Package com.tangosol.net.partition

Class ObservableSplittingBackingCache

java.lang.Object
com.tangosol.util.Base
com.tangosol.util.AbstractKeyBasedMap
com.tangosol.util.AbstractKeySetBasedMap
com.tangosol.util.WrapperObservableMap
com.tangosol.net.partition.ObservableSplittingBackingMap
com.tangosol.net.partition.ObservableSplittingBackingCache
All Implemented Interfaces:
Disposable, CacheMap, ConfigurableCacheMap, PartitionAwareBackingMap, ObservableMap, AutoCloseable, Map
public class ObservableSplittingBackingCache extends ObservableSplittingBackingMap implements ConfigurableCacheMap
The ObservableSplittingBackingCache is an implementation of the ConfigurableCacheMap interface that works as an observable backing map in a partitioned system. In other words, it acts like a LocalCache, but it internally partitions its data across any number of caches that implement the ConfigurableCacheMap interface. Note that the underlying backing maps must implement the ConfigurableCacheMap interface or a runtime exception will occur.
Author:
cp 2009.01.16

  • Field Details

    • MAX_PARTITION_MAP_UNIT_FACTOR

      protected static final int MAX_PARTITION_MAP_UNIT_FACTOR
      The maximum unit factor for partition maps.
      See Also:

    • m_cHighUnits

      protected int m_cHighUnits
      High units is the number of units that triggers eviction. The value -1 indicates that this cache has not been instructed to override the high units of the underlying caches.

    • m_cLowUnits

      protected int m_cLowUnits
      Low units is the number of units to evict down to. The value -1 indicates that this cache has not been instructed to override the low units of the underlying caches.

    • m_cHighUnitsCalibrated

      protected int m_cHighUnitsCalibrated
      The high units adjusted based on the partition unit factor.

    • m_cLowUnitsCalibrated

      protected int m_cLowUnitsCalibrated
      The low units adjusted based on the partition unit factor.

    • m_nUnitFactor

      protected int m_nUnitFactor
      The unit factor. The value -1 indicates that this cache has not been instructed to override the unit factor of the underlying caches.

    • m_cExpiryDelayMillis

      protected int m_cExpiryDelayMillis
      The expiry delay. The value -1 indicates that this cache has not been instructed to override the expiry delay of the underlying caches.

    • m_cHighUnitFairShare

      protected int m_cHighUnitFairShare
      The fair share of high units for each partition map.

    • m_cLowUnitFairShare

      protected int m_cLowUnitFairShare
      The fair share of low units for each partition map.

    • m_policy

      protected ConfigurableCacheMap.EvictionPolicy m_policy
      The eviction policy. The value of null indicates that this cache has not been instructed to override the eviction policy of the underlying caches.

    • m_calculator

      protected ConfigurableCacheMap.UnitCalculator m_calculator
      The unit calculator. The value of null indicates that this cache has not been instructed to override the unit calculator of the underlying caches.

    • m_acache

      protected ConfigurableCacheMap[] m_acache
      A cached array of the backing ConfigurableCacheMap instances.

    • m_apprvrEvict

      protected ConfigurableCacheMap.EvictionApprover m_apprvrEvict
      An optional EvictionApprover registered with this cache.

    • m_clzPartitionMap

      protected Class m_clzPartitionMap

  • Constructor Details

    • ObservableSplittingBackingCache

      public ObservableSplittingBackingCache(BackingMapManager bmm, String sName)
      Create a ObservableSplittingBackingCache that adds ConfigurableCacheMap functionality to an ObservableSplittingBackingMap.
      Parameters:
      bmm - a callback that knows how to create and release the backing maps that this ObservableSplittingBackingCache is responsible for
      sName - the cache name for which this backing map exists

