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Oracle® Coherence Java API Reference
Release 3.7.0.0

E18683-01


com.tangosol.net.cache
Class SerializationCache

java.lang.Object
  extended by com.tangosol.util.Base
      extended by com.tangosol.util.AbstractKeyBasedMap
          extended by com.tangosol.util.AbstractKeySetBasedMap
              extended by com.tangosol.net.cache.SerializationMap
                  extended by com.tangosol.net.cache.AbstractSerializationCache
                      extended by com.tangosol.net.cache.SerializationCache

All Implemented Interfaces:
CacheMap, ConfigurableCacheMap, ObservableMap, java.util.Map

public class SerializationCache
extends AbstractSerializationCache
implements CacheMap, ConfigurableCacheMap

A version of SerializationMap that implements an LRU policy.

This implementation is partially thread safe. It assumes that multiple threads will not be accessing the same keys at the same time, nor would any other thread be accessing this cache while a clear() operation were going on, for example. In other words, this implementation assumes that access to this cache is either single-threaded or gated through an object like WrapperConcurrentMap.

The primary reason why SerializationCache is a sub-class of SerializationMap instead of combining their functionality is that SerializationMap represents a passive store, and thus does not implement the ObservableMap interface, while SerializationCache represents an active store, and thus clients of it would have to always handle potential events, even if it were not size-limited.

Since:
Coherence 2.2
Author:
cp 2003.05.28

Nested Class Summary
protected  class SerializationCache.EntryAttributes
          A class that holds on to the expiry time and touch order for an entry.
 class SerializationCache.EntrySet
          A set of entries backed by this map.
static class SerializationCache.InternalEvictionPolicy
          The InternalEvictionPolicy represents a pluggable eviction policy for the non-pluggable built-in (internal) eviction policies supported by this cache implementation.

 

Nested classes/interfaces inherited from class com.tangosol.util.AbstractKeySetBasedMap
AbstractKeySetBasedMap.KeyIterator, AbstractKeySetBasedMap.KeySet, AbstractKeySetBasedMap.ValuesCollection

 

Nested classes/interfaces inherited from interface com.tangosol.net.cache.ConfigurableCacheMap
ConfigurableCacheMap.Entry, ConfigurableCacheMap.EvictionPolicy, ConfigurableCacheMap.UnitCalculator

 

Field Summary
protected  ConfigurableCacheMap.UnitCalculator m_calculator
          The unit calculator to use to limit size of the cache.
protected  long m_cCurUnits
          Current number of units to in the cache.
protected  long m_cMaxUnits
          Maximum number of units to manage in the cache.
protected  int m_nUnitFactor
          The unit factor.

 

Fields inherited from interface com.tangosol.net.cache.CacheMap
EXPIRY_DEFAULT, EXPIRY_NEVER

 

Constructor Summary
SerializationCache(BinaryStore store, int cMax)
          Construct a SerializationCache on top of a BinaryStore.
SerializationCache(BinaryStore store, int cMax, boolean fBinaryMap)
          Construct a SerializationCache on top of a BinaryStore.
SerializationCache(BinaryStore store, int cMax, java.lang.ClassLoader loader)
          Construct a SerializationCache on top of a BinaryStore.

 

