LocalCache Class |
14c (14.1.1.0)
F23534-02
A local in-memory cache implementation.
Inheritance HierarchyNamespace: Tangosol.Net.Cache
Assembly: Coherence (in Coherence.dll) Version: 14.1.1.14 (14.1.1.14)
SyntaxC#
public class LocalCache : SynchronizedDictionary, IConfigurableCache, IObservableCache, IConcurrentCache, IQueryCache, IInvocableCache, ICache, IDictionary, ICollection, IEnumerable
The LocalCache type exposes the following members.
Constructors| Name | Description | |
|---|---|---|
 | LocalCache |
Construct the cache manager.
|
| LocalCache(Int32) |
Construct the cache manager.
|
| LocalCache(Int32, Int32) |
Construct the cache manager.
|
| LocalCache(Int32, Int32, Double) |
Construct the cache manager.
|
| LocalCache(Int32, Int32, ICacheLoader) |
Construct the cache manager.
|
Properties| Name | Description | |
|---|---|---|
 | CacheHits |
Gets the rough number of cache hits since the cache statistics
were last reset.
|
| CacheLoader |
Gets or sets the loader used by this LocalCache.
|
| CacheMisses |
Gets the rough number of cache misses since the cache statistics
were last reset.
|
| CacheStatistics |
Gets the ICacheStatistics for this cache.
|
 | CacheStore |
Determine the store used by this LocalCache, if any.
|
| CalculatorType |
Gets or sets the current unit calculator type for the cache.
|
| Count |
Gets the number of elements contained in the
ICache.
(Overrides SynchronizedDictionaryCount.) |
| CurrentKeyMask |
Gets or sets the current key mask for the current thread.
|
| Delegate |
Return the delegate IDictionary.
(Inherited from SynchronizedDictionary.) |
| Entries |
Get a collection of ICacheEntry instances
within the cache.
|
| EvictionPolicy |
Determine the current external eviction policy, if any.
|
| EvictionType |
Gets or sets the current eviction type.
|
| ExpiryDelay |
Gets or sets the "time to live" for each individual cache entry.
|
| FlushDelay |
Gets or sets the delay between cache flushes.
|
| FlushTime |
Gets or sets the date/time offset in milliseconds at which the
next cache flush is scheduled.
|
| HighUnits |
Gets or sets the limit of the cache size in units.
|
| HitProbability |
Gets the rough probability (0 <= p <= 1) that any
particular "get" invocation will be satisfied by an existing
entry in the cache, based on the statistics collected since the
last reset of the cache statistics.
|
| IndexMap |
The index IDictionary used by this LocalCache.
|
| IsFixedSize |
Get a value indicating whether this dictionary has a fixed size.
(Inherited from SynchronizedDictionary.) |
| IsReadLockHeld |
Determines whether or not the current thread holds a read lock.
(Inherited from SynchronizedDictionary.) |
| IsReadOnly |
Get a value indicating whether this dictionary is read-only.
(Inherited from SynchronizedDictionary.) |
| IsSynchronized |
Gets a value indicating whether access to this dictionary
is thread-safe.
(Inherited from SynchronizedDictionary.) |
| IsWriteLockHeld |
Determines whether or not the current thread holds the write lock.
(Inherited from SynchronizedDictionary.) |
| Item |
Gets or sets the element with the specified key.
(Overrides SynchronizedDictionaryItemObject.) |
| Keys |
Get the keys collection.
(Overrides SynchronizedDictionaryKeys.) |
| LowUnits |
Gets or sets the point to which the cache will shrink when it
prunes.
|
| PruneLevel |
The percentage of the total number of units that will remain
after the cache manager prunes the cache.
|
| Storage |
Get underlying cache storage.
|
| SyncRoot |
Get an object that can be used to synchronize access to this
dictionary.
(Inherited from SynchronizedDictionary.) |
| UnitCalculator |
Gets or sets the current external unit calculator, if any.
|
| Units |
Gets the number of units that the cache currently stores.
|
| Values |
Get the values collection.
