CompositeCache Class |
14c (14.1.1.0)
F23534-02
ICache implementation that wraps two caches - a
front cache (assumed to be "inexpensive" and probably
"incomplete") and a back cache (assumed to be "complete" and
"correct", but more "expensive") - using a read-through/write-through
approach.
Inheritance HierarchyNamespace: Tangosol.Net.Cache
Assembly: Coherence (in Coherence.dll) Version: 14.1.1.14 (14.1.1.14)
SyntaxC#
public class CompositeCache : ICache, IDictionary, ICollection, IEnumerable, ICacheStatistics, IDisposable
The CompositeCache type exposes the following members.
Constructors| Name | Description | |
|---|---|---|
 | CompositeCache(ICache, ICache) |
Construct a CompositeCache using two specified
caches:
|
| CompositeCache(ICache, ICache, CompositeCacheStrategyType) |
Construct a CompositeCache using two specified
caches:
|
Properties| Name | Description | |
|---|---|---|
 | AverageGetMillis |
Determine the average number of milliseconds per "get"
invocation since the cache statistics were last reset.
|
| AverageHitMillis |
Determine the average number of milliseconds per "get"
invocation that is a hit.
|
| AverageMissMillis |
Determine the average number of milliseconds per "get" invocation
that is a miss.
|
| AveragePruneMillis |
Determine the average number of milliseconds per cache pruning.
|
| AveragePutMillis |
Determine the average number of milliseconds per "put"
invocation since the cache statistics were last reset.
|
| BackCache |
Obtain the back cache reference.
|
| CacheControl |
Obtain the IConcurrentCache that should be used to
synchronize the front cache modification access.
|
| CacheHits |
Determine the rough number of cache hits since the cache
statistics were last reset.
|
| CacheHitsMillis |
Determine the total number of milliseconds (since that last
statistics reset) for the "get" operations for which an entry
existed in this cache.
|
| CacheMisses |
Determine the rough number of cache misses since the cache
statistics were last reset.
|
| CacheMissesMillis |
Determine the total number of milliseconds (since that last
statistics reset) for the "get" operations for which no entry
existed in this map.
|
| CachePrunes |
Determine the rough number of cache pruning cycles since the
cache statistics were last reset.
|
| CachePrunesMillis |
Determine the total number of milliseconds (since that last
statistics reset) spent on cache pruning.
|
| CacheStatistics |
Obtain the CacheStatistics for this cache.
|
| Count |
Gets the number of elements contained in the
BackCache.
|
| Entries |
Gets a collection of ICacheEntry instances
within the cache.
|
| FrontCache |
Obtain the front cache reference.
|
| HitProbability |
Determine the rough probability (0 <= p <= 1) that the next
invocation will be a hit, based on the statistics collected since
the last reset of the cache statistics.
|
| InvalidationHits |
Determine the rough number of front cache invalidation hits
since the cache statistics were last reset.
|
| InvalidationMisses |
Determine the rough number of front cache invalidation
misses since the cache statistics were last reset.
|
| InvalidationStrategy |
Obtain the invalidation strategy used by this
CompositeCache.
|
 | IsCoherent |
Determine if changes to the back cache affect the front cache so
that data in the front cache stays in sync.
|
| IsFixedSize |
Gets a value indicating whether the BackCache
object has a fixed size.
|
| IsReadOnly |
Gets a value indicating whether the BackCache
object is read-only.
|
| IsSynchronized |
Gets a value indicating whether access to the back cache is
synchronized (thread safe).
|
| Item |
Gets or sets the element with the specified key.
|
| Keys |
Obtain an ICollection of the keys contained in this cache.
|
| SyncRoot |
Gets an object that can be used to synchronize access to the back
cache.
|
| TotalGets |
Determine the total number of "get" operations since the cache
statistics were last reset.
|
| TotalGetsMillis |
Determine the total number of milliseconds spent on "get"
operations since the cache statistics were last reset.
|
| TotalPuts |
Determine the total number of "put" operations since the cache
statistics were last reset.
|
| TotalPutsMillis |
Determine the total number of milliseconds spent on "put"
operations since the cache statistics were last reset.
|
| TotalRegisterListener |
Determine the total number of
RegisterListener(Object) operations since the cache
statistics were last reset.
|
| Values |
Obtain an ICollection of the values contained in this
cache.
|
Methods| Name | Description | |
|---|---|---|
| Add |
Associates the specified value with the specified key in this
cache.
|
| Clear |
Clears both the front and back caches.
|
| Contains |
Check whether or not this cache contains a mapping for the
specified key.
|
| CopyTo |
Copies the elements of the BackCache to an
Array, starting at a particular Array index.
|
| Dispose |
Calls Release to release the resources associated with this cache.
|
 | EnsureInvalidationStrategy |
Ensure that a strategy has been choosen and that any appropriate
global listeners have been registered.
|
| Equals |
Compares the specified object with this dictionary for equality.