Method Summary
protected  void checkExpiry()
          Make sure that the cache does not contain expired items.
protected  void checkSize()
          Make sure the size of the cache isn't too big.
 void clear()
          Clear all key/value mappings.
 boolean containsKey(java.lang.Object oKey)
          Returns true if this map contains a mapping for the specified key.
 boolean containsValue(java.lang.Object oValue)
          Returns true if this Map maps one or more keys to the specified value.
 void evict()
          Flush items that have expired.
 void evict(java.lang.Object oKey)
          Evict a specified key from the cache, as if it had expired from the cache.
 void evictAll(java.util.Collection colKeys)
          Evict the specified keys from the cache, as if they had each expired from the cache.
 void flush()
          Deprecated. use evict()
 java.lang.Object get(java.lang.Object oKey)
          Returns the value to which this map maps the specified key.
 ConfigurableCacheMap.Entry getCacheEntry(java.lang.Object oKey)
          Locate a cache Entry in the cache based on its key.
protected  java.lang.String getDescription()
          Assemble a human-readable description.
 ConfigurableCacheMap.EvictionPolicy getEvictionPolicy()
          Obtain the current EvictionPolicy used by the cache.
protected  LongArray getExpiryArray()
          Get the Expiry data structure.
 int getExpiryDelay()
          Determine the default "time to live" for each individual cache entry.
 int getFlushDelay()
          Determine the delay between cache flushes.
 int getHighUnits()
          Determine the limit of the cache size in units.
 int getLowUnits()
          Determine the point to which the cache will shrink when it prunes.
protected  LongArray getLruArray()
          Get the LRU data structure.
 int getMaximumSize()
          Deprecated. as of Coherence 3.5, use getHighUnits()
protected  long getTouchCounter()
          Determine the next value from the touch counter.
 ConfigurableCacheMap.UnitCalculator getUnitCalculator()
          Obtain the current UnitCalculator used by the cache.
 int getUnitFactor()
          Determine the factor by which the Units, LowUnits and HighUnits properties are adjusted.
 int getUnits()
          Determine the number of units that the cache currently stores.
 SerializationCache.EntryAttributes instantiateEntryAttributes(SerializationCache.EntryAttributes attrOrig, long ldtExpires, long nTouch, int cUnits)
          Factory pattern: Construct an attribute holder for an entry.
protected  java.util.Set instantiateEntrySet()
          Factory pattern: Create a Set that represents the entries in the Map.
 boolean isEmpty()
          Returns true if this map contains no key-value mappings.
 java.lang.Object put(java.lang.Object oKey, java.lang.Object oValue)
          Associates the specified value with the specified key in this map.
 java.lang.Object put(java.lang.Object oKey, java.lang.Object oValue, long cMillis)
          Associates the specified value with the specified key in this cache.
 void putAll(java.util.Map map)
          Copies all of the mappings from the specified map to this map.
protected  void registerKey(java.lang.Object oKey, Binary binKey, Binary binValue)
          Register a new key for the SerializationMap.
protected  void registerKey(java.lang.Object oKey, Binary binKey, Binary binValue, int cMillis)
          Register a new key for the SerializationMap.
 java.lang.Object remove(java.lang.Object oKey)
          Removes the mapping for this key from this map if present.
protected  boolean removeBlind(java.lang.Object oKey)
          Removes the mapping for this key from this map if present.
protected  void setBinaryStore(BinaryStore store)
          Configures the BinaryStore that this map will use for its storage.
 void setEvictionPolicy(ConfigurableCacheMap.EvictionPolicy policy)
          Set the EvictionPolicy for the cache to use.
 void setExpiryDelay(int cMillis)
          Specify the default "time to live" for cache entries.
 void setFlushDelay(int cMillis)
          Specify the delay between cache flushes.
 void setHighUnits(int cMax)
          Update the maximum size of the cache in units.
 void setLowUnits(int cUnits)
          Specify the point to which the cache will shrink when it prunes.
 void setMaximumSize(int cMax)
          Deprecated. as of Coherence 3.5, use setHighUnits(int)
 void setUnitCalculator(ConfigurableCacheMap.UnitCalculator calculator)
          Set the UnitCalculator for the cache to use.
 void setUnitFactor(int nFactor)
          Determine the factor by which the Units, LowUnits and HighUnits properties are adjusted.
 int size()
          Returns the number of key-value mappings in this map.
 java.lang.String toString()
          Returns a string representation of this Map.
protected  void touch(java.lang.Object oKey)
          Touch an object to pop it to the top of the LRU
protected  void unregisterKey(java.lang.Object oKey)
          Unregister a key from the SerializationMap.

