public async Task TryRemoveAsync(CacheIdentity id)
{
using (await _locker.AcquireAsync())
{
_cache.Remove(id);
}
}
public async Task TryAddAsync(CacheIdentity id, CacheEntry entry)
{
using (await _locker.AcquireAsync())
{
_cache.EnsureKeyExists(id, new List <CacheEntry>());
_cache[id].Add(entry);
}
}
public async Task <IList <CacheEntry> > TryGetAsync(CacheIdentity id)
{
using (await _locker.AcquireAsync())
{
if (_cache.ContainsKey(id))
{
return(_cache[id]);
}
else
{
return(null);
}
}
}
public async Task InvokeAsync(HttpContext httpContext, URIProviderService uriProvider, IServiceProvider serviceProvider, ILoggerFactory loggerFactory, UserManager <User> userManager)
{
var logger = loggerFactory.CreateLogger("Response caching");
var requestURI = uriProvider.GetCurrentRequestURI();
var cacheKey = new CacheIdentity(requestURI);
var cacheEntry = await tryGetCacheAsync();
var manager = new CacheManagerFeature(_storage, cacheEntry?.IsRequestDataSet ?? false, cacheEntry?.RequestData);
httpContext.Features.Set <ICacheManagerFeature>(manager);
if (cacheEntry != null)
{
logger.LogInformation($"Serving response from cache...");
await setResponseAsync();
await executeHandlerAsync();
}
else
{
await nextAndPopulateAsync();
}
///////////////////////////////////////////////////////////////////////
async Task setResponseAsync()
{
httpContext.Response.StatusCode = cacheEntry.StatusCode;
foreach (var header in cacheEntry.Headers)
{
httpContext.Response.Headers[header.Key] = header.Value;
}
await httpContext.Response.Body.WriteAsync(cacheEntry.ResponseBody);
}
async Task executeHandlerAsync()
{
CacheHandlerDelegate handler = null;
var has = cacheEntry.CachingInfo.CacheEntryKey == null
? false
: _cacheHandlers.TryGetValue(cacheEntry.CachingInfo.CacheEntryKey, out handler);
if (has && handler != null)
{
var scope = new CacheScope(cacheEntry.IsRequestDataSet, cacheEntry.RequestData, serviceProvider);
await handler(scope);
}
}
async Task <CacheEntry> tryGetCacheAsync()
{
var cache = await _storage.TryGetAsync(cacheKey);
if (cache != null)
{
foreach (var c in cache)
{
if (await c.Policy.CanBeServedAsync(httpContext, serviceProvider, c.PolicyMetadata))
{
return(c);
}
}
}
return(null);
}
async Task nextAndPopulateAsync()
{
byte[] cacheBuffer = null;
{
var originalBodyStream = httpContext.Response.Body;
var cacheStream = new MemoryStream();
httpContext.Response.Body = cacheStream;
try
{
// Allow MVC action to execute (so that we will be able to get endpoint info later)
await _next(httpContext);
}
finally
{
cacheBuffer = cacheStream.ToArray();
await originalBodyStream.WriteAsync(cacheBuffer);
httpContext.Response.Body = originalBodyStream;
}
}
var endpoint = httpContext.Features.Get <IEndpointFeature>()?.Endpoint;
// Endpoint will be null if the URL didn't match an action, e.g. a 404 response
if (endpoint != null && httpContext.Response.IsSuccessStatusCode())
{
var cachingInfo = tryGetCacheAttribute();
if (cachingInfo != null)
{
if (cachingInfo.CacheDuration > 0)
{
var policy = _cachePolicies[cachingInfo.CachePolicy];
if (await policy.CanBeSavedAsync(httpContext, serviceProvider))
{
var routeData = httpContext.Features
.Get <RouteDataProviderFeature>().RouteData
.ToArray();
var cache = new CacheEntry(cachingInfo,
cacheBuffer,
httpContext.Response.StatusCode,
httpContext.Response.Headers,
manager.IsRequestDataSet,
manager.RequestData,
routeData,
policy,
await policy.GenerateMetadata(httpContext, serviceProvider));
await _storage.TryAddAsync(cacheKey, cache);
logger.LogInformation($"Response for request to {requestURI} has been added to cache for {cachingInfo.CacheDuration}s");
}
}
}
ServerResponseCacheAttribute tryGetCacheAttribute()
{
// Does not work for page handlers
var attr = endpoint.Metadata.GetMetadata <ServerResponseCacheAttribute>();
if (attr == null) // Fallback for page handlers
{
var attributesProvider = httpContext.Features
.Select(f => f.Value as PageHandlerAttributesProviderFeature)
.SkipNulls()
.FirstOrDefault();
attr = attributesProvider == null
? attr
: attributesProvider.Attributes.Select(a => a as ServerResponseCacheAttribute)
.SkipNulls()
.FirstOrDefault();
}
return(attr);
}
}
}
}
