private void PreemptiveCache(String category, String searchString, int page, int perPage, int catID)
{
// Try to cache next page
// TODO: If cacher is already in progress when page is requested, wait for completion
Debug.WriteLine("Async cache started " + DateTime.Now.ToLongTimeString());
ResponseContainer cacheThese = AmazonData.AWSQuery(searchString, category, page + 1, perPage);
if (cacheThese.error == null)
{
MemoryCache.Cache(cacheThese, page + 1, perPage, searchString, catID);
}
Debug.WriteLine("Async cache completed " + DateTime.Now.ToLongTimeString());
}
/// <summary>
/// Controller action for product query
/// </summary>
/// <returns>Query results as json.</returns>
/// <param name="catID">Category ID</param>
/// <param name="searchString">Search Keywords</param>
/// <param name="page">Starting page of query</param>
/// <param name="perPage">Items per page</param>
public String Json(int catID, String searchString, int page = 1, int perPage = 10)
{
// Sanitize user inputs
String category = ProductCategories.ResolveCategory(catID);
page = Math.Max(1, page);
page = Math.Min(10, page);
perPage = Math.Max(1, perPage);
perPage = Math.Min(70, perPage);
searchString = Regex.Replace(searchString, "[^a-z A-Z|0-9]", "");
// Check if is cached
ResponseContainer products = MemoryCache.Acquire(page, perPage, searchString, catID);
if (products == null)
{
products = AmazonData.AWSQuery(searchString, category, page, perPage);
// Try to cache current page
if (products.error == null)
{
MemoryCache.Cache(products, page, perPage, searchString, catID);
}
}
else
{
Debug.WriteLine("Retrieved page {0} from cache", page);
}
// Start new async thread to cache next page
Action <String, String, int, int, int> cacheDelegate = PreemptiveCache;
cacheDelegate.BeginInvoke(category, searchString, page, perPage, catID, cacheDelegate.EndInvoke, null);
// Return response
JavaScriptSerializer jsSerializer = new JavaScriptSerializer();
Response.AddHeader("Content-Type", "text/plain");
Debug.WriteLine("query returned.");
return(jsSerializer.Serialize(products));
}