com.stoyanr.evictor.map

Class ConcurrentMapWithTimedEvictionDecorator<K,V>

java.lang.Object

java.util.AbstractMap<K,V>

com.stoyanr.evictor.map.ConcurrentMapWithTimedEvictionDecorator<K,V>

Type Parameters:

K - the type of keys maintained by this map

V - the type of mapped values

All Implemented Interfaces:

ConcurrentMapWithTimedEviction<K,V>, ConcurrentMap<K,V>, Map<K,V>

Direct Known Subclasses:

ConcurrentHashMapWithTimedEviction

public class ConcurrentMapWithTimedEvictionDecorator<K,V>
extends AbstractMap<K,V>
implements ConcurrentMapWithTimedEviction<K,V>

A ConcurrentMapWithTimedEviction implementation which decorates an existing ConcurrentMap implementation. This class uses an instance of EvictionScheduler for automatically evicting entries upon expiration.

This class does not allow null to be used as a value. Whether or not null can be used as a key depends on the map being decorated.

This class and its views and iterators implement all of the optional methods of the Map and Iterator interfaces.

Author:

Stoyan Rachev

Nested Class Summary

Nested classes/interfaces inherited from class java.util.AbstractMap

AbstractMap.SimpleEntry<K,V>, AbstractMap.SimpleImmutableEntry<K,V>

Nested classes/interfaces inherited from interface java.util.Map

Map.Entry<K,V>

Constructor Summary

Constructors

Constructor and Description
ConcurrentMapWithTimedEvictionDecorator(ConcurrentMap<K,EvictibleEntry<K,V>> delegate, EvictionScheduler<K,V> scheduler) Creates a new map that supports timed entry eviction with the specified delegate and eviction scheduler.

Method Summary

Methods

Modifier and Type	Method and Description
void	clear() Removes all of the mappings from this map.
boolean	containsKey(Object key) Returns true if this map contains a mapping for the specified key and it has not expired yet.
boolean	containsValue(Object value) Returns true if this map maps one or more keys to the specified value and at least one of them has not expired yet.
Set<Map.Entry<K,V>>	entrySet() Returns a Set view of the mappings contained in this map.
V	get(Object key) Returns the value to which the specified key is mapped, or null if this map contains no mapping for the key or it has expired.
Set<K>	keySet() Returns a Set view of the keys contained in this map.
V	put(K key, V value) Associates the specified value with the specified key in this map.
V	put(K key, V value, long evictMs) Associates the specified value with the specified key in this map for the specified duration.
V	putIfAbsent(K key, V value) If the specified key is not already associated with a value, associate it with the given value.
V	putIfAbsent(K key, V value, long evictMs) If the specified key is not already associated with a value, associate it with the given value for the specified duration.
V	remove(Object key) Removes the mapping for a key from this map if it is present.
boolean	remove(Object key, Object value) Removes the entry for a key only if currently mapped to a given value.
V	replace(K key, V value) Replaces the entry for a key only if currently mapped to some value.
V	replace(K key, V value, long evictMs) Replaces the entry for a key only if currently mapped to some value, for the specified duration.
boolean	replace(K key, V oldValue, V newValue) Replaces the entry for a key only if currently mapped to a given value.
boolean	replace(K key, V oldValue, V newValue, long evictMs) Replaces the entry for a key only if currently mapped to a given value, for the specified duration.
int	size() Returns the number of key-value mappings in this map.

Methods inherited from class java.util.AbstractMap

clone, equals, hashCode, isEmpty, putAll, toString, values

Methods inherited from class java.lang.Object

finalize, getClass, notify, notifyAll, wait, wait, wait

Methods inherited from interface java.util.Map

equals, hashCode, isEmpty, putAll, values

Constructor Detail

ConcurrentMapWithTimedEvictionDecorator

public ConcurrentMapWithTimedEvictionDecorator(ConcurrentMap<K,EvictibleEntry<K,V>> delegate,
                                       EvictionScheduler<K,V> scheduler)

Creates a new map that supports timed entry eviction with the specified delegate and eviction scheduler.

Parameters:

delegate - the actual map implementation to which all operations will be eventually delegated

scheduler - the scheduler used for automatically evicting entries when the time they are allowed to stay in the map has elapsed

Throws:

NullPointerException - if either the delegate or the scheduler is null

Method Detail

size

public int size()

Returns the number of key-value mappings in this map. If the map contains more than Integer.MAX_VALUE elements, returns Integer.MAX_VALUE. This may include entries may not have yet been evicted, but since it is a ConcurrentMap, it is ok to return a weakly consistent value.

