internal async Task <bool> TryServeCachedResponseAsync(ResponseCachingContext context, IResponseCacheEntry cacheEntry)
{
var cachedResponse = cacheEntry as CachedResponse;
if (cachedResponse == null)
{
return(false);
}
context.CachedResponse = cachedResponse;
context.CachedResponseHeaders = cachedResponse.Headers;
context.ResponseTime = _options.SystemClock.UtcNow;
var cachedEntryAge = context.ResponseTime.Value - context.CachedResponse.Created;
context.CachedEntryAge = cachedEntryAge > TimeSpan.Zero ? cachedEntryAge : TimeSpan.Zero;
if (_policyProvider.IsCachedEntryFresh(context))
{
// Check conditional request rules
if (ContentIsNotModified(context))
{
_logger.LogNotModifiedServed();
context.HttpContext.Response.StatusCode = StatusCodes.Status304NotModified;
}
else
{
var response = context.HttpContext.Response;
// Copy the cached status code and response headers
response.StatusCode = context.CachedResponse.StatusCode;
foreach (var header in context.CachedResponse.Headers)
{
response.Headers[header.Key] = header.Value;
}
// Note: int64 division truncates result and errors may be up to 1 second. This reduction in
// accuracy of age calculation is considered appropriate since it is small compared to clock
// skews and the "Age" header is an estimate of the real age of cached content.
response.Headers[HeaderNames.Age] = HeaderUtilities.FormatNonNegativeInt64(context.CachedEntryAge.Value.Ticks / TimeSpan.TicksPerSecond);
// Copy the cached response body
var body = context.CachedResponse.Body;
if (body.Length > 0)
{
try
{
await body.CopyToAsync(response.Body, StreamUtilities.BodySegmentSize, context.HttpContext.RequestAborted);
}
catch (OperationCanceledException)
{
context.HttpContext.Abort();
}
}
_logger.LogCachedResponseServed();
}
return(true);
}
return(false);
}
