/// <summary>
/// Invokes the logic of the middleware.
/// </summary>
/// <param name="httpContext">The <see cref="HttpContext"/>.</param>
/// <returns>A <see cref="Task"/> that completes when the middleware has completed processing.</returns>
public async Task Invoke(HttpContext httpContext)
{
var context = new ResponseCachingContext(httpContext, _logger);
// Should we attempt any caching logic?
if (_policyProvider.AttemptResponseCaching(context))
{
// Can this request be served from cache?
if (_policyProvider.AllowCacheLookup(context) && await TryServeFromCacheAsync(context))
{
return;
}
// Should we store the response to this request?
if (_policyProvider.AllowCacheStorage(context))
{
// Hook up to listen to the response stream
ShimResponseStream(context);
try
{
await _next(httpContext);
// If there was no response body, check the response headers now. We can cache things like redirects.
StartResponse(context);
// Finalize the cache entry
FinalizeCacheBody(context);
}
finally
{
UnshimResponseStream(context);
}
return;
}
}
// Response should not be captured but add IResponseCachingFeature which may be required when the response is generated
AddResponseCachingFeature(httpContext);
try
{
await _next(httpContext);
}
finally
{
RemoveResponseCachingFeature(httpContext);
}
}
