/// <summary>
/// This will make the browser and server keep the output
/// in its cache and thereby improve performance.
/// See http://en.wikipedia.org/wiki/HTTP_ETag
/// </summary>
/// <param name="path">
/// The combined path to the items.
/// </param>
/// <param name="context">
/// the <see cref="T:System.Web.HttpContext">HttpContext</see> object that provides
/// references to the intrinsic server objects
/// </param>
/// <param name="responseType">
/// The HTTP MIME type to to send.
/// </param>
/// <param name="futureExpire">
/// Whether the response headers should be set to expire in the future.
/// </param>
/// <param name="fileMonitors">
/// The file Monitors.
/// </param>
protected void SetHeaders(string path, HttpContext context, ResponseType responseType, bool futureExpire, IList <string> fileMonitors)
{
// Generate a hash from the combined last write times of any monitors and
// the path.
StringBuilder stringBuilder = new StringBuilder();
stringBuilder.Append(path);
if (fileMonitors != null)
{
foreach (string fileMonitor in fileMonitors)
{
FileInfo fileInfo = new FileInfo(fileMonitor);
stringBuilder.AppendFormat("{0}", fileInfo.LastWriteTimeUtc);
}
}
int hash = stringBuilder.ToString().GetHashCode();
HttpResponse response = context.Response;
HttpCachePolicy cache = response.Cache;
response.ContentType = responseType.ToDescription();
cache.VaryByHeaders["Accept-Encoding"] = true;
if (futureExpire)
{
int maxCacheDays = CruncherConfiguration.Instance.MaxCacheDays;
cache.SetExpires(DateTime.UtcNow.AddDays(maxCacheDays));
cache.SetMaxAge(new TimeSpan(maxCacheDays, 0, 0, 0));
if (fileMonitors != null)
{
response.AddFileDependencies(fileMonitors.ToArray());
cache.SetLastModifiedFromFileDependencies();
}
cache.SetValidUntilExpires(false);
}
else
{
cache.SetExpires(DateTime.UtcNow.AddDays(-1));
cache.SetMaxAge(new TimeSpan(0, 0, 0, 0));
}
cache.SetRevalidation(HttpCacheRevalidation.AllCaches);
string etag = string.Format(CultureInfo.InvariantCulture, "\"{0}\"", hash);
string incomingEtag = context.Request.Headers["If-None-Match"];
cache.SetETag(etag);
cache.SetCacheability(HttpCacheability.Public);
if (string.Compare(incomingEtag, etag, StringComparison.Ordinal) != 0)
{
return;
}
response.Clear();
response.StatusCode = (int)HttpStatusCode.NotModified;
response.SuppressContent = true;
}