(Overrides ObjectEquals(Object).) |
| Finalize | Allows an object to try to free resources and perform other cleanup operations before it is reclaimed by garbage collection. (Inherited from Object.) |
| GetAll |
Get the values for all the specified keys, if they are in the
cache.
|
| GetEnumerator |
Returns an enumerator that iterates through a cache.
|
| GetHashCode |
Return the hash code value for this dictionary.
(Overrides ObjectGetHashCode.) |
| GetType | Gets the Type of the current instance. (Inherited from Object.) |
| Insert(Object, Object) |
Associates the specified value with the specified key in this
cache.
|
| Insert(Object, Object, Int64) |
Associates the specified value with the specified key in this
cache.
|
| InsertAll |
Copies all of the mappings from the specified dictionary to this
cache (optional operation).
|
| InstantiateBackCacheListener |
Factory pattern: instantiate back cache listener.
|
| InstantiateFrontCacheListener |
Factory pattern: instantiate front cache listener.
|
| InvalidateFront |
Invalidate the key from the front.
|
 | IsPriming |
Check if the specified event is a "priming" one.
|
| MemberwiseClone | Creates a shallow copy of the current Object. (Inherited from Object.) |
| RegisterDeactivationListener |
Instantiate and register a DeactivationListener with the back cache.
|
| RegisterFrontListener |
Register the global front cache listener.
|
| RegisterListener |
Register the global back cache listener.
|
| RegisterListener(Object) |
Register the back cache listener for the specified key.
|
| RegisterListeners |
Register the back map listeners for the specified set of keys.
|
| Release |
Release the CompositeCache.
|
| Remove |
Remove the mapping for this key from this cache if present.
|
| RemoveKeyHolder |
Remove the key holder from the ThreadLocal object.
|
| ResetFrontMap |
Reset the front map.
|
| ResetHitStatistics |
Reset the cache statistics.
|
| ResetInvalidationStrategy |
Reset the "current invalidation strategy" flag.
|
| SetKeyHolder |
Set up a thread local Set to hold all the keys that might be evicted
from the front cache.
|
| ToString |
For debugging purposes, format the contents of the
CompositeCache in a human readable format.
(Overrides ObjectToString.) |
| TryLock |
Lock the keys in the given set without blocking.
|
| UnregisterDeactivationListener |
Unregister back cache deactivation listener.
|
| UnregisterFrontListener |
Unregister the global front cache listener.
|
| UnregisterListener |
Unregister the global back cache listener.
|
| UnregisterListener(Object) |
Unregister the back cache listener for the specified key.
|
| UnregisterListeners |
Unregister the back cache listener for the specified keys.
Note: all the keys in the passed-in set must be locked and will be unlocked. |
| Validate |
Validate the front cache entry for the specified back cache
event.
|
Fields| Name | Description | |
|---|---|---|
 | m_strategyCurrent |
The current invalidation strategy, which at times could be
different from the target strategy.
|
| m_strategyTarget |
The invalidation strategy that this cache is to use.
|
| s_tloKeys |
The ThreadLocal to hold all the keys that are evicted while the front cache
is updated during get or getAll operation.
|
RemarksIf the back cache implements IObservableCache interface, the CompositeCache provides four different strategies of invalidating the front cache entries that have changed by other processes in the back cache:
- ListenNone strategy instructs the cache not to listen for invalidation events at all. This is the best choice for raw performance and scalability when business requirements permit the use of data which might not be absolutely current. Freshness of data can be guaranteed by use of a sufficiently brief eviction policy for the front cache.
- ListenPresent strategy instructs the CompositeCache to listen to the back cache events related only to the items currently present in the front cache. This strategy works best when each instance of a front cache contains distinct subset of data relative to the other front cache instances (e.g. sticky data access patterns).
- ListenAll strategy instructs the CompositeCache to listen to all back cache events. This strategy is optimal for read-heavy tiered access patterns where there is significant overlap between the different instances of front caches.
- ListenAuto strategy instructs the CompositeCache implementation to switch automatically between ListenPresent and ListenAll strategies based on the cache statistics.
- ListenLogical strategy instructs the CompositeCache to listen to all back map events that are not synthetic. A synthetic event could be emitted as a result of eviction or expiration. With this invalidation stategy, it is possible for the front map to contain cache entries that have been synthetically removed from the back (though any subsequent re-insertion will cause the corresponding entries in the front map to be invalidated).
The front cache implementation is assumed to be thread safe; additionally any modifications to the front cache are allowed only after the corresponding lock is acquired against the CacheControl property.
Note:null values are not cached in the front cache and therefore this implementation is not optimized for caches that allow null values to be stored.
See Also