  • Method Details

    • createPartition

      public void createPartition(int nPid)
      Add a partition to the PartitionAwareBackingMap.
      Specified by:
      createPartition in interface PartitionAwareBackingMap
      Overrides:
      createPartition in class ObservableSplittingBackingMap
      Parameters:
      nPid - the partition id that the PartitionAwareBackingMap will be responsible for, starting at this instant

    • destroyPartition

      public void destroyPartition(int nPid)
      Remove a partition from the PartitionAwareBackingMap.
      Specified by:
      destroyPartition in interface PartitionAwareBackingMap
      Overrides:
      destroyPartition in class ObservableSplittingBackingMap
      Parameters:
      nPid - the partition id that the PartitionAwareBackingMap will no longer be responsible for, starting at this instant

    • getUnits

      public int getUnits()
      Determine the number of units that the cache currently stores.

      Note: It is expected that the return type will be widened to a long in Coherence 4.

      Specified by:
      getUnits in interface ConfigurableCacheMap
      Returns:
      the current size of the cache in units

    • getHighUnits

      public int getHighUnits()
      Determine the limit of the cache size in units. The cache will prune itself automatically once it reaches its maximum unit level. This is often referred to as the "high water mark" of the cache.

      Note: It is expected that the return type will be widened to a long in Coherence 4.

      Specified by:
      getHighUnits in interface ConfigurableCacheMap
      Returns:
      the limit of the cache size in units

    • setHighUnits

      public void setHighUnits(int cMax)
      Update the maximum size of the cache in units. This is often referred to as the "high water mark" of the cache.

      Note: It is expected that the parameter will be widened to a long in Coherence 4.

      Specified by:
      setHighUnits in interface ConfigurableCacheMap
      Parameters:
      cMax - the new maximum size of the cache, in units

    • getLowUnits

      public int getLowUnits()
      Determine the point to which the cache will shrink when it prunes. This is often referred to as a "low water mark" of the cache. If the cache incrementally prunes, then this setting will have no effect.

      Note: It is expected that the parameter will be widened to a long in Coherence 4.

      Specified by:
      getLowUnits in interface ConfigurableCacheMap
      Returns:
      the number of units that the cache prunes to

    • setLowUnits

      public void setLowUnits(int cUnits)
      Specify the point to which the cache will shrink when it prunes. This is often referred to as a "low water mark" of the cache.

      Note: It is expected that the parameter will be widened to a long in Coherence 4.

      Specified by:
      setLowUnits in interface ConfigurableCacheMap
      Parameters:
      cUnits - the number of units that the cache prunes to

    • getUnitFactor

      public int getUnitFactor()
      Determine the factor by which the Units, LowUnits and HighUnits properties are adjusted. Using a binary unit calculator, for example, the factor 1048576 could be used to count megabytes instead of bytes.

      Note: This property exists only to avoid changing the type of the units, low units and high units properties from 32-bit values to 64-bit values. It is expected that the parameter will be dropped in Coherence 4.

      Specified by:
      getUnitFactor in interface ConfigurableCacheMap
      Returns:
      the units factor; the default is 1

    • setUnitFactor

      public void setUnitFactor(int nFactor)
      Determine the factor by which the Units, LowUnits and HighUnits properties are adjusted. Using a binary unit calculator, for example, the factor 1048576 could be used to count megabytes instead of bytes.

      Note: This property exists only to avoid changing the type of the units, low units and high units properties from 32-bit values to 64-bit values. It is expected that the parameter will be dropped in Coherence 4.