Specified by:

size in interface Map<K,V>

Overrides:

size in class AbstractMap<K,V>

Returns:

the number of key-value mappings in this map

containsKey

public boolean containsKey(Object key)

Returns true if this map contains a mapping for the specified key and it has not expired yet. More formally, returns true if and only if this map contains a mapping for a key k such that (key==null ? k==null : key.equals(k)). (There can be at most one such mapping.).

Specified by:

containsKey in interface Map<K,V>

Overrides:

containsKey in class AbstractMap<K,V>

Parameters:

key - key whose presence in this map is to be tested

Returns:

true if this map contains a mapping for the specified key and it has not expired yet.

Throws:

ClassCastException - if the key is of an inappropriate type for this map

NullPointerException - if the specified key is null and the delegate map does not permit null keys

containsValue

public boolean containsValue(Object value)

Returns true if this map maps one or more keys to the specified value and at least one of them has not expired yet. More formally, returns true if and only if this map contains at least one mapping to a value v such that (value==null ? v==null : value.equals(v)).

Specified by:

containsValue in interface Map<K,V>

Overrides:

containsValue in class AbstractMap<K,V>

Parameters:

value - value whose presence in this map is to be tested

Returns:

true if this map maps one or more keys to the specified value and at least one of them has not expired yet.

Throws:

ClassCastException - if the value is of an inappropriate type for this map

NullPointerException - if the specified value is null

get

public V get(Object key)

Returns the value to which the specified key is mapped, or null if this map contains no mapping for the key or it has expired.

If the delegate map permits null values, then a return value of null does not necessarily indicate that the map contains no mapping for the key; it's also possible that the map explicitly maps the key to null. The containsKey operation may be used to distinguish these two cases.

Specified by:

get in interface Map<K,V>

Overrides:

get in class AbstractMap<K,V>

Parameters:

key - the key whose associated value is to be returned

Returns:

the value to which the specified key is mapped, or null if this map contains no mapping for the key or it has expired

Throws:

ClassCastException - if the key is of an inappropriate type for this map

NullPointerException - if the specified key is null and the delegate map does not permit null keys

put

public V put(K key,
    V value)

Associates the specified value with the specified key in this map. If the map previously contained a mapping for the key, the old value is replaced by the specified value.

Specified by:

put in interface Map<K,V>

Overrides:

put in class AbstractMap<K,V>

Parameters:

key - key with which the specified value is to be associated

value - value to be associated with the specified key

Returns:

the previous value associated with key, or null if there was no mapping for key. (A null return can also indicate that the map previously associated null with key, if the delegate supports null values.)

Throws:

UnsupportedOperationException - if the put operation is not supported by the delegate map

ClassCastException - if the class of the specified key or value prevents it from being stored in this map

NullPointerException - if the specified key is null and the delegate map does not permit null keys, or if the specified value is null

IllegalArgumentException - if some property of the specified key or value prevents it from being stored in this map

put

public V put(K key,
    V value,
    long evictMs)

Associates the specified value with the specified key in this map for the specified duration. If the map previously contained a mapping for the key, the old value is replaced by the specified value. (A map m is said to contain a mapping for a key k if and only if m.containsKey(k) would return true .)

Specified by:

put in interface ConcurrentMapWithTimedEviction<K,V>

Parameters:

key - key with which the specified value is to be associated

value - value to be associated with the specified key

evictMs - the time in ms during which the entry can stay in the map (time-to-live). When this time has elapsed, the entry will be evicted from the map automatically. A value of 0 for this argument means "forever", i.e. put(key, value, 0) is equivalent to put(key, value).

Returns:

the previous value associated with key, or null if there was no mapping for key. (A null return can also indicate that the map previously associated null with key, if the implementation supports null values.)

Throws:

UnsupportedOperationException - if the put operation is not supported by the delegate map

ClassCastException - if the class of the specified key or value prevents it from being stored in this map

NullPointerException - if the specified key is null and the delegate map does not permit null keys, or if the specified value is null

IllegalArgumentException - if some property of the specified key or value prevents it from being stored in this map, or if evictMs is negative

putIfAbsent

public V putIfAbsent(K key,
            V value)

If the specified key is not already associated with a value, associate it with the given value. This is equivalent to

 if (!map.containsKey(key))
     return map.put(key, value);
 else
     return map.get(key);
 

except that the action is performed atomically.

Specified by:

putIfAbsent in interface ConcurrentMap<K,V>

Parameters:

key - key with which the specified value is to be associated

value - value to be associated with the specified key

Returns:

the previous value associated with the specified key, or null if there was no mapping for the key. (A null return can also indicate that the map previously associated null with the key, if the implementation supports null values.)

