Class CacheItem

NCache uses a "key" and "value" structure for storing objects in the cache. When an object is added in cache it is stored as value and metadata against the specified key. This combination of value and metadata is defined as CacheItem in NCache. The value of the objects stored in the cache can range from being simple string types to complex objects.

CacheItem class in NCache has properties that enable you to set metadata for the item to be added in the cache in an organized way. In scenarios where multiple attributes have to be set while adding an item in the cache, using CacheItem is preferred. Using CacheItem class object removes the problem of using multiple API overloads on adding/updating data in the cache. You can easily use the basic API overload and add/update data easily using CacheItem.

Inheritance
System.Object
CacheItem
Assembly: Alachisoft.NCache.Client.dll
Syntax
public class CacheItem : ICloneable
Examples

The following example shows how you can create an instance of CacheItem class and add it to the ICache

ICache cache = CacheManager.GetCache("demoCache");

Product product = new Product();
CacheItem item = new CacheItem(product);
item.Expiration = new Expiration(ExpirationType.Sliding, TimeSpan.FromMinutes(5));
item.Priority = CacheItemPriority.High;

cache.Add("productKey", item);

Constructors

Name Description
CacheItem(Object)

Initialize new instance of cache item.

Properties

Name Description
CreationTime

Specifies when the item was added in the cache for the first time.
Dependency

The file or cache key dependencies for the item. When any dependency changes, the object becomes invalid and is removed from the cache. If there are no dependencies, this property contains a null reference.
Expiration

This property sets Expiration for the cache item. After the specified timespan, the item expires from cache. If expiration is not set then it is disabled.

Group

Groups help you create a logical partition of your cached data for easy retrieval. Group information can be added with an item by setting the Group property of CacheItem. This reduces the complication of using API overloads for adding groups at the time of adding/updating item in the cache.
LastModifiedTime

This property of CacheItem stores the last modified time of the cache item. If an item is updated in cache its last modified time is updated as well. Last modified time is checked when Least Recently Used based eviction is triggered.

NamedTags

With Named Tags, the user is able to store additional information (of any type) required to query the object stored as string. Users are required to provide the list of named tags, each having two parameters, "key" (name of a tag) as string and "value" (assigned value) as any primitive type.

NCache then allows you to search your objects through these named tags. Named tags can be specified by using this property of CacheItem.

Priority

When the application's cache is full or runs low on memory, the cache selectively purges items to free system memory. When an item is added to the Cache, you can assign it a relative priority compared to the other items stored in the Cache using this property.

This eliminates the problem of using API overloads for setting the priority. Items that are assigned higher priority values are less likely to be deleted from the cache when the server is processing a large number of requests, while items assigned lower priority values are more likely to be deleted.

ResyncOptions

This property is used to define the ResyncOptions for the cache item.
SyncDependency

Synchronizes two separate caches so that an item updated or removed from one cache can have the same effect on the synchronized cache. For cache sync dependency, an item must exist in cache before another item can be added with a dependency on it. This property lets you set the cache sync dependency with a cache item.

Tags

Using Tags, you can associate keywords(s) with your cache items. You can mark your data with tags, which act as identifiers for your cache items. Using this property, you can easily set tags for a cache item.
Version

NCache uses cache item versioning. CacheItemVersion is a property associated with every cache item. It is basically a numeric value that is used to represent the version of the cached item which changes with every update to an item.

This property allows you to track, whether any change occurred in an item or not. When you fetch an item from cache, you also fetch its current version from the cache.

Methods

Name Description
Clone()

Creates a shallow copy of the cache item.
GetValue<T>()

Returns the value stored in the CacheItem.
SetCacheDataNotification(CacheDataNotificationCallback, EventType, EventDataFilter)

You can use this to notify applications when their objects are updated or removed in the cache. Callbacks can be registered against EventType for the key the items is inserted to. Callbacks are overridden for the same EventType, if called again.

CacheDataNotificationCallback defines the callback to be used for notifications. EventType describes the type of event you want to register. If that event is triggered, a notification will be received.

SetValue(Object)

Sets the value of the cache item.