      Specified by:
      setUnitFactor in interface ConfigurableCacheMap
      Parameters:
      nFactor - the units factor; the default is 1

    • getEvictionPolicy

      public ConfigurableCacheMap.EvictionPolicy getEvictionPolicy()
      Obtain the current EvictionPolicy used by the cache.
      Specified by:
      getEvictionPolicy in interface ConfigurableCacheMap
      Returns:
      the EvictionPolicy used by the cache

    • setEvictionPolicy

      public void setEvictionPolicy(ConfigurableCacheMap.EvictionPolicy policy)
      Set the EvictionPolicy for the cache to use.
      Specified by:
      setEvictionPolicy in interface ConfigurableCacheMap
      Parameters:
      policy - an EvictionPolicy

    • evict

      public void evict(Object oKey)
      Evict a specified key from the cache, as if it had expired from the cache. If the key is not in the cache, then the method has no effect.
      Specified by:
      evict in interface ConfigurableCacheMap
      Parameters:
      oKey - the key to evict from the cache

    • evictAll

      public void evictAll(Collection colKeys)
      Evict the specified keys from the cache, as if they had each expired from the cache.

      The result of this method is defined to be semantically the same as the following implementation: 

      
 for (Iterator iter = colKeys.iterator(); iter.hasNext(); )
     {
     Object oKey = iter.next();
     evict(oKey);
     }
      Specified by:
      evictAll in interface ConfigurableCacheMap
      Parameters:
      colKeys - a collection of keys to evict from the cache

    • evict

      public void 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.
      Specified by:
      evict in interface ConfigurableCacheMap

    • getEvictionApprover

      public ConfigurableCacheMap.EvictionApprover getEvictionApprover()
      Obtain the registered EvictionApprover.
      Specified by:
      getEvictionApprover in interface ConfigurableCacheMap
      Returns:
      the EvictionApprover (could be null)

    • setEvictionApprover

      public void setEvictionApprover(ConfigurableCacheMap.EvictionApprover approver)
      Set the EvictionApprover for this ConfigurableCacheMap.
      Specified by:
      setEvictionApprover in interface ConfigurableCacheMap
      Parameters:
      approver - the EvictionApprover

    • getExpiryDelay

      public int getExpiryDelay()
      Determine the default "time to live" for each individual cache entry.
      Specified by:
      getExpiryDelay in interface ConfigurableCacheMap
      Returns:
      the number of milliseconds that a cache entry value will live, or zero if cache entries are never automatically expired

    • setExpiryDelay

      public void setExpiryDelay(int cMillis)
      Specify the default "time to live" for cache entries. This does not affect the already-scheduled expiry of existing entries.
      Specified by:
      setExpiryDelay in interface ConfigurableCacheMap
      Parameters:
      cMillis - the number of milliseconds that cache entries will live, or zero to disable automatic expiry

    • getNextExpiryTime

      public long getNextExpiryTime()
      Determine the next expiry time for the cache entries. This value is supposed to be used only by the "active" expiry algorithms, so for implementations that choose to return the value of zero the entries will be evicted as with pre-existing "passive" expiry approach.
      Specified by:
      getNextExpiryTime in interface ConfigurableCacheMap
      Returns:
      the earliest time (using the SafeClock) that one or more cache entries will expire or zero if the cache is empty, its entries never expire or the implementation chooses to avoid the pro-active eviction

    • getCacheEntry

      public ConfigurableCacheMap.Entry getCacheEntry(Object oKey)
      Locate a cache Entry in the cache based on its key.
      Specified by:
      getCacheEntry in interface ConfigurableCacheMap
      Parameters:
      oKey - the key object to search for
      Returns:
      the Entry or null

    • getUnitCalculator

      public ConfigurableCacheMap.UnitCalculator getUnitCalculator()
      Obtain the current UnitCalculator used by the cache.
      Specified by:
      getUnitCalculator in interface ConfigurableCacheMap
      Returns:
      the UnitCalculator used by the cache

    • setUnitCalculator

      public void setUnitCalculator(ConfigurableCacheMap.UnitCalculator calculator)
      Set the UnitCalculator for the cache to use.
      Specified by:
      setUnitCalculator in interface ConfigurableCacheMap
      Parameters:
      calculator - a UnitCalculator

    • getPartitionMapType

      public Class getPartitionMapType()
      Return the uniform type used by each partition map.
      Returns:
      the type of partition map

    • prepareUpdate

      protected void prepareUpdate(Map mapPartition, Map mapUpdate)
      Prepare mapPart, a map representing a partition, for the impending changes in which all of the mappings from mapUpdate will be copied to mapPart.

