Class Long2ObjectCache<V>
- Type Parameters:
V
- type of values stored in theMap
The eviction strategy is to remove the oldest in a set if the key is not found, or if found then that item. The newly inserted item becomes the youngest in the set. Sets are evicted on a first in, first out, manner unless replacing a matching key.
A good set size would be in the range of 2 to 16 so that the references/keys can fit in a cache-line (assuming references are 32-bit references and 64-byte cache lines, YMMV). A linear search within a cache line is much less costly than a cache-miss to another line.
Null values are not supported by this cache.
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Nested Class Summary
Nested ClassesModifier and TypeClassDescription(package private) class
Base iterator implementation that contains basic logic of traversing the element in the backing array.final class
Iterator over entries which supports access to unboxed keys viaLong2ObjectCache.EntryIterator.getLongKey()
.final class
Set of entries which supports cached iterator to avoid allocation.final class
Iterator over keys which supports access to unboxed keys viaLong2ObjectCache.KeyIterator.nextLong()
.final class
A key set implementation which supports cached iterator to avoid allocation.final class
Collection of values which supports cached iterator to avoid allocation.final class
An iterator over values. -
Field Summary
FieldsModifier and TypeFieldDescriptionprivate long
private long
private long
private final int
private Long2ObjectCache<V>.EntrySet
private final long[]
private Long2ObjectCache<V>.KeySet
private final int
private final int
private final int
private int
private Long2ObjectCache<V>.ValueCollection
private final Object[]
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Constructor Summary
ConstructorsConstructorDescriptionLong2ObjectCache
(int numSets, int setSize, Consumer<V> evictionConsumer) Constructs cache with provided configuration. -
Method Summary
Modifier and TypeMethodDescriptionlong
The number of times a cache hit has occurred on theget(long)
method.long
The number of times a cache miss has occurred on theget(long)
method.long
The number of items that have been put in the cache.int
capacity()
Get the total capacity for the map to which the load factor will be a fraction of.void
clear()
Clear down all items in the cache.compute
(long key, LongObjectToObjectFunction<? super V, ? extends V> remappingFunction) Attempts to compute a mapping for the specified key and its current mapped value (ornull
if there is no current mapping).computeIfAbsent
(long key, LongFunction<? extends V> mappingFunction) Get a value for a given key, or if it does ot exist then default the value via aLongFunction
and put it in the cache.computeIfAbsent
(Long key, Function<? super Long, ? extends V> mappingFunction) computeIfPresent
(long key, LongObjectToObjectFunction<? super V, ? extends V> remappingFunction) If the value for the specified key is present attempts to compute a new mapping given the key and its current mapped value.computeIfPresent
(Long key, BiFunction<? super Long, ? super V, ? extends V> remappingFunction) boolean
containsKey
(long key) Overloaded version ofMap.containsKey(Object)
that takes a primitive long key.boolean
containsKey
(Object key) boolean
containsValue
(Object value) entrySet()
boolean
void
forEach
(BiConsumer<? super Long, ? super V> action) void
forEachLong
(LongObjConsumer<? super V> consumer) Implementation of theforEach(BiConsumer)
that avoids boxing of keys.get
(long key) Overloaded version ofMap.get(Object)
that takes a primitive long key.getOrDefault
(long key, V defaultValue) Returns the value to which the specified key is mapped, or defaultValue if this map contains no mapping for the key.int
hashCode()
boolean
isEmpty()
keySet()
If the specified key is not already associated with a value or is associated with null, associates it with the given non-null value.Overloaded version ofMap.put(Object, Object)
that takes a primitive long key.void
void
putAll
(Long2ObjectCache<? extends V> map) Put all values from the given map longo this one without allocation.putIfAbsent
(long key, V value) If the specified key is not already associated with a value (or is mapped tonull
) associates it with the given value and returnsnull
, else returns the current value.putIfAbsent
(Long key, V value) remove
(long key) Overloaded version ofMap.remove(Object)
that takes a primitive long key.boolean
Removes the entry for the specified key only if it is currently mapped to the specified value.boolean
Replaces the entry for the specified key only if it is currently mapped to some value.boolean
Replaces the entry for the specified key only if currently mapped to the specified value.boolean
void
replaceAll
(BiFunction<? super Long, ? super V, ? extends V> function) void