(Overrides SynchronizedDictionaryValues.) |
Methods| Name | Description | |
|---|---|---|
| AcquireReadLock |
Acquire a read lock.
(Inherited from SynchronizedDictionary.) |
| AcquireReadLock(Int32) |
Acquire a read lock.
(Inherited from SynchronizedDictionary.) |
| AcquireWriteLock |
Acquire a write lock.
(Inherited from SynchronizedDictionary.) |
| AcquireWriteLock(Int32) |
Acquire a write lock.
(Inherited from SynchronizedDictionary.) |
| Add |
Adds an element with the provided key and value to the cache.
(Overrides SynchronizedDictionaryAdd(Object, Object).) |
| AddCacheListener(ICacheListener) |
Add a standard cache listener that will receive all events
(inserts, updates, deletes) that occur against the cache, with
the key, old-value and new-value included.
|
| AddCacheListener(ICacheListener, Object, Boolean) |
Add a cache listener for a specific key.
|
| AddCacheListener(ICacheListener, IFilter, Boolean) |
Add a cache listener that receives events based on a filter
evaluation.
|
| AddIndex |
Add an index to this IQueryCache.
|
 | AddInternal |
Add new cache entry and raise Inserted event if necessary.
|
| AdjustUnits |
Adjust current size.
|
| Aggregate(ICollection, IEntryAggregator) |
Perform an aggregating operation against the entries specified by
the passed keys.
|
| Aggregate(IFilter, IEntryAggregator) |
Perform an aggregating operation against the collection of
entries that are selected by the given IFilter.
|
| CheckFlush |
Flush the cache if it needs to be flushed.
|
| CheckSize |
Check if the cache is too big, and if it is prune it by
discarding the lowest priority cache entries.
|
| Clear |
Removes all elements from the ICache object.
(Overrides SynchronizedDictionaryClear.) |
| ClearInternal |
Utility method to support clear and truncation operations.
|
| ConfigureEviction |
Configure the eviction type and policy.
|
| ConfigureUnitCalculator |
Configure the unit calculator type and implementation.
|
| Contains |
Determines whether the object contains an element with the
specified key.
(Overrides SynchronizedDictionaryContains(Object).) |
| ContainsKey |
Determines whether the IDictionary object contains an
element with the specified key.
|
| ContainsValue |
Determines whether the IDictionary object contains an
element with the specified value.
|
| CopyTo |
Copies the elements of the IDictionary to an Array,
starting at a particular index.
(Overrides SynchronizedDictionaryCopyTo(Array, Int32).) |
| CreateEntry |
Creates an ICacheEntry.
|
| DispatchEvent |
Dispatch the passed event.
|
| EnsureEntry |
Create a LocalCacheEntry object for the specified key.
|
| EnsureEntryCollection |
Create an array of LocalCacheEntry objects for the specified
ICache and the keys collection.
|
| EnsureIndexMap |
Obtain the IDictionary of indexes maintained by this cache.
|
| Equals | Determines whether the specified object is equal to the current object. (Inherited from Object.) |
| Evict |
Evict all entries from the cache that are no longer valid, and
potentially prune the cache size if the cache is size-limited
and its size is above the caching low water mark.
|
| Evict(Object) |
Evict a specified key from the cache, as if it had expired from
the cache.
|
| EvictAll |
Evict the specified keys from the cache, as if they had each
expired from the cache.
|
| 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.
|
| GetCacheEntry |
Locate a cache entry in the cache based on its key.
|
| GetEntries(IFilter) |
Return a collection of the entries contained in this cache
that satisfy the criteria expressed by the filter.
|
| GetEntries(IFilter, IComparer) |
Return a collection of the entries contained in this cache
that satisfy the criteria expressed by the filter.
|
| GetEntry |
Locate an LocalCacheEntry in the cache based on its key.
|
| GetEntryInternal |
Locate an LocalCacheEntry in the cache based on its key.
|
| GetEnumerator |
Returns an ICacheEnumerator object for the
ICache instance.
|
| GetHashCode | Serves as the default hash function. (Inherited from Object.) |
| GetKeys |
Return a collection of the keys contained in this cache for
entries that satisfy the criteria expressed by the filter.
|
| GetObjectData |
Populates SerializationInfo with the data needed to serialize this
object.