Throws:

UnsupportedOperationException - if the put operation is not supported by the delegate map

ClassCastException - if the class of the specified key or value prevents it from being stored in this map

NullPointerException - if the specified key is null and the delegate map does not permit null keys, or if the specified value is null

IllegalArgumentException - if some property of the specified key or value prevents it from being stored in this map

putIfAbsent

public V putIfAbsent(K key,
            V value,
            long evictMs)

If the specified key is not already associated with a value, associate it with the given value for the specified duration. This is equivalent to

 if (!map.containsKey(key))
     return map.put(key, value, evictMs);
 else
     return map.get(key);
 

except that the action is performed atomically.

Specified by:

putIfAbsent in interface ConcurrentMapWithTimedEviction<K,V>

Parameters:

key - key with which the specified value is to be associated

value - value to be associated with the specified key

evictMs - the time in ms during which the entry can stay in the map (time-to-live). When this time has elapsed, the entry will be evicted from the map automatically. A value of 0 for this argument means "forever", i.e. putIfAbsent(key, value, 0) is equivalent to putIfAbsent(key, value).

Returns:

the previous value associated with the specified key, or null if there was no mapping for the key. (A null return can also indicate that the map previously associated null with the key, if the implementation supports null values.)

Throws:

UnsupportedOperationException - if the put operation is not supported by the delegate map

ClassCastException - if the class of the specified key or value prevents it from being stored in this map

NullPointerException - if the specified key is null and the delegate map does not permit null keys, or if the specified value is null

IllegalArgumentException - if some property of the specified key or value prevents it from being stored in this map, or if evictMs is negative

remove

public V remove(Object key)

Removes the mapping for a key from this map if it is present. More formally, if this map contains a mapping from key k to value v such that (key==null ? k==null : key.equals(k)), that mapping is removed. (The map can contain at most one such mapping.)

Returns the value to which this map previously associated the key, or null if the map contained no mapping for the key or it has expired.

If the delegate map permits null values, then a return value of null does not necessarily indicate that the map contained no mapping for the key; it's also possible that the map explicitly mapped the key to null.

The map will not contain a mapping for the specified key once the call returns.

Specified by:

remove in interface Map<K,V>

Overrides:

remove in class AbstractMap<K,V>

Parameters:

key - key whose mapping is to be removed from the map, if it has not expired yet.

Returns:

the previous value associated with key, or null if there was no mapping for key or it has expired.

Throws:

UnsupportedOperationException - if the remove operation is not supported by the delegate map

ClassCastException - if the key is of an inappropriate type for this map

NullPointerException - if the specified key is null and the delegate map does not permit null keys

remove

public boolean remove(Object key,
             Object value)

Removes the entry for a key only if currently mapped to a given value. This is equivalent to

 if (map.containsKey(key) && map.get(key).equals(value)) {
     map.remove(key);
     return true;
 } else
     return false;
 

except that the action is performed atomically.

Specified by:

remove in interface ConcurrentMap<K,V>

Parameters:

key - key with which the specified value is associated

value - value expected to be associated with the specified key

Returns:

true if the value was removed without being expired

Throws:

UnsupportedOperationException - if the remove operation is not supported by the delegate map

ClassCastException - if the key or value is of an inappropriate type for this map

NullPointerException - if the specified key is null and the delegate map does not permit null keys, or if the specified value is null

replace

public V replace(K key,
        V value)

Replaces the entry for a key only if currently mapped to some value. This is equivalent to

 if (map.containsKey(key)) {
     return map.put(key, value);
 } else
     return null;
 

except that the action is performed atomically.

Specified by:

replace in interface ConcurrentMap<K,V>

Parameters:

key - key with which the specified value is associated

value - value to be associated with the specified key

Returns:

the previous value associated with the specified key, or null if there was no mapping for the key. (A null return can also indicate that the map previously associated null with the key, if the delegate map supports null values.)

Throws:

UnsupportedOperationException - if the put operation is not supported by the delegate map

ClassCastException - if the class of the specified key or value prevents it from being stored in this map

NullPointerException - if the specified key is null and the delegate map does not permit null keys, or if the specified value is null

IllegalArgumentException - if some property of the specified key or value prevents it from being stored in this map

replace

public V replace(K key,
        V value,
        long evictMs)

Replaces the entry for a key only if currently mapped to some value, for the specified duration. This is equivalent to

 if (map.containsKey(key)) {
     return map.put(key, value, evictMs);
 } else
     return null;
 

except that the action is performed atomically.