 

Methods inherited from class com.tangosol.net.cache.AbstractSerializationCache
addMapListener, addMapListener, addMapListener, dispatchEvent, dispatchPendingEvent, getMapListenerSupport, hasListeners, removeMapListener, removeMapListener, removeMapListener

 

Methods inherited from class com.tangosol.net.cache.SerializationMap
eraseStore, fromBinary, getBinaryStore, getCacheStatistics, getClassLoader, getInternalKeySet, getKeyMap, instantiateKeyMap, isBinaryMap, setBinaryMap, setClassLoader, toBinary

 

Methods inherited from class com.tangosol.util.AbstractKeySetBasedMap
instantiateKeyIterator, instantiateKeySet, instantiateValues, isInternalKeySetIteratorMutable, iterateKeys

 

Methods inherited from class com.tangosol.util.AbstractKeyBasedMap
clone, entrySet, equals, getAll, hashCode, keySet, values

 

Methods inherited from interface com.tangosol.net.cache.CacheMap
getAll

 

Methods inherited from interface com.tangosol.util.ObservableMap
addMapListener, addMapListener, addMapListener, removeMapListener, removeMapListener, removeMapListener

 

Methods inherited from interface java.util.Map
entrySet, equals, hashCode, keySet, values

 

Field Detail

m_cMaxUnits

protected long m_cMaxUnits
Maximum number of units to manage in the cache.

m_cCurUnits

protected long m_cCurUnits
Current number of units to in the cache.

m_calculator

protected ConfigurableCacheMap.UnitCalculator m_calculator
The unit calculator to use to limit size of the cache.

m_nUnitFactor

protected int m_nUnitFactor
The unit factor.

Constructor Detail

SerializationCache

public SerializationCache(BinaryStore store,
                          int cMax)
Construct a SerializationCache on top of a BinaryStore.
Parameters:
store - the BinaryStore to use to write the serialized objects to
cMax - the maximum number of items to store in the binary store

SerializationCache

public SerializationCache(BinaryStore store,
                          int cMax,
                          java.lang.ClassLoader loader)
Construct a SerializationCache on top of a BinaryStore.
Parameters:
store - the BinaryStore to use to write the serialized objects to
cMax - the maximum number of items to store in the binary store
loader - the ClassLoader to use for deserialization

SerializationCache

public SerializationCache(BinaryStore store,
                          int cMax,
                          boolean fBinaryMap)
Construct a SerializationCache on top of a BinaryStore.
Parameters:
store - the BinaryStore to use to write the serialized objects to
cMax - the maximum number of items to store in the binary store
fBinaryMap - true indicates that this map will only manage binary keys and values
Since:
Coherence 2.4

Method Detail

clear

public void clear()
Clear all key/value mappings.
Specified by:
clear in interface java.util.Map
Overrides:
clear in class AbstractSerializationCache

containsKey

public boolean containsKey(java.lang.Object oKey)
Returns true if this map contains a mapping for the specified key.
Specified by:
containsKey in interface java.util.Map
Overrides:
containsKey in class AbstractKeySetBasedMap
Parameters:
oKey - key whose presence in this map is to be tested.
Returns:
true if this map contains a mapping for the specified key, false otherwise.

containsValue

public boolean containsValue(java.lang.Object oValue)
Returns true if this Map maps one or more keys to the specified value.
Specified by:
containsValue in interface java.util.Map
Overrides:
containsValue in class SerializationMap
Parameters:
oValue - value whose presence in this map is to be tested.
Returns:
true if this Map maps one or more keys to the specified value, false otherwise

get

public java.lang.Object get(java.lang.Object oKey)
Returns the value to which this map maps the specified key.
Specified by:
get in interface java.util.Map
Overrides:
get in class SerializationMap
Parameters:
oKey - the key object
Returns:
the value to which this map maps the specified key, or null if the map contains no mapping for this key
See Also:
Map.containsKey(Object)

isEmpty

public boolean isEmpty()
Returns true if this map contains no key-value mappings.
Specified by:
isEmpty in interface java.util.Map
Overrides:
isEmpty in class AbstractKeySetBasedMap
Returns:
true if this map contains no key-value mappings