replaceAllLong
(LongObjectToObjectFunction<? super V, ? extends V> function) Replaces each entry's value with the result of invoking the given function on that entry until all entries have been processed or the function throws an exception.void
Reset the cache statistics counters to zero.private void
shuffleDown
(int setBeginIndex) private void
shuffleUp
(int fromIndex, int toIndex) int
size()
toString()
values()
Methods inherited from class java.lang.Object
clone, finalize, getClass, notify, notifyAll, wait, wait, wait
Methods inherited from interface java.util.Map
getOrDefault
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Field Details
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cachePuts
private long cachePuts -
cacheHits
private long cacheHits -
cacheMisses
private long cacheMisses -
size
private int size -
capacity
private final int capacity -
setSize
private final int setSize -
setSizeShift
private final int setSizeShift -
mask
private final int mask -
keys
private final long[] keys -
values
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evictionConsumer
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valueCollection
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keySet
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entrySet
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Constructor Details
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Long2ObjectCache
Constructs cache with provided configuration.- Parameters:
numSets
- number of sets, must be power or two.setSize
- size of a single set, must be power or two.evictionConsumer
- consumer to be notified when entry is being evicted from the cache.
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Method Details
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cacheHits
public long cacheHits()The number of times a cache hit has occurred on theget(long)
method.- Returns:
- the number of times a cache hit has occurred on the
get(long)
method.
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cacheMisses
public long cacheMisses()The number of times a cache miss has occurred on theget(long)
method.- Returns:
- the number of times a cache miss has occurred on the
get(long)
method.
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cachePuts
public long cachePuts()The number of items that have been put in the cache.- Returns:
- number of items that have been put in the cache.
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resetCounters
public void resetCounters()Reset the cache statistics counters to zero. -
capacity
public int capacity()Get the total capacity for the map to which the load factor will be a fraction of.- Returns:
- the total capacity for the map.
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size
public int size() -
isEmpty
public boolean isEmpty() -
containsKey
- Specified by:
containsKey
in interfaceMap<Long,
V>
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containsKey
public boolean containsKey(long key) Overloaded version ofMap.containsKey(Object)
that takes a primitive long key.- Parameters:
key
- for indexing theMap
- Returns:
- true if the key is found otherwise false.
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containsValue
- Specified by:
containsValue
in interfaceMap<Long,
V>
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get
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get
Overloaded version ofMap.get(Object)
that takes a primitive long key.- Parameters:
key
- for indexing theMap
- Returns:
- the value if found otherwise null
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getOrDefault
Returns the value to which the specified key is mapped, or defaultValue if this map contains no mapping for the key.- Parameters:
key
- whose associated value is to be returned.defaultValue
- the default mapping of the key.- Returns:
- the value to which the specified key is mapped, or
defaultValue
if this map contains no mapping for the key.
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forEach
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forEachLong
Implementation of theforEach(BiConsumer)
that avoids boxing of keys.- Parameters:
consumer
- to be called for each key/value pair.
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computeIfAbsent
- Specified by:
computeIfAbsent
in interfaceMap<Long,
V>
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computeIfAbsent
Get a value for a given key, or if it does ot exist then default the value via aLongFunction
and put it in the cache.Primitive specialized version of
Map.computeIfAbsent(K, java.util.function.Function<? super K, ? extends V>)
.- Parameters:
key
- to search on.mappingFunction
- to provide a value if the get returns null.- Returns:
- the value if found otherwise the default.
