private async Task ExecuteRequestAndCache(HttpContext context, string key, CacheAttribute attribute)
{
var originalBodyStream = context.Response.Body;
using (var responseBody = new MemoryStream())
{
context.Response.Body = responseBody;
await _next(context);
if (IsCachableResponse(context.Response))
{
context.Response.Body.Seek(0, SeekOrigin.Begin);
var buffer = new byte[Convert.ToInt32(context.Response.Body.Length)];
context.Response.Body.Read(buffer, 0, buffer.Length);
var options = GetOptions(attribute);
_cache.Set(key, buffer, options);
_cache.Set(GetContentTypeKey(key), context.Response.ContentType, options);
context.Response.Body.Seek(0, SeekOrigin.Begin);
await responseBody.CopyToAsync(originalBodyStream);
}
}
}
private bool IsClearCacheAction(HttpContext context, CacheAttribute cacheAttr)
{
return((new[] { "PATCH", "POST", "PUT" }.Any(method => method.Equals(context.Request.Method,
StringComparison.CurrentCultureIgnoreCase)) &&
!cacheAttr.AsGet) ||
context.Request.Method.Equals("DELETE", StringComparison.CurrentCultureIgnoreCase));
}
private async Task ExecuteRequest(HttpContext context, string key, CacheAttribute attribute)
{
if (!IsClearCacheAction(context, attribute))
{
await ExecuteRequestAndCache(context, key, attribute);
}
else
{
await _next(context);
}
}
private async Task InvokeCached(HttpContext context, CacheAttribute attribute)
{
var key = GetKey(context);
if (IsClearCacheAction(context, attribute))
{
_cache.Remove(key);
_cache.Remove(GetContentTypeKey(key));
}
_cache.TryGetValue(key, out object value);
if (value == null)
{
await ExecuteRequest(context, key, attribute);
}
else
{
_cache.TryGetValue(GetContentTypeKey(key), out string contentType);
await SetResponseFromCache(context, (byte[])value, contentType);
}
}
private MemoryCacheEntryOptions GetOptions(CacheAttribute attribute)
{
return(new MemoryCacheEntryOptions
{
AbsoluteExpiration = attribute.AbsoluteExpiration > DateTime.MinValue
? attribute.AbsoluteExpiration
: (DateTimeOffset?)null,
AbsoluteExpirationRelativeToNow = attribute.AbsoluteExpirationRelativeToNow > int.MinValue
? TimeSpan.FromSeconds(attribute.AbsoluteExpirationRelativeToNow)
: (TimeSpan?)null,
Priority = attribute.Priority,
SlidingExpiration = attribute.SlidingExpiration > int.MinValue
? TimeSpan.FromSeconds(attribute.SlidingExpiration)
: (TimeSpan?)null,
Size = attribute.Size > long.MinValue
? attribute.Size
: (long?)null
});
}