put

public java.lang.Object put(java.lang.Object oKey,
                            java.lang.Object oValue)
Associates the specified value with the specified key in this map.
Specified by:
put in interface CacheMap
Specified by:
put in interface java.util.Map
Overrides:
put in class AbstractSerializationCache
Parameters:
oKey - key with which the specified value is to be associated
oValue - value to be associated with the specified key
Returns:
previous value associated with specified key, or null if there was no mapping for key

putAll

public void putAll(java.util.Map map)
Copies all of the mappings from the specified map to this map. The effect of this call is equivalent to that of calling AbstractKeyBasedMap.put(java.lang.Object, java.lang.Object) on this map once for each mapping in the passed map. The behavior of this operation is unspecified if the passed map is modified while the operation is in progress.
Specified by:
putAll in interface java.util.Map
Overrides:
putAll in class AbstractSerializationCache
Parameters:
map - the Map containing the key/value pairings to put into this Map

remove

public java.lang.Object remove(java.lang.Object oKey)
Removes the mapping for this key from this map if present. Expensive: updates both the underlying cache and the local cache.
Specified by:
remove in interface java.util.Map
Overrides:
remove in class AbstractSerializationCache
Parameters:
oKey - key whose mapping is to be removed from the map
Returns:
previous value associated with specified key, or null if there was no mapping for key. A null return can also indicate that the map previously associated null with the specified key, if the implementation supports null values.

size

public int size()
Returns the number of key-value mappings in this map.
Specified by:
size in interface java.util.Map
Overrides:
size in class AbstractKeySetBasedMap
Returns:
the number of key-value mappings in this map

removeBlind

protected boolean removeBlind(java.lang.Object oKey)
Removes the mapping for this key from this map if present. This method exists to allow sub-classes to optmiize remove functionalitly for situations in which the original value is not required.
Overrides:
removeBlind in class AbstractSerializationCache
Parameters:
oKey - key whose mapping is to be removed from the map
Returns:
true iff the Map changed as the result of this operation

put

public java.lang.Object put(java.lang.Object oKey,
                            java.lang.Object oValue,
                            long cMillis)
Associates the specified value with the specified key in this cache. If the cache previously contained a mapping for this key, the old value is replaced. This variation of the CacheMap.put(Object oKey, Object oValue) method allows the caller to specify an expiry (or "time to live") for the cache entry.
Specified by:
put in interface CacheMap
Parameters:
oKey - key with which the specified value is to be associated
oValue - value to be associated with the specified key
cMillis - the number of milliseconds until the cache entry will expire, also referred to as the entry's "time to live"; pass CacheMap.EXPIRY_DEFAULT to use the cache's default time-to-live setting; pass CacheMap.EXPIRY_NEVER to indicate that the cache entry should never expire; this milliseconds value is not a date/time value, such as is returned from System.currentTimeMillis()
Returns:
previous value associated with specified key, or null if there was no mapping for key. A null return can also indicate that the map previously associated null with the specified key, if the implementation supports null values

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(java.lang.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(java.util.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()
Flush items that have expired.
Specified by:
evict in interface ConfigurableCacheMap
Specified by:
evict in class AbstractSerializationCache

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

getFlushDelay

public int getFlushDelay()
Determine the delay between cache flushes. A cache flush evicts entries that have expired.

This value is used by cache implementations that periodically evict entries that have expired; this value has no meaning for cache implementations that aggressively evict entries as they expire.

Specified by:
getFlushDelay in interface ConfigurableCacheMap
Returns:
the number of milliseconds between cache flushes, or zero which signifies that the cache never flushes

setFlushDelay

public void setFlushDelay(int cMillis)
Specify the delay between cache flushes. A cache flush evicts entries that have expired.

This value is used by cache implementations that periodically evict entries that have expired; this value has no meaning for cache implementations that aggressively evict entries as they expire.

