Cache Manager design problem

Steve Holdorf

I have some basic code for a cache manager provided below. My design is far from complete and I need help. What I need is a single cache manager CacheManager.cs GetCacheItem method that accepts as parameters a cache key, business object delegate method and a variable set of parameters. This manager should be able to get and retrieve items in cache, handle dependencies, and work with every business manager object in the project (i.e. bc_CustomerManager.GetCustomer, bc_ProductManager.GetProduct, etc.) Anyone who can assist me or work with me on this would be wonderful. Cache Manager GetCacheItem:

    public object GetCacheItem(String sCacheKey, QueryExpression QueryExpression, params object\[\] parameters)
    {
        object objCacheItem = null;

        if (!CachingEnabled)
        {
            return objCacheItem;
        }

        if (CacheItem<Object>(sCacheKey) != null)
        {
            return CacheItem<Object>(sCacheKey);
        }
        else
        {
            lock (syncObject)
            {
                if (CacheItem<Object>(sCacheKey) != null)
                {
                    return CacheItem<Object>(sCacheKey);
                }
                else
                {
                    Object cacheItem = QueryExpression(parameters);

                    AddToCache<Object>(sCacheKey, cacheItem);

                    return cacheItem;
                }
            }
        }
    }

In my project I have a business layer and a data layer. I am not sure where and how the code below should be called. Incomplete code call to CacheManager.GetCacheItem:

    // Main delegate on which all Get requests are based on.
    delegate object QueryExpression(params object\[\] parameters);

    // Create instance of cacheManager
    CacheManager cacheManager = new CacheManager();

    // Create instance of BC\_Assects
    BC\_Assects bc\_Assects = new BC\_Assects();
    
    // Make the generic get cache item call GetAssetsByCollectionID must be declared as a QueryExpression delegate
    DataTable dt = (DataTable) cacheManager.GetCacheItem(sCacheKey, bc\_Assects.GetAssetsByCollectionID, parameters);

Thank you very much!

Steve

Steve Holdorf

I got something working. Here is a sample cache manager and aspx page. Now, all I need is to handle dependicies. Can anyone help?

aspx code:

protected void Page\_Load(object sender, EventArgs e)
{
    // Create instance of cacheManager
    CacheManager cacheManager = new CacheManager();

    // Create instance of BC\_Customer
    BC\_Customer bc\_Customer = new BC\_Customer();

    string\[\] param1 = { "customers", "stephen", "lisa" };

    // Must be declared as InsertExpression degelate
    cacheManager.InsertInCache(bc\_Customer.InsertCustomerName, param1);

    // Make the generic get cache item call must be declared as a QueryExpression delegate
    List<string> cNameList = (List<string>)cacheManager.GetCacheItem(bc\_Customer.GetCustomerName, param1);

    DropDownList1.DataSource = cNameList;
    DropDownList1.DataBind();

    string\[\] param2 = { "products", "Book", "Card" };

    // Create instance of BC\_Products
    BC\_Products bc\_Products = new BC\_Products();

    // Must be declared as InsertExpression degelate
    cacheManager.InsertInCache(bc\_Products.InsertProductName, param2);


    // Make the generic get cache item call must be declared as a QueryExpression delegate
    List<string> pNameList = (List<string>)cacheManager.GetCacheItem(bc\_Products.GetProductName, param2);

    DropDownList2.DataSource = pNameList;
    DropDownList2.DataBind();

}

Cache manager:

// Main delegate on which all Get requests are based on.
public delegate object QueryExpression(params object[] parameters);

// Main delegate on which all insert requests are based on.
public delegate object InsertExpression(params object[] parameters);

/// <summary>
/// Summary description for CacheManager
/// </summary>
public class CacheManager
{

public TimeSpan CacheDuration { get; set; }
private static object syncObject = new object();
private bool CachingEnabled = true;

private bool HasKey(string Key)
{            
    return (HttpContext.Current.Cache\[Key\] != null);
}

private Object CacheItem(string sCacheKey)
{
    return (Object)HttpRuntime.Cache\[sCacheKey\];
}

public object GetCacheItem(QueryExpression QueryExpression, params object\[\] param)
{
    object objCacheItem = null;

    if (!CachingEnabled)
    {
        return objCacheItem;
    }

    if

Steve Holdorf

Now, the cache manager handles dependencies. See below:

// Main delegate on which all Get requests are based on.
public delegate object QueryExpression(params object[] parameters);

// Main delegate on which all insert requests are based on.
public delegate object InsertExpression(params object[] parameters);

/// <summary>
/// Summary description for CacheManager
/// </summary>
public class CacheManager
{

public TimeSpan CacheDuration { get; set; }
private static object syncObject = new object();
private bool CachingEnabled = true;

private bool HasKey(string Key)
{            
    return ((Object)HttpRuntime.Cache\[Key\] != null);
}

private Object CacheItem(string sCacheKey)
{
    return (Object)HttpRuntime.Cache\[sCacheKey\];
}

public object GetCacheItem(QueryExpression QueryExpression, params object\[\] param)
{
    object objCacheItem = null;

    if (!CachingEnabled)
    {
        return objCacheItem;
    }

    if (CacheItem((string) param\[0\]) != null)
    {
        return CacheItem((string) param\[0\]);
    }
    else
    {
        lock (syncObject)
        {
            if (CacheItem((string)param\[0\]) != null)
            {
                return CacheItem((string) param\[0\]);
            }
            else
            {
                Object cacheItem = QueryExpression(param);

                DateTime expiration = DateTime.Now.Add(new TimeSpan (6000));

                HttpContext.Current.Cache.Add((string) param\[0\], (List<string>) cacheItem, null, expiration,
                    TimeSpan.Zero, System.Web.Caching.CacheItemPriority.Default, null);

                return cacheItem;
            }
        }
    }
}

public Object InsertInCache(InsertExpression insertExpression, params object\[\] param)
{
    System.Web.Caching.CacheDependency cacheDependency;

    string\[\] dependencyKey = { (string) param\[1\] };

    if (HasKey((string) param\[0\]))
    {
        return CacheItem((string)(param\[0\]));
    }

    DateTime expiration = DateTime.Now.Add(new TimeSpan (6000));

    cacheDependency = new System.Web.Caching.CacheDependency(null, dependencyKey);

    HttpContext.Current.Cache.Add((string) param\[0\], insertExpression(param), 
        (param\[1\] == "" ? null : (cacheDependency)), expiration,