Specified by:

replace in interface ConcurrentMapWithTimedEviction<K,V>

Parameters:

key - key with which the specified value is associated

value - value to be associated with the specified key

evictMs - the time in ms during which the entry can stay in the map (time-to-live). When this time has elapsed, the entry will be evicted from the map automatically. A value of 0 for this argument means "forever", i.e. replace(key, value, 0) is equivalent to replace(key, value).

Returns:

the previous value associated with the specified key, or null if there was no mapping for the key. (A null return can also indicate that the map previously associated null with the key, if the delegate map supports null values.)

Throws:

UnsupportedOperationException - if the put operation is not supported by the delegate map

ClassCastException - if the class of the specified key or value prevents it from being stored in this map

NullPointerException - if the specified key is null and the delegate map does not permit null keys, or if the specified value is null

IllegalArgumentException - if some property of the specified key or value prevents it from being stored in this map, or if evictMs is negative

replace

public boolean replace(K key,
              V oldValue,
              V newValue)

Replaces the entry for a key only if currently mapped to a given value. This is equivalent to

 if (map.containsKey(key) && map.get(key).equals(oldValue)) {
     map.put(key, newValue);
     return true;
 } else
     return false;
 

except that the action is performed atomically.

Specified by:

replace in interface ConcurrentMap<K,V>

Parameters:

key - key with which the specified value is associated

oldValue - value expected to be associated with the specified key

newValue - value to be associated with the specified key

Returns:

true if the value was replaced

Throws:

UnsupportedOperationException - if the put operation is not supported by the delegate map

ClassCastException - if the class of a specified key or value prevents it from being stored in this map

NullPointerException - if the specified key is null and the delegate map does not permit null keys, or if the specified value is null

IllegalArgumentException - if some property of a specified key or value prevents it from being stored in this map

replace

public boolean replace(K key,
              V oldValue,
              V newValue,
              long evictMs)

Replaces the entry for a key only if currently mapped to a given value, for the specified duration. This is equivalent to

 if (map.containsKey(key) && map.get(key).equals(oldValue)) {
     map.put(key, newValue, evictMs);
     return true;
 } else
     return false;
 

except that the action is performed atomically.

Specified by:

replace in interface ConcurrentMapWithTimedEviction<K,V>

Parameters:

key - key with which the specified value is associated

oldValue - value expected to be associated with the specified key

newValue - value to be associated with the specified key

evictMs - the time in ms during which the entry can stay in the map (time-to-live). When this time has elapsed, the entry will be evicted from the map automatically. A value of 0 for this argument means "forever", i.e. replace(key, oldValue, newValue, 0) is equivalent to put(key, oldValue, newValue).

Returns:

true if the value was replaced

Throws:

UnsupportedOperationException - if the put operation is not supported by the delegate map

ClassCastException - if the class of a specified key or value prevents it from being stored in this map

NullPointerException - if the specified key is null and the delegate map does not permit null keys, or if the specified value is null

IllegalArgumentException - if some property of a specified key or value prevents it from being stored in this map, or if evictMs is negative

clear

public void clear()

Removes all of the mappings from this map. The map will be empty after this call returns.

Specified by:

clear in interface Map<K,V>

Overrides:

clear in class AbstractMap<K,V>

Throws:

UnsupportedOperationException - if the clear operation is not supported by the delegate map

keySet

public Set<K> keySet()

Returns a Set view of the keys contained in this map. The set is backed by the map, so changes to the map are reflected in the set, and vice-versa. If the map is modified while an iteration over the set is in progress (except through the iterator's own remove operation), the results of the iteration are undefined. The set supports element removal, which removes the corresponding mapping from the map, via the Iterator.remove, Set.remove, removeAll, retainAll, and clear operations. It does not support the add or addAll operations.

Specified by:

keySet in interface Map<K,V>

Overrides:

keySet in class AbstractMap<K,V>

Returns:

a set view of the keys contained in this map

entrySet

public Set<Map.Entry<K,V>> entrySet()

Returns a Set view of the mappings contained in this map. The set is backed by the map, so changes to the map are reflected in the set, and vice-versa. If the map is modified while an iteration over the set is in progress (except through the iterator's own remove operation, or through the setValue operation on a map entry returned by the iterator) the results of the iteration are undefined. The set supports element removal, which removes the corresponding mapping from the map, via the Iterator.remove, Set.remove, removeAll , retainAll and clear operations. It does not support the add or addAll operations.

Specified by:

entrySet in interface Map<K,V>

Specified by:

entrySet in class AbstractMap<K,V>

Returns:

a set view of the mappings contained in this map