <param name="request"> </param>
/// <param name="cacheClient"></param>
/// <param name="region"></param>
/// <returns></returns>
private static bool GetCachedResponse(IInvocation invocation, object request, ICacheClient cacheClient, string region)
{
if (!cacheClient.RegionExists(region))
{
return(false);
}
var strategy = ResponseDataCachingStrategy.Get(invocation.Method);
var cacheKeys = strategy.GetCacheKeys(request);
if (cacheKeys == null || cacheKeys.Length == 0)
{
return(false);
}
var cacheData = new Dictionary <string, object>();
foreach (var cacheKey in cacheKeys)
{
var data = cacheClient.Get(cacheKey, new CacheGetOptions(region));
if (data != null) //Assume null is not a relevant cache entry.
{
cacheData[cacheKey] = data;
}
}
if (cacheData.Count > 0)
{
var response = strategy.ConstructResponse(request, cacheData);
if (response != null)
{
invocation.ReturnValue = response;
return(true);
}
}
return(false);
}