Specified by:
setFlushDelay in interface ConfigurableCacheMap
Parameters:
cMillis - the number of milliseconds between cache flushes, or zero to never flush

getCacheEntry

public ConfigurableCacheMap.Entry getCacheEntry(java.lang.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

flush

public void flush()
Deprecated. use evict()
Flush items that have expired.

toString

public java.lang.String toString()
Returns a string representation of this Map. The string representation consists of a list of key-value mappings in the order returned by the Map's entrySet view's iterator, enclosed in braces ("{}"). Adjacent mappings are separated by the characters ", " (comma and space). Each key-value mapping is rendered as the key followed by an equals sign ("=") followed by the associated value. Keys and values are converted to strings as by String.valueOf(Object).
Overrides:
toString in class SerializationMap
Returns:
a String representation of this Map

setBinaryStore

protected void setBinaryStore(BinaryStore store)
Configures the BinaryStore that this map will use for its storage.
Overrides:
setBinaryStore in class SerializationMap
Parameters:
store - the BinaryStore to use

getMaximumSize

public int getMaximumSize()
Deprecated. as of Coherence 3.5, use getHighUnits()
Determine the maximum number of entries that the cache will hold.
Returns:
the maximum number of entries that the cache will hold

setMaximumSize

public void setMaximumSize(int cMax)
Deprecated. as of Coherence 3.5, use setHighUnits(int)
Change the maximum number of entries that the cache will hold.
Parameters:
cMax - the new maximum number of entries that the cache will hold

getTouchCounter

protected long getTouchCounter()
Determine the next value from the touch counter.
Returns:
the next value from the touch counter

getLruArray

protected LongArray getLruArray()
Get the LRU data structure. The key is a touch count, the value is the Object key for the cache.
Returns:
the the LRU data structure

getExpiryArray

protected LongArray getExpiryArray()
Get the Expiry data structure. The key is a date/time value, the value is a set of Object keys for the cache that expire at that time.
Returns:
the the Expiry data structure

getDescription

protected java.lang.String getDescription()
Assemble a human-readable description.
Overrides:
getDescription in class AbstractSerializationCache
Returns:
a description of this Map

registerKey

protected void registerKey(java.lang.Object oKey,
                           Binary binKey,
                           Binary binValue)
Register a new key for the SerializationMap. This method maintains the internal key Set for the SerializationMap.
Overrides:
registerKey in class SerializationMap
Parameters:
oKey - the key that has been added to the map
binKey - the binary form of the key
binValue - the binary form of the value

registerKey

protected void registerKey(java.lang.Object oKey,
                           Binary binKey,
                           Binary binValue,
                           int cMillis)
Register a new key for the SerializationMap. This method maintains the internal key Set for the SerializationMap.
Parameters:
oKey - the key that has been added to the map
binKey - the binary form of the key (null if only TTL change)
binValue - the binary form of the value (null if only TTL change)
cMillis - the TTL value (in milliseconds) for the entry

touch

protected void touch(java.lang.Object oKey)
Touch an object to pop it to the top of the LRU
Parameters:
oKey - the key of the object to touch

unregisterKey

protected void unregisterKey(java.lang.Object oKey)
Unregister a key from the SerializationMap. This method maintains the internal key Set for the SerializationMap.
Overrides:
unregisterKey in class SerializationMap
Parameters:
oKey - the key that has been removed from the map

checkSize

protected void checkSize()
Make sure the size of the cache isn't too big.

checkExpiry

protected void checkExpiry()
Make sure that the cache does not contain expired items.

instantiateEntryAttributes

public SerializationCache.EntryAttributes instantiateEntryAttributes(SerializationCache.EntryAttributes attrOrig,
                                                                     long ldtExpires,
                                                                     long nTouch,
                                                                     int cUnits)
Factory pattern: Construct an attribute holder for an entry.
Parameters:
attrOrig - the previous attributes for this entry, if any
ldtExpires - the date/time at which the entry expires, or zero
nTouch - the touch counter assigned to the entry
cUnits - the number of storage units used by the entry

instantiateEntrySet

protected java.util.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

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