(Inherited from SynchronizedDictionary.) |
| GetType | Gets the Type of the current instance. (Inherited from Object.) |
| GetValues(IFilter) |
Return a collection of the values contained in this cache for
entries that satisfy the criteria expressed by the filter.
|
| GetValues(IFilter, IComparer) |
Return a collection of the values contained in this cache for
entries that satisfy the criteria expressed by the filter.
|
| HasListeners |
Determine if the LocalCache has any listeners at all.
|
| 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).
|
| InstantiateCacheEnumerator |
Factory method for cache enumerator.
|
| InstantiateCacheEvent |
Factory pattern: instantiate a new CacheEventArgs
corresponding to the specified parameters.
|
| InstantiateEntriesCollection |
Factory method that creates virtual collection of cache entries.
|
| InstantiateInternalListener |
Factory pattern: Instantiate an internal
ICacheListener to listen to this cache and report
changes to the ICacheStore.
|
| InstantiateKeysCollection |
Factory method that creates virtual collection of cache keys.
|
| InstantiateValuesCollection |
Factory method that creates virtual collection of cache values.
|
| Invoke |
Invoke the passed IEntryProcessor against the entry
specified by the passed key, returning the result of the
invocation.
|
| InvokeAll(ICollection, IEntryProcessor) |
Invoke the passed IEntryProcessor against the
entries specified by the passed keys, returning the result of the
invocation for each.
|
| InvokeAll(IFilter, IEntryProcessor) |
Invoke the passed IEntryProcessor against the set
of entries that are selected by the given IFilter,
returning the result of the invocation for each.
|
| IsFlushRequired |
Check if the cache needs to be flushed.
|
| Load |
Indicates to the cache that the specified key should be loaded
into the cache, if it is not already in the cache.
|
| LoadAll |
Indicates to the cache that it should load data from its loader
to fill the cache; this is sometimes referred to as
"pre-loading" or "warming" a cache.
|
| LoadAll(ICollection) |
Indicates to the cache that the specified keys should be loaded
into the cache, if they are not already in the cache.
|
| Lock(Object) |
Attempt to lock the specified item and return immediately.
|
| Lock(Object, Int64) |
Attempt to lock the specified item within the specified period of
time.
|
| MemberwiseClone | Creates a shallow copy of the current Object. (Inherited from Object.) |
| Peek |
Checks for a valid entry corresponding to the specified key in
the cache, and returns the corresponding value if it is.
|
| PeekAll |
Checks for a valid entry corresponding to each specified key in
the cache, and places the corresponding value in the returned
dictionary if it is.
|
| PeekEntryInternal |
Locate an LocalCacheEntry in the cache based on its key.
|
| Prune |
Prune the cache by discarding the lowest priority cache entries.
|
| ReleaseReadLock |
Release a read lock.
(Inherited from SynchronizedDictionary.) |
| ReleaseWriteLock |
Release a write lock.
(Inherited from SynchronizedDictionary.) |
| Remove |
Removes the element with the specified key from the
ICache object.
(Overrides SynchronizedDictionaryRemove(Object).) |
| RemoveCacheListener(ICacheListener) |
Remove a standard cache listener that previously signed up for
all events.
|
| RemoveCacheListener(ICacheListener, Object) |
Remove a cache listener that previously signed up for events
about a specific key.
|
| RemoveCacheListener(ICacheListener, IFilter) |
Remove a cache listener that previously signed up for events
based on a filter evaluation.
|
| RemoveExpired |
Remove an entry because it has expired.
|
| RemoveIndex |
Remove an index from this IQueryCache.
|
| RemoveInternal |
Remove an entry.
|
| ResetHitStatistics |
Reset the cache statistics.
|
| ScheduleFlush |
Schedule the next flush.
|
| ToString |
Returns a string representation of this LocalCache object.