      This implementation will check if mapPart is under-allocated for high units. If this is the case, demand the entitled unit amount from other maps.

      Overrides:
      prepareUpdate in class ObservableSplittingBackingMap
      Parameters:
      mapPartition - the map to be mutated with the contents of mapUpdate
      mapUpdate - the map of changes to be applied

    • claimUnused

      protected void claimUnused(ConfigurableCacheMap mapRequestor)
      Claim as many units as possible from existing maps without causing over-allocated maps to evict.
      Parameters:
      mapRequestor - the map requesting its fair share of units

    • claimAll

      protected void claimAll(ConfigurableCacheMap mapRequestor)
      Claim the full entitlement of units for mapRequestor. This method should only be invoked if the map has insufficient units, based on a pending put request, however does not occupy its fair share.
      Parameters:
      mapRequestor - the map demanding its entitled fair share

    • adjustUnits

      protected void adjustUnits(int cUnits)
      Adjust the number of units for each map with the pool of units provided. The units provided is a total across all maps with the adjustment per map being made as prescribed below.

      The provided units may be positive or negative, with the latter suggesting that this number of units should be retrieved, thus decremented, from child maps. If the provided units is positive, maps that are over-allocated may consumer the provided amount. If the provided units is negative maintain a positive delta between the fair share and their current high units may consume the minimum between what is available from the provided units and the determined delta. If the provided units is negative, those maps whose current high unit allocation is more than the fair share will have this delta decremented until the debt (cUnits) is reclaimed.

      Parameters:
      cUnits - the number of units to either disseminate (positive unit value) or retract across the maps

    • initializeConfiguredProperties

      protected void initializeConfiguredProperties()
      Initialize the configurable properties of this cache-map.

    • getPartitionCache

      protected ConfigurableCacheMap getPartitionCache(Object oKey)
      Obtain the backing cache for a particular key. If the key is not owned by a partition represented by this ObservableSplittingBackingCache, then a runtime exception is thrown.
      Parameters:
      oKey - the key of the desired entry
      Returns:
      the backing cache

    • getPartitionCacheArray

      protected ConfigurableCacheMap[] getPartitionCacheArray()
      Obtain the array of backing caches.
      Returns:
      an array of all the per-partition backing caches

    • getCalibratedHighUnits

      protected int getCalibratedHighUnits()
      Determine the high units adjusted based on the partition unit factor.
      Returns:
      the limit of the cache size in units adjusted by partition unitFactor

    • getCalibratedLowUnits

      protected int getCalibratedLowUnits()
      Determine the low units adjusted based on the partition unit factor.
      Returns:
      the number of units adjusted by partition unitFactor that the cache prunes to

    • getPartitionUnitFactor

      protected int getPartitionUnitFactor()
      Determine the unit factor for individual partition maps.
      Returns:
      the unit factor for partition maps

    • getLowUnitFairShare

      protected int getLowUnitFairShare()
      Return the fair share of low-units per partition map.
      Returns:
      the fair share of low-units per partition map

    • getHighUnitFairShare

      protected int getHighUnitFairShare()
      Return the fair share of high-units per partition map.
      Returns:
      the fair share of high-units per partition map

    • calcUnitFairShare

      protected int calcUnitFairShare(int cUnits)
      Return the fair share of units for each child maps. The units provided would typically be either the high or low units allowed for all maps under this map.
      Parameters:
      cUnits - the units to distribute across all child maps
      Returns:
      the fair share of units for each child map

    • instantiateEntrySet

      protected Set instantiateEntrySet()
      Factory pattern: Create a Set that represents the entries in the Map.
      Overrides:
      instantiateEntrySet in class AbstractKeySetBasedMap
      Returns:
      a new instance of Set that represents the entries in the Map