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computeIfPresent
public V computeIfPresent(Long key, BiFunction<? super Long, ? super V, ? extends V> remappingFunction) - Specified by:
computeIfPresent
in interfaceMap<Long,
V>
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computeIfPresent
public V computeIfPresent(long key, LongObjectToObjectFunction<? super V, ? extends V> remappingFunction) If the value for the specified key is present attempts to compute a new mapping given the key and its current mapped value.Primitive specialized version of
Map.computeIfPresent(Object, BiFunction)
.- Parameters:
key
- with which the specified value is to be associated.remappingFunction
- the function to compute a value.- Returns:
- the new value associated with the specified key, or null if none.
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compute
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compute
Attempts to compute a mapping for the specified key and its current mapped value (ornull
if there is no current mapping).Primitive specialized version of
Map.compute(Object, BiFunction)
.- Parameters:
key
- with which the specified value is to be associated.remappingFunction
- the function to compute a value.- Returns:
- the new value associated with the specified key, or null if none.
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merge
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merge
If the specified key is not already associated with a value or is associated with null, associates it with the given non-null value. Otherwise, replaces the associated value with the results of the given remapping function, or removes if the result isnull
.Primitive specialized version of
Map.merge(Object, Object, BiFunction)
.- Parameters:
key
- with which the resulting value is to be associated.value
- the non-null value to be merged with the existing value associated with the key or, if no existing value or a null value is associated with the key, to be associated with the key.remappingFunction
- the function to recompute a value if present.- Returns:
- the new value associated with the specified key, or null if no value is associated with the key.
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putIfAbsent
- Specified by:
putIfAbsent
in interfaceMap<Long,
V>
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putIfAbsent
If the specified key is not already associated with a value (or is mapped tonull
) associates it with the given value and returnsnull
, else returns the current value.Primitive specialized version of
Map.putIfAbsent(Object, Object)
.- Parameters:
key
- with which the specified value is to be associated.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.
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put
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put
Overloaded version ofMap.put(Object, Object)
that takes a primitive long key. -
remove
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remove
Removes the entry for the specified key only if it is currently mapped to the specified value.Primitive specialized version of
Map.remove(Object, Object)
.- Parameters:
key
- key with which the specified value is associated.value
- expected to be associated with the specified key.- Returns:
true
if the value was removed.
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remove
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remove
Overloaded version ofMap.remove(Object)
that takes a primitive long key.- Parameters:
key
- for indexing theMap
- Returns:
- the value if found otherwise null
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replace
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replace
Replaces the entry for the specified key only if currently mapped to the specified value.Primitive specialized version of
Map.replace(Object, Object, Object)
.- Parameters:
key
- with which the specified value is associated.oldValue
- expected to be associated with the specified key.newValue
- to be associated with the specified key.- Returns:
true
if the value was replaced.
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replace
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replace
Replaces the entry for the specified key only if it is currently mapped to some value.Primitive specialized version of
Map.replace(Object, Object)
.- Parameters:
key
- with which the specified value is associated.value
- to be associated with the specified key.- Returns:
- the previous value associated with the specified key.
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replaceAll
- Specified by:
replaceAll
in interfaceMap<Long,
V>
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replaceAllLong
Replaces each entry's value with the result of invoking the given function on that entry until all entries have been processed or the function throws an exception.Primitive specialized version of
Map.replaceAll(BiFunction)
.NB: Renamed from forEach to avoid overloading on parameter types of lambda expression, which doesn't play well with type inference in lambda expressions.
- Parameters:
function
- the function to apply to each entry.
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shuffleUp
private void shuffleUp(int fromIndex, int toIndex) -
shuffleDown
private void shuffleDown(int setBeginIndex) -
clear
public void clear()Clear down all items in the cache.If an exception occurs during the eviction function callback then clear may need to be called again to complete.
If an exception occurs the cache should only be used when
size()
reports zero. -
putAll
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putAll
Put all values from the given map longo this one without allocation.- Parameters:
map
- whose value are to be added.
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keySet
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values
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entrySet
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toString
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equals
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hashCode
public int hashCode()
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