(Overrides ObjectToString.) |
| Truncate |
Removes all mappings from this map.
|
| Unlock |
Unlock the specified item.
|
Fields| Name | Description | |
|---|---|---|
  | DEFAULT_EXPIRE |
By default, the cache entries never expire.
|
| DEFAULT_FLUSH |
By default, expired cache entries are flushed on a minute
interval.
|
 | DEFAULT_KEY_MASK |
The default key mask that ignores nothing.
|
| DEFAULT_PRUNE |
By default, when the cache prunes, it reduces its entries by 25%,
meaning it retains 75% (.75) of its entries.
|
| DEFAULT_UNITS |
By default, the cache size (in units) is infinite.
|
| m_avgTouch |
For a prune cycle, this value is the average number of touches
that an entry should have. This value is used by the hybrid
eviction policy.
|
| m_dict |
Wrapped, non-thread safe dictionary.
(Inherited from SynchronizedDictionary.) |
| m_lastPrune |
The last time that a prune was run. This value is used by the
hybrid eviction policy.
|
Extension Methods| Name | Description | |
|---|---|---|
 | GetOrDefault |
Returns the value to which the specified key is mapped, or
the defaultValue if this cache contains no mapping for the key.
(Defined by InvocableCacheEx.) |
| InsertIfAbsent |
If the specified key is not already associated with a value
(or is mapped to null) associates it with the given value and
returns null, else returns the current value.
(Defined by InvocableCacheEx.) |
| Remove |
Removes the entry for the specified key only if it is currently
mapped to the specified value.
(Defined by InvocableCacheEx.) |
| Replace(Object, Object) | Overloaded.
Replaces the entry for the specified key only if it is
currently mapped to some value.
(Defined by InvocableCacheEx.) |
| Replace(Object, Object, Object) | Overloaded.
Replaces the entry for the specified key only if currently
mapped to the specified value.
(Defined by InvocableCacheEx.) |
RemarksThe implementation is thread safe and uses a combination of Most Recently Used (MRU) and Most Frequently Used (MFU) caching strategies.
The cache is size-limited, which means that once it reaches its maximum size ("high-water mark") it prunes itself (to its "low-water mark"). The cache high- and low-water-marks are measured in terms of "units", and each cached item by default uses one unit. All of the cache constructors, except for the default constructor, require the maximum number of units to be passed in. To change the number of units that each cache entry uses, either set the Units property of the cache entry, or extend the ICache implementation so that the inner LocalCacheEntry class calculates its own unit size. To determine the current, high-water and low-water sizes of the cache, use the cache object's Units, HighUnits and LowUnits properties. The HighUnits and LowUnits properties can be changed, even after the cache is in use. To specify the LowUnits value as a percentage when constructing the cache, use the extended constructor taking the percentage-prune-level.
Each cached entry never expires by default. To alter this behavior, use a constructor that takes the expiry-millis; for example, an expiry-millis value of 10000 will expire entries after 10 seconds. The ExpiryDelay property can also be set once the cache is in use, but it will not affect the expiry of previously cached items.
The cache can optionally be flushed on a periodic basis by setting the FlushDelay property or scheduling a specific flush time by setting the FlushTime property.
Cache hit statistics can be obtained from the CacheHits, CacheMisses and HitProbability read-only properties. The statistics can be reset by invoking ResetHitStatistics. The statistics are automatically reset when the cache is cleared (the Clear method).
The LocalCache implements the IObservableCache interface, meaning it provides event notifications to any interested listener for each insert, update and delete, including those that occur when the cache is pruned or entries are automatically expired.
This implementation is designed to support extension through inheritence. To override the one-unit-per-entry default behavior, extend the inner Entry class and override the CalculateUnits(Object) method.
See Also