/// <summary>
/// Get a fileHanderCacheItem for the requested file.
/// </summary>
/// <param name="entityStoredWithCompressionType">The compression type to use for the file.</param>
/// <param name="entityCacheItem">The fileHandlerCacheItem </param>
/// <returns>Returns true if a fileHandlerCacheItem can be created; otherwise false.</returns>
public bool TryGetFileHandlerCacheItem(ResponseCompressionType entityStoredWithCompressionType, out EntityCacheItem entityCacheItem)
{
entityCacheItem = null;
// If the response bytes are already cached, then deliver the bytes directly from cache
var cacheKey = EmbeddedResourceEntityResponderType + ":" + entityStoredWithCompressionType + ":" + ResourcePath;
var cachedValue = CacheManager.Get <EntityCacheItem>(cacheKey);
if (cachedValue != null)
{
entityCacheItem = cachedValue;
}
else
{
//File does not exist
if (!DoesEntityExists)
{
return(false);
}
//File too large to send
if (ResourceSize > MaxFileSizeToServe)
{
return(false);
}
var etag = string.Empty;
var lastModifiedFileTime = ResourceLastModified;
//When a browser sets the If-Modified-Since field to 13-1-2010 10:30:58, another DateTime instance is created, but this one has a Ticks value of 633989754580000000
//But the time from the file system is accurate to a tick. So it might be 633989754586086250.
var lastModified = new DateTime(lastModifiedFileTime.Year, lastModifiedFileTime.Month,
lastModifiedFileTime.Day, lastModifiedFileTime.Hour,
lastModifiedFileTime.Minute, lastModifiedFileTime.Second);
var contentType = MimeTyper.GetMimeType(ResourceExtension);
var contentLength = ResourceSize;
//ETAG is always calculated from uncompressed entity data
switch (MimeSetting.EtagMethod)
{
case EtagMethodType.MD5:
using (var resourceStream = _assembly.GetManifestResourceStream(ResourcePath))
{
etag = Hasher.CalculateMd5Etag(resourceStream);
}
break;
case EtagMethodType.LastModified:
etag = lastModified.ToString("r");
break;
default:
throw new Exception("Unknown etag method generation");
}
entityCacheItem = new EntityCacheItem
{
Etag = etag,
LastModified = lastModified,
ContentLength = contentLength,
ContentType = contentType,
CompressionType = ResponseCompressionType.None
};
if (MimeSetting.ServeFromMemory &&
(contentLength <= MimeSetting.MaxMemorySize))
{
// When not compressed, buffer is the size of the file but when compressed,
// initial buffer size is one third of the file size. Assuming, compression
// will give us less than 1/3rd of the size
using (var memoryStream = new MemoryStream(
entityStoredWithCompressionType == ResponseCompressionType.None
?
Convert.ToInt32(ResourceSize)
:
Convert.ToInt32((double)ResourceSize / 3)))
{
GetEntityData(entityStoredWithCompressionType, memoryStream);
var entityData = memoryStream.ToArray();
var entityDataLength = entityData.LongLength;
entityCacheItem.EntityData = entityData;
entityCacheItem.ContentLength = entityDataLength;
entityCacheItem.CompressionType = entityStoredWithCompressionType;
}
}
//Put fileHandlerCacheItem into cache with 30 min sliding expiration, also if file changes then remove fileHandlerCacheItem from cache
CacheManager.Insert(
cacheKey,
entityCacheItem,
null,
Cache.NoAbsoluteExpiration,
MimeSetting.MemorySlidingExpiration,
CacheItemPriority.BelowNormal,
null);
}
